Phan i. Dai Cuong

8/9/2019 Phan i. Dai Cuong

1/113

PHN I

I CNG VI SINH Y HC

I TNG NGHIN CUV LCH S PHT TRIN CA VI SINH VT HC

Mc tiu hc tp

1. Trnh by c i tng nghin cu ca vi sinh vt hc.

2. Trnh by c lch s pht trin ca vi sinh vt hc v hng gii quytbnh nhim trng hin nay.

I. I TNG NGHIN CU CA VI SINH VT HC

Vi sinh vt hc (Microbiology) l khoa hc kho st hot ng ca cc visinh vt (t Hylp micros l nh b, bios l s sng v logos l khoa hc).

Vi sinh vt l cc sinh vt nh b mt trn khng thy v ch c phthin bng knh hin vi.

Mun o kch thc ca vi sinh vt, ngi ta s dng cc n v sau:

Micromet ( m, micrometre) = 10-6

m Nanomet (nm, nanometre) = 10-9m

Angstrom = 10-10m

Vi sinh vt bao gm vi khun, nm men, nm mc, to, nguyn sinh ngvt v virus. Trc khi khm ph vi sinh vt ngi ta chia sinh vt lm hai gii:gii ng vt v gii thc vt. Sau khi khm ph vi sinh vt ngi ta nhn thyvi sinh vt kt hp nhng c tnh ca thc vt v ng vt vi tt c nhng thp c th c, cho nn vic phn loi sinh vt thnh hai gii lm pht sinh mt

s iu khng hp l. V d nh nm men c phn loi l thc vt v phn lnkhng di ng mc d chng t c nhng tnh cht ca thc vt v cho thynhng lin h sinh tin ha m nt vi nguyn sinh ng vt.

Nm 1866 nh khoa hc c E. Haeckel ngh xp vi sinh vt vo mtgii ring, gii Nguyn sinh (Protista). Gii ny phn bit vi thc vt v ngvt s t chc n gin ca chng: d n bo hoc a bo, t bo ca chngkhng bit ha thnh m.

Nm 1969 nh sinh thi hc M R.H. Whittaker xut h thng phnloi nm gii: l gii Khi sinh (Prokaryota hay Monera) bao gm vi khun

v vi khun lam, gii Nguyn sinh (Protista), gii Nm (Fungi), gii Thc vt(Plantae) v gii ng vt (Animalia).

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Theo kin ngh ca nh sinh vt hc Trung Quc Trn Th Tng nm1979 th nhm gii sinh vt nhn tht bao gm gii Thc vt, gii Nm v giing vt, nhm gii sinh vt nhn nguyn thu bao gm gii Vi khun v giiVi khun lam, cn gii Virus thuc v nhm gii sinh vt cha c t bo.

Theo quan im hin i (P.H. Raven, G.B. Johnson, 2002) th mi sinhvt trn th gii thuc v 6 gii khc nhau: gii C khun (Archaebacteria), giiVi khun (Eubacteria), gii Nguyn sinh (Protista), gii Nm (Fungi), gii Thcvt (Plantae) v gii ng vt (Animalia).

Phn ln vi sinh vt nm trong 4 gii: C khun, Vi khun, Nguyn sinhv Nm ca h thng 6 gii ni trn.

T bo nhn tht c nhn cha mt s i nhim sc th, mng nhn nilin vi li ni cht nguyn sinh. Nguyn tng ca t bo nhn tht c li

ni cht nguyn sinh, khng bo v nhng plastit t sao chp. Nhng plastitcha ADN ring v nhn ln bng phn lit. Nhng plastit bao gm ti lp thcha h thng chuyn ch in t ca s phosphoryl ha v lc lp nhngsinh vt quang hp cha lc dip t v nhng thnh phn quang hp khc.

Nguyn tng bn cht lipoprotein nm bn trong mng t bo. Nhiu vi sinhvt t bo nhn tht c vch t bo to nn bi celluloza, chitin hoc oxytsilic.T bo nhn tht c th di ng nh nhng lng. Nhng lng ny gm mt

b 9 si nh bao quanh 2 si nh trung tm.

T bo nhn nguyn thu (T bo nhn s) c cu trc t bo n gin.

Nhn ch gm c mt nhim sc th khng mng nhn, nhng vch t bo liphc tp hn. T bo nhn nguyn thu khng c plastit t sao chp nh ti lpth v lc lp. Enzyme cytochrom c tm thy mng t bo; nhng c thquang hp, nhng sc t quang hp c tm thy nhng phin mng nmdi mng t bo. Vi khun thng tch t vt liu d tr di hnh thc nhnght nh khng ha tan, dng polyme, trung tnh, tr thm thu. Vt liu cacbonc bin i bi mt s vi khun thnh polyme polyaxit- - hydrobutyric v

bi nhng vi khun khc thnh polyme glucoza tng t nh glycogen gi lgranuloza. Nhng ht nh d tr c s dng nh ngun C lc s tng hp

protein v axit nucleic c thc hin tr li. Mt cch tng t mt vi vikhun oxy ha sulfua bin i lng tha H2S mi trng bn ngoi thnhnhng ht sulfua ni bo. Nhiu vi khun tch tr pht pht hu c thnh nhnght nh polymemetaphosphate gi l volutin.

Virus khc vi tt c cc c th c t bo k c vi khun v Rickettsia.Virion hay l ht virus gm mt phn t ADN hoc ARN nm bn trong mt v

protein gi l capsid. Vo bn trong t bo vt ch, axit nucleic ca virus sdng b my tng hp ca t bo hnh thnh axit nucleic v nhng thnh

phn khc ca virus. Axit nucleic v nhng thnh phn protein c hiu kt hp

thnh ht virus xm nhim hon chnh gi l virion. Virion c phng thchvo mi trng bn ngoi v bt u qu trnh xm nhim t bo vt ch.

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II. S LC LCH S PHT TRIN CA VI SINH VT HC

1. S pht hin vi sinh vt

S pht hin vi sinh vt gn lin vi s pht minh knh hin vi. Antonvan Leeuwenhoek (1632 - 1723) ngi H Lan, l ngi u tin th k XVIInhn thy vi sinh vt nh nhng knh hin vi phng i 270 - 300 ln m ng ch to (1676). Do s hn ch v phng i v phn gii ca knh hinvi cho nn nhng nghin cu hin vi ca c th sng rt b hn ch v mi nu th k XIX chic knh hin vi hon chnh u tin mi ra i v t chon nay con ngi ln lt sng to ra hng lot cc loi knh hin vi quanghc khc nhau th nhiu s kin quan trng mi c pht hin.

2. S trng thnh ca vi sinh vt hc

Trong th k XVII v sut th k XVIII vi sinh vt hc ch ch trng v

phn m t, tuy nhin cng c mt s cng trnh xut sc nh Spallanzani sdng mi trng nui cy kh khun bng nhit, Edward Jenner pht minhvaccine u ma, Zinke pht hin tc nhn ca bnh di trong nc bt cach b di.

Th k XIX mi cho thy nhng bc pht trin ln v vi sinh vt hcnh cng lao ca Louis Pasteur v Robert Koch.

L.Pasteur (1822 - 1895) hon chnh vic nghin cu vi sinh vt. Vi sinhvt khng nhng c m t chnh xc m cn c kho st y v nhngtnh cht sinh l.

L.Pasteur l nh vi sinh vt hc v i c cng:

- Chm dt tranh lun v thuyt t sinh bng cc th nghim xut sc vibnh c ngng.

- Pht hin tc nhn ca s ln men nh ln men ru, ln men thi l visinh vt: cc vi sinh vt pht trin to thnh cc enzyme chu trch nhim vhin tng ln men.

- Xc nh vai tr tc nhn gy bnh ca cc vi sinh vt trong bnh nhim

trng- Khi qut ha vn vaccine v tm ra phng php iu ch mt s

vaccine phng bnh nh vaccine bnh than, vaccine bnh t g... v pht minhvaccine di.

R.Koch (1843 - 1910) cng ng gp ln lao cho vi sinh vt hc nhnhng cng trnh:

- Pht trin nhng k thut c nh v nhum vi khun.

- S dng mi trng c phn lp vi khun rng.

- Nu tiu chun xc nh bnh nhim trng.

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- Khm ph vi khun lao, vi khun t.

Nh cng lao ca L.Pasteur, R.Koch v nhiu nh bc hc khc, phn lncc vi khun gy bnh ngi v ng vt u c khm ph u th kXX. Lc by gi vi sinh hc tr thnh mt khoa hc ng dng quan trng

trong lnh vc y hc, nng nghip v cng nghip.Trong lm sng, khoa ly thnh lp tip nhn bnh nhn nhim

trng, khoa ngoi s dng phng php phu thut st trng, tin caphng php phu thut v trng ngy nay.

3. Nhng thnh tu hin i

Trong nhng thp k gn y t mt khoa hc ng dng, vi sinh vt hc tr thnh mt khoa hc c bn lm pht sinh mt ngnh khoa hc mi: sinhhc phn t v di phn t v cng vi cc ngnh khoa hc khc to nn mt

cuc cch mng khoa hc k thut hin i.Nh nhng hiu bit v di truyn hc hin i m m hnh nghin cu l

E.coli, Watson v Crick pht hin mu cu trc ca ADN v c ch sao chpbn bo tn lm c s cho s hnh thnh sinh hc phn t v di phn t.Nhng pht hin k diu v c cu ca m di truyn v cc cu trc khc ca tbo sng c s dng lm c s cho s pht trin cng nghip sinh hc, ngnhcng nghip cho php con ngi can thip vo qu trnh hnh thnh v pht trinca sinh vt phc v li ch ca con ngi .

Gn y nhng k thut tng hp gen, tho ghp gen lm cho cng nghsinh hc tr thnh mt lc lng sn xut mi nhn ca nn kinh t th gii.Trong lnh vc y hc nhng k thut trn c nhiu trin vng gii quyt cc

bnh di truyn, phng chng cc bnh nhim trng, bnh ung th .

III. NHNG VN HIN NAY CA VI SINH VT Y HC

Trong y hc, vi sinh vt l cn nguyn ca cc bnh nhim trng. V vykhi xt v tm quan trng hin nay ca vi sinh vt y hc phi cp ti tnh hnhcc bnh nhim trng.

T ngn xa bnh nhim trng l mt tai ha cho nhn loi. Bnh uma, bnh dch hch, bnh dch t ... git cht hng triu ngi, tn ph nhiulng mc, thnh ph.

T khi vi sinh vt hc trng thnh cho n nay con ngi c khnng dn dn ch ng c bnh nhim trng. Nhng con ng ch ng tin ti xa b bnh nhim trng l con ng kh khn v lu di.

Thnh tu vang di u tin xy ra vo nm 1891 lc Von Behring cusng mt em b nh huyt thanh khng bch hu, m u thi k huyt thanhliu php. Thc t cho thy huyt thanh liu php c nhng mt hn ch v ch

hu hiu i vi nhng bnh nhim c t vi khun nh bch hu, un vn, hoith sinh hi .v.v...

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Thnh tu vang di th hai l cng lao ca G.Domagk pht minhsulfonamit nm 1935. Nhng dn dn v kh sulfonamit t ra yu km khng kh nng iu tr phn ln cc bnh nhim trng thng gp.

Nm 1940 Fleming, Florey v Chain pht minh penicillin v a vo iu

tr m u thi i khng sinh. Trong sut hai thp k, nhiu khng sinh huhiu c pht minh v ngi ta c th ch ng mt cch hu hiu cc bnhnhim trng. Nhng thi gian cho thy bnh nhim trng vn cn lu mi giiquyt xong v cc vi khun khng thuc c quan st trong cc loi vikhun. May mn l cc khng sinh hu hiu mi khm ph gi khng chocc vi khun khng thuc pht trin quy m qu ln khng ch ng c. uthp k 80, thc t cho thy cc vi khun khng thuc xut hin ngy cng nhiunhng cc khng sinh hu hiu mi khm ph tr nn him dn. Tr nhngkhng sinh thuc nhm quinolon, nhng khng sinh c gi l mi ch l s

xp xp li hay l s thay i cu trc phn t ca nhng khng sinh khmph t trc bng k thut bn tng hp hoc tng hp.

Hin nay, phn ln cc bnh nhim trng c ch ng mt cch huhiu, cc v dch c dp tt nhanh chng nhng vn cn nghin cu nhiu ch ng cc vi khun khng thuc v tm cc thuc hu hiu iu tr cc bnhvirus.

Hng gii quyt bnh nhim trng hin nay c th l s dng ng thiba bin php sau:

- Thc hin mt chin lc khng sinh hn ch cc vi khun khngthuc.

- Tip tc tm kim cc khng sinh hu hiu mi iu tr bnh vi khunv pht minh cc thuc khng virus hu hiu.

- iu ch cc vaccine hu hiu bng cc k thut hin i nh cng nghgen phng nga cc bnh nhim trng, dn dn tin n xa b chng nhtrng hp bnh u ma trn phm vi ton th gii.

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HNH TH , CU TO V SINH LCA VI KHUN

Mc tiu hc tp

1. M t c cc loi hnh th ca vi khun2. M t c cu trc ca t bo vi khun3. Trnh by c cc nt c bn ca sinh l vi khun

I. HNH TH CA VI KHUNVi khun thng thng c hnh th nht nh do vch t bo xc nh.

Mt s khng vch ( hnh thc L) nh Mycoplasma khng c hnh th nhtnh. ng knh trung bnh ca vi khun khang 1 m . Nhng i din nhnht nh Mycoplasma c ng knh khang 0,1 m v nhng i din ln

hn c kch thc hng chc m nh Spirilium volutans 20 m. Cc vi khungy bnh c kch thc t 0,2 m n 10 mV hnh th ngi ta c th chia vi khun thnh cu khun, trc khun v

vi khun hnh xon.1. Cu khun :

L nhng vi khun hnh cu, hnh trng hay hnh ht c ph1.1. Micrococci (n cu)

y l nhng cu khun xp hng u hoc khng u, l nhng tpkhun tm thy trong khng kh v nc.1.2. Diplococci (Song cu)

L nhng cu khun xp tng i phn chia trong mt mt phng. Mt sgy bnh cho ngi nh ph cu, lu cu, cu khun mng no.1.3. Stretococci (Lin cu):

L nhng cu khun xp thnh chui ngn hoc di. Mt s lai gy bnhcho ngi nh Streptococcus pyogenes thuc nhm A ca Lancefield.1.4. Tetracocci (T cu)

Cc cu khun hp thnh 4, phn chia theo hai mt phng, rt t khi gybnh.1.5. Sarcina (Bt cu)

Cc cu khun xp thnh 8-16 con, phn chia theo ba mt phng, thngtm thy trong khng kh.1.6. Staphylococci (T cu)

Cc cu khun hp thnh m nh chm nho, phn chia theo mt phng,mt s loi gy bnh cho ngi v thng pht trin nhanh chng tnh khngvi nhiu khng sinh.2. Trc khun

L nhng vi khun c hnh que thng.2.1.Bacteria

L nhng trc khun hiu kh, khng to nha bo nh vi khun ngmt, vi khun bch cu, vi khun lao...

