Antimicrobial sensitivity

Biochemical tests

cultureMicroscopic examination

Laboratory diagnosis

pathogenicityBacteria

penicillin1- Oxidase + Ve2- Utilize : Glucose- maltose

Chocolate blood agar ( transparent or grey colonies incubation in CO2

Gram –Ve dipiococci( intracellular in pus cells )

CSFPyogenic meningitides ( headache- vomiting- stiff neck )

Niesseria meningitidis

Resistant to penicillin

1- Oxidase + Ve2- Utilize : glucose only

1- Modified New York City ( MNYC)2- Thayer martin ( transparent or grey colonies )

Gram –Ve dipiococci( intracellular in pus cells )

Urethal & cervical exudates- urine – eye swab

Gonorrhoeae ( sexual transmitted) – acute conjunctivitis in infants of mother with Gonorrhoeae

Niesseria gonorrhoeae

1- Gram Negative cocci

2- Gram Positive cocci

Antimicrobial

sensitivity

Biochemical tests

cultureMicroscopic

examination

Laboratory diagnosis

pathogenicityBacteria

1- All staphylococci are catalase + Ve2- coagulase +Ve3- DNAase +Ve4- liquefy gel5- hemolyse blood

1-Blood agar ( yellow to cream colonies some strains beta- haemolytic2- macConkey agar (small deep pink due to lactose fermentation )3- Mannitol salt agar agar ( yellow due to Mannitol fermentation )4- nutrient agar ( golden yellow )

Gram +Ve in cluster ( grape like cluser )

Pus –skin swab - sputum – CSF – blood – Faeces – vomit in food poisoning

Pneumonia – impetigo – wound infection – osteomyelitis – food poisoning due to enterotoxins Normal flora in 40% of health people

Staphylococcus

aureus

Penicillin &

Erythromycin

1- sensitive to Bacitracin disk2- anti- streptolysin O ( ASO )

1- Blood agar ( small white beta- haemolytic colonies )2-Crystal violet blood agar ( selective for S. pyoggenes )3- macConkey agar ( no growth )

Gram +Ve in chains,pairs – some strains are capsulated

Throat swab – pus swab - blood

Sore throat ( tonsillitis, pharyngitis ) – scarlet fever – otitis media – impetigo – rhrumatic fever – glomeruloneph

Streptococcus

pyogenes

( Group A )

ritis - Normal flora in upper respiratory tract

Penicillin &

Erythromycin

1- Hippurate hydrolysis +Ve by adding ferric chloride give heavy brown precipitate2- CAMP ( extracellular protein produced by S. agalactiae enhance haemolysis with S. aureus beta- lysin

1- Blood agar ( grey ,mucoid beta- hemolytic colonies )2- kanamycin blood agar ( selective for S. agalactiae )3- MacConkey agar

Gram +Ve in chains,pairs – some strains are capsulated

CSF – ear swab – vaginal swab - blood

Septic abortion – gynecological sepsis – UTI – neonatal septicemia – meningitis – normal flora in femal genital tract

Strepotococcus

agalactiae( Group

B )

Penicillin , Erythromycin & co-

trimoxazole

1- Bile solubility test (clear turbidity) 2- sensitive

1- Blood agar ( mucoid alpha- haemolytic2- chocolate agar with CO2

Gram +Ve elongated diplococcus – short chains

Sputum – exudates- blood - CSF

Lobar pneumonia – bronchitis – meningitis – conjunctivitis –

Strepotococcuspneumoni

ae

to optochin disk

capsulatednormal flora in upper respiratory tract

Gram +Ve in chains

Endocarditis- dental caries – bacteraemiaNormal flora in upper respiratory tract

StrepotococcusViridians

Sensitive to Ampicillin & resistant

to Cephalospo

rin

1- Aesculin hydrolysis +Ve ( Black- brown color )2- litmust Milk decolorization ( reduce litmus milk & give pale yellow color)3- growth in 6.5% NaCl & 40% bile

Grow over wide temperature 10-45 C1- Blood agar 2- macConkey agar ( small pink colonies due to lactose fermentation)3- CLED( small yellow colonies due to lactose fermentation)

Gram +Ve in chains,pairs

Site of infection

UTI – biliary tract – wound- ulcers – endocarditis- meningitis – normal flora in vagina & intestinal tract

Strepotococcus

Fecalis( Enterococcus )

