Yersinia & pasteurella
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Yersinia & pasteurella

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  • Envelope (F-1) antigen: This is a protein-polysaccharide complex which is highly expressed at 37 degrees in the mammalian host but not in the flea and is anti-phagocytic. V and W proteins: These plasmid-coded proteins are associated with rapid proliferation and septicemia.
  • Low calcium response ( lcr ) : This is a plasmid-coded gene that enables the organism to grow in a low Ca++ (intracellular) environment. It also coordinates the production of several other virulence factors, such as V, W and yop s ( Yersinia outer proteins). Yops: A group of 11 proteins, which are coded by plasmids, are essential for rodent pathogenesis and are responsible for cytotoxicity, inhibition of phagocyte migration and engulfment and platelet aggregation. Coagulase and Plasminogen activator: Both of these are plasmid-coded proteins. Coagulase is responsible for micro thrombi formation P lasminogen activator promotes the dissemination of the organism. It also destroys C3b on the bacterial surface, thus attenuating phagocytosis.

Yersinia & pasteurella Yersinia & pasteurella Presentation Transcript

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