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Yersinia & pasteurella


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Yersinia & pasteurella

  1. 1. YERSINIA AND PASTEURELLA Eligius Lyamuya, MD, MMed, PhD Department of Microbiology and Immunology, Muhimbili University of Health and Allied Sciences
  2. 2. LEARNING OBJECTIVES <ul><li>Know the general characteristics of Yersinia and Pasteurella </li></ul><ul><li>Understand the growth characteristics, virulence factors and pathogenesis of infection caused by Y. Pestis, Y enterocolitica, Y. pseudotuberculosis and P. multocida </li></ul><ul><li>Know the various methods for laboratory diagnosis of infections due to Yersiniae </li></ul><ul><li>Know the general principles of treatment, prevention and control of plague </li></ul><ul><li>Know the general principles of treatment, prevention and control of other infections caused by Yersinia spp and Pasteurella spp </li></ul>
  3. 3. YERSINIA <ul><li>Family: Enterobacteriaceae </li></ul><ul><li>Genus: Yersinia </li></ul><ul><li>Species of medical importance: </li></ul><ul><ul><li>Yersinia pestis </li></ul></ul><ul><ul><li>Yersinia enterocolitica </li></ul></ul><ul><ul><li>Yersinia pseudotuberculosis </li></ul></ul>
  4. 4. GENERAL CHARACTERISTICS <ul><li>Coccobacillary, ovoid or rod shaped, bipolar staining </li></ul><ul><li>Gram negative </li></ul><ul><li>Aerobic or facultatively anaerobic </li></ul><ul><li>Grow on ordinary media </li></ul><ul><li>Best growth temp. 25-30  C </li></ul><ul><li>Oxidase -ve, Catalase +ve, Indole -ve, ONPG +ve, Urease +ve except Y. pestis </li></ul>
  5. 5. Stained preparation showing Yersinia pestis
  6. 6. Yersinia pestis
  7. 7. CULTURAL CHARACTERISTICS <ul><li>Polymorphism in old cultures </li></ul><ul><li>Capsulated forms in exudates from lesions </li></ul><ul><li>In broth, stalactites (hanging growth) seen with oil overlay, granular deposits if no oil </li></ul><ul><li>Colonies on MCA disappear after 2-3 days due to autolysis </li></ul>
  8. 8. Biotypes <ul><li>Biotype Glycerol Nitrite </li></ul><ul><li>acidification reduction </li></ul><ul><li>Y. pestis var orientalis - + </li></ul><ul><li>Y. pestis var antiqua + + </li></ul><ul><li>Y. pestis var medievalis + - </li></ul>
  9. 9. ANTIGENIC STRUCTURE-1 <ul><li>LPS </li></ul><ul><li>Capsular (envelope) antigenic complex </li></ul><ul><ul><li>F1 antigen </li></ul></ul><ul><ul><li>Heat labile </li></ul></ul><ul><ul><li>Develops at 37  C </li></ul></ul><ul><li>Somatic antigenic complex </li></ul><ul><ul><li>V and W antigens </li></ul></ul><ul><ul><li>Heat stable </li></ul></ul><ul><ul><li>Develops at 20  C and 37  C </li></ul></ul>
  10. 10. ANTIGENIC STRUCTURE-2 <ul><li>Other virulence factors:- </li></ul><ul><ul><li>Low calcium response ( lcr ) gene </li></ul></ul><ul><ul><li>Yops ( Yersinia outer proteins) </li></ul></ul><ul><ul><li>Coagulase produced at 28  C </li></ul></ul><ul><ul><li>Plasminogen activator </li></ul></ul>
  11. 11. PATHOGENESIS <ul><li>Agent for plague </li></ul><ul><li>Transmission: Wild rodent epizootics  semidomestic rodents  domestic rodents  fleas  man  man transmission: fleas, Pulex irritans , airborne (pneumonic) </li></ul><ul><li>Injection into man by fleas  regional lymph nodes  blood stream  organs (spleen, liver, kidneys, others) </li></ul><ul><li>Causes infarcts, necrosis and haemorrhage </li></ul>
