Occurrence of Verocytotoxin-ProducingEscherichia coliO157 on Dutch Dairy Farms

Abstract

During the period from September 1996 through November 1996, 10 Dutch dairy farms were visited to collect fecal samples from all cattle present. The samples were examined for the presence of verocytotoxin (VT)-producing Escherichia coli (VTEC) of serogroup O157 (O157 VTEC) by immunomagnetic separation following selective enrichment. Cattle on 7 of the 10 dairy farms tested positive for O157 VTEC, with the proportion of cattle infected varying from 0.8 to 22.4%. On the seven farms positive for O157 VTEC, the excretion rate was highest in calves ages 4 to 12 months (21.2%). In a follow-up study, two O157 VTEC-positive farms and two O157 VTEC-negative farms identified in the prevalence study were revisited five times at intervals of approximately 3 months. Cattle on each farm tested positive at least once. The proportion of cattle infected varied from 0 to 61.0%. Excretion rates peaked in summer and were lowest in winter. Again, the highest prevalence was observed in calves ages 4 to 12 months (11.8%). O157 VTEC strains were also isolated from fecal samples from horses, ponies, and sheep and from milk filters and stable flies. O157 VTEC isolates were characterized by VT production and type, the presence of the E. coli attaching-and-effacing gene, phage type, and pulsed-field gel electrophoretic genotype. No overlapping strain types were identified among isolates from different farms except one. The predominance of a single type at each sampling suggests that horizontal transmission is an important factor in dissemination of O157 VTEC within a farm. The presence of more than one strain type, both simultaneously and over time, suggests that there was more than one source of O157 VTEC on the farms. Furthermore, this study demonstrated that the O157 VTEC status of a farm cannot be ascertained from a single visit testing a small number of cattle.

Seasonal variation of Shiga toxin-encoding genes (stx) and detection ofE. coliO157 in dairy cattle from Argentina

“…The low prevalence of STEC O157 detected in milking cows (0AE2%) and calves (0AE8%) agrees with results obtained by LeJeune et al (2006) who found 0AE6% of O157 in dairy cows from Ohio (USA). A previous study carried out in a feedlot from Argentina shows higher percentages of STEC O157 (6AE8%) when the animals were serially sampled (Padola et al 2004) and these results were similar to those found in dairy cattle from other countries (Chapman et al 1993;Heuvelink et al 1998;Jackson et al 1998;Vold et al 1998;Synge and Paiba 2000;Nielsen et al 2002;Fitzgerald et al 2003;Vicente et al 2005). These data indicate that STEC O157 is an uncommon serogroup for bovine in Argentina, although it has been isolated from cattle and human faeces by other authors in this country (Orskov et al 1987;Rivas et al 1996;Padola et al 2004).…”

“…In France, the prevalence obtained was similar (Fremaux et al 2006). These values were higher than those found in some countries such as the Netherlands (8AE8-22AE4%) (Heuvelink et al 1998), Australia (16AE7%) (Cobbold and Desmarchelier 2000) and the USA (8%) (Wells et al 1991). However, there are countries with higher prevalence such as Switzerland (44AE3%) (Busato et al 1999), Canada (62AE1%) (Jackson et al 1998) and Brazil (52-82%) (Leomil et al 2003;Moreira et al 2003;Vicente et al 2005).…”

“…(LeJeune et al 2006). The term Shiga toxin-producing E. coli (STEC) refers to E. coli serotypes capable of producing Shiga toxin type 1 (Stx1), type 2 (Stx2), or both, encoded by stx1 and stx2 genes, respectively (Paton and Paton 1998) which are thought to cause the vascular endothelial damage observed in patients with haemorrhagic colitis (HC) and haemolytic uraemic syndrome (HUS) (Heuvelink et al 1998). Although the mechanisms of action of Stxs are thought to be similar, the cytotoxicity of Stx2 may be stronger than Stx1 and there is evidence supporting the hypothesis that Stx2-producing strains are potentially more virulent than those producing Stx1 (Thorpe et al 2002).…”

“…Calves have been considered the bovine category with the highest prevalence of STEC (Nielsen et al 2002), but other researchers found the highest prevalence in heifers (Cobbold and Desmarchelier 2000). The reasons for this difference between age groups are unknown but might reflect differences in ruminal development, immune response, diet, aspects of cattle management, among other factors (Heuvelink et al 1998;Vicente et al 2005). Previous studies in other countries had documented that Stx1-producing strains were predominant in calves and Stx2-producing strains were more common in adult cows (Cho et al 2006).…”

Shiga-toxin-producing Escherichia coli in faeces of healthy dairy cows, sheep and goats: prevalence and virulence properties

“…Using a sensitive ELISA method, Zhao et al (1995) detected STEC O157:H7 in 22% of investigated control herds, from which E. coli O157:H7 had not been isolated previously. In a Dutch study, using immunomagnetic separation technique, STEC O157 occurred in seven out of 10 dairy farms (Heuvelink et al 1998). Kudva et al (1997) isolated and characterized E. coli O157:H7 and non-O157 STEC strains from sheep.…”