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Sharq Elneil College

School of Medical Laboratory Sciences

Department of Microbiology

Medical Bacteriology course

Mr.Mahadi Hassan Mahmoud Bsc, Msc, MIBMS Microbiology

08 April 2014

genus yersinia includes

yersinia pestis, the cause of plauge

y.pseudotuberculosis

y.enterocolitica, important causes of diarrhoeal disease

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francisella tularensis occasionally causes septic infections.

several species of pasteurlla are primarily animal pathogens but also causes human disease.

Gram-negative rod short, pleomorphic

Intracellular pathogen

Zoonotic infection

exhibit bipolar staining.

they are catalase positive,

oxidase negative,

microaerophilic or facultative anaerobic.

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World-wide problem

India has had latest scare (100s infected)

Sporadic cases in the U.S., south-western mostly

Usually associated with contact with squirrels and other urban animals

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Flea bite

Bacilli travel to lymph nodes

Infection results in swelling and pain (Bubo seen in picture below)

High fever, chills, headache, nausea

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Clinical Syndromes (Septicemic Plague)

Can penetrate and invade bloodstream

All organs infected

Lungs (secondary pneumonic plague)

Danger to close contacts

Clinical Syndromes (Primary Pneumonic Plague)

Spread via respiratory droplets

1 bacilli can cause disease in patient

Severe hemorrhaging

Death in hours

100% mortality if untreated, or late treatment

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50-75% mortality when it goes to bloodstream

Endotoxin shock primary problem

Intravascular coagulation

Multi-organ failure

“bruising” on skin……this is how it got the name the ”black death”

See the same thing with Neisseria meningitidis

Yersinia pestis and plauge

Plauge is an infection of wild rodents, rodents, rodents, transmitted from one rodent to another and occasionally from rodent to human by the bites of fleas (black death).

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I. Bubonic Plague: Interhuman Transmission:

> Bubonic Disease >Pneumonic

Plague > Exhales the Organism in

Droplets.

Pestis Minor:

ii. Septicaemic Plague:

iii. Pneumonic Plague:

Symptoms

After i.p of 2-7days,there is high fever and painful lymphadenopathy, common with greatly enlarged, tender nodes (buboes) in the groin of axillae. vomiting and diarrhoea may occur with early sepsis. later D.I.C. lead to hypotension, renal and cardiac failure. y. p, multiplies intravascular and can be seen in B. smears.

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Specimens:

Blood is taken for culture

Aspirates of enlarged lymph nodes for smear and culture.

Acute and convalescent sera may be Examined for antibody level

Pneumonia sputum is cultured,

Meningitis C.S.F is taken for smear and culture.

Stained with giemsa

waysons

I.F stain.

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Culture: all materials are cultured on

B.A

MaCconkey

infusion broth.

on solid media growth is slow but b.

cultures are often positive in 24hrs.

Serology:

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Sensetive to

streptomycin.

Tetracycline

some times given in combination.

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A Quarantinable Disease.

Control of Urban Plague:

Garbage Disposal.

Y. enterocolitica and Y. pseudotuberculosis

These are non lactose fermenting

G-ve rods that are Urase+ and Oxid-.They grow best at 25 cand also motile, but not motile at37c,

Diagnostic tests:

Specimen, culture, serology.

Treatment: most yersiniae infections with diarrheal are self limited.

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Francisella Tularensis and

Tularemia

F.Tularences, is widely found in animal reservoirs and transmitted to human by biting arthropods, inhalation or ingestion of contaminated water or food.

Morphology and identification

F.T, is small G-ve pleomorphic rods, it rarely seen in smears of tissue.

Specimen: blood is taken for serologic tests.

Culture:

growth does not occur in most ordinary media

small colonies appear in 1-3 days on glucose cysteine B.A incubated 37c under aerobic condition.

the organism identified usually by its growth requirement and I.F stain.

Caution: the organism is highly infectious.

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Serology:

there is one or more AG can cross react with brucella.

Diagnostic tests:

generally smears and cultures are not contributory

diagnostic tests rests on serology, paired serum collected 2 weeks apart can show arise in titer, titer of 1:60 is highly suggestive.

Antibiogram

Sensetive to:

Streptomycin

Gentamicin

Tetracycline equally effective, but relapses occur morely frequently.

Ceftriaxone is not effective.

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These are primarily animal pathogens

non motile

G-ve coco bacilli

They are aerobe and facultative

anaerobe they are grow in ordinary

media at 37c .they are O+ve, Cat+ve.

Pathology The most common presentation is a history

of animal bite followed by an acute onset

of redness, swelling and pain, fever is often

low grade, lymphadenopathy is variable.

infections some times present as

bacteremia or chronic respiratory infection

without an evident connection with

animals.

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species routine

nutri-

ent

media

bile

salt

media

Motil

ity

At 22c

At

37 c Acid (no gas)

from

maltose

sucrose

y. pestis + + - -- + -

y. pseudo-

tuberculosis

+ + + - + -

y. enterocolitica + + + - +b +

p. multocida + - - - - +

F tularensis - - - - + -

species slicin indol

e

urea

se

oxidas

e

cat onpg Orithine

decarbo

xylase

Y. pestis + - - - + + -

Y. pseudo

tuberculosis

+ - + - + + -

Y. enterocolitica - - + - + + +

P. multocida - + - -/+ + - +

P. ureae - - + + + - +

F. tularensis … - - … +/- …. -

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