Gram Postive Bacillus

8/18/2019 Gram Postive Bacillus

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Ve Bacilli+Gram

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* There are 2 important clinically species :

1- Bacillus (( aerobic and faculitative anaerobic , spore forming ))2- Clostridium (( obligate anaerobic , spore forming ))




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acillus anthracis

*larg Gr+Ve bacilli. usually arranged in chain

*spore forming ,non motile bacilli.

*spores are oval , central& non-projecting

*capsule consists of polypeptide glutamic acid.

* polysaccharide cell wall .

*faculitative anaerobic .

* nonfastidious growth (( not need complex media ))

*highly infection organism

haracteristics

*infected animals, human are accidental host .

*spores remain viable for years in contaminated soil &

resistant heat up to 150 C for hour .

Habitat

*direct contact

*airborne routeTransmission

*capsule =antiphagocytosis

* There are 3 extotoxin :-

- Edma toxin . – lethal toxin .

*antrax exotoxin = CNS distress , respiratory failure &

anoxia

* Spore can survive in soil for years .

Pathogenesis

*cutaneous anthrax ( malignant pustule ) . fatal rate 10%

* gastrointestinal anthrax .

* inhalation anthrax .

*enteric anthrax (fatal rate 50%)

*pulmonary anthrax (woolsorters disease ) (fatal rate

50%)

*meningitis following anthrax bacteremia .

Diseases

(medusa head ) colonies on blood agar .

*McFadyean reaction (capsule stains red – mauve with

loeffler polychrome methylene blue .

*catalase

* DFA Test : Positive . (( Direct Fluorescent AntiBody ))

*non hemolytic colonies .

* capsule not observed in culture . but observed with

Indian ink stain

Laboratory

Identification




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acillus anthracis

larg Gr+ Ve bacilli , usually arranged in chain

Spore forming & motile bacilli

Spores are oval , central & non –projecting .

Non capsulated bacilli

faculitative anaerobes

nonfastidious growth(( not need complex media ))

Opprtunistic infection .

haracteristics

* soil ,vegetation , water , food includes cerals meat &

spicesHabitat

Foodborne routeTransmission

heat stable enterotoxin = causes emetic

gastroenteritis .

heat- labile enteroxin = causes diarrheal

gastroenteritis .

spore can survive in soil .

cytotoxic enzyme : Destruction Tissues .

Pathogenesis

* toxic food poisoning includes 2 types of infections :

1-emetic gastroenteritis ( severe nausea & vomiting )

2- diarrheal gastroenteritis ( abdominal pain & profuse

watery stool )

* ocular infection

* intravenous catheter .

Diseases

( medusa head ) colonies .

complete hemolysis on blood agar .(( Beta

Hemolytic ))

Laboratory

Identification




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acteriumCoryneb

gram +Ve bacilli (( club shaped )) .

aerobic and faculitative anaerobic .

non spore forming .

non Acid fast .

non motile .

catalase +Ve .

most (( but not all )) Ferment carbohydrate .

high guanine and cytocine content .

meta chromatic granulces .




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Corynebacterium diphtheriae

*Gr+ Ve Polymorphic bacilli (club-shaped) .

*cells appear in chineses-letter arrangement .

* non capsulate , non sporing , non motile .

*Facultative anaerobes .

*Ferment carbohydrate .

* Most grow well in lipid free media .

haracteristics

Nasopharynx & occasionally skin of human

Habitat

droplets spread

direct contactTransmission

Diphtheria exotoxin = block protein synthesis

Unknown Virulance Factors.Pathogenesis

diphtheria :

1- localized inflammation of the throat

2-

infecting organisms do not invade but rather

elaborate an exotoxin that spreads through blood

3-

pharynx , larynx , & nose are main sites

4- pseudo – membrane is formed & may lead to

respiratory obstruction

5-mainly affecting infants over 1 year old children &

young adults

6- Endocarditis

Diseases

Specific media for C.diphtheria :-

1- cysteine tellurite agar

2-

serum tellurite agar .

back colonies on blood tellurito agar

Use loeffler medium to recover C.diphtheria .

detection toxin by Elek test .

teelurite inhibit growth of most upper respiratory

bacteria and gram negative rods .

Laboratory

Identification




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Mycobacterium

gram +Ve bacilli .

non motile .

fastidious growth (( Need Complex media )) .

acid fast .

non spore forming .

aerobic .

Cell Wall Rich With Lipid (( making the organism resistant to mostdisinfects , detergents , common antibacterial )) .




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Mycobacterium tuberculosis

acid fast bacilli , slightly curved (ziehl – neelsen

stain : red cooler )

cell wall rich with lipid (( making the organism

resistant to most disinfects , detergents , common

antibacterial )) . non-capsulate , non –sporing , non –motile

obligate aerobes

highly infection organism

haracteristics

Strict human pathogen

Habitat

droplets spread

direct contact foodborn route (rarely)

Transmission

capsule = Antiphagocytois .