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2.2. BacilliL nhng trc khun hiu kh tuyt i to nha bo v d trc khun bnh

than.2.3.Clostridia

L nhng trc khun k kh Gram dng to nha bo, v d trc khunun vn, trc khun ng c tht.3. Vi khun hnh xon3.1. Phy khun

Ch c mt phn ca hnh xon nn c hnh du phy, v d phy khunt.

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3.2.Xon khunC nhiu vng xon, v d xon khun giang mai, Leptospira, Borrelia.

II. CU TO CA T BO VI KHUN

Khc vi cc thnh vin ca protista lp trn c nhn tht nh t bo ngvt v thc vt, vi khun c t bo nhn s, nhn ch c mt nhim sc th,khng c mng nhn, khng c ti lp th, khng c b my phn bo nhng cct bo li phc tp hn.1. Vch t bo

S hin din ca vch t bo vi khun c pht hin bng hin tungly tng, bng cch nhum v bng phn lp trc tip.Tc dng c hc nh siu m phi hp vi ly tm cho php thu hoch vch t

bo rng, tch ri khi nguyn tng.1.1.Vch t bo vi khun gram dng

Knh hin vi in t cho thy vch t bo dy t 15 n 50 nm. Thnhphn ch yu l mucopeptit gi l murein, mt cht trng hp m nhng n vho hc l nhng ng amin. N-acetyl glucosamin v axt N-acetyl muramicv nhng chui peptit ngn cha alanin, axt glutamic v axt diaminopimelichoc lysin. Ngoi ra vch t bo ca mt s vi khun gram dng cn cha axtteichoic. mt vi lai vi khun, axt teichoic chim ti 30% trng lng khca vch t bo.1.2. Vch t bo vi khun Gram m gm ba lp

Lp mucopeptit mng hn khang 10nm v hai lp lipoprotein v

lipopolysaccharide bn ngoi, lp lipoprotein cha tt c nhng axt aminthng thng. Khng c axt teichoic, vch t bo vi khun gram m cha mtlng lipit ng k, khong 20 % trng lng kh ca vch t bo.1.3.Chc nng ca vch t bo

Vch t bo vi khun c nhiu chc nng:- Duy tr hnh th ca vi khun: Vch cng to nn b khung, lm cho vi

khun c hnh th nht nh .- Quyt nh tnh bt mu gram ca vi khun: S bt mu gram khc nhau

vi khun gram dng v gram m l do tnh thm thu khc nhau i vi cn

ca hai nhm vi khun . Nu dng lysozym bin i vi khun gram dngthnh protoplast khng c vch th protoplast li bt mu gram m.- To nn khng nguyn thn O ca vi khun ng rut: iu ch

khng nguyn 0 ca vi khun ng rut x l vi khun khng di ng bngnhit v cn.

- To nn ni c t ca vi khun ng rut. Ni c t ch c gii talc vi khun b li gii. vi khun ng rut, ni c t l nhng phc hplipopoly-saccarit dn xut t vch t bo.2. Mng nguyn tng

L mng bn thm dy khong 10nm nm st vch t bo. Ngi ta c thchng minh s hin din ca n bng hin tng ly tng hoc nhum vi xanh

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Victoria 4R. N cha 60-70% lipit, 20-30% protein v mt lng nh hydratcacbon. Mng nguyn tng c chc nng ro cn thm thu ca t bo, ngncn khng cho nhiu phm vt vo bn trong t bo nhng li xc tc vicchuyn ch hat ng ca nhiu phm vt khc vo bn trong t bo. Hn na

mng t bo cha nhiu h thng enzyme v v vy c chc nng ging nh tilp th ca ng vt v thc vt. Mng nguyn tng cho thy nhng ch lmvo gi l mc th. vi khun Gram dng mc th kh pht trin cho thyhnh nh nhiu l ng tm. vi khun Gram m mc th ch l vt nhn ngin.3. Nguyn tng

L cu trc c bao bc bn ngoi bi mng nguyn tng, trng thgel, cu trc ny gm 80% nc, cc protein c tnh cht enzyme, cacbohydrat,lipid v cc ion v c nng cao, v cc hp cht c trng lng phn tthp. Nguyn tng cha dy c nhng ht hnh cu ng knh 18nm gi lribsm. Ngoi ra cn c th tm thy nhng ht d tr glycogen, granulosahoc polymetaphotphat.4. Nhn t bo

C th thy vi knh hin vi nh sng sau khi nhum hoc soi trc tip knh hin vi pha tng phn. Nhn c th hnh cu, hnh que, hnh qu t hochnh ch V. Kho st knh hin vi in t nhn khng c mng nhn v bmy phn bo. N l mt si DNA trng lng phn t 3x10 9 dallon v chamt nhim sc th duy nht di khong 1mm nu khng xon. Nhn ni lin mt u vi th mc. S ni lin ny gi mt vai tr ch yu trong s tch ri 2

nhim sc th con sau khi si nhim sc th m tch i. Trong s phn chianhn hai mc th qua ch ni lin vi mng nguyn tng di chuyn theo nhnghng i nghch theo hai nhm con ni lin vi chng. Nh th mng nguyntng t ng nh mt b my th s ca s gin phn vi mc th m nhnvai tr thai v sc.5. Lng ca vi khun

Lng chu trch nhim v tnh di ng ca vi khun. Ngi ta quan st sdi ng ca vi khun knh hin vi nhn git treo hoc t mt git vi khun lam knh v ph mt l knh mng. Lng di 3-12 m hnh si gn sng, mnh

10- 20nm ) nn phi nhum vi axt tannic to thnh mt lp kt ta lm dylng d pht hin. Lng pht xut t th y ngay bn di mng nguyn tngv c chuyn ng xoay trn. Bn cht protein n to nn do s tp hp nhngn v ph gi l flagellin to thnh mt cu trc hnh tr rng. Cch thc mclng l mt c tnh di truyn. mt s loi nhiu lng mc quanh thn, mts lai mt lng mc cc v mt s loi khc mt chm lng mt cc.

Nu lng b lm mt i bng c hc th lng mi c to thnh nhanh chng.Lng ng vai tr khng nguyn nh khng nguyn H vi khun ng rut.6. Pili

L nhng ph b hnh si, mm mi hn lng, mnh hn nhiu v c xuhng thng ng knh 2-3 nm v di t 0,3-1nm, tm thy t mt n hng

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trm mt ngoi vi khun, bn cht protein. Pili pht xut trong mng nguyntng v xuyn qua vch t bo. Pili c tm thy vi khun gram m nhngcng c th tm thy mt s vi khun gram dng. Pili F c nhim v trong stip hp. Nhng pili khc gip cho vi khun bm vo nim mc hoc b mt

khc ca t bo.7. V ca vi khun

V l mt cu trc nhy bc quanh vch t bo ca mt s vi khun,thng l polysaccharide, ch c v ca B.anthracis l mt polypeptide acid D-glutamic. V c th pht hin d dng huyn dch mc tu, n hin ranh mt vng sng gia mi trng m c v t bo vi khun trng r hn.Cng c th pht hin bng phn ng phnh v hoc bng k thut nhum c

bit. S t bin to thnh v rt d nhn bit v t bo c v to nn khun lcbng lng hoc nhy M trong khi t bo khng v to nn khun lc x x R.Nhim v duy nht c bit ca v l bo v vi khun chng thc bo vchng virut mun gn vo vch t bo .

8. Nha boNhng thnh vin caBacillus, Clostridium v Sporosarcina to thnh

ni nha bo di nh hng ca mi trng bn ngoi khng thun li, mi tbo lm pht sinh mt nha bo. Nha bo c th nm gia, u nt hoc gnu nt ty theo loi, vch nha bo cha nhng thnh phn mucopeptide v axtdipicolinic. S d khng ca nha bo vi ha cht c l do tnh khng thm

thu ca vch nha bo, s khng vi nhit lin h n trng thi mt nccao. V chu ng vi iu kin khng thn li bn ngoi nha bo gp phnquan trng trong kh nng ly bnh ca trc khun hiu kh to nha bo nhtrc khun than hoc trc khun k kh to nha bo nh Clostridia, nht l trckhun un vn, hoi th, sinh hi, ng c tht.III. SINH L VI KHUN

Nh cc sinh vt khc vi khun cng dinh dng, chuyn hoa v phttrin.1. S dinh dng

pht trin vi khun i hi mi trng nui cy cha y nhngyu t dinh dng bao gm nhng hp cht cn thit cung cp nng lng vnhng hp cht c dng lm nguyn liu tng hp nhng vt liu mi cat bo. V nguyn liu tng hp, vi khun i hi nhng nhu cu v muikhong nh PO43-, K+, Mg2+ vi lng ng k, mt s ion ( nguyn t vi lng )ch cn mt nng rt thp nh Fe2+, Zn2+, Mo2+, Ca2+, cc ion ny thngtm thy trong nc v trong cc mui khong khng tinh khit. Ngun C dothc n nng lng cung cp. Ngun N thng thng l protein hoc mt muiamoni.

Phn ln vi khun nu c cung cp y nhng yu t trn th c khnng tng hp cc cht cu to ca t bo. Nhng mt s vi khun mt kh nng

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tng hp mt vi hp cht v i hi c cung cp trong mi trng nuicy. l nhng yu t pht trin; chng c chia thnh hai loi, mt loi cnc cung cp tng lng nh v m nhn chc v xc tc nh mt thnh

phn ca mt enzyme v d vitamin B, mt loi cn c cung cp tng lng

ln v c dng lm nguyn liu cu to t bo nh axit amin, purin,pyrimidin.Ngoi ra nhng iu kin vt l nh nhit pH, p sut oxy cng nh

hng n s pht trin cn c iu chnh thch hp.2. S chuyn ha

Bao gm tt c nhng phn ng ha hc xy ra nhng t bo sng. Nhnhng phn ng nng lng c chit t mi trng v c s dng chosinh tng hp v pht trin. Trong chuyn ha quan trng nht l s oxy hasinh hc.2.1. S oxy ha sinh hc

S oxy ha c nh ngha nh l s loi b in t t mt c cht kmtheo s loi b ion hydr tc l s loi b nguyn t hydr. V vy s oxy hac xem nh l s vn chuyn nguyn t hydr. C cht b oxy ha c gil cht cho hydr v phm vt b kh c gi l cht nhn hydro. Phn ln hpcht hu c mt ion hydr do loi b in t. in t khng th trng thi tdo trong dung dch v khng th loi b khi mt c cht nu khng c mt chtthch hp nhn n. S vn chuyn in t l ct li ca s oxy ha v s kh.

Ty theo bn cht ca cht nhn hydro cui cng ngi ta chia s oxy hasinh hc thnh ba hnh thc : H hp hiu kh, h hp k kh v ln men. Cht

nhn hydr cui cng l oxy phn t (O2) trong s h hp hiu kh, l mt hpcht v c (nitrat, sulfat, cacbonat ) trong s h hp k kh, l mt hp cht huc trong s ln men.V nhu cu oxy ngi ta chia thnh :

- Vi khun hiu kh bt buc nh vi khun lao v mt vi trc khun tonha bo, nhng vi khun ny i hi oxy v thiu kh nng ln men.

- Vi khun k kh bt buc nh Clostridia, Propionibactrium, chng chpht trin khi khng c oxy.

- Vi khun ty nh nm men, vi khun ng rut. Nhng vi khun ny

c th sng khng c oxy nhng i thnh chuyn ha h hp lc c oxy.2.2. S h hp hiu kh

Cht nhn hydr cui cng l oxy phn t. C cht thng thng lng nhng cng c th l axt bo, axt amin. in t c chuyn t chtcho hydr n cht nhn hydr qua nhiu bc. in t ly t cht cho hydro cth u tin chuyn n mt coenzyme th nht A, A do b kh thnh AH2.Mt enzyme khc li xc tc s chuyn in t t AH2 n mt coenzyme thhai B. AH2 do c oxy ha tr li thnh A v B tr nn tr thnh BH. Qutrnh ny c th tip din qua nhiu bc to nn dy chuyn h hp in t t

cht cho hydr n oxy

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Hnh 1: minh ho v dy chuyn in tKt qu cui cng l s hnh thnh mt sn phm oxy ha, mt sn phm

kh v nng lng. Nng lng pht sinh hoc c d tr trong cc dy nisn nng lng hoc ta thnh nhit.2.3. S h hp k kh

C cht c th l hp cht hu c nhng cng c th l cht v c. Chtnhn in t y khng phi oxy khng kh m l nitrat, sulfat, cacbonat....

2.4. S ln menC cht l hp cht hu c nhng cht nhn in t cng l hp cht huc. y, trong dy chuyn in t thng thng ch c NAD l cht mangin t trung gian.

Hnh 2: S chuyn in t trong s ln men

So vi s h hp, s ln men km hiu qu hn nhiu, n cung cp ATP19 ln t hn i vi 1 mol glucoza chuyn ha. Mt vi khun pht trin vi mtlng gii hn glucoza cho thy hiu sut pht trin (trng lng kh vi khun /trng lng c cht chuyn ha) ln hn trong iu kin hiu kh so vi iukin k kh.3. S pht trin ca vi khun

T bo nhn ln trong s pht trin. vi khun n bo, s pht trin lmgia tng s lng vi khun mt sn phm cy. Vi khun nhn ln bng phnlit. Mt th h c nh ngha nh l s tng i t bo. Thi gian th h lkhan thi gian cn thit d tng i s t bo. Thi gian th h thay i ty laivi khun, 20 pht E.coli, 20 - 24 gi vi khun lao.

