yersinia, shigella, proteus

Yersinia

• Gram-negative rod or coccobacilli

• Facultative anaerobe

• Oxidase-positive

• Catalase-positive

• Non-spore-forming

human body temperature

Most species are flagellated at ambient temperatures, but

non-motile at

Y. pestis

Non-motile both at room and human body temp

Yersiniosis

Disease caused by Yersinia infection is called

Yersinia pestis

• transmitted mainly by fleas from rodents

• Human infections can occur - cuts, bites, scratches and aerosols

• cats are susceptible

Y. pseudotuberculosis

Wild roderns, lagomorphs, birds and environemnt

Y. enterolitica

• intestinal tract of wild and domestic animals

• Pigs are carriers of strains that are pathogenic for human

• Type III protein secretion system

• Yersinia out proteins (yops)

• Virulence factors that are common to pathogenic yersiniae:

• These virulence factors disable host immune defense

Type III protein secretion system

• Consists of assemblage of proteins that form a hollow tube-like structure through which effector

Yersinia outer proteins (Yops)

• Blocks phagocytosis and downregulates inflammatory responses

Yersinia pestis

• The Black Death killed ~60% of Europeans in the middle ages

• Previously thought it originated in China in the 1300s

• Introduced along silk road trade routes

• Europeans brought it to North America

Sweden

First evidence human plague from 4,900 years ago in

Neolithic decline (population decline)

• Spread during the ______

• Large settlements may have facilitated disease emergence

• Outbreaks likely started in larger communities, and spread along with trade

• Local lymphadenitis (bubo) [bubonic plague]

• Pneumonia (pneumonic plague)

• Septicemia (septicemic plague)

Yersinia pestis ( Bubonic Plague)

• plagie is manifested as:

• Justinian plague

• Black Death (estimated 17-28 million people in Europe died)

• Third Pandemic (estimated 10 million people died)

  • Yersinia pestis was officially identified

Three plagues

2-6 days

Initial signs and symptoms in human plague appear ____ after contact with the organism

• fever

• headache

• chills

• Swollen tender lymph nodes (buboes)

Symptoms

Swollen tender lymph nodes (buboes)

• Involve inguinal and femoral lymph nodes

• This reflects lymphatic drainage of organisms originating from fleabites on the lower leg

septicemia

• if untreated, plague progressed to ______

  • Fever,

  • lethargy,

  • seizures,

  • prostration

Yersinia pestis

Yersinia pestis

Y. Pestis SYLVATIC PLAGUE

• occurs as a cycle between wild rodents and fleas

  • Prairie dogs highly susceptible

• Can then serve as a source for other animals

• Cats and dogs can get sick if they eat infected rodent, or bitten by flea

• Bubonic

• Septicemic

• Pneumonic

Sylvatic Plague Three Forms

Bubonic

• lymphadenomegaky, most often submandibular LN following eating infected rodents

• May just look like abscess

• High fever

Fever

• may or may not follow bubonic form

• Hematogenous dissemination

• Death 1-2 days

Pneumonic

• may follow haemarogenous dissemination

• May be due to inhaling infectious droplets

• Serious zoonotic risk

• Another reason to beware the hissing cat - especially in endemic regions!

Dogs

____ less likely to develop clinical illness than cats

Streptomycin

Sylvatic plague

• treatment of choice is

• doxycycline

• Gentamicin

• Chloramphenicol

Sylvatic olague

• also reasonable choice for treatment

Parenteral antibiotics

Generally, start with _____ and switch to oral with improvement

Y. Pestis

Xeniosylla cheopsis, oriental rat flea

Yersinia oseudotuberculosis

• Most commonly sporadic disease, abscessation of internal organs

• Found in the intestine and can cause of enteric infections in variety of species

• Mammals, birds and possibly humans

• Cold wet weather

• Poor diet

• Association with stressful manipulations (ex. handling farmed deer)

Y. pseudotuberculosis

• Cause enteric disease in ruminants under stressful conditions

Cattle and sheep

In _____ can see abortion

• 1-9% of affected animals

Guinea pigs

• Y. pseudotuberculosis is cause of “pseudotuberculosis” in

• Reported to cause septicemia in wide variety of species

• Septicemic form

• Nodules in interrnal organs

Y. pseudotuberculosis

• two forms

Y. pseudotuberculosis

Y. enterocolitica

• Primarily an enteric pathogen

• Associated with eating undercooked pork

• Symptoms vary with age

• Rarely associated with enteric diease in ruminants

• fever

• Abdominal pain

• Diarrhea which may b bloody

Y. enterocolitica

• Young children symptoms

• fever

• Abdominal pain which can mimic appendicitis

Y. enterocolitica

• older children symptoms

iron overload

• Septicemia can occur and is associated with

• Treatment: iron-chelating agents

Y. ruckeri

• Rainbow trout, which are widely farmed are very susceptible

• Most often affects fry and fingerling fish

• Outbreaks have low, sustained mortality leads to large losses

• Behavioral changes (swimming near surface, loss of appetite)

• Subcutaneous hemorrhages

• Post-mortem reveals septicemia

Y. yuckeri

Y. ruckeri

• Lymph nodes

• Edematous tissue

• Nasopharyngeal swab

• Transtracheal aspirates

• Cerebrospinal fluid

• Blood

• Fecal samples (Y. enterocolitica and Y. pseudotuberculosis)

Sample collection for Yersinia

Kill any fleas

• Handle sample with extreme caution

• Animal, whether alive or dead, should be treated promptly to

Coccobacilli

Gram negative

Bipolar

____ (closed safety pin) staining

• seen in smears from tissue specimens

• Can be stained with Giemsia

Y. pestis

grows poorly on agars with desoxycholate

Y. enterocolitica and Y. pseudotuberculosis

• grows well on media with desoxycholate

• Cold enrichment procedure may be necessary for fecal samples

Y. enterocolitica

Yersinia selective medium (CIN agar) with cefsulodin, irgasin and novobiocin is designed for isolation from fecal sample

• nutrient agar

• Blood agar

• MacConkey agar

Yersinia grows on

• Colonies tend to be smaller and they grow slower compared to other enterobacteria

35˚C in ambient air

Yersinia

Incubation is at

Non-hemolytic

Yersinia is _____ on blood agar

Yersinia selective medium

dark red center with transparent periphery

Negative

Yersinia

• lactose

• Catalase

• Oxidase

Glucose with production of acid

Ferments ____ but no gas

Disc Diffusion Method

For determination of antimicrobial susceptibility

Agar Dilution Technique

For MIC

Doxycycline

First line of antibiotic for this pathogen

Shigella

• Habitat: Intestinal tract of humans and other primates

• Causes dysentery / diarrhea in humans and other primates

• Very few reports of infection in other animals

• Dogs can be infected from human owners and may excrete the bacteria for short periods, without clinical signs

Proteus mirabilis and Proteus vulgaris

• habitat: feces of mammals and environment

• Causes uti of dogs and horses

• Associated w otitis externa in dogs and cats

• Causes diarrhea in young mink, lambs, calves, goats, and pups