Assessment of Virulence Factors Characteristic of Human Escherichia coli Pathotypes and Antimicrobial Resistance in O157:H7 and Non-O157:H7 Isolates from Livestock in Spain

Abstract

eThe distribution of virulence factors (VFs) typical of diarrheagenic Escherichia coli and the antimicrobial resistance (AMR) profiles were assessed in 780 isolates from healthy pigs, broilers, and cattle from Spain. VF distribution was broader than expected, although at low prevalence for most genes, with AMR being linked mainly to host species. P athogenic isolates of Escherichia coli are characterized by the presence of virulence factors (VFs) that can be combined, leading to different pathotypes (1). Six distinct intestinal pathotypes have been differentiated, including enteropathogenic (EPEC), enterotoxigenic (ETEC), enterohemorrhagic (EHEC), enteroaggregative (EAEC), enteroinvasive (EIEC), and diffusely adherent (DAEC) E. coli (2). The main reservoirs for EPEC, EAEC, and EIEC are humans (1, 3). In contrast, EHEC transmission from animals to humans may also occur through fecal contamination of food or water. In addition to the conventional E. coli pathotypes, novel hybrid pathotypes may emerge, as occurred with EAEC/ EHEC O104:H4 of the German outbreak, which spread across several European countries, affecting almost 4,000 people and causing more than 50 deaths (4).Limited information on the distribution of E. coli pathotypes in healthy livestock (especially non-Shiga toxin-producing E. coli [STEC]) and the possible association between the carriage of VF and their antimicrobial resistance (AMR) patterns is available. In this study, we evaluated the distribution of VFs and AMR profiles in E. coli isolates recovered from healthy livestock in Spain.All these E. coli isolates were recovered in 2009 (n ϭ 780) through the Spanish Surveillance Network of Antimicrobial Resistance in Bacteria of Veterinary Origin (VAV Network) (5). Isolate distribution was as follows: 50 O157:H7 E. coli strains from cattle and 730 E. coli strains (278 from pigs, 196 from broilers, and 256 from cattle) belonging to other serotypes (referred to here as non-O157:H7 E. coli regardless whether they were EHEC). These isolates were recovered from pooled samples collected at Spanish slaughterhouses selected according to their slaughter capacity and located in different regions within the country. Isolates were obtained by culturing pooled feces samples from pigs (2 animals per pool, 556 individual fecal samples analyzed), cattle (2 animals per pool, 512 individual fecal samples analyzed) and broilers (3 animals per pool, 588 individual fecal samples analyzed). Each pool represented one slaughter batch from one single farm.Samples from pigs, broilers, and cattle were cultured on MacConkey agar plates (6). In addition, cattle feces were processed to obtain E. , bfpA, pInv, and aggR) and the somatic and flagellar antigens of O157:H7 and O104:H4 serotypes were assessed in all isolates using conventional PCR (see Table S1 in the supplemental material). The ␤-D-glucuronidase-encoding gene uidA was also included for E. coli confirmation (7). In addition, the stx 2 PCR product from two swine isolates was sequenced to assess their stx 2 type (8). Al...

Escherichia coliO157:H7 in wild boars (Sus scrofa) and Iberian ibex (Capra pyrenaica) sharing pastures