( Group D )

species Haemolysis Sensitivity to Bacitracin

CAMP Aesculin Hydrolysis

Streptococcus pyogenesGroup A

Beta sensitive negative negative

Strepotococcus agalactiaeGroup B

Beta resistant positive negative

Strepotococcus FecalisGroup D

Non haemolytic resistant negative positive

3- Aerobic and facultative anaerobic Gram negative Bacilli

Biochemical tests

cultureMicroscopic examination

Laboratory diagnosis

pathogenicityBacteria

1- indole :+ Ve2- motility : +Ve3- MR : +Ve4- nitrare : +Ve

IMVC++--

1- Blood agar ( some strains are haemolytic2- MacConkey : pink colonies due to lactose fermentation3- CLED : yellow colonies due to lactose fermentation4- XLD : yellow color5- DCA : growth inhibited6- EMB : black colonies with metallic shine6- KIA : yellow butt – yellow slant produce Acid & gas

Gram –Ve motile rods

Urine – pus – faeces – CSF - blood

UTI – wound infection – meningitis – bacteraemia in neonates - diarrhea

E. coli

1- citrate : +Ve2- urease: +Ve3- MR: +Ve/-Ve4- Vp : +Ve/-

1- blood agar : large grey white mucoid colonies2- macConkey : mucoid pink colonies due to lactose fermentation3- CLED : yellow colonies due to lactose fermentation

Gram –Ve non motile capsulated rods

Urine – pus – sputum

Chest infection (bronchopneumonia – abscesses ) - UTI

Klebsiella pneumoni

a

Ve5- nitrate : +Ve

IMVC--++

6- KIA : yellow butt – yellow slant produce Acid & gas

1- urease : +Ve2- PPA: +ve3- motility : +Ve4- Citrate : +Ve

1-bloodagar : fishy odour – swarming2- MacConkey & XLD: swarming inhibited due to bile salts3- CLED : swarming inhibited due electrolyte deficient4- KIA : yellow butt – red slant produce gas & H2S

Gram -Ve pleomorphic rods actively motile

Urinr – pus UTI ( Alkaline ) – abdominal & wound infection

Proteus mirabilis

1-KSA :a- Pink ( alkaline ) slope & yellow ( acid ) butt indicating fermentation of glucose not lactoseb- produce gas except S. typhic-produce H2S except S. paratyphi A

1-blood culture ( blood Columbia agar - diphasic medium )2- blood agar ( subculture ):grey- white some strains appear mucoid3- XLD(selective media ):pink color with black center due to H2S4- MacConkey & DCA : pale color with black center

Gram -Ve rods actively motile – non- sporing except S. typhi

1- for enteric fever ( blood- faeces- urine )2- for enterocolitis ( faeces – blood )3- for bacteraemia

1- Enteric fever ( typhoid & paratyphoid )2- enterocolitis3- Bacteraemia

salmonella

2- citrate : +Ve except S. paratyphi A3- MR: +Ve

IMVC-+-+

4- Widal test ( O & H

antibodies )

( blood )

1-KIA : pink (alkaline ) slope & yellow( acid ) butt indicating fermentation of glucose not lactose – no H2S production2- MR: +ve

Selective media1-XLD: red-pink colonies without black center2-MacConkey & DCA: pale color due to non lactose fermentation –S. sonnei produce pink color on prolonged incubation

Gram -Ve1-fresh faecal specimen2-transport medium for delayed faecal specimen

Bacillary dysentery or shigellosis- transmission by faecal oral route

Shigella

1-Catalase : +ve2- MR: +ve

Optimum temp. 27C ( culture should be incubated at room temp.)1-blood agar: small shiny non haemolytic colonies after 24- 48hr.2-macConkey :very small translucent pink after 24-48hr. ( non lactose fermentation but it

Small Gram –Ve coccobacillus – capsulated show bipolar staining with methylene

Bubo aspirates- sputum- blood

Plague ( Bubonic – pneumonic – septicaemic Transimission : 1-infected fleas (Xenopsylla ) from rats or

Yersinia pestis

take up red dye of indicator in the medium )

blue, Giemsadomestic animals ( dogs,cats )2- inhaling organisms in airborn droplets

1- oxidase : +Ve2- Citrate : + Ve3- oxidation- fermentation test :Yellow color ( in oxidative opened tube )

1- blood agar: large flat spreading colonies often are haemolytic2-macConkey : pale color due to NLF3- CLED : geen color due to NLF3- KIA : pink-red slope with metallic appearance – pink-red butt

Gram –Ve motile rod some strains are capsulated- obligatory aerobic Produce pigmenta- blue geenb-yellow green

Pus – urine- sputum- effusions - blood

Opportunistic hospital acquired infection1-skin infection ( burn, wound,ulcers )2- UTI ( following catherization )3- Respiratory tract infection 4- ear infection (otitis externa)5- eye infection

Pseudomonas

aeruginosa

1- oxidase : +Ve2-indole : + Ve

Grow best in alkaline pH1- TCBS ( selective media ):sucrose fermenting yellow colonies 2- KIA: red slope and yellow butt3- blood agar : often produce beta

