PCR detection of virulence genes and molecular epidemiology of STEC 0157 isolates from French abattoirs

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

The main pathogenic enterohemorrhagic Escherichia coli (EHEC) strains 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) isolates, with the same genetic characteristics as the 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 higher in young dairy bulls (P<0.05) than in 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 the top five STEC, evaluated through a weighted arithmetic mean of the prevalence by categories, was estimated to 1.8% in slaughtered adult cattle in France.

Regional variation in the prevalence of E. coli O157 in cattle: a meta-analysis and meta-regression

BACKGROUND

Escherichia coli O157 (EcO157) infection has been recognized as an important global public health concern. But information on the prevalence of EcO157 in cattle at the global and at the wider geographical levels is limited, if not absent. This is the first meta-analysis to investigate the point prevalence of EcO157 in cattle at the global level and to explore the factors contributing to variation in prevalence estimates.

METHODS

Seven electronic databases- CAB Abstracts, PubMed, Biosis Citation Index, Medline, Web of Knowledge, Scirus and Scopus were searched for relevant publications from 1980 to 2012. A random effect meta-analysis model was used to produce the pooled estimates. The potential sources of between study heterogeneity were identified using meta-regression.

PRINCIPAL FINDINGS

A total of 140 studies consisting 220,427 cattle were included in the meta-analysis. The prevalence estimate of EcO157 in cattle at the global level was 5.68% (95% CI, 5.16-6.20). The random effects pooled prevalence estimates in Africa, Northern America, Oceania, Europe, Asia and Latin America-Caribbean were 31.20% (95% CI, 12.35-50.04), 7.35% (95% CI, 6.44-8.26), 6.85% (95% CI, 2.41-11.29), 5.15% (95% CI, 4.21-6.09), 4.69% (95% CI, 3.05-6.33) and 1.65% (95% CI, 0.77-2.53), respectively. Between studies heterogeneity was evidenced in most regions. World region (p<0.001), type of cattle (p<0.001) and to some extent, specimens (p = 0.074) as well as method of pre-enrichment (p = 0.110), were identified as factors for variation in the prevalence estimates of EcO157 in cattle.

CONCLUSION

The prevalence of the organism seems to be higher in the African and Northern American regions. The important factors that might have influence in the estimates of EcO157 are type of cattle and kind of screening specimen. Their roles need to be determined and they should be properly handled in any survey to estimate the true prevalence of EcO157.

Prevalence of verotoxigenic Escherichia coli O157:H7 in fecal and ear samples from slaughtered cattle in Sweden

A national verotoxigenic Escherichia coli (VTEC) O157:H7 monitoring study was carried out among cattle at slaughter in Sweden during 2005 and 2006. Sixty (3.4%; 95% confidence interval, 3.3 to 3.5%) of 1,758 fecal samples collected and 54 (12%; 95% confidence interval, 11.9 to 12.4 %) of 446 ear samples tested positive for VTEC O157:H7. Ear samples were included to evaluate whether they could be used to assess general VTEC O157:H7 contamination at slaughter. The respective prevalences of positive fecal and ear samples were 16 and 21% for older calves, 3.5 and 10% for young stock, and 1.6 and 12% for adult cattle. There were significant differences between the age groups for the fecal samples, but not for the ear samples. It could be that ear samples are less subject to age variations due to environmental factors, or perhaps this observation was due to fewer ear samples being collected in this study. Within the age groups, the prevalence of VTEC O157:H7-positive ear samples was significantly higher than that of fecal samples for young stock and adult cattle. Furthermore, the prevalence of positive ear samples fluctuated more widely throughout the year than that of positive fecal samples. The fecal prevalence data can be used as baseline data against which future intervention strategies can be evaluated, and the ear samples can be used as an indicator of environmental contamination. The results of the ear samples are too limited to determine if they can be used to detect hide contamination and risk of carcass contamination.

Undercooked ground beef and person-to-person transmission as major risk factors for sporadic hemolytic uremic syndrome related to Shiga-toxin producing Escherchia coli infections in children in France

In a prospective matched case-control study of sporadic pediatric hemolytic uremic syndrome related to Shiga-toxin producing Escherichia coli infection in France, eating undercooked ground beef, contact with a person with diarrhea, and drinking well water during the summer period were identified as risk factors. Prevention efforts in France should focus on reducing not only food-borne but also person-to-person transmission.