3.1. S pht trin ly tha :V hai t bo con c th pht trin cng mt tc nh t bo m nn s

t bo trong rut sn phm cy tng ln vi thi gian nh mt cp s nhn 20, 21,22, 23.....Ngha l s pht trin ly tha.

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Tc pht trin ca mt sn phm cy mt thi gian xc nh t l vis t bo hin din thi gian . S lin h ny c th biu th di dng

phng trnh saudN

= kN (1)dTPhn tch phng trnh trn ta c :

N = N0 e kt (2)Trong N0 l s t bo thi gian 0 v N l s t bo bt k thi gian t sau. Trong phng trnh (2), k l hng s pht trin :

Gii phng trnh theo k ta c :Ln N - Ln N0

k = (3)t

Chuyn sang logarit thp phnlog N - log N0

k = 2,302t2 - t1

Nh vy k biu th tc logarit t nhin ca s t bo tng ln vithi gian v c th xc nh bng th.

Hnh 3. Tc logarit t nhin ca s t bo tng ln vi thigian.3.2. ng biu din pht trin :

Cy vo mt mi trng lng nhng vi khun ly t mt sn phm cytrc pht trin n bo ha, ln lt xc nh s t bo trong mt 1ml v

biu din logarit ca nng t bo theo thi gian th thu c ng biu dinpht trin.ng biu din gm 4 pha:

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DI TRUYN VI KHUN

Mc tiu hc tp

1. Trnh by c cc c ch vn chuyn di truyn vi khun.2. Trnh by c cc c ch di truyn tnh khng thuc vi khun.

Di truyn l s duy tr cc c im qua nhiu th h. C s vt cht cadi truyn l nhim sc th. Nhim sc th ca vi khun v d nh ca E.coli gm5x106 i nucleotide chia thnh nhiu on gi l gen, mi gen quyt nh stng hp mt protein c hiu. Nhng protein c hiu nh enzyme v nhngcu to khc ca t bo xc nh tt c cc tnh trng ca mt c th.

Nhim sc th chu s nhn i trc khi phn bo. Do mi t bo connhn mt b gen tng ng vi t bo m. S nhn i ca nhim sc th lmt qu trnh chnh xc, tuy nhin mi gen c mt xc xut nh v sai st trongsao chp, do lm pht sinh t bin. t bin xy ra ngu nhin khng cn scan thip ca mi trng bn ngoi vi mt tn sut rt nh t 10-5 n 10-9.

I. S VN CHUYN DI TRUYN VI SINH VT

S tin ha ca vi sinh vt ph thuc vo s bin d v s chn lc. Ndin ra chm chp, lc s bin d xy ra do tch ly nhng bin d lin tip mt

chng sinh vt. Qu trnh ny tr nn nhanh chng vi sinh vt nh cc vi sinhvt pht trin nhng c ch vn chuyn di truyn gia cc c th.

Vi khun vn chuyn nhng yu t di truyn qua ba c ch: bin np, tinp v tip hp.

Trong bin np, mt on ADN c vn chuyn vo t bo nhn. y lmt c ch th s ca s vn chuyn gen.

Trong ti np v tip hp, nhng plasmid c vn chuyn qua trunggian ca phage hoc qua tip xc.

Plasmid l nhng phn t ADN dng vng trn nm ngoi nhim sc thv c kh nng t sao chp. Plasmid c trng khi nh so vi nhim sc th. Hai

plasmid gi l khng ph hp nu chng khng th tn ti bn vng trong cngmt t bo. Nhng plasmid F mang nhn t sinh sn F. Nhng plasmid cng tnti trong mt vi khun vi nhn t F gi l Fi+ nu chng ngn cn s tip hpca F, gi l Fi- trong trng hp ngc li.

1. Bin np (Transformation)

Bin np l s vn chuyn ADN ha tan ca nhim sc th t vi khun

cho sang vi khun nhn. Khi t bo vi khun b v do lm tan (lysis), ADN dng

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vng trn ca chng thot ra mi trng thnh cc on thng vi chiu dikhc nhau, c kh nng gy bin np cho cc t bo nhn khc.

Griffith nm 1928 khm ph s bin np ph cu bng th nghimsau chut nht :

- Tim vo chut ph cu sng S1 c v th chut cht v nhim khunhuyt.

- Tim vo chut ph cu R1 sng khng v th chut khng cht.

- Tim vo chut ph cu S1 cht th chut khng cht.

- Tim vo chut hn hp ph cu S1 cht vi R1 sng th chut cht vnhim khun huyt. T mu chut phn lp c S1 sng c v.

Griffith cng nh cc nh khoa hc thi by gi cha hiu ngha su xa

ca s kin.Alloway nm 1933 thc hin th nghim ng nghim v phn lp c

ph cu S1 hn hp ph cu S1 cht v ph cu R1 sng.

Avery, Mac-Leod, Mac-Carthy nm 1944 phn lp c nhn t binnp v xc nh l ADN. Nhng lc by gi gii khoa hc cha chp nhn ADNl cht liu di truyn. n nm 1952 lc Hershey v Chase chng minh ADNca Phage i vo bn trong vi khun trong khi v Protein b gi bn ngoi thADN mi c cng nhn l nhn t bin np.

S bin np c khm ph thm nhiu vi khun khc: Hemophilus,Neisseria, Streptococcus, Bacillus, Acinetobacter...

Trong bin np, t bo nhn phi trng thi sinh l c bit c gi lkh np (competence) mi c kh nng tip nhn ADN ha tan ca t bo cho.Trng thi kh np xut hin trong mt giai on nht nh ca qu trnh phttrin ca t bo vo lc t bo ang tng hp vch.

Sau khi xm nhp, phn t ADN si kp b mt endonuclease ct mngt bo thnh on ngn si n v i vo nguyn tng . on ADN si n kti vi ADN ca t bo nhn on tng ng ri ti t hp; bng cch

ADN bin np kt hp vo nhim sc th ca t bo nhn. Nhim sc th ti thp l phn t ADN si kp ca t bo nhn trong mt on ngn ca mtsi c thay th bng mt on ADN ca t bo cho.

i vi vi khun ng rut, s tip nhn i hi s bin i b mt cat bo bng cch x l vi CaCl2 .

ngha ca s bin np:

S bin np cho php kt hp vo nhim sc th vi khun ADN tng hphoc ADN bin i invitro.

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Bin np cng c s dng xc nh nhng vng rt nh trn bn di truyn ca vi khun.

Bin np c th xy ra trong thin nhin. Ngi ta chn lc vi khunti t hp c lc tng lc tim 2 chng ph cu vo phc mc chut nht. Nh

th s bin np c mt ngha dch t hc, tuy nhin s vn chuyn di truynbng bin np khng hu hiu bng s vn chuyn di truyn bng plasmid.

2. Ti np (Transduction)

Ti np l s vn chuyn ADN t vi khun cho n vi khun nhn nhphage. Trong ti np chung, phage c th mang bt k gen no ca vi khun chosang vi khun nhn. Trong ti np c hiu, mt phage nht nh ch mang cmt s gen nht nh ca vi khun cho sang vi khun nhn.

2.1. S ti np chung

Kiu ti np ny c Zinder v Lederberg khm ph nm 1951 lc khost s tip hp Salmonella. Lc lai ging chng L22 v chng L2, mi chngmang mt cp tnh trng t bin khc nhau th thu c vi mt t l nh mts t bo ti t hp mang mt cp tnh trng t bin nh t bo hoang di gc,

phage P22 c tm thy trong nc lc canh khun ca 2 chng vi khun trn.Phage P22 c lc vi chng L2 nhng n ha vi chng L22. Lc cho P22 vocanh khun L2 th tt c t bo ca L2 b dung gii v phng thch phage P22trong c mt t phage cha mt mnh ADN ca L2. Lc cho chng L22 vodung dch phage P22 ni trn th mt s phage vn chuyn nhng gen ca L2 vo

L22 v vi khun t dng nh type hoang di c pht sinh qua ti t hp.2.2 S ti np c hiu

Nm 1954 Mores nhn thy phage n ha c th thc hin mt kiu tinp khc gi l ti np c hiu. N ch vn chuyn mt nhm gii hn gen,nhm gen c chuyn nm st ch prophage gn vo nhim sc th. S tinp c hiu vn chuyn nhng gen c hiu nhim sc th v i hi s tchhp ca phage. Hn na khc vi ti np chung, phage ti np c hiu ch c

phng thch lc chiu tia cc tm ch khng bao gi t tch ri khi nhim sc

th.Lc chiu tia cc tm vo mt canh khun E.coli K12 Gal+ sinh tan vi

phage th trong nhng phage c phng thch c khong 10 -6 d Gal. dGal l phage mang gen Gal nhng thiu mt dan ADN m n li trnnhim sc th ca vi khun. l phage khng hon chnh khng th nhn lnnu khng b sung on ADN b thiu nhng c th vn chuyn gen Gal. Lccho dch dung gii ni trn vo canh khun E.coli K12 Gal- th thu c khang10-6 vi khun ti np galactose dng tnh. l hin tng ti np tn s thpLFT (Low Frequency Transduction). Mt s t t bo trong canh khun E.coli

K12 Gal- nhim dch LFT tr nn hai ln sinh tan vi phage bnh thng vphage dGal. Nhng t bo ny hnh thnh clont bo hai ln sinh tan. Lc

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chiu tia cc tm vo nhng t bo ni trn th thu c mt dch phage trong nhng phage v phage dGal bng nhau. l s ti np tn s cao (HighFrequency Transduction).

ngha ca s ti np:

S ti np c th cho php xc nh nhng gen rt gn nhau nhim scth, do c s dng thit lp bn di truyn. Da vo tn s ti np haigen cng mt lc ngi ta c th xc nh khong cch gia cc gen v nh thxc nh v tr ca chng.

Trong thin nhin s ti np gi mt vai tr c ngha trong ly lan ccplasmid khng thuc vi khun gram dng nh plasmid penicillinase t cu.Ngoi ra prophage c th em li cho vi khun mt s tnh cht c bit quantrng v d prophage trc khun bch hu.

3. Tip hp (Conjugation)Tip hp l hin tng vn chuyn nhng yu t di truyn t vi khun

cho (c) sang vi khun nhn (ci) khi hai vi khun tip xc vi nhau.

Lederberg v Tatum ln u tin nm 1946 pht hin ra s tip hp vikhun. Hn hp hai bin chngE.coli K12 vi nhau. Chng 1 khuyt dng viBiotin v Methionin nhng c kh nng tng hp Threonin v Leucin k hiu B-

M-T+ L+. Chng 2 khuyt dng vi Threonin v Leucin nhng tng hp cBiotin v Methionin, k hiu B+M+T- L-.

C hai bin chng ny khng mc c trong mi trng tng hp tithiu khng cha bn cht trn nn khng to thnh khun lc.

Nu trn hai bin chng trn vi nhau ri cy vo mi trng ti thiu ththy mc cc khun lc vi tn s 10-6 . iu ny cho thy hai chng lai vikhun qua trao i gen to thnh cc t bo ti t hp c kh nng tng hp

bn cht: Biotin, Methionin, Threonin, Leucin, k hiu B+, M+, T+, L+.

Hin tng tip hp lin quan n nhn t sinh sn F. Nhn t F l mtplasmid. T bo cha F l t bo c hay t bo F+ ng vai tr t bo cho. T

bo khng cha F hay l t bo ci F

-

dng vai tr t bo nhn. Trong th nghimtip hp trn, chng (1) ng vai tr chng cho v chng (2) ng vai tr chngnhn.

T cc t bo F+, Cavalli phn lp c cc t bo Hfr (High frequencyof recombination) c kh nng vn chuyn gen vi mt tn s cao. Khi lai Hfr xF- th thu c cc t bo ti t hp 1000 ln nhiu hn khi lai F+x F-.

Trong cc t bo F+ nhn t F to nn mt lc c bit gi l lc tip hp.Chnh nh lc ny m xy ra s tip hp gia cc vi khun.

Trong cc t bo Hfr nhn t F tch hp vo nhim sc th ca vi khunv ch c kh nng sao chp cng vi nhim sc th. t bo Hfr nhn t F

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cng to nn mt lc tip hp, nhng trong qu trnh tip hp v nm cui bgen, n y b gen vo t bo nhn qua cu nguyn tng ni lin hai t botip hp.

t bo Hfr trong mt s trng hp F c th tch ri khi nhim sc th

v mang theo mt on ADN ca nhim sc th v c gi l F. F c khnng t sao chp v c th vn chuyn vo t bo nhn. F c th vn chuynmt s tnh trng ca mt vi khun ny sang mt vi khun khc. F c sdng phn lp v vn chuyn mt s gen chn lc.

Tip hp thng xy ra gia nhng vi khun cng loi nhng cng c thxy ra gia nhng vi khun khc loi nh E.coli vi Salmonella hoc Shigellanhng tn s ti t hp thp.

ngha ca s tip hp:

S tip hp l mt cng c kho st quan trng trong nhiu lnh vc sinhl v di truyn vi khun v n cho php to nn nhng vi khun phi hp nhiut bin khc nhau.

Nh k thut tip hp ngt qung ngi ta thit lp bn nhim sc thca vi khun. Ngoi ra chng F c s dng nghin cu hot ng ca mts gen.

Trong thin nhin s tip hp gi mt vai tr ng k trong bin d ca vikhun c bit trong ly lan tnh khng thuc gia cc vi khun Gram m.

II. DI TRUYN V TNH KHNG THUCCc vi khun khng thuc c tm thy khp ni k c nhng ni cha

bao gi s dng khng sinh. Ngay khi pht minh penicilin nm 1940, vi khunkhng penicilin c bo co. Ngy nay vn khng thuc tr thnh mi

bn tm hng u trong iu tr cc bnh nhim trng v khng sinh l mtth nghim hng ngy cc phng xt nghim vi trng.

S hnh thnh tnh khng thuc vi sinh vt l do s bin i gen nhim sc th hoc do tip nhn plasmid khng thuc.

Vi khun tr nn khng thuc qua 4 c ch: t bin, ti t hp hoc thuhoch plasmid khng thuc hoc thu hoch transposon .

