YERSINIA, PASTEURELLA

1. YERSINIA, PASTEURELLA

2. GENUS YERSINIA: • Short, gram negative bacilli showing bipolar staining • Three medically imp species: • Y.pestis- Plague • Y.pseudotuberculosis: rodents • Y.enterocolitica – enteric disaese in humans • Primary pathogens of rodents and accidentally infect man

3. Morphology: • Nonmotile except (Y.pseudotuberculosis & Y.enterocolitica) • Named after Alexander Yersin – discovered plague bacilli YERSINIA PESTIS • Causative agent of plague Morphology: Short, gram negative bacilli- bipolar staining SAFETY PIN APPEARENCE

5. Culture: • Nutrient agar: small transparent colonies • Blood agar: non haemolytic , dark brown colonies due to absorption of haemin pigment • Mac conkey agar: Non lactose fermenting colonies • Ghee broth : organisms grown in s flask of oil or ghee - a characteristic growth occurs which hangs down from the under the surface of the oil, resembling stalactites – STALACITE GROWTH

6. BIOCHEMICAL REACTIONS: • Ferments glucose, Mannitol and maltose with production of acid only • Catalase positive • Indole, urease, citrate, MR, VP – negative

7. BIOTYPES OF Y.pestis: • Based on glycerol fermentation and nitrate reduction

8. VIRULENCE FACTORS:

9. PLAGUE

10. PATHOGENESIS of PLAGUE: • Y.pestis – natural pathogen of rodents • Causes zoonotic disease – PLAGUE • Transmitted by bite of rat flea (X.cheopis) • Two natural cycles of the disease: • Urban plague – man & rodents • Sylvatic plague – wild animals & rodents

11. Cycles of Plague

13. In man plague occurs in 3 forms: • Bubonic plague • Pneumonic plague • Septicaemic plague BUBONIC PLAGUE: • Plague bacillus enters the body via bite of an infected rat flea on the legs. • Inguinal lymph nodes involved – bubonic plague: Lymph nodes enlarge and suppurate

14. Fever chills and malaise • Bacteria reach the blood & disseminated • If not treated may progress to meningeal plague PNEUMONIC PLAGUE: • Highly infectious form • Involving lungs producing haemorrhagic pneumonia • Transmitted by droplet infection • Usually secondary to bubonic plague • Fever, cough with expectoration

15. SEPTICAEMIC PLAGUE: • Presence of bacteria in the blood • Usually complication of pneumonic or bubonic plague • Massive hemorrhage – BLACK DEATH EPIDEMIOLOGY: • Plague- Zoonotic disease • Spread from domestic rats to man by bite of rat flea • Plague – greatest killer in history of mankind • Several epidemics • in India – outbreak in 1994 (Maharashtra, Gujarat, Delhi, UP, MP , Karnataka)

16. 2002 outbreak in Shimla • Scattered natural foci still exist: Kolar, Bead- Lathur belt in Maharashtra, Shimla and Uttaranchal LAB DIAGNOSIS: Specimens; • Pus/ fluid aspirated from infected lymph nodes • Sputum / blood in pneumonic plague • Blood in septicemic plague • Splenic tissue- postmortem • CSF in meningeal plague

18. Direct microscopy: • Gram stain- gram negative coccobacilli • Methylene blue stain- bipolar staining (WAYSON stain) Culture: Blood agar: incubated at 270C Biochemical tests for identification On ghee broth- stalactite growth Animal inoculation: • Rats injected s/c with exudates from lymph nodes. • Animals die in 2-5days. • Postmortem reveals- regional lymph nodes congested. • Bacteria found in spleen, heart blood etc

19. Antigen detection: • F 1 glycoprotein antigen – detected in aspirated fluid by ELISA or immunoflourescence Serological tests: • Detection of antibodies to F1 antigen by CFT PCR: rapid & sensitive for diagnosis of plague in clinical samples

20. TREATMENT: • Tetracycline –drug of choice • Streptomycin, Chloramphenicol, kanamycin can be used VACCINE: • Killed vaccine: whole bacterial culture antigen of plague bacillus • Live vaccine: prepared from 2 avirulent strains of Y.pestis CHEMOPROPHYLAXIS: • Close contacts – tetracycline 500mg 6th hrly for one week.

21. YERSINIA ENTEROCOLITICA • gastroenteritis • Transmission • fecal contamination, domestic animals • water • milk • meat

22. Found worldwide • Found in pigs, cats and dogs • Human also infected by ingestion of contaminated food or water • Some infections result from eating contaminated meat • Is able to survive refrigerator temperatures (can use “cold enrichment” to isolate)

23. Human disease are of three types: • Self limiting gastroenteritis/ enterocolitisin young children • Mesenteric adenitis and inflammatory terminal ileitis in older children ( mimics appendicitis) • Systemic disease seen in adults: bacteremia, meningitis, arthralgia, erythema nodosum

24. Lab diagnosis: isolation of bacteria from feces on Mac conkey agar or on selective media using cold enrichment • Biochemical identification • GNB motile at 250C, non motile at 370C

25. Yersinia pseudotuberculosis • Pathogen of rodents, particularly guinea pigs • Septicemia with mesenteric lymphadenitis, similar to appendicitis • Motile at 220C

26. PASTEURELLA MULTOCIDA • Non motile, gram negative bacilli • Oxidase positive • Indole positive • Does not grow on MacConkey media • Found in the respiratory tract of dogs, cats and cattle • Human infections – rare • Wound sepsis following animal bites, meningitis following head injury , pneumonia, etc • Treated with tetracycline, streptomycin & penicillin

27. FRANCISELLA TULARENSIS • Causative agent of tularemia: infection of rodents originally described in Tulare county, California • Human infection by: Direct contact with infected rodents or tick bites or ingestion of contaminated food/ water or by aerosols • Minute, capsulated, GNB • Intracellular parasite: fastidious growth requirement: Francis blood dextrose cystine agar

28. Human tularemia: local ulceration with lymphadenitis, a typhoid like fever with glandular enlargement • Respiratory disease: • Highly infectious disease • Diagnosis by culture or inoculation into guinea pigs • Abs detection • An attenuated vaccine is available: administered by scarification to individuals at high risk of infection