  12. 12. CLINICAL TYPES <ul><li>Bubonic </li></ul><ul><li>Septicaemic </li></ul><ul><li>Pneumonic </li></ul><ul><li>Others: </li></ul><ul><ul><li>Plague meningitis </li></ul></ul><ul><ul><li>Tonsillar or pharyngeal plague </li></ul></ul><ul><ul><li>Plague carbuncle </li></ul></ul>
  13. 13. LABORATORY DIAGNOSIS <ul><li>Specimens </li></ul><ul><ul><li>Bubo aspirate </li></ul></ul><ul><ul><li>Sputum </li></ul></ul><ul><ul><li>Blood </li></ul></ul><ul><ul><li>Others depending on clinical presentation </li></ul></ul><ul><li>Tests </li></ul><ul><ul><li>Staining (Wayson’s, methylene blue, Gram) </li></ul></ul><ul><ul><li>Culture </li></ul></ul><ul><ul><li>Serology </li></ul></ul>
  14. 14. EPIDEMIOLOGY-1 <ul><li>Disease of antiquity </li></ul><ul><li>First documented epidemic ?1320 BC (Biblical evidence) </li></ul><ul><li>Major pandemics: </li></ul><ul><ul><li>Justinian plague: -6 th C </li></ul></ul><ul><ul><li>Black death: -14 th C </li></ul></ul><ul><ul><li>Oriental plague: -Late 19 th C </li></ul></ul>
  15. 15. EPIDEMIOLOGY-2 <ul><li>Primarily a disease of rodents and their fleas </li></ul><ul><li>Case fatality if untreated: 50-75% for bubonic plague; 100% for septicaemic plague </li></ul><ul><li>Incidence declining globally since early 20 th C </li></ul><ul><li>Some countries (including Tanzania) continue to be affected </li></ul><ul><li>Reservoirs: Rodents, Fleas ( Xenopsilla spp) </li></ul><ul><li>Plague foci: World wide in countries lying between 50  N and 35  S; in Tanzania-central, northern and eastern parts </li></ul>
  16. 17. EPIDEMIOLOGY-3 <ul><li>Epidemic types: Sylvatic (rural) plague, Domestic (urban) plague </li></ul><ul><li>Risk factors: </li></ul><ul><ul><li>Occupation (hunters, farmers) </li></ul></ul><ul><ul><li>Poor housing </li></ul></ul><ul><ul><li>Sleeping on the floor </li></ul></ul><ul><ul><li>Not keeping cats </li></ul></ul><ul><ul><li>Socio-cultural factors </li></ul></ul>
  17. 18. CONTROL AND PREVENTION-1 <ul><li>Control of epidemics </li></ul><ul><ul><li>Mitigate public hysteria </li></ul></ul><ul><ul><li>Treat cases </li></ul></ul><ul><ul><li>Closely monitor contacts </li></ul></ul><ul><ul><li>Investigate all deaths </li></ul></ul><ul><ul><li>Kill fleas (insecticides) </li></ul></ul><ul><ul><li>Kill rodents (rodenticides) when flea index <0.5 </li></ul></ul>
  18. 19. CONTROL AND PREVENTION-2 <ul><li>Case recognition, medical intervention and field investigation </li></ul><ul><ul><li>Identify the most likely source of infection in the area </li></ul></ul><ul><ul><li>Institute appropriate sanitation and control measures to stop the exposure source </li></ul></ul><ul><ul><li>Ensure dissemination of information concerning areas with active plague transmission, the clinical features of plague and the case definition to health workers </li></ul></ul><ul><ul><li>Verify that patients have been placed on appropriate antibiotic treatment and that local supplies of antibiotics are adequate to handle further cases </li></ul></ul><ul><ul><li>Isolate pneumonic plague patients </li></ul></ul>
