医学微生物学英文版课件_11.doc

Vibrio sp Gram-negative rods Curves or comma shaped Non-spore forming Highly motile-single polar flagella Associated with salt water Oxidase positive Facultative anaerobe Tolerate alkaline conditions to pH90 Readily cultivated Simple nutritional requirements Vibrio cholerae Antigenic structure Common heat-labile flagellar H antigen O lipopolysaccharide confers serologic specificity More than 150 O antigen serogroups Only O-1 and 0139 serogroups cause Asiatic cholera Three serotypes Ogawa Inaba Hikojima Two biovars classic and El Tor 2 biotypes of serogroup O-1 Classical biotype El Tor biotype Serogroup 139 V cholerae - Transmission Vibrio cholerae Epidemiology Epidemic cholera-spread by contaminated water under conditions of poor sanitation Endemic-consumption of raw seafood Copepods Vibrio cholerae Pathogenesis Ingest 108-1010 organisms Non invasive infection of small intestine Organisms secrete enterotoxin Watery diarrhea Cholera toxin Enterotoxin-cholera toxin-CtxAB Encoded by a prophage Molecular mass of 84000 daltons A subunit-ADP-ribosylating toxin B subunit-bind GM1-gangliosides on enterocytes A subunit ADP ribosylates Gs-alpha which regulates activation of adenlyate cyclase Result is persistent increase in cAMP levels Hyper secretion of Na Cl K bicarbonate and H20 Vibrio cholerae-Clinical manifestations Asymptomatic colonization to fatal diarrhea Onset 2-3 days after ingestion Abrupt onset of watery diarrhea and vomiting Rice water stools Severe fluid and electrolyte loss-dehydration metabolic acidosis hypovolemic shock renal failure Death 60 if untreated 1 if treated for fluid loss Pathogenicity of V cholera Dehydration and death Massive secretion of ionswater into gut lumen Immunity Strong immunity after recovery SIgA Bacteriological Diagnosis Specimens stool vomitus Stained smear Culture alkaline peptone water of agar plate and TCBS agar plate Quick immunological methods immunofluorescent ball test PCR Vibrio-Prevention and Control Improved sanitation Fluid and electrolyte replacement Antibiotic prophylaxis Improved food handling Vibrio parahemolyticus One kind of halophilic vibrios optimal NaCl concentration contained in culture media is 35 hemolysin related to its pathogenicity can be detected by human or rabbit RBC test Kanagawa test cause food poisoning in human beings raw sea-food Vibrio Vibrio cholerae -gastroenteritis Vibrio parahaemolyticus -gastroenteritis wound infection bacteremia Vibrio vulnificus -wound infection bacteremia food feces water fresh salt Iron sequestration Siderophores Motility Flagellum Exotoxin Accessory cholera enterotoxin Exotoxin Zona occludens Releases bacteria from mucosal cells Hemagglutination protease adhesin Accessory colonization factor Adherence to mucosal cells adhesin Coregulated pilus Hypersecretic of electrolytes and water Cholera toxin Biological effect Virulence factor Virulence factors of Vcholerae O1 and O139 Clinical manifestations Self-limiting diarrhea to mild cholera-like illness 24 hours after ingestion-explosive water diarrhea Head