1. t bin thnh khng thuc

Nhiu th nghim chng minh tnh khng thuc pht sinh do t bin,nh th tnh khng thuc lin h n s bin i gen nhim sc th v c thdi truyn cho cc th h sau. S t bin xy ra vi tn sut 10-5 - 10 -9 .

Trong tnh khng thuc, khng sinh gi vai tr chn lc ch khng phivai tr ch o. Vic s dng rng ri khng sinh lm pht trin nhanh chng cc

vi khun khng thuc bng cch git cht cc vi khun nhy cm, to iu kincho vi khun khng thuc pht sinh do t bin chim u th.

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2. S ti t hp

Lc mt t bin khng thuc xut hin mt qun th vi khun th vikhun khng thuc c th vn chuyn gen khng thuc n cc vi khun nhycm theo mt trong 3 c ch vn chuyn di truyn: bin np, ti np v tip hp

ty theo loi vi khun. S ti t hp gia 2 vi khun, mi vi khun khng mtkhng sinh lm xut hin nhng vi khun khng vi c 2 loi khng sinh. Trongthin nhin, s vn chuyn gen khng thuc trong ti np v tip hp xy ra vimt tn sut thp khong 10-5. Trong bin np tn sut cha c bit, nhngc th cn thp hn na.

3. Thu hoch plasmid khng thuc

Hai c ch khng thuc trn lin quan n gen khng thuc nm trnnhim sc th. y tnh khng thuc lin h n plasmid nm ngoi nhim sc

th. Plasmid khng thuc c vn chuyn theo nhng c ch khc nhau tytheo vi khun Gram dng hoc vi khun Gram m.

3.1. Plasmid khng thuc vi khun Gram m

Nm 1946 ln u tin Nht Bn ngi ta phn lp nhiu chngShigella khng vi nhiu khng sinh : streptomycin, chloramphenicol,tetracyclin, sulfonamit. Nhn t chu trch nhim v tnh khng nhiu thuc lmt plasmid khng thuc goi l nhn t R. Nhn t R in hnh l mt plasmidln vi 2 phn, chc nng ring bit. Phn th nht RTF gi l nhn t vnchuyn khng (Resistance transfer factor), khong 80 kb cha nhng gen ca

s t sao chp v ca s tip hp. Phn kia nh hn l quyt nh khng (Rdeterminant), kch thc rt thay i v cha gen khng thuc (R genes) RTF vquyt nh khng thng thng to nn mt n v. Nhn t R thng ti thp vi nhau lm pht sinh nhng t hp mi v khng thuc.

Nhn t R khng nhng c th ly truyn rng ri trong nhiu loi vikhun ng rut m cn c th ly truyn cho nhiu vi khun khc nh vikhun t, vi khun dch hch...

Nhn t R ly truyn trong vi khun qua tip xc nn tnh khng thuc lan

trn trong mt qun th vi khun nhy cm nh mt bnh truyn nhim .3.2. Plasmid khng thuc vi khun Gram dng

S khng ca nhiu chng t cu vng vi penicillin, erythromycin vnhiu khng sinh cng do plasmid gy nn. Plasmid vi khun Gram dngkhng th vn chuyn bng tip hp m bng ti np qua trung gian ca phage.Hin nay phn ln nhng chng t cu khng penicillin bnh vin u mang

plasmid penicillinase.

4.Thu hoch transposon

Transposon cn gi l gen nhy l nhng on ADN, kch thc nhcha mt hay nhiu gen c 2 u tn cng l nhng chui nucleotic ging nhau

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nhng ngc chiu nhau (inverted repeat). c th nhy t plasmid vo nhim scth hoc t nhim sc th vo plasmid hoc t plasmid n plasmid. Tt c migen trong c gen khng thuc c th nm trn transposon. Nhng transposonch o s khng kim loi nng, s to thnh c t v kh nng s dng mt s

cht chuyn ha (lactose, raffinose, histidin, hp cht lu hunh) c m t.c bit quan trng trong vi sinh hc l nhng transposon khng khng sinh nhTn3 mang gen khng ampicillin, Tn5 mang gen khng kanamycin, Tn10 manggen khng tetracyclin, Tn4 mang gen khng ba khng sinh ampicillin,streptomycin v sulfamit.

NH HNG CA CC NHN T NGOI CNH

N S PHT TRIN CA VI SINH VT

Mc tiu hc tp

1. Trnh by c tc ng ca mt s nhn t vt l, ho hc v sinh hc lns pht trin ca vi sinh vt.

2. Gii thch c c ch tc ng ca mt vi yu t vt l, ho hc v sinhhc ln s pht trin ca vi sinh vt.

S tn ti v pht trin ca vi sinh vt chu nh hng trc tip ca ccnhn t ca mi trng xung quanh nh nhit , nh sng, ha cht, cc bcx, pH...Cc nhn t ny c th chia lm 3 nhm ln: cc nhn t vt l, ccnhn t ha hc v cc nhn t sinh hc. Hiu c nh hng ca cc nhn tny i vi s pht trin ca vi sinh vt ng dng trong cng tc tit trng,kh trng cc dng c y t, dc phm, ty u mi trng, phng m, phng

bnh nhn, nghin cu vi sinh vt...

I. NHN T VT L

1. Vn ng c gii

Vi sinh vt chu nh hng ca cc tn s rung ng ca mi trng, yut ny c th c tc dng kch thch hay c ch s pht trin ca vi sinh vt vtiu dit vi sinh vt.

- Khi lc canh khun vi tn s va (1-60 ln / pht ) th c tc ng ttn s pht trin ca vi khun do tng kh nng thng kh, thc y s phn

bo...

- Khi lc mnh th li c ch s pht trin ca vi khun, nu lc ko di thc th tiu dit cc vi sinh vt.

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Vn ng c gii thng c ng dng khi nui cy vi sinh vt lmtng sinh khi hoc thu nhn s lng ln sn phm do vi khun bi tit ra...

2. Lm mt nc

Nc cn thit cho hot ng sng ca vi sinh vt, lm mt nc th vi sinhvt s cht. Tc cht ty thuc vo mi trng vi khun sng.

- Huyn dch vi khun trong nc nu em lm kh th vi khun cht rtnhanh.

- Huyn dch vi khun trong th keo khi lm kh vi khun cht chm hn.

- Huyn dch vi khun nu lm ng bng nhanh trc ri mi tin hnhlm mt nc th vi khun cht rt t. Phng php ny c p dng lmng kh vi khun nhm bo qun vi khun trong thi gian di.

Trng thi nha bo l trng thi mt nc t nhin ca vi khun. Nha bochu c kh hanh lu di.

3. Hp ph

Than hat, gel albumin, mng lc s... c kh nng hp ph vi khun v shp ph ny lm thay i kh nng sng ca vi khun. c p dng lm vkhun cc sn phm ca huyt thanh, cc sn phm khng chu nhit...

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4. pH

pH ca mi trng c nh hng n hat ng sng ca vi khun dolm thay i s cn bng v trao i cht gia mi trng v vi khun c thgit cht vi khun. Mi loi vi khun ch thch hp vi mt gii hn pH nht

nh (t 5,5 n 8,5), a s l pH trung tnh (pH=7), bi v pH ni bo ca tbo sng l trung tnh. mi trng kim, Pseudomonas v Vibrio pht trintt, c tnh ny rt hu ch phn lp chng. Trong khi Lactobacillus phttrin tt hn pH=6 hoc thp hn. Trong qu trnh iu ch cc mi trngnui cy phi m bo pH thch hp th vi khun mi pht trin tt. Trong titkhun hoc kh khun ngi ta c th s dng cc ha cht c pH rt axit hocrt kim loi tr vi khun.

5. p sut

5.1. p sut thy tnh (p sut c gii)Vi khun c kh nng chu c p sut cao ca khng kh, thng t

2000-5000 atm i vi virus, phage; t 5000-6000 atm i vi cc vi khunkhng c nha bo; t 17000-20000 atm i vi cc vi khun c nha bo. C chtc ng ca p sut c gii i vi vi khun cha c r.

5.2. p sut thm thu

p sut thm thu ca mi trng xung quanh c tc ng mnh n t bovi khun do tnh thm thu ca mng nguyn tng. a s cc vi khun pht

trin thch hp khi mi trng c p sut thm thu bng 7 atm (dung dchNaCl 0,9%).

- Trong dung dch nhc trng, do p sut thm thu bn trong t bo caohn mi trng nn nc b ht vo t bo vi khun lm t bo phnh to ln vv.

- Trong dung dch u trng, p sut thm thu mi trng cao nn ncb ht ra mi trng lm t bo b teo li.

6. Nhit

Nhit l yu t nh hng rt ln n s pht trin ca vi khun. Miloi vi sinh vt pht trin trong mt gii hn nhit nht nh, da vo khongnhit pht trin ti u, vi khun c th c chia lm 3 nhm: nhm a mc nhit ti u gia 20oC-45oC, nhm a lnh c nhit ti u di 20oC vnhm a nng c nhit ti u trn 45oC. nhit qu thp vi khun khng

pht trin c nhng c th cn sng; cn nhit cao hoc rt cao th vikhun b tiu dit.

- Nhit thp: nhit thp cc phn ng chuyn ha ca vi khun bgim i, c th b ngng li. Mt s vi sinh vt b cht nhng a s vn sng

trong thi gian di. Lc lm ng bng vi sinh vt th mt s b cht, nhng nu

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lm ng bng rt nhanh th s vi sinh vt sng st nhiu hn. Ngi ta s dngc im ny bo qun cc chng vi khun nhit thp.

- Nhit cao: Nhit cao c kh nng git cht vi khun. Sc khngca vi khun vi nhit cao ty tng chng loi v ty theo trng thi sinh

trng hay trng thi nha bo. a s cc vi khun trng thi sinh trng nhit 56-60oC trong 30 pht l cht v 1000C th cht ngay. Th nha bochu c nhit cao hn v lu hn 1210C trong 15-30 pht ni hp micht hoc 1700C trong 30 pht - 1 gi nhit kh mi b tiu dit.

- C ch tc dng ca nhit cao i vi vi khun:

+ Protein b ng c

+ Enzyme b ph hy

+ Tn thng mng nguyn tng lm thay i tnh thm thu.

+ Ph hy cn bng l - ha trong t bo do tng tc phn ng sinh vtha hc.

+ Gii phng axit nucleic

7. Bc x

- nh sng mt tri: nh sng mt tri do c tia cc tm c bc sng t200-300 nm, nht l 253,7nm, c tc dng st khun.

- Tia Rnghen: c hiu ng dit khun v gy t bin i vi vi sinh vt

- Nguyn t phng x: to ra cc bc x , v trong tia , ctc dng dit khun hay c ch vi khun pht trin. Cn tia t c tc dng.

C ch tc dng ca bc x: Do nguyn tng ca vi khun c thnh phncu to bng cc phn t rt phc tp, cc phn t ny c kh nng hp th mtcch chn lc nhng tia bc x c bc sng khc nhau. Th d nh axit nucleicca vi khun c kh nng hp th tia bc x di 253,7nm, lc qu trnh saochp ca DNA b bin i hoc b c ch hoc DNA b ph hy khng thunnghch lm vi khun cht.

8. Siu mKhi nhng tn s ca chn ng vt qu 20.000 ln/1 pht th gi l siu

m (do tai ta khng nghe c na). Siu m c kh nng git cht vi khun donhng chn ng c tn s cao pht sinh ra p sut co gin cao lm cho t bo vikhun b x tan; cng c th nc trong t bo vi khun di tc dng ca sium pht sinh ra H2O2 c tc dng git cht vi khun; siu m cng c th phhy h thng keo lm cho cht keo ng li.

9. Tia laser

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Tia laser do nng lng cao v tp trung nn trong mt thi gian cc kngn c th lm cho vt cht nng chy v bay hi, c th tng nhit , p sutti ch ln rt cao nn cng c tc dng git cht vi khun.

II. CC NHN T HA HC

Cc ha cht trong mi trng c nh hng hoc kch thch hoc cch s pht trin ca vi khun. Cc ha cht c tc dng kch thch s pht trinvi khun c ng dng trong nui cy vi khun... Cc ha cht c tc dngc ch hoc tiu dit vi khun c s dng lm cht ty u, cht kh khunhoc st khun ty theo mc ch s dng v nng s dng.

1. Cht ty u, cht kh khun

- Cht ty u l nhng ha cht c kh nng git cht cc vi khun gybnh v vi sinh vt khc, cn i vi nha bo th tc dng git khun mt phn.

Cht ty u s dng trn b mt cc dng, cc dng c y t, cc cht thi cabnh vin...

- Cht kh khun l nhng ha cht c tc dng ngn cn s pht trin cavi khun, cht ny ch c tc dng git cht vi khun mt phn nhng c tcdng c ch vi khun rt mnh. Cht kh khun c th dng v khun vtm, ni tim chch...Thc ra cht ty u v kh khun ch khc nhau v nng khi s dng. V d: phnol nng 2-5% th dng ty u, cn khi nng thp hn 100 -1000 ln th dng lm cht kh khun.

- Ch s phenol l t l gia nng ti thiu ca cht ty u c tc dngdit khun v nng ti thiu ca phenol khi s dng i vi mt chng vikhun nht nh. Ch s ny c dng lm n v nh gi tc dng dit khunca mt ha cht.

2. Cc nhn t ha hc nh hng n s pht trin ca vi khun

2.1. Axit v baz

Axit v baz c kh nng phn li thnh ion H+ v OH- rt mnh, lm chopH ca mi trng thay i v c tc dng dit khun hoc c ch s pht trinca vi khun.

2.2. Cc mui kim loi

Khi ha tan vo trong nc th mui ca nhiu kim loi nng c kh nngphn li thnh ion v c tac dng dit khun, kh nng dit khun ca cc muikim loi nng c th do s kt hp ca cc ion kim loi vi nhng nhm -SHca protein t bo. Hot tnh dit khun theo th t Hg, Ag, Cu, Zn. V d :

- Mui thy ngn: c dng nhiu nht ty u nh sublim (HgCl2),...

- Mui bc: c tc dng st khun nh nitrat bc (dung dch argyrol).

- Mui ng: sunpht ng dng cha bnh nm ngoi da.

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H2O2, KMnO4, thuc nhum thng pha thnh dung dch lng dng lmcht st khun. Thuc nhum thng c dng c ch s pht trin ca tpkhun trong cc mi trng chn lc.