Gram –Ve curved rods motile ( with single flagellum at

Faecal specimen

rice water stool ( enterotoxin activates adenylate cyclase within

Vibrio cholera

haemolytic coloniesone end )intestine result in secretion of large fluid & electrolytes transmission by faecal oral routes

1-catalase : +Ve2-oxidase : +Ve3- urease : +Ve

B rucella is difficult to isolate & it more isolated from blood in acute brucellosis during time of fever1- tryptone soya (tryptic soy )diphasic medium :B. abortus requiring CO2 & keep for weeks with subculture every few days2- serum dextrose agar : smooth,mucoid,rough colony3- B. abortus & B. suis produce H2S

Small Gram –Ve coccobacilli or short rods

1-Blood or bone marrow in acute stage2- serum for serology

Brucellosis or undulant fever ( zoonotic disease )

Brucella

1-Oxidase:+Ve 2-Nitrate reduction : +Ve

Grow best moist CO2 & media contain haemin & NAD ( factor X ) or NADP ( factor V )1-chocolate agar2- satellitism test : S. aureus in blood agar produce factor V & haemin released by haemolysin enhance growth of H. influenza

Small Gram –Ve coccobacillus or short rod

CSF- nasopharyngeal specimens – pus – blood ( specimens must be cultured as

1-pyogenic (purulent ) meningitis in young children below 5 years old2- pneumonia (adult )3- acute epiglottitis

Haemophilus

influenzae

soon as possible & not refrigerated )

( fatal airway obstruction )4- cellulitis

Oxidase : +VeStrict aerobic ( specimens must be cultured as soon as possible )1- Charcoal cephalexin blood agar ( selective & enrichment media ) : incubated for 2-6 days in CO2 moist aerobically produce small mercury like mucoid colonies

Small capsulated Gram –Ve cocobacillus ( singly or in chains )

Nasopharyngeal secretion collected by aspiration

Whooping cough ( infection of mucosa of upper respiratory tract )

Bordetella pertussis

1- oxidase : +Ve2- catalase : +Ve3- Na hippurate hydrolysis : +Ve

Strictly microaerophilic reduired (10% CO2 ) – thermophilic ( 36 – 43 c )1- Blood agar : non haemolytic droplet like colonies2- Butzler virion medium : selective media

Spirally curved motile G-Ve , with faecal smear (1% basic fuchsin)Appear linked to wings of gulls or "S" or comma shape

Diarrheal feces contain blood ,pus, mucus

Enteritis – watery diarrhea or dysentery ( main source are unpasteurized milk – fecal oral route )

campylobacter

1- oxidase : +Ve2- catalase : +Ve

Microaerophilic required CO2 ( grow slowly forming grey translucent colonies within 3-7 days1- blood agar : slightly beta –

Small spiral or S shape G-Ve

Gastric biopsy – stool - serum for

Chronic gastritis lead to ulceration & may cause

Helicobacter pylori

3- urease : +Ve

haemolytic serologygastric carcinoma

4- Anaerobic Gram Negative Bacteria

1- They ferment wide ranges of carbohydrates

Strict anaerobic they fastidious they require media containing blood & menadione ( vit. K ) 1- blood agar ; grey , non haemolytic

G-Ve rods pleomorophic

Pus – exudates- infection tissue -

Abdominal infection ( particularly following

Bacteroides fragilis

( glucose – maltose – lactose )2- Aesculin hydrolysis : +Ve3- can grow in 20 % Bile tolerant test

coloniesbloodsurgery ) – peritonitis – gynaecological infections ( puerperal sepsis )- lung , cerebral abscesses – soft tissue infections

5- Anaerobic Gram positive spore forming bacilli

Gas gangrene ( myconecrosis )

Clostridium

– food poisoningperfringens

Tetanus ( lock-jaw ) , fatal disease caused by neurotoxin

Clostridium tetani

Fatal food poisoning cause paralysis ( botulism )

Clostridium

botulinum

Antibiotic associated diarrhea ( pseudomembranous colitis )

Clostridium difficile

6-Facultative anaerobic Gram positive spore forming bacilli

Anthrax ( cutaneous – pulmonary –

Bacillus anthracis

meningoencephalitis ) by herbivore as sheep, cattle, goats

Food poisoning from infected rice & other cereals

Bacillus cereus

7-Facultative anaerobic Gram positive non spore forming bacilli

Diphtheria ( nasal , nasopharyngeal , tonsillar diphtheria ) in young children – odema of neck – grey yellow membrane , it can block the passage of air & cause death

Corynebacterium

diphtheriae

Meningitis & septicemia

Listeria monocyto

mainly in ( neonate , pregnant women , elderly persons

genes

8- Spirochetes

Sexual transmitted disease cause 1- sexual acquired Syphilis2-congenital acquired Syphilis

Treponema

pallidium

Leptospirosis ( Flu- like illness ) by infected animal urine as dogs

Leptospira

interrogans