  19. 20. CONTROL AND PREVENTION-3 <ul><li>Vaccine not available for wide use </li></ul><ul><li>Continuous surveillance of rodent and human plague </li></ul><ul><ul><li>Conduct investigation to identify animals and flea species that are implicated in the plague enzootic cycle in the region and develop a programme on environmental management to limit its potential spread </li></ul></ul><ul><ul><li>Active long-term surveillance of zoonotic foci and rapid response to reduce exposure during epizootic outbreaks </li></ul></ul>
  20. 21. Yersinia enterocolotica
  21. 22. CULTURAL CHARACTERISTICS <ul><li>Capsules in vivo, not in culture </li></ul><ul><li>Multiplies at 4  C </li></ul><ul><li>Slow growth on artificial media </li></ul><ul><li>Selective/enrichment media needed for isolation from faecal specimens </li></ul>
  22. 23. ANTIGENIC STRUCTURE <ul><li>6 biotypes </li></ul><ul><li>Several serotypes, 3, 8 and 9 responsible for most human infections </li></ul><ul><li>Enterotoxin produced at T <30  C </li></ul>
  23. 24. <ul><li>PATHOGENESIS </li></ul><ul><li>Faeco-oral transmission </li></ul><ul><li>Causes gastroenteritis; sometimes septicaemia and mesenteric lymphadenitis in the elderly </li></ul><ul><li>LAB. DIAGNOSIS </li></ul><ul><li>Specimens </li></ul><ul><ul><li>Faeces, Blood </li></ul></ul><ul><li>Tests </li></ul><ul><ul><li>Culture: cold enrichment, subculture on selective media </li></ul></ul><ul><ul><li>Serology </li></ul></ul>
  24. 25. Yersinia pseudotuberculosis
  25. 26. <ul><li>GENERAL FEATURES </li></ul><ul><li>Non capsulated </li></ul><ul><li>Grows poorly on MCA </li></ul><ul><li>ANTIGENIC STRUCTURE </li></ul><ul><li>Serotypes 1-6, type 1 most common </li></ul><ul><li>Six O groups (I-IV) </li></ul>
  26. 27. <ul><li>PATHOGENESIS </li></ul><ul><li>Zoonosis </li></ul><ul><li>Causes mesenteric adenitis in man </li></ul><ul><li>LAB. DIAGNOSIS </li></ul><ul><li>Specimens </li></ul><ul><li>Mesenteric lymphnode biopsy, Blood </li></ul><ul><li>Tests </li></ul><ul><li>Culture: incubate at 37  C for 18 hrs </li></ul><ul><li>Serology </li></ul>
  27. 28. PASTEURELLA <ul><li>Genus: Pasteurella </li></ul><ul><li>Species of importance: </li></ul><ul><li>P. multocida </li></ul><ul><li>P. haemolytica </li></ul><ul><li>P. pneumotropica </li></ul><ul><li>P. ureae </li></ul>
  28. 29. P. multocida <ul><li>Gram negative coccobacilli, smaller than Yersiniae </li></ul><ul><li>Non-motile, non-sporing </li></ul><ul><li>Capsulated in culture </li></ul><ul><li>Bipolar staining with methylene blue </li></ul><ul><li>Aerobic, facultatively anaerobic </li></ul><ul><li>Does not grow on MCA </li></ul><ul><li>Oxidase positive </li></ul>
  29. 30. <ul><li>ANTIGENIC STRUCTURE </li></ul><ul><li>15 serotypes, 4 capsular Ags and 11 somatic Ags </li></ul><ul><li>PATHOGENESIS </li></ul><ul><li>Zoonosis, virulent to animals and birds </li></ul><ul><li>Rare human infections: </li></ul><ul><ul><li>local abscess </li></ul></ul><ul><ul><li>Meningitis </li></ul></ul><ul><ul><li>RT infections </li></ul></ul><ul><li>LAB. DIAGNOSIS </li></ul><ul><li>Specimens </li></ul><ul><li>Depending on clinical presentation </li></ul><ul><li>Tests </li></ul><ul><li>Culture </li></ul>