2.8. Cc tc nhn c hot tnh b mt

Nhng hp cht ny c gi l thuc ty tng hp. Dit khun mnh mnht l nhng thuc ty cation trong hiu qu hn c l nhng hp chtamonium bc 4 nh benzalkonium chlorua. Nhng hp cht ny c s dngrng ri kh khun. Chng tc ng bng cch lm tan mng t bo vi khundo ha tan mng lipit che ch vi khun v lm bin th protein.

3. C ch tc ng ca cc ha cht i vi t bo vi khun.

- Ph hy mng t bo: do ion ha, thay i sc cng b mt, lm tan mnglipit che ch vi khun...

- Bin i chc nng ca protein v cc axit nucleic...- Tc ng ha hc lm gii phng oxy phn t, clo... c tc dng git cht

vi khun.

4. Cc yu t nh hng n tc dng ca cc cht ty u v st khun.

- Nng ca ha cht: nng cng cao th tc dng cng mnh.

- Thi gian tip xc: tip xc cng lu th tc dng cng mnh.

- Nhit

- Thnh phn ca mi trng xung quanh: do cc cht hu c c tc dngbo v vi khun hoc tc dng vi ha cht lm gim hiu lc.

- Mt vi sinh vt ti ni kh trng

- Kh nng khng ca vi sinh vt (virus c lp v lipit s nhy cm vicht ho tan lipit nh cn, phenol hn l nhng virus khng c v).

III. NHN T SINH VT

Trong qu trnh tn ti ca vi sinh vt nu chng phi sng trong iu kin

c vi sinh vt khc th chng c th b cnh tranh sinh tn, b tiu dit hoc songsong tn ti.

1. Cht i khng (Bacterioxin)

Nhiu loi vi khun khi pht trin th tng hp cc cht i khng c tcdng c ch cc vi khun cng loi hoc cc loi ln cn. V d : Colixin ca

E.coli, Staphylococxin ca T cu...Chng c bn cht protein hoc phc hpgluxit-lipit-protein, c tc ng c hiu vi cc vi khun nhy cm.

2. Phage

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L virus ca vi khun, phage xm nhp cc vi khun c hiu, nhn ln vph v t bo vi khun. Phage cng c th cng tn ti v nhn ln vi vi khun trng thi n ha.

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3. Interferon

L cht do t bo sn sinh ra khi b virus xm nhp, c bn chtglycoprotein, c tc dng c ch s nhn ln ca virus.

4. Cht kch thchMt s vi khun khi pht trin sn sinh ra mt cht lm thun li cho vi

khun khc pht trin. V d nhHemophilus mc tt xung quanh khun lc Tcu (do T cu sinh ra yu t V cn thit choHemophilus pht trin) ...

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TIT TRNG - KH TRNGV KHNG SINH

Mc tiu hc tp

1. Nu c cc phng php tit trng v kh trng trong phng th nghim.2. Trnh by c nh ngha khng sinh, cc c ch tc dng ca khng sinh.3. K c cc nhm thuc khng sinh v hiu qu ca chng vi cc nhm vikhun chnh.4. M t c cc c ch khng ca vi khun vi khng sinh, ngun gc ca

s khng, cch theo di s khng v mc ch ca phi hp khng sinhtrong iu tr bnh nhim trng

I. TIT TRNG V KH TRNG

1. Tit trngTit trng l s lai b tt c vi sinh vt sng (gm th dinh dng v nha

bo ca chng) bng nhit , bng tia bc x, bng cc ha cht hoc bng ccbin php c hc. Tit trng l cng vic cn thit trong y hc nhm git chtcc vi sinh vt sinh bnh khi dng c y t, sinh vt phm, dc phm... Trong

phng th nghim vi sinh vt, tit trng l bin php khng th thiu c chovic phn lp, nui cy v lu gi cc vi khun thun khit. Ngi ta dng nhiu

phng php tit trng khc nhau trong phng th nghim vi sinh hc.- Cc phng php tit trng bng dng nhit nh t nng trn ngn

la ,dng l sy kh 160-1700C, dng nhit m trong ni p sut, hoc chngcch thy ngt qung kiu Tyndal .

- Tit trng bng cc tia bc x: cc tia bc x cc tm , tia gamma, tiabeta c tc dng git cht vi sinh vt, c dng tit trng dng c, ch phmsinh hc...

- Tit trng bng c hc dng cc my lc, vi khun s b gi li pha trnmy lc. Phng php ny dng tit trng cc mi trng nui cy vi khun.2. Kh trng (hay kh khun)

Thut ng ny dng cho cc tc nhn vt l, v thng l ha hc c kh

nng git cht vi sinh vt sng trn cc dng, dng c th nghim, phng thnghim, phng bnh ...Tc nhn vt l nh tia cc tm c dng kh trng phng m, phng

nui cy vi khun .Nhiu ha cht c bit c dng cho mc ch kh trng phng lm

vic, phng th nghim, kh trng cc dng, dng c th nghim nh xphng, phenol , cc hp cht halogen, cc mui kim loi, cn...

Thut ng st khun (antiseptic) c s dng cho cc ha cht dng git cht vi sinh vt trn b mt ca c th con ngi hoc ng vt m khng

lm tn thng t chc ca c th. Cc ha cht ny t c vi c th v thng nng thp. Nh vy mt ha cht c th s dng lm dung dch kh khun

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hoc s dng st khun ph thuc vo mc ch s dng v nng cht sdng v d phenol khi nng 2-5% c dng nh cht kh trng, cn khi nng thp hn 100 n 1000 ln c dng lm cht st khun .

II. CC CHT KHNG SINH1. nh ngha

Thut ng khng sinh theo nh ngha ban u l nhng tc nhn khngkhun c ngun gc t vi sinh vt, chng c tc dng chng vi khun hu hiu nng rt thp. Lc u cc khng sinh u chit t mi trng nui cy nmmc hoc vi khun, sau nhiu khng sinh c bn tng hp bng cch bini cu trc phn t ca khng sinh thu c khng sinh mi.

Hin nay khng sinh c xem nh l nhng hp cht ha hc c tcdng cn khun hoc dit khun vi c ch tc ng mc phn t, hu hiu liu lng thp v c th s dng iu tr bnh nhim trng.

Cc khng sinh c tc dng c hiu i vi mt loi vi khun hoc mtnhm vi khun nht nh. Cc khng sinh c hot tnh khc nhau, c loi c phkhng khun rng, c loi c ph khng khun hp.2. C ch tc dng ca khng sinh2.1. c ch tng hp vch t bo

Khc vi t bo ng vt, vi khun c vch t bo. Loi b vch hocngn cn s to thnh vch u lm tan t bo vi khun. Vch t bo vi khuncha mucopeptit cn gi l murein hay peptidoglycan. Cc penicilline vcephalosporin tc ng ln cc phn t protein chn lc c hiu nn c ch s

lin kt ngang cui cng ca cu trc mucopeptit ca vch t bo, vi khun ddng b tan.

Cc khng sinh khc nh bacitracin, vancomycin, novobiocin, D-cycloserin cng c ch s to vch ca vi khun bng c ch s hnh thnhmucopeptit ca vch .2.2. c ch chc nng ca mng nguyn tng

Mng nguyn tng hot ng nh mt mng bn thm. Mng ny thmthu cc cht chn lc v nh vy kim sot c cc thnh phn bn trong cacc t bo. Nu s ton vn ca mng nguyn tng b ph v th cc thnh

phn ni bo thot ra khi t bo v t bo cht. Mng t bo ca mt s vikhun v nm d b ph v bi mt s thuc khng sinh hn t bo ng vt dohot tnh tc dng chn lc ca cc khng sinh ny ln cc nhm cu trc hahc c bit c mng ca vi khun hoc ca nm m khng c t bo ngvt. Polymycin c tc ng mng nguyn tng ca vi khun gram m, polyenc tc ng mng nguyn tng ca nm.2.3. c ch tng hp protein

Nhiu thuc khng sinh c ch tng hp protein ca vi khun:2.3.1.Chloramphenicol: chloramphenicol v cc dn cht thuc nhm ny ngn

cn s kt hp axit amin vo chui peptit mi sinh n v 50S ca ribosome vikhun qua vic cn tr tc ng ca enzyme peptidyl-transferaza.

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2.3.2. Cc tetracyclin: tetracyclin v cc thuc khng sinh nhm ny c ch stng hp protein ca vi khun bng cch ngn cn s gn lin ca amino acyl-RNA vn chuyn vo n v 30S ca ribosome .2.3.3. Cc macrolid v lincomycin: Cc khng sinh nhm ny ngn cn s tng

hp protein bng cnh tranh v tr kt hp ca axit amin ribosome v bngcch phong b phn ng dy chuyn aminoacyl.2.3.4. Cc aminoglycoside: cc thuc khng sinh nhm aminoglycoside c chtng hp protein bng cch gn vo protein tip nhn trn n v 30S caribosome lm c sai thng tin ca ARN thng tin lm hnh thnh cc proteinkhng c hat tnh, ngoi ra cn lm tch cc ribosome trng thi polymerthnh monomer2. 4. Tc dng c ch s hnh thnh acid nucleic2.4.1. Cc sulfonamid v trimethoprim: i vi nhiu vi sinh vt, axit para-aminobenzoic (vit tt l PABA) l mt cht chuyn ha cn thit trong qutrnh tng hp axit folic cn thit tng hp purin v ADN. Sulfonamid do ccu trc tng t nh PABA nn c th i vo phn ng thay cho PABA, huqu l mt cht tng t nh axit folic nhng khng c hat tnh c to thnhv ngn cn s pht trin ca vi khun.

Trimethoprim c ch enzyme dihydro folic reductase, enzyme ny bini axit dihydro folic thnh axit tetrahydro folic, mt giai an trong chui

phn ng tng hp purin v DNA.S phi hp mt trong cc sulfonamid vi trimethoprim, hai cht tc ng

hai khu khc nhau ca mt qu trnh tng hp lm tng r hat tnh ca

thuc, cotrimoxazol (sulfamethoxazol v trimethoprim) l ch phm phi hp sdng hiu qu trong iu tr cc bnh nhim trng2.4.2. Rifampin: Rifampin v cc dn cht kt hp vi ARN polymerase phthuc ADN v nh th c ch s tng hp ARN vi khun.2.4.3.Cc quinolone: Cc quinolon v cacboxy fluoroquinolon kt hp vo ADNgyrase nn c ch tng hp ADN.3. Cc nhm thuc khng sinh3.1. Sulfonamid

L nhng hp cht thay th nhm amit (SO2NH2) hoc nhm amin (NH2)

ca axit sulfanilamic.Sulfonamid c tc dng cn khun i vi vi khun gram m v vi khun

gram dng. Chng c ch nhiu vi khun gram dng v vi khun ng rutbao gmE.coli,Klebsiella vProteus.

Cc sulfonamid c s dng rng ri nh sulfaguanidin, sulfadiazim,sulfisoxazol, sulfamethoxazol, sulfadimethoxin....

Tr ngi chnh ca cc thuc nhm sulfamid l vi khun tr nn khngvi thuc nhanh chng, thm vo nhiu sulfamid c th gy phn ng phnghim trng. Nn hin nay cc thuc nhm sulfamid ch c dng hn ch.

Ch phm sulfamid ang c dng rng ri hin nay l cotrimoxazol lphi hp ca sulfamethoxazol v trimethoprim. Thuc ny c dng trong iu

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tr cc nhim trng ng tiu ha, h hp v tit niu. Dng phi hp khc lfansidar bao gm sulfadoxin v pyrimethamin c hiu qu trong iu tr st rt,t hiu qu i vi bnh nhim trng .3. 2. Cc betalactamin

Cc thuc ny trong cng thc ha hc c cha vng beta-lactam baogm cc penicillin v cc cephalosporin.3.2.1 Cc penicillin

Cc penicillin c nhn chung l axit 6 amino-penicillanic hp bi mtvng thiazolidin v mt vng -lactam cc penicillin ny khc vi penicillinkhc ch gc R gn vo nhn chung.Cc penicillin dng trong iu tr thuc 3 nhm chnh :

- Cc penicillin c hot tnh cao i vi vi khun gram dng, b ph hybi enzyme penicillinase: penicillin G, penicillin V (phenoxy methylpenicillin),

benzathin penicillin.- Cc penicillin c hot tnh i vi vi khun gram dng, khng ivi enzyme penicillinase: methicillin, nafcillin, oxacillin, dicloxacillin .

- Cc penicillin c hot tnh rng i vi c vi khun gram dung v vikhun gram m, b ph hy bi enzyme penicillinase. Cc penicillin nhm ny

bao gm:+ Cc aminopenicillin: ampicillin, amoxicillin, becampicillin,

metampicillin.+ Cc carboxy penicillin: carbenicillin, ticarcillin.+ Cc ureidopenicillin: azlocillin, mezlocillin, piperacillin.

Ngoi 3 nhm chnh trn hin nay ngi ta cn c cc penicillin phi hptrong ngi ta kt hp cc penicillin khc nhau vi nhng cht c chenzyme lactamase dng iu tr cc nhim trng do vi khun khng snxut enzyme lactamase. Hai cht c ch enzyme ny c dng phi hpvi cc penicillin l axit clavulanic v sulbactam: cc thuc ca s kt hp nynh: timentin gm ticarcillin v axit lavulanic, augmentin (amoxicillin va.clavulanic), unasyn (ampicillin & sulbactam).

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3.2.2 Cc cephalosporinCc cephalosporin c mt nhn chung l axit faminocephalo-sporanic

hnh thnh bi mt vng lactam kt hp vi mt vng dihydrotiazin thay thhydro cu nhm amin bng cc gc R khc nhau th thu c cc cephalosporin

bn tng hp .Cc cephaloporin c hot tnh vi c vi khun gram dng v vi c vikhun gram m .

Da vo tnh khng khun cc cephalosporin c chia cc th h:- Cc cephalosporin th h th nht:Bao gm cephalothin, cephazolin, cephalein, cefaclor. Cc thuc ny c

hot tnh i vi t cu lin cu A, ph cu,E. coli,Klebsiella,Proteus..- Cephalosporin th h th hai:Cc thuc nhm ny c hot tnh tt hn cc thuc cephalosporin th h

th nht chng li E. coli, Klebsiella, Proteus, Citrobacter, Enterobacter,H.influenzae, N.gonorrhoe, N. meningitidis. Cc thuc nhm ny gm:cefamandol, cefuroxime, cefonicid, cefoxitin...

