Escherichia coli O157:H7 and Non‐O157 Shiga Toxin‐producing E. coli in Healthy Cattle, Sheep and Swine Herds in Northern Spain

Abstract

Three-hundred and forty-five herds (17 swine, 122 dairy sheep, 124 beef and 82 dairy cattle) were investigated for prevalence of Shiga toxin-producing Escherichia coli (STEC). Rectal faecal samples were selectively enriched and then examined by immunodetection techniques (Immunomagnetic Separation with anti-E. coli O157 Dynabeads, ImmunoMagnetic cell Separation (IMS) and automated enzyme-linked fluorescent immunoassay using VIDAS) and polymerase chain reaction (PCR) (rfbE and fliC genes) to assess the prevalence of E. coli O157:H7. Prevalence of non-O157 STEC was estimated by PCR screening for stx genes of 10 lactose-positive colonies grown on MacConkey agar after enrichment. PCR was used on all STEC isolates to detect stx(1), stx(2), eaeA and E-hlyA genes. Both immunodetection methods showed a moderate-good level of agreement (kappa = 0.649) but IMS showed 87.5% complementary sensitivity. Prevalence of positive herds for E. coli O157:H7 was estimated at 8.7% for sheep and 3.8% for cattle, whereas all the porcine herds tested negative. Non-O157 STEC were also absent from swine, but were isolated more frequently from ovine (50.8%) than bovine herds (35.9%). Within-herd prevalences of excretion of E. coli O157:H7 established by individual testing of 279 sheep (six herds) and 30 beef cattle (one herd) were 7.3% and 6.7% respectively. PCR analysis of 49 E. coli O157:H7 and 209 non-O157 isolates showed a different distribution of virulence genes. All E. coli O157:H7 were stx(2) gene-positive, eaeA was detected in 95.9%, and the toxigenic profile stx(2)/eaeA/E-hlyA was present in 75.5% of the isolates. Among the non-O157 STEC, prevalence of eaeA was significantly lower (5.3%) and E-hlyA was present in 50.2% of the isolates but only sporadically associated with eaeA. stx(2) was predominant in non-O157 isolates from cattle, whereas in sheep the combination stx(1)/stx(2) was more prevalent. This study demonstrated the wide distribution of STEC in ruminant herds, which represent an important reservoir for strains that pose a potential risk for human infections.

Detection of virulence factors and antimicrobial resistance patterns in shiga toxin-producing Escherichia coli isolates from sheep

“…On the other hand, Oporto et al (2008) observed a prevalence of 67.4% of stx1/stx2, far above the 17.9% of stx1 in STEC isolated from sheep in Spain. Experiments with rats indicated that stx2 is 100 times more potent than stx1 (Tesh et al 1993).…”

“…Similar results were observed by (Pinaka et al 2013), who detected no rfbO157 and flicH7 genes in isolates from goats, sheep and cattle, but found eae in 54.9% (28/51), which was not confirmed in our study. Also in Spain, the majority of sheep STEC isolates was non--O157, with only 8.7% O157:H7-positive STEC (Oporto et al 2008). O157 STEC isolates are worldwide involved in different disease outbreaks in humans, while in recent years, outbreaks involving non-O157 isolates have been increasingly reported (Hedican et al 2009, Scheutz et al 2011.…”

Faecal shedding of verotoxigenic Escherichia coli in cattle in the Czech Republic

“…In Italy, VTEC O157 were detected in faeces from 42% (Albonetti et al, 2004) and 24% of slaughtered cattle (Alonso et al, 2007). Oporto et al (2008) detected VTEC O157:H7 and non-O157 in 3.8% and 35.9% of cattle herds, respectively. Data from Norway showed the finding of VTEC O157 in up to 75% of all animals examined (Urdahl et al, 2003).…”

Elazığ’da Mezbahalarda Kesilen Sığırlardan ve Piyasada Satılan Kıymalardan Shiga Toksin Üreten Escherichia coli O157’nin İzolasyonu, Virulens Genleri ve Antibiyotiklere Duyarlılıkları

“…The agar plates were incubated at 37°C for 24 h. Sorbitol negative colonies on CT-SMAC Agar were considered presumptive E. coli O157. Presumptive E. coli O 157 colonies were confirmed by amplification of the gene encoding O157 somatic antigen (rfbE) by PCR 19 .…”