Prevalence of Carriage of Shiga Toxin-Producing Escherichia coli Serotypes O157:H7, O26:H11, O103:H2, O111:H8, and O145:H28 among Slaughtered Adult Cattle in France
Abstract
The main pathogenic enterohemorrhagic Escherichia coli (EHEC) are defined as Shiga toxin (Stx)-producing E. coli (STEC) belonging to one of the following serotypes: O157:H7, O26:H11, O103:H2, O111:H8 and O145:H28. Each of these five serotypes is known to be associated with a specific subtype of the intimin-encoding gene (eae). The objective of this study was to evaluate the prevalence of bovine carriers of these 'top five' STEC in the four adult cattle categories slaughtered in France. Fecal samples were collected from 1,318 cattle, including 291 young dairy bulls, 296 young beef bulls, 337 dairy cows and 394 beef cows. A total of 96 E. coli isolates including 33 'top five' STEC and 63 atypical enteropathogenic E. coli (aEPEC), with the same genetic characteristics as 'top five' STEC strains except that they lacked an stx gene, were recovered from these samples. O157:H7 was the most frequently isolated STEC serotype. The prevalence of 'top five' STEC (all serotypes included) was 4.5% in young dairy bulls, 2.4% in young beef bulls, 1.8% in dairy cows and 1.0% in beef cows. It was significantly highest in young dairy bulls (p\\textless0.05) compared to the other 3 categories. The basis for these differences between categories remains to be elucidated. Moreover, simultaneous carriage of STEC O26:H11 and STEC O103:H2 was detected in one young dairy bull. Lastly, the prevalence of bovine carriers of 'top five' STEC, evaluated through a weighted arithmetic mean of the prevalence by categories, was estimated to 1.8% in French slaughtered adult cattle.