An outbreak of Escherichia coli O157 : H7 infections and haemolytic uraemic syndrome associated with consumption of unpasteurized apple cider

During October 1996, an outbreak of Escherichia coil O157:H7 infections amo ng Connecticut residents occurred. An epidemiologic investigation included enhanced surveillance and a case-control study. Clinical isolates of Escher ichia coli O157:H7 were typed by pulsed-field gel electrophoresis (PFGE). I mplicated cider samples were analysed by culture and polymerase chain react ion (PCR). Consumption of implicated cider was associated with illness; (ma tched odds ratio = undefined, 95 % confidence interval = 3.5-infinity). Ult imately, a total of 14 outbreak-associated patients were identified. All is olates analysed by PFGE yielded the outbreak-associated subtype. Escherichi a coli O157:H7 was not cultured from three cider samples; PCR analysis dete cted DNA fragments consistent with Escherichia coli O157:H7 in one. This ou tbreak was associated with drinking one brand of unpasteurized apple cider. PFGE subtyping supported the epidemiologic association. PCR analysis detec ted microbial contaminants in the absence of live organisms. Washing and br ushing apples did not prevent cider contamination.