Yersinia pestis
Dr.ruaa Elias College of Medicine Department: MicrobiologyList of Contents:
Objectives Important properties Sources and Transmission Virulence factors Pathogenesis and Clinical Finding Diagnosis TreatmentObjectives:
-Yersinia pestis causes bubonic purpura is a cutaneous manifestation of vasculitis which can lead to gangrene necrosis (Black Death). -Arises via hematogenous spread of the organisms from buboes, or from inhalation of infected aerosols The students must learn all detail about the virulence factors,pathogenicity and diagnosis, treatment of these very important bacteriaImportant properties
-Gram negative rods or coccobacilli (Bipolar staining). -Non-spore forming, non-motile, encapsulated, aerobic intracellular bacteria.Source and Transmission
Animals are reservoirs for the organism especially urban and woodland rats, squirrels, and prairie dogs. Vector transmission occurs via flea bite.Source and Transmission
Transmission may also occur via ingestion of infected animals, and via infected human aerosols.Virulence Factors
Pathogenesis and Clinical Findings:
Pathogenesis and Clinical Findings:Bubonic purpura is a cutaneous manifestation of vasculitis which can lead to gangrene necrosis (Black Death). Infection is often fatal within days. Symptoms arise a few days after flea bite.
Pathogenesis and Clinical Findings:
Diagnosis-direct examination of smears of fluid from lymph nodes or sputum, - Blood cultures obtained two days after admission grew gram-negative rods. Non-lactose fermenter, may not be visible on MAC or EMB at 24 h Oxidase and urease negative Catalase positive Growth often better at 28oC
Treatment
streptomycin, chloramphenicol, and gentamycin. Formalin-inactivated and live attenuated vaccines are available and should be given to persons involved in high-risk activities.Summary
Yersinia pestis is, Gram negative rods or coccobacilli (Bipolar staining), encapsulated, aerobic intracellular bacteria. Animals are reservoirs for the organism especially urban and woodland rats, squirrels, and prairie dogs. Vector transmission occurs via flea bite. Has virulance facter Endotoxin (LPS),Capsule,Envelope antigen: (enhances survival within phagocytes). Coagulase: causes blood clotting, Fibrinolysin, The ability to survive in animal blood and flea gut.Yersinia pestis causing Bubonic Plague, Bubonic purpura, Septic Plague, Pneumonic Plague :Bronchopneumonia, Diagnosis direct examination of smears of fluid from lymph nodes or sputum, by Blood cultures obtained two days after admission grew gram-negative rods. Non-lactose fermenter, may not be visible on MAC or EMB at 24 h Oxidase and urease negative Treatment by streptomycin, chloramphenicol, and gentamycinReferences
Medical Microbiology, edited by Jawetz,E., Brooks,G.F.; Carroll,K.C.;Butet,J.S.; Mores,S.A.and Mietzner,T.A. 2010. 25 th ed. Medical Microbiology, edited by Jawetz,E., Brooks,G.F.; Butet,J.S and Mores,S.A. 2004. 23 th ed. Internet access.