- Cephalosporin th h th ba:C ph tc dng khng khun bao trm ton b vi khun ng tiu ha, tuy

nhin c tc dng km vi vi khun gram dng, thuc nhm ny c th chia 02nhm, nhm c tc dng chng Pseudononas aeruginosa gm ceftazidime vcefoperazone, v cc nhm khng c tc dng chng P. aeruginosa bao gmcefotaxim, ceftazidime, ceftizoxime, moxalactam. Nhiu thuc nhm ny thm vomng no tt nn c dng iu tr vim mng no do vi khun gram m.3.2.3. Monobactam v Carbapenem:

Hai nhm thuc ny khc vi cc beta-lactam v cu to ha hc nhngc ch tc dng l c ch tng hp vch tng t nh cch tc dng ca cc

beta lactam, aztreonam l thuc thuc nhm monobactam c sn hin nay, phkhng khun gii hn trn vi khun gram m tng t nh cc aminoglycoside.

Imipenem l khng sinh carbapenem c sn hin nay, ph khng khunca thuc ny c xem l rng nht trong cc thuc khng sinh hin nay baotrm ln cc vi khun gram dng gm c lin cu D, c tc dng chng li huht cc vi khun gram m k c P.aeruginosa, v c tc dng chng li vi

khun k kh.3.3. Cc khng sinh aminoglycoside

Gm streptomycin, neomycin, gentamycin, tobramycin, amikacin,kanamycin

Cc khng sinh nhm ny c tc dng dit khun bao gm c vi khungram dng v nhiu vi khun gram m. gentamycin, tobramycin, neomycin ctc dng chngP.aeruginosa, tri li streptomycin c tc dng vi vi khun laonn l thuc dnh ring iu tr lao.3. 4. Cc thuc tetracyclin

C cng thc ha hc tng t nhau. Cc thuc khc nhau ch cc gcR khc nhau.

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Cc thuc ny bao gm tetracyclin, chlotetracyclin, oxytetracyclin,doxycyclin, minocyclin, thuc nhm ny c tc dng cn khun vi vi khungram dng v gram m, cc tetracyclin c hiu qu viRickettsia, Chlamydia,Mycoplasma pneumoniae vLeptospira.

3. 5. ChloramphenicolLc u chit xut t Streptomyces venezuelae nhng hin nay c tnghp. Thuc ny c tc dng cn khun v ph khng khun rng. N c hiuqu trong bnh thng hn v cc nhim trng doRickettsia.3. 6. Macrolit v cc thuc tng t

Cc thuc khng sinh macrolit gm erythromycin, oleandomycin,spiramycin. Cc khng sinh thuc nhm ny c tc dng cn khun, chng tcdng tt trn vi khun gram dng, mt s vi khun gram m nh phy khunt. Erythromycin l thuc an ton nn c dng lm thuc thay th penicillintrong cc nhim trng do vi khun gram dng bnh nhn d ng vi

penicillin. Lincomycin v clindamycin c c ch tc dng v hat ph tng tnh erythromycin.3.7. Polypeptid

Khng sinh nhm polypeptit ch yu l polymycin, ph tc dng ch yudit khun vi vi khun gram m k c Pseudomonas. Polymycin c vi thnkinh v thn, hin nay t c dng ng ton thn iu tr cc nhim trnggram m. Cac thuc c polymycin thng c dng iu tr nhim trng tich.3.8. Rifamycin

L khng sinh chit sut t Streptomyces mediterranei, cht dn xut bntng hp l rifampin, hai thuc ny c hat ph i vi mt s vi khun gramm v gram dng, vi khun ng rut, vi khun khng acid cn. Rifamycindo vy l thuc s dng ch yu iu tr bnh lao hin nay.3.9. Cc quinolon v cacboxy - fluoroquinolon

Hp cht quinolon tng hp u tin l axit nalidixic ch yu dng iu tr nhim trng ng tit niu. Cc cacboxy-fluoroquinolon l cc dncht t axit nalidixic, cc thuc ny c tc dng dit khun i nhiu vi khungram dng v vi khun gram m k c t cu khng vi methicillin v

P.aeruginosa, chng cn cn c tc dng chng Mycoplasma v Chlamydia.Cc fluoroquinolon c s dng trong nhiu nhim trng cc c quan. Mt sfluoroquinolon thng dng hin nay gm ciprofloxacin, enoxacin, norfloxacin,

pefloxacin.4. S khng ca vi khun vi thuc khng sinh4.1. C ch khng thuc khng sinh ca vi khun

Nhiu c ch khng thuc khng sinh ca vi khun c kho st. nhng chng vi khun khc nhau, s khng vi mt lai khng sinh c th domt hc nhiu c ch khc nhau.

4.1.1.Tng s ph hy thuc do enzyme

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y l c ch khng thng thng qua trung gian ca plasmid. V din hnh l enzyme beta lactamase gy nn s khng vi cc khng sinh betalactamin. Cc vi khun sn xut enzyme penicillinase th khng vi cc

penicillin, cc vi khun to c enzyme cephalosporinase th khng vi cc

cephalosporin, cc aminoglycoside b bt hat bi cc enzyme phosphorylase,adenylase, acetylase. Chloramphenizol b bt hat bi acetylase.4.1.2. S bin i receptor ca thuc

y l c ch quan trng. S bin i protein c hiu vi thuc ribosome lm vi khun tr nn khng i vi thuc khng sinh nh s khng vi cc thuc nhm aminoglycoside, erythromycin, khng virifampin trn c s thay i mt amino axit trn tiu n v beta ca enzymeARN polymerarase ph thuc ADN lm thay i s gn vo enzyme ny carifampin. S khng ca sulfonamid v trimethoprim cng tng t do s bini ca phn t enzyme nn sulfamid khng c nhn vo phn ng tnghp acid folic.4.1.3.Gim tnh thm mng nguyn tng

Tnh cht ny do s mt hoc thay i h thng vn chuyn mngnguyn tng. S khng ny gp cc khng sinh nh cc beta lactamin,chloramphenicol, quinolon, tetracyclin v trimethoprim. Ngoi ra ro cn thmthu bnh thng ca mng nguyn tng cng chu trch nhim cho s khng t nhin ca nhiu thuc.4.1.4.Tng s to thnh mt enzyme

C ch ny c th lin quan n s sn xut gia tng s lng enzyme c

ch nh c thy mt s vi khun mang plasmid khng thuc hoc lin hn s to thnh mt enzyme mi c i lc mnh hn vi mt c cht khc sovi thuc nh trong trng hp khng vi sulfonamid.

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st v dch t hc tnh khng thuc ca vi khun gip cho cc thy thuc lmsng chn thuc khng sinh thch hp iu tr bnh nhim trng. Xc nh nhy cm ca vi khun vi thuc khng sinh bng nhng phng php phngth nghim tin cy v thng nht c cc d kin c th so snh c. Th

nghim nhy cm ca vi khun trong phng th nghim, cn gi l khngsinh , c th c thc hin bng phng php ha long hoc bng phngphp khuch tn trn mi trng c. Khi thc hin khng sinh vi khun cnphi c nui cy thun khit, a s vi khun gy bnh ngi khi phn lpcn 16-18 gi mi pht trin, nu bnh phm ch thun mt lai vi khun th cnthm 16-18 gi na lm khng sinh , nh vy kt qu khng sinh smnht cng mt 36 - 48 gi, trong trng hp bnh phm nhiu vi khun, hocnhiu vi khun pht trin chm cn thi gian lu hn. i vi mt s vi khunm tnh khng sinh n nh v r rng th khng cn thit phi lm khng sinh

nh vi khun bch hu, lin cu A tan mu . Tnh cht khng khngsinh ca vi khun c tnh cht dch t, do vy kt qu khng sinh ca cc vikhun gy bnh c th khc nhau gia bnh vin ny v bnh vin khc vnhng vng khc nhau, ngay c trong cng mt bnh vin nhy cm ca vikhun cng thay i hng ngy. V vy cc phng th nghim vi khun bnhvin cn lm khng sinh chn khng sinh thch hp trong iu tr bnhnhim trng .4.2.5. Phi hp khng sinh

Phi hp khng sinh iu tr bnh nhim trng nhm mt s mc tiusau :

- Gim kh nng xut hin chng vi khun khng. i vi vi khun khng do t bin th phi phi hp khng sinh lm gim tn sut t bin kp,v d t bin ca vi khun lao khng streptomycin l 10 -7, t bin khngrifamycin l 10-9 th xc xut t bin khng c vi c hai th thuc trn l10-7x10-9 = 10-16. y chnh l l do phi phi hp khng sinh iu tr lao.

- iu tr cc nhim khun hn hp : Mt lai khng sinh c ph tc ngtrn mt nhm vi khun nht nh. Trong cc nhim khun do nhiu lai vikhun th phm nh vim phi, vim phc mc... thng do c vi khun i khv vi khun k kh. Phi hp khng sinh th s dit dc c hai lai vi khun

ny.- tng kh nng dit khun: V d phi hp sulfamethoxazol v

trimethoprim lm tng kh nng dit khun i vi nhiu vi khun so vi khidng n c mt trong hai thuc trn. Mc ch ny c dng trong trnghp iu tr cc nhim trng doPseudomonas aeruginosa thng ngi ta phihp carbenicllin v gentamicin...

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I CNG VIRUS

Mc tiu hc tp

1. Trnh by c nhng c im , kch thc, hnh th v cu trc ca virus.2. Trnh by c s nhn ln ca virus v hu qu ca s nhn ln ca virustrong t bo.

3. Trnh by c cc hnh thi nhim virus v cc phng php nui cy virus.

I. S LC LCH S PHT HIN VIRUS

Nm 1796 E.Jenner cho chng u phng bnh u ma. L.Pasteur

d tm ra vaccine chng bnh di vo nm 1885, nhng cha chng minh ctc nhn gy bnh v chng khng trng thy c knh hin vi quang hc vkhng mc mi trng nui cy nhn to.

Nm 1892 D.I. Ivanovski chng minh c rng mm bnh gy bnhkhm thuc l c th chui qua cc lc vi khun bng s. Ivanovski cho rng l mt cht c tng t nh c t do cy b bnh tit ra.

Nm 1898 M.W.Beijerinck chng minh rng chnh tc nhn gy bnhkhm thuc l ch khng phi cht c ca n i qua c lc vi khun vng dng ting Latin l virus (mm c) gi mm bnh ny.

Nm 1898 F.Loeffler v P.Frosch chng minh c tnh qua lc s catc nhn gy bnh l mm long mng b .

Nm 1915 - 1917 F.W.Twort v F.H. dHrelle pht hin ra virus ca vikhun v t tn l Bacteriophage, sau ny thng gi tt l phage.

Nm 1935, W.M. Stanley ln u tin tch bit v kt tinh c viruskhm thuc l.

T nm 1940 tr i knh hin vi in t c hon thin dn cho phpquan st c hnh dng v cc thnh phn cu trc ca virus.

II. NHNG C IM CA VIRUS

Virus l tc nhn nhim trng nh nht (ng knh t 20 - 300 nm ) cth lt qua cc lc vi khun, c cu to rt n gin. Virus l mt i phn tnucleoprotein c c tnh c bn ca mt sinh vt, nhng khng c kh nng tsinh sn, khng c cu to t bo, khng c qu trnh trao i cht v c th coichng l trung gian gia cc cht sng v cht v sinh.

Virus khc bit vi cc vi sinh vt khc cc c im sau y:

- Virus ch cha mt loi axit nucleic duy nht: hoc l ADN hoc lARN, khng bao gi cha ng thi c 2 loi axit nhn.

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- Virus sinh sn bng cch sao chp t vt liu di truyn duy nht cachng, khng phn chia bng cch phn i nh cc vi khun.

- Virus k sinh bt buc trong t bo sng, chng da vo ngun nnglng v b my ca t bo (v d cc ribosome, ARN vn chuyn...) tng

hp protein.- Virus tng hp cc thnh phn ca chng mt cch ring r v sau t

lp rp vi nhau to thnh nhng ht virus mi.

- Virus khng nhy cm vi cc khng sinh thng thng.

III. KCH THC, HNH TH V CU TRC CA VIRUS

1. Kch thc

Virus c kch thc rt nh b, c th qua c cc lc vi khun. Chnh v

th m ch c th quan st thy virus qua knh hin vi in t.n v o kch thc ca virus l nanomet (nm)

1 nm =1/1000 micromet

Mi loi virus c mt kch thc nht nh (t 20-300 nm) v khng thayi trong sut qu trnh pht trin.

2. Hnh th

Phn ln cc virus c mt hnh th nht nh, c trng cho tng loivirus.

Mt s loi hnh th virus thng gp:

-Hnh cu : virus cm, si, bi lit.

-Hnh khi a din :Adenovirus,Papovavirus.

-Hnh que : virus khm thuc l.

-Hnh vin gch : virus u ma

-Hnh di trng (inh ghim): phage T2 caE.coli

3. Cu trcVirus c cu trc rt n gin, khng c cu to t bo. Tt c cc ht

virus u c hai thnh phn c bn: axit nucleic l thnh phn mang mt m ditruyn ca virus v capsid l v protein bao quanh axit nucleic. Li axit nucleicv capsid hp li to thnh nucleocapsid. i vi mt s virus, nucleocapsid cnc bao quanh bi mt v lipit hay lipoprotein gi l bao ngoi (envelope hoc

peplos)

3.1. Axit nucleic ca virus

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Mi mt ht virus u c mt trong hai loi axit nucleic hoc l ADNhoc l ARN. Axit nucleic nm gia ht virus to thnh li hay h gen cavirus.

Phn t ADN ca virus phn ln dng ADN 2 si v c mt s t

dng ADN 1 si nhParvoviridae. Phn t ARN ca virus a s dng ARN 1si, tr mt s t dng ARN 2 si nhReoviridae.

Cc axit nucleic ch chim 1-2% trng lng phn t ca ht virus nhngc chc nng c bit quan trng :

- Axit nucleic mang ton b m thng tin di truyn c trng cho tngvirus.

