1Microorganisms Causing Foodborne DiseaseFamily Vibrionaceae•Vibrio cholerae•Vibrio parahaemolyticus•Vibrio vulnificusFamily Vibrionaceae• Gram-negative rods– Straight or curved• Motile by polar flagella–Except Enhydrobacter(non-motile)• Facultatively anaerobic•Fermentative• Oxidase positive– Few exceptions of no importance in food microbiology • Most have aquatic habitatsFamily Vibrionaceae• Genera–Aeromonas–Enhydrobacter–Photobacterium–Plesiomonas–Vibrio2Vibriospecies of medical importance•V. alginolyticus•V. cholerae•V. cincinnatiensis•V. damsella•V. fluvialis•V. furnissii•V. harveyi•V. hollisae•V. metschnikovii•V. mimicus•V. parahaemolyticus•V. vulnificusMorphology of VibriocellsV. cholerae V. parahaemolyticus V. vulnificusV. cholerae• Different serogroups– O1 is the serogroup associated with most pandemics– Non-O1 can also cause diarrhea– O111 has acquired great importance in India, Pakistan and the Middle East3V. choleraeO1•Human pathogen• Typically associated with water– Contaminated food played an important role during the Latin American pandemic • There have been 7 pandemics over the history– We are currently suffering the 7thpandemic– Caused by V. choleraebiotype El Tor– Serotypes Ogawa, Inaba and HikojimaV. parahaemolyticus• Hallophilic (needs salt to grow)– 0.5 – 8%, optimum 2-3%•pH– Grows best at vales above neutrality (7.5 – 8.5)•Min awis 0.937 – 0.986 – Depending on solute• Temperature– 10 – 43°C, optimum 37°C• Grows rapidly– Generation time 7 – 9 min– Compare to GT of 20 min for enterobacteriaceaeV. parahaemolyticus• Primarily associated with coastal inshore water• Does not grow or survive well at water temperatures – <15°C or in deep waters (high pressure) • Can survive in coastal sediments during the cold season at water temperature <10°C• Its pathogenicity is related to a hemolysin that is detected by the Kanagawa test– Experimental ingestion of Kanagawa + isolates has resulted in diarrhea– Experimental ingestion of Ka – isolates does not produce diarrhea4V. parahaemolyticus•V. parahaemolyticfood poisoning– Incubation period 9 – 25 h• Disease symptoms – Profuse watery diarrhea, fever, abdominal pain and vomiting– Last for up to 8 days• Associated invariably with seafood– Both shellfish and finfish• Outbreaks are occasionally reported in the U.S.– It is the most common cause of food poisoning in JapanV. vulnificus• Halophilic• Marine habitat, coastal waters• Highly sensitive to cold• Isolated from coastal waters during warm seasons– Seldom recovered from water during cold seasonIncidence of V. vulnificusin coastal waters by sampling month1617303335282720100102030405060708090100JFMAMJJASONDMonth% isolationWatertemperature (°C)Oliver, 19875V. vulnificus• Highly invasive•Syndromes:–Primary septicemia• 26 h Incubation period High • fatality rate (~50%)• Associated with eating raw oysters (85%)• Secondary lesions appear in patinets– Wound infections• 16 h Incubation period• Usually from harvesting or shucking oysters• Fatality rate of 22%• Most cases occur with pre existing conditions– Liver disease, diabetes, alcoholism• High concentration of iron in serumEffects of V. vulnificusinfectionWound infectionSecondary lesionIsolation of Vibriospp.• Alkaline enrichment– Alkaline peptone water (pH 8.6 – 9.0)– Tellurite bile salt broth (pH 9.0 – 9.2)• Isolation on thiosulfate citrate bile salts sucrose agar (TCBS)–V. choleraeproduces acid from sucrose–V. parahaemolyticusand V. vulnificusdo not produce acid from sucrose–V. vulnificusis differentiated from V. parahaemolyticusby its ability to ferment lactose• Further biochemical and serological tests for species confirmation6Characteristics of Vibriocolonies on TCBSV. cholerae V. parahaemolyticus V.