SummaryThis study determined the prevalence of theeaeA gene and its relationship to serotype and type of verotoxin produced in a collection of 432 verotoxigenicEscherichia coli(VTEC) obtained from the faeces of healthy cows and calves in a systematic random survey involving 80 dairy farms in Southwest Ontario. A PCR amplification procedure involving primer pairs which target the conserved central region of the O157:H7eaeA. gene showed that 151 (35·2%) strains were positive for the eaeA gene. All isolates (9–21 for each O group) of O groups 5, 26, 69, 84, 103, 111, 145 and 157 were positive, whereas all isolates (7–34 for each O group) of O groups 113, 132, and 153 and serotype O156:NM (38 isolates) were negative foreaeA. Seventy-three percent of 130 isolates ofeaeA-positive serotypes produced VT1 only compared with 20% of 253 isolates ofeaeA-negative serotypes. We conclude that there is a strong association between certain O groups and theeaeA gene, that serotypes ofeaeA-positive and eaeA-negative VTEC implicated in human and cattle disease are present at high frequency in the faeces of healthy cattle, that VT1 is more frequently associated witheaeA-positive than witheaeA-negative serogroups, and that the eaeA gene is more frequently found in VTEC from calves compared with VTEC from adult cattle.
Sources of psychrophilic and psychrotolerant clostridia causing spoilage of vacuum-packed chilled meats, as determined by PCR amplification procedure