- Axit nucleic quyt nh kh nng gy nhim trng ca virus trong t bocm th.

- Axit nucleic quyt nh chu k nhn ln ca virus trong t bo cm th- Axit nucleic mang tnh khng nguyn c hiu ca virus.

3.2. Capsid

Capsid l cu trc bao quanh li axit nucleic. Bn cht ha hc ca capsidl protein. Capsid c cu to bi cc n v hnh thi gi l capsomer baogm cc phn t protein c sp xp c trng cho tng loi virus. Cc capsomerc sp xp theo mt trt t khng gian xc nh to nn cc kiu i xng cacapsid : hoc i xng xon hoc i xng khi hoc i xng phc hp.

Capsid ca virus c cc chc nng sau y:

- V protein c tc dng bo v axit nucleic ca virus.

- Protein capsid mang tnh khng nguyn c hiu ca virus.

- Capsid ng vai tr quan trng trong giai on bm v xm nhp t boca virus.

- Capsid gi cho hnh th v kch thc ca virus lun lun c n nh.

3.3. V ngoi (envelope)

Cc virus nh Herpesviridae, Flaviviridae, Orthomyxoviridae,Paramyxoviridae,... cn c thm mt lp v bao bc ngoi capsid gi lenvelope hoc peplos. Bn cht ha hc ca v ngoi l mt phc hp lipid,

protein v gluxit. V ngoi c ngun gc t mng bo tng hoc mng nhnca t bo ch nhng b virus ci to v mang tnh khng nguyn c hiucho virus. V ngoi c th b cc dung mi ha tan lipid (nh ether, muimt , ...) ph hy.

V ngoi ca virus c chc nng :

- Tham gia vo s bm ca virus vo t bo cm th

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- Tham gia vo giai on lp rp v gii phng virus ra khi t bo sauchu k nhn ln.

Nhng virus khng c v ngoi gi l virus trn.

3.4. Gai protein

Trn v ngoi ca mt s virus c nhng mu gai protein li ln c th cnhng chc nng ring bit nh ngng kt hng cu t hoc enzymeneuraminidase hot ng .

3.5. Mt s enzyme

Virus khng c mt h enzyme chuyn ha hon chnh nh vi khun,nhng trong thnh phn cu trc ca mt s virus c mt vi loi protein c hottnh enzyme. Ph bin nht l cc polymerase nh ARN polymerase, ADN

polymerase, ADN polymerase ph thuc ARN (enzyme sao chp ngc)...

4. Virion

Ht virus hon chnh c kh nng gy nhim trng cho t bo cm thc gi l virion. Ty theo tng loi virus, virion c th c capsid trn hoccapsid c v ngoi.

5. Pseudovirion

Ht virus nhn vt liu di truyn ca t bo ch trong qu trnh saochp thay cho axit nucleic ca virus c gi l pseudovirion. Nhng ht

pseudovirion ny khi quan st di knh hin vi in t chng ging ht ccvirion bnh thng, nhng chng khng c hot tnh nhim trng v khng thnhn ln c. Cc ht ny c kh nng chuyn cc gen ca t bo t mt t

bo ch ny n mt t bo ch khc.

6. Viroid

Viroid l mt tc nhn nhim trng nh b gy bnh thc vt v c th mt vi nhim trng virus chm ca ng vt. Tc nhn ny ch c axit nucleic(phn t ARN dng vng kn, trng lng phn t 70.000-120.000) khng clp protein cu trc.

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IV. PHN LOI VIRUS

C nhiu cch phn loi virus. Hin nay vic phn loi virus da theonhng tiu chun c bn sau y:

- Loi axit nucleic (ADN hoc ARN) v cu trc ca chng (s si).- i xng ca capsid.

- C hoc khng c v ngoi (envelope).

- Cu trc gen virus

- ng knh v s lng capsomer ca virus

- Cc enzyme

- Nhy cm vi ether

- Tnh khng nguyn- Triu chng hc

Cn c vo cc tiu chun trn chia virus ra thnh cc h (...viridae),ging (...virus), loi v type virus.

Theo s phn loi hin nay, cc virus ca ngi v ng vt c xngsng c chia thnh 22 h khc nhau: 8 h virus cha ADN v 14 h viruscha ARN.

Cc h virus cha ADN gm c:

- Parvoviridae - Iridoviridae

- Polyomaviridae - Poxviridae

- Papillomaviridae - Hepadnaviridae

- Adenoviridae - Herpesviridae

Cc h virus cha ARN gm c:

- Reoviridae - Paramyxoviridae

- Picornaviridae - Rhabdoviridae- Astroviridae - Filoviridae

- Caliciviridae - Arenaviridae

- Togaviridae - Coronaviridae

- Flaviviridae - Bunyaviridae

- Orthomyxoviridae - Retroviridae

V. S NHN LN CA VIRUS

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- cc virus cha ADN hai si: u tin cc thng tin di truyn ca virusc sao chp t ADN sang ARN thng tin nh ARN polymerase ph thucADN. Cc ARN thng tin ca virus s ng vai tr truyn tin to ra ccADN v cc protein ca virus.

- cc virus cha ARN mt si dng: cc thng tin di truyn ca virusc m ha trong phn t ARN s sao chp sang mt ARN b sung nh cARN polymerase ph thuc ARN v t chng c lm khun mu to racc ARN ca virus. ng thi cc ARN ca virus cng ng vai tr ca ARNthng tin tng hp nn cc protein ca virus.

- cc virus cha ARN c enzyme sao chp ngc: cc thng tin ditruyn c m ha trong ARN ca virus c sao chp ngc to ra mtADN trung gian nh c enzyme sao chp ngc (reverse transcriptase; ADN

polymerase ph thuc ARN).T ADN trung gian cc m thng tin di truyn ca

virus s c sao chp sang ARN thng tin, t chng tip tc c sao chp tng hp ra cc ARN virus v cc protein virus.

4. S lp rp cc thnh phn ca virus

Sau khi cc thnh phn c bn ca virus c tng hp v c tchly phong ph trong t bo ch th s bt u qu trnh lp rp. Hnh nh c chlp rp cc thnh phn ca virion xy ra t pht do kt qu ca s tng tc

phn t c bit ca cc cao phn t capsid vi axit nucleic virus to thnhcc virion.

Vic lp rp ng s to ra cc virus hon chnh (cc virion) v nu lprp sai s to ra cc virus khng hon chnh (ht DIP) hoc to ra cc virus gi(Pseudovirion).

5. S gii phng cc ht virus ra khi t bo

Virus thot ra khi t bo ch theo nhiu kiu khc nhau ty theo loivirus.

Nhiu virus c gii phng theo kiu ph v mng t bo lm hy hoit bo v cc virus ng lot c phng thch. Hoc c gii phng nh s

xut bo (exocytosis) hoc qua cc rnh c bit m khng lm hy hoi t boch.

Cc virus c v ngoi c gii phng theo kiu ny chi qua cc ch cbit ca mng t bo ch v virus s nhn c mt phn ca mng t bo ch.

Thi gian nhn ln ca virus thng ngn hn rt nhiu so vi vikhun.V d t virus ban u, mt t bo b nhim virus cm c th to ra hngnghn virus mi sau khong 5 - 6 gi.

VI. HU QU CA S NHN LN CA VIRUS TRONG T BO

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Khi virus xm nhp v nhn ln trong cc t bo to ra cc th h virusmi th c th gy nhiu hu qu khc nhau ty thuc vo bn cht sinh hc cat bo v ca virus.

1.T bo b hy hoi

Sau khi virus xm nhp v nhn ln trong t bo th hu ht cc t bo bph hy . Do cc hot ng bnh thng ca t bo b c ch , cc cht cn thitcho t bo khng c tng hp m ch tng hp ra cc ht virus mi v vy t

bo b cht. y l trng hp hay gp nht .

nui cy t bo in vitro c th thy cc t bo b nhim virus bin dng,dnh li vi nhau, ly gii .

2. T bo b tn thng nhim sc th

Virus c th lm cho nhim sc th ca t bo ch b gy, b phn mnh,b o ln v trt t sp xp v gy ra cc hu qu nh:2.1. D tt bm sinh, thai cht lu

ph n c thai, c bit trong ba thng u ca thi k mang thai, m bnhim virus th s lm sai lch nhim sc th c th dn ti mt s thiu ht

bm sinh trong qu trnh hnh thnh bo thai v gy ra trng thi nhim viruscho bo thai .

2.2. T bo tng sinh v hn to khi u

Cc t bo b nhim mt s loi virus (ch yu l cc virus gy ra khi u)c hin tng mt c ch tip xc khi t bo sinh sn nn to ra nhng m tbo chng cht ln nhau .

3. To ra cc tiu th c trng cho cc virus khc nhau

Trong cc t bo nhim virus c th xut hin cc th vi trongnhn(Adenovirus ), hoc trong bo tng (tiu th Negri ca virus di ), hoc chai ni (virus si ). Bn cht cc tiu th c th do tch t nhng virion hocnhng thnh phn ca virion hoc c th l cc ht phn ng ca t bo khinhim virus .

Cc tiu th ny c th nhum soi thy di knh hin vi quang hc vda vo c th chn on gin tip s nhim virus trong t bo .

4. To ht virus khng hon chnh (DIP: Defective interfering particles)

Ht virus khng hon chnh l virus ch c capsid, khng c hoc ckhng hon chnh axit nucleic. Do vy cc ht DIP khng c kh nng nhn lnc lp khi vo trong cc t bo, c ngha l ht DIP khng c kh nng gynhim trng cho t bo. Nhng ht DIP c th giao thoa c hiu vi nhngvirus ng chng .

5. Cc hu qu ca s tch hp genom virus vo ADN t bo ch

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Axt nucleic ca virus tch hp vo ADN ca t bo ch c th dn ti cchu qu khc nhau:

- Chuyn th t bo (transformation) v gy nn cc khi u hoc ung th.

- Lm thay i khng nguyn b mt ca t bo.

- Lm thay i mt s tnh cht ca t bo.

- T bo tr thnh t bo sinh tan.

6 . Kch thch t bo tng hp Interferon

Interferon l nhng glycoprotein c trng lng phn t khong 17.000 -25.000 Daltons do cc t bo tng hp ra sau khi b kch thch bi cc cht cmng sinh interferon nh cc virus hoc cc cht cm ng khc.

C 3 loi Interferon: Interferon-alpha, interferon-beta v interferon-gama.

Cc loi ny c phn bit bi cc khng th c hiu. Interferon-alpha thngdo cc t bo bch cu sinh ra. Interferon-beta c sn xut bi cc nguyn bosi. Interferon-gama l mt lymphokin do cc t bo lympho T sinh ra.

Mt s tnh cht ca interferon:

- Tnh khng nguyn yu.

- Xut hin sm (vi gi ) sau kch thch ca cht cm ng.

-Tnh cht chng virus ca interferon mang tnh c hiu loinhngkhng c hiu vi virus: Interferon do cc t bo loi no sinh ra th chc tc dng c ch s nhn ln ca virus t bo ca loi (v d ch cinterferon sn xut t cc t bo c ngun gc t ngi mi c tc dng bo vcho ngi). Tri li, interferon c ph tc dng rng c ch s nhn ln canhiu loi virus khc nhau ch khng phi ch vi virus cm ng sinhinterferon.

- Interferon khng tc ng trc tip ln virus nh khng th m phnng c ch s nhn ln ca virus xy ra bn trong t bo.

C ch sinh interferon ca t bo:

t bo ngi c 15 gen khc nhau m ha cho interferon-alpha, ch c1 gen m ha cho interferon-beta v 1 gen m ha cho interferon-gama. Bnhthng cc gen ny trng thi c ch v khng hot ng. Cc cht cm ngsinh interferon c tc dng gii c ch cho cc gen ny lm cho chng tr lidng hot ng v do t bo s tng hp ra cc Interferon. Cht cm ngquan trng nht i vi cc gen alpha v beta l cc virus, nhng i vi gengama l cc cht hot ha lympho bo T. Hai loi interferon-alpha v interferon-

beta c tc dng chng virus mnh hn so vi interferon-gama. Cc interferon-gama c tc dng iu ha min dch v c ch cc t bo ung th mnh hn cc

interferon-alpha v interferon-beta.

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C ch tc dng chng virus ca interferon:

Interferon gn vo cc th th c hiu dnh cho interferon trn b mtmng t bo, gy ra gii c ch mt s gen m ha cc protein c ch virus.Di tc dng kch thch ca interferon c t nht 2 gen ca t bo c hot

ha tng hp ra 2 enzyme l: elF2 kinase v 2, 5-oligoadenylatesynthetase. elF2 l yu t khi ng cn thit cho vic gn ARN thng tin voribosome; elF2 kinase phosphoryl ha yu t elF2 v lm bt hot elF2 do ngn cn s tng hp protein ca virus. Oligoadenylate c tc dng hot haribonuclease ca t bo phn hy ARN thng tin ca virus, do c ch stng hp protein virus.

Nh vy, interferon ch th hin tc dng chng virus trong t bo sngv thc cht l kch thch t bo dng c ch enzyme phn hy ARN thngtin ca virus v c ch tng hp protein ca virus.

VII. KH NNG GY BNH

Virus c kh nng gy bnh cho ngi. Mt virus c th gy ra nhiu hichng khc nhau v ngc li mt hi chng c th do nhiu virus khc nhaugy ra.

Nhim virus c th chia lm hai loi chnh ty theo thi gian c tr cavirus trong c th:

1. Tc ng ca virus ln c th xy ra trong thi gian ngn

Loi ny bao gm hai hnh thi nhim virus sau y:- Nhim virus cp tnh: c c im l thi gian bnh ngn( t mt vi

ngy n mt vi tun l ) v tip theo sau cc triu chng c trng cho tcnhn gy bnh pht trin. Nhim virus cp c th kt thc khi hon ton, hocmt phn, hoc t vong.Trong qu trinh hi phc virus b thi tr.

- Nhim virus khng biu l: nhim virus khng c triu chng, virus trong c th mt thi gian ngn v thi tr nhanh. Xc minh c virus trong cth nh pht hin hiu gi khng th trong huyt thanh.