Ability to multiply inside macrophages .Pathogenesis

tuberculosis :

1- primary tuberculosis in lungs & lymph nodes

2-

progressive primary tuberculosis-tuberculous bronchopneumonia

- military tuberculosis

-tuberculosis meningitis- bone & joint tuberculosis

- genito- urinary tuberculosis3- post –primary tuberculosis :

-T.B.remains dormant for years after primary

tuberculosis

-it reactivates due to delayed hypersenseitivity

- it may involve all manifestation in progressive

Primary tuberculosis

Diseases

rough , dry & yellow colonis on Lowenstein –

Jensen medium after 2-3 weeks at 37 C

detection of acid fast bacilli under light

microscope .

tuberculin skin test + kuantiferon-TB test =

sensitive marker

Laboratory

Identification




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Mycobacterium leprae

acid fast bacilli , slightly curved (ziehl –neelsen

stain : red cooler )

cell wall rich with lipid (( making the organismresistant to most disinfects , detergents , common

antibacterial )) .

non-capsulate , non –sporing , non –motile

obligate aerobes

haracteristics

Strict human pathogen

Habitat

direct contact

airborne spread

incidence of disease in contact is low

spread in the community is slow

Transmission

principal target cell for this bacterium is schwann

cell

this bacteria causes anaesthesia & miscle

paralysis

Pathogenesis

leprosy :

1-

slow , chronic &progressive infection

2- minaly affects the skin & peripheral nerves

3- long incubation period , usually form 3- 5 years

4- tow forms of leprosy :

-lepromatous (lesions spread & involve mucous

membrane . this form is progressive & severe , large

number of bacteria are found in the body which acts

as kind of unlimited culture medium )

- tuberculoid (lesions are localized & tend to be

bening , this form is self – healing )

Diseases

no growth on Lowenstein – Jensen medium

detection of acid fast bacilli in smears or secretion

from lesions

diagnosis with specific skin test .

Microscope sensitive to : lepromatous .

Laboratory

Identification




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P Clostridium SP

(Anaerobic, spore-forming,Gram-positive Rods)

-All anaerobic, gram-positive rods capable of forming endospores was placed in the

genus (Clostridium).

-Clostridium spp was defined by four properties

1)presence of endospores.

2)strict(obligate) anaerobic.

3)inability to reduce sulfate to sulfite.

4)gram-positive cell wall structure.

-the Clostridium are ubiquitous in soil, water, and sewage and part of the normal flora

in gastrointestinal tract of animal and human.




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Clostridium tetani

larg Gr+ Ve bacilli

sporing , motile bacilli

spores are spherical , terminal ( drumstick )

non capsulate bacilli

obligate anaerobes

difficult to grow.because the organism is

extremely sensitive to oxygen toxicity.

Not ferment carbohydrates.

haracteristics

soil & commensal in intestinal tract of animal . spore remain viable after dry heat up to 160 C for

1 hour .

Habitat

Via major or minor wounds .Transmission

tetanolysin ( exotoxin) = lyses erythrocytes .

tetanospasmin ( exotoxin ) = neurotoxin that

affects CNS causing muscular rigidty and spasns .

spore formation.

Pathogenesis

*tetanus ( human & animals)

1- generalized tetanus

2-localized tetanus

3-neonatal tetanus

Diseases

swarming colonies on blood agar

detection of neurotoxin by serological method .Laboratory

Identification




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Clostridium perfringens

relatively larg Gr + Ve bacilli , usually arranged

in chain

non motile bacilli & capsulate bacilli

spores are oval , subterminal & non – projecting

spores rarely seen in infected materials

anaerobes , but it can tolerate exposure to air for

short time

hemolytic in culture.

Replicate rapidly

Type A is responsible for most human disease.

haracteristics

soil & water & intestinal tract of human and

animals

bacteria & spores common contaminants of raw

meats

spores remain viable after heat up to 100 C for up

to 3 hours

Habitat

direct contact

endogenous spread

foodborne route

Transmission

alpha toxin = destroys cell membranes

enterotoxin = associated with food – poisoning

DNAse = hydrolyses DNAPathogenesis

gas gangrene

food poisoning

septicemia.

Soft- tissue infections.

Diseases




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beta hemolytic colonies on blood agar

entire edge for colonies on blood agar

detection of alpha toxin via the nagler reaction

Laboratory

Identification

Clostridium difficile

larg Gr+ Ve bacilli usually arranged in chain

sporing , motile bacilli

spores are oval

obligate anaerobes

part of the normal intestinal flora

haracteristics

Soil & water & intestinal contents of various animals .

Faeces of 3-5 % of healthy adults.

Regularly , present in faeces of healthy adult infant .

Habitat

Endogenous spread .

Faecal – oval routeTransmission

toxin A ( enterotoxin) = antiphagocytosis

toxin B ( cytotoxin )

Pathogenesis

pseudo – membranous colitis

antibiotic- associated diarrhoea

Diseases




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difficult to isolate in ordinary media

detection toxins in faecesLaboratory

Identification




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Clostridium botulinum

larg Gr +Ve bacilli

sporng , motile bacilli

sporing are oval , terminal or subterminal &

projecting

non capsulate bacilli

obligate anaerobes

fastidious growth.

haracteristics

soil , vegetable & fruits are the normal habitat

canned products

spores remain viable after heat up to 100 C for up

to 3 hours

Habitat

Foodborne routeTransmission

spore formation

Botulinum toxin

Binary toxin.Pathogenesis

botulism

1- this food poisoning is intoxication rather than an

infection .

*Food borne botulism

*infant botulism

*inhalation botulism

Diseases

*irregulary round colonies on blood agar

* detection of toxin in the food or serum from the patient

is the way of confirming the diagnosis

Laboratory

Identification




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Bacilli VE +GRAM

اجع ر م ىلع دا م ت عالا متوة د م ت ع م

یة جرا خ تا ر ك ذ م و تا صخل م و

یھ ل ع دا م ت عالا مت يذل ا عجر م ل ا

اد كلي ھو م ت عا

Medical Microbiology

لف مل ل Patrick Murray

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Documents

Gram Postive Bacillus