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Yersinia Yersinia pestis (Plague). Dr / Tamer El Mokadem. Yersinia pestis. Morphology: Gram – ve short oval non motile bacilli, capsulated(Envelope) Wayson,Giemsa,Methylene blue stains <<< Biolar staining ( Safety pin appearance ) Cultural characters: Facultative anaerobes,
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Yersinia Yersinia pestis (Plague) Dr / Tamer El Mokadem
Yersinia pestis Morphology: • Gram –ve short oval non motile bacilli, capsulated(Envelope) • Wayson,Giemsa,Methylene blue stains<<< Biolar staining (Safety pin appearance) Cultural characters: • Facultative anaerobes, • Blood agar at 27-30 c: • MacConkey agar: Pale non lactose fermenting. Animal innoculation: • Highly lethal to white rats (sc)
Virulence factors: • Endotoxin(LPS)<<< Endotoxic shock • F1 antigen(in the capsule): Antiphagocytic • V-W antigens (in virulent yersinia): Antiphagocytic • Yops(Yersinia outer proteins): inhibit phagocytosis & cytokines & mediate invasion • Exotoxin : Lethal to mices • Bacteriocin(Pesticin)
Plague • Zoonotic disease transmitted from rat to rat & from rat to man by the bite of fleas (Xenopsylla cheopis)<<<< multiply in the groin and axilla Lymph nodes(enlarged& tender)<<<(Bubonic plague)<<< Blood<<< endotoxic shock, DIC, Skin bleeding (Septicaemic plague)<<< disseminate to organs & form abscesses<<<may reach the lung(Pneumonic plague) N.B: Pneumonic plague may result from inhalation N.B: Y.pestis is considerd a bioterrorism or biological warfare agent (small pox-anthrax-botulinum toxin-plague)