2. Tc ng ko di ca virus trong c thC bn hnh thi nhim trng ca loi ny u c c im l trng thi

mang virus ko di:

- Nhim virus tn ti dai dng: virus tn ti dai dng khng c triu chngnhng c km theo thi virus ra mi trng chung quanh. Hnh thi ny c thc hnh thnh sau khi bnh phc sc khe. N ng vai tr quan trng trongdch t v l nguy c trc tip gy nhim mi trng. V d bnh vim gan B.

- Nhim virus tim tng: virus tn ti dai dng, khng c triu chng

nhng khng thi virus ra mi trng xung quanh. Trong nhim virus tim tngvirus c th di dng tin virus, axit nucleic ca virus c th tch hp vo b

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gen ca t bo ch. Trong mt vi trng hp do nh hng ca mt hay nhiutc nhn nh chn thng, stress, gim min dch, v.v..., tin virus c th chot ha v chuyn sang trng thi nhn ln, gy bnh cp tnh cho c th. V d

bnh herpes.

- Nhim virus mn tnh: virus tn ti dai dng c km theo mt hoc vitriu chng lc ban u, sau tn thng bnh l tip tc pht trin trong mtkhang thi gian di. c im trong tin trin ca nhim virus mn tnh l cnhng thi k sc khe bnh nhn kh ln, bnh thuyn gim, xen k vinhnhg giai on bnh bng pht, ko di mt vi thng c khi hng nm.

- Nhim virus chm: y l mt hnh thi tc ng c bit gia virus vic th v c nhng c im l thi gian nung bnh khng c triu chng kodi nhiu thng hoc nm, tip theo l s pht trin chm nhng khng ngngtng ln ca cc triu chng v kt thc bng nhng tn thng rt nng hoc t

vong.

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VIII. NUI CY VIRUS

Virus ng vt c th nui cy c trn mt h thng t bo sng baogm ng vt cm th, phi g v cc t bo nui trong ng nghim (in vitro)

1. ng vt th nghim cm thTrc khi k thut phi g v nui cy t bo c pht minh th tim

nhim ng vt l phng php duy nht nui cy virus. Mi loi virus cmt vi ng vt cm th ring. V d i vi Arbovirus, ng vt th nghimcm th thng c s dng l chut nht trng mi .

Ty theo loi virus c th s dng nhng ng vt cm th khc nhau nhchut nht cn b, chut nht, chut lang, th, kh... v nhng ng gy nhimkhc nhau: tim, ung, nh mi, mt.

Hin nay ng vt c s dng sn xut vaccine v phn lp mt s tvirus m ng vt th nghim l vt ch nhy cm duy nht hoc vt ch cchn l.

2.Phi g

Thng dng trng g p 9-12 ngy, lc phi to thnh, khoangi v khoang niu pht trin y .

Ty theo mc ch : phn lp, th nghim, sn xut vaccine v ty theoloi virus, c th tim nhim vo mng niu m (virus u ma, u vaccine,

Herpesvirus),vo khoang i (virus cm, quai b), vo khoang niu (virus cm,quai b , virus Newcastle).

3. Nui cy t bo

X l m bng trypsin tch ri t bo ri nui t bo trong ng nghimc cha cc mi trng nui c bit. T bo pht trin thnh mt lp t bo un bm vo mt trong cu ng nghim c gi l nui cy t bo mt lp.

Cc loi t bo thng dng trong nui cy virus:

- T bo nguyn pht: l nhng t bo c ngun gc t m ng vt, thc

vt hay cn trng c nui cy thnh mt lp t bo trong ng nghim thngdng nui cy phn lp virus. Cc t bo nguyn pht c c im ch sdng mt ln, khng th cy truyn nhiu ln c. Nhng m thng dng sn xut t bo nguyn pht l thn kh, thn bo thai ngi, thn chut ng,m ca phi g v.v...

- T bo thng trc: c ngun gc t m ng vt, thc vt hay cntrng c cy truyn nhiu ln m khng b thoi ho. Cc t bo thngtrc hin nay thng dng nh t bo Hela, Hep-2, Vero, C6 / 36,...

- T bo lng bi ca ngi: l dng t bo bo thai ngi. Dng t bo

ny c hnh thi bnh thng, nhim sc th lng bi c hnh th bnh thng ,c th cy truyn c nhiu ln (t 40-100 ln), chng khng cha cc virus

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tim tng nh cc loi t bo nguyn pht nui mt ln, do thng c sdng trong sn xut vaccine sng .

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BACTERIOPHAGE

Mc tiu hc tp

1. Trnh by c hnh thi v cu trc ca phage.2. Nu c mi quan h gia phage v vi khun tc ch.

Bacteriophage thng gi tt l phage c Twort pht hin T cunm 1915 v sau dHerelle cng pht hin c vi khun l. Phage l virusc kh nng xm nhim vi khun. Mi vi khun c th l vt ch ca mt hocnhiu phage. Phage c s dng kho st s lin h gia k sinh v vt ch,s nhn ln ca virus, vn chuyn cc yu t di truyn trong nghin cu sinh hc

phn t.I. HNH THI V CU TRC CA PHAGE

Nhng phage c kho st nhiu nht l nhng phage xm nhim E.coli.Hnh thi ca nhng phage ny di knh hin vi in t trng ging nh hnhthi ca tinh trng gm c u v ui.

u c cu trc i xng hnh khi, capsid hp bi nhiu capsomer kthp thnh mt cu trc hnh lng tr, thng thng c thit din thng hnh 6cnh. Bn trong u cha axit nucleic. Phn ln phage cha ADN 2 si, cng c

phage cha ADN 1 si. Nhng phage cha ARN 1 si cng c tm thy.ui c cu trc dng hnh xon. phage T2 mt nh ca u c ko

di thnh ui di 95 nm. N hp bi 2 phn lng vo nhau: ng bn trongcng ng knh 8 nm thng vi u, v bn ngoi hnh xon ng knh 20nm co rt c theo chiu dc nh ci l xo. Tn cng l mt tm 6 gc migc c mt si nh vo. Phn tn cng ca ui to nn mt h thng ca

phage bm vo b mt vi khun.

II. MI QUAN H GIA PHAGE V VI KHUN TC CH

1. Phage c lc v phage n haLc gp vi khun cm th, phage hp ph ln b mt ca vi khun v axit

nucleic c bm vo bn trong. Axit nucleic cung cp m di truyn t bovi khun cho tng hp axit nucleic v cc n v protein capsid ca phage. Ccthnh phn ny t lp rp hnh thnh nhng phage con. Vi khun b ly gii v

phage t do c phng thch. l phage c lc.

Nhiu phage c gi l phage n ha lc xm nhim vi khun th axitnucleic ca phage tch hp vo nhim sc th ca vi khun. Trong qu trnh

phn bo axit nucleic ca phage c sao chp ng thi vi nhim sc th ca

vi khun. dng tch hp axit nucleic ca phage c gi l prophage. Vikhun cha prophage nhim sc th gi l vi khun sinh tan. Sau mt s ln

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phn bo prophage c th tch ri khi nhim sc th v tr thnh phage clc. N cho tng hp nhng phage con, lm tan vi khun v phng thch nhng

phage c lc.

Cng c trng hp vi khun sinh tan mt prophage v tr thnh vi

khun bnh thng.2. H thng sinh tan

Nhng phage n ha khng ly gii vi khun m chng nhim v hnh nhsao chp ng thi vi vi khun trong nhiu th h.

vi khun sinh tan axit nucleic ca phage tch hp vo nhim sc th cavi khun v c gi l prophage.

H thng sinh tan c nhng c im sau :

2.1. Min dchLc mt vi khun mang mt prophage n tr nn min dch vi phage tngng. Phage c th c hp ph nhng ri b loi ra khi t bo lc phn bo.

Nhng phage n ha lm xut hin t bo cht trn p c ch s nhn ln caphage v phong ta s tch ri ca phage.

2.2. S cm ng

Nhng vi khun sinh tan c th cm ng bng nhiu cch khc nhau phng thch phage c lc, v d : di nh hng ca tia cc tm phn ln vi

khun sinh tan phng thch phage. Cng c mt s trng hp prophage t ngtch ri nhim sc th v tr thnh phage sinh dng.

2.3. t bin thnh c lc

Hu qu ca s nhim phage mt vi khun hnh nh c xc nh bis cnh tranh gia s sao chp ca phage v s to thnh cht trn p. Nu qutrnh sao chp tin xa trc khi xut hin cht trn p th vi khun b ly gii.

Nu cht trn p xut hin sm th vi khun sng st v tr nn sinh tan.

Phage n ha cng c th t bin thnh phage c lc. Hai type binchng c quan st. Trong type th nht s t bin lm cho phage khngvi cht trn p, trong type th 2 phage mt kh nng to thnh cht trn p.

3. Phng php kho st phage

V cng nh tt c virus phage ch nhn ln t bo sng. V kch thckhng cho php quan st trc tip nu khng c knh hin vi in t nn cnthit theo di hot ng ca chng bng phng tin gin tip. Trong mc chny ngi ta s dng s kin mt ht phage cho vo mt lp vi khun ang phnchia trn thch dinh dng s to nn mt vng phn gii sng trn film mc ca vi khun ang pht trin. Vng phn gii ny gi l mt plaque; n

c to thnh do t bo vi khun b nhim phage phn gii v phng thchnhiu ht phage mi, nhng phage ny lin xm nhim nhng t bo vi khun k

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cn. Qua trnh ny tun t lp li cho n khi s pht trin ca vi khun trnda thch ngng li do ht thc n v tch t phm vt c. Lc thao tc kholo, mi ht phage to nn mt plaque. Mi vt liu cha phage c th nhlng nh th bng cch pha long thch hp v cho vo da thch dinh dng

mc dy c vi khun nhy cm. m plaque cng tng t nh m khun lctrong nh lng vi khun.

Phn lp v tinh ch: kho st nhng tnh cht vt l v ha hc caphage cn phi iu ch mt lng y virus tinh ch khng cha vt liu tbo. Trong mc ch mi trng lng nui cy vi khun vt ch c tipchng phage v cho n khi mi trng nui cy hon ton ly gii. Lc nydch thy phn ch cha ht phage v mnh vn vi khun, chng c ly ring

bng li tm phn bit. Phn phage li tm c th lm dung dch treo v ra rikho st nhng tnh cht vt l v ha hc hoc soi knh hin vi in t.

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III. NG DNG CA BACTERIOPHAGE

1. ng dng trong nghin cu sinh hc phn t

Phage c dng lm phng tin vn chuyn gen trong nghin cu sinh

hc phn t, rt nhiu phage c s dng nghin cu di truyn vi khun. Schuyn np l qu trnh vn chuyn gen vi khun qua trung gian ca phage.Mt vi chng phage v d phage P22 c th vn chuyn bt c gen no ca vikhun, l s chuyn np tng qut. Trong s chuyn np c hiu, mt s

phage c hiu v d phage ch vn chuyn mt s gen ca vi khun cho sangvi khun nhn.

2. ng dng trong chn on vi khun v dch t hc

Phage c s dng nh type phage vi khun. Mi loi vi khun cth gm nhiu type phage khc nhau do bn cht ca receptor vi khun i vi

cc phage khc nhau. Ngi ta chn mt s b phage. Trong mi b phage,mi phage ch lm li gii mt type phage ca mt loi vi khun. Vic nh type

phage c gi tr v chn on vi khun v nht l v dch t hc.

Phage n ha c th tch hp vo nhim sc th vi khun bch hu; ch trng thi sinh tan vi khun bch hu mi to thnh c t.

3. ng dng khc

Tuy c kh nng xm nhim vi khun, phage khng c s dng iu tr bnh nhim trng v nhng th nghim iu tr khng em li kt qu.

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PHNG NGA V IU TR BNH VIRUS

Mc tiu hc tp

1.Trnh by c cc bin php phng nga s tip xc vi tc nhn nhimtrng.

2. Trnh by c phng php phng nga v iu tr bng liu php mindch c hiu.

3.Trnh by c phng php phng nga v iu tr bng liu php ho hc.

I. PHNG NGA S TIP XC VI TC NHN NHIM TRNG

Cc bin php phng nga nh: ci thin v sinh, ci thin ngun ncsinh hot, cch ly bnh nhn, kh trng tit trng dng c v mi trng, dittc nhn trung gian truyn bnh... c p dng thch hp trong tng bnh, tngv dch.

Nhng bin php k trn gp phn ng k gii quyt bnh virus,nhng vic thc hin i hi nhiu cng sc v tin ca. Bin php dit tc nhntrung gian truyn bnh l mt bin php phng dch hu hiu.

II. PHNG NGA V IU TR BNG LIU PHP MIN DCH CHIU

Liu php min dch nhm lm tng cng min dch bo v c hiu cac th i vi cc thnh phn ca virus. Bao gm liu php min dch ch ngl chng nga cc vaccine chng virus v liu php min dch th ng l timcc globulin min dch.

1. Liu php min dch ch ng

Cc vaccine chng virus, cng nh tt c cc loi vaccine, d trn skch thch ch ng h thng min dch bng cch a vo trong c th khngnguyn ca tc nhn nhim trng c lm mt kh nng gy bnh cho

ngi, lm cho c th t to ra tnh trng min dch chng li tc nhn gy bnh.Tnh trng min dch m c th c c sau khi s dng vaccine l kt qu cas p ng min dch i vi cc thnh phn khng nguyn c trong vaccine.

Vic s dng vaccine phng bnh l mt phng thc ch yu lmgim t l mc v t l t vong ca cc nhim trng virus. Cc vaccine virusc s dng hin nay c th bao gm virus sng c lm gim c lc,virus b bt hat, hoc cc thnh phn cu trc ca virus. Cc thnh phn cutrc ca virus c th c ch to nh k thut ti t hp ADN hoc thu c tvirion.

1.1. Vaccine bt hot (cn c gi l vaccine cht )

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Loi vaccine ny c sn xut bng cch lm bt hot virus bng cc tcnhn l ha nh nhit, formol, beta propiolacton hoc tia cc tm. Nh vy, loivaccine ny bao gm cc virion tinh khit v b git cht, do mt kh nnggy nhim trng, mt kh nng gy bnh.

Vaccine bt hot gy nn s p ng min dch tt lc tim liu lng,ng thi gian. N c th chng nga cho nhng i tng b suy gim mindch cng nh ph n c thai.

Vaccine bt hot thng khng gy c min dch lu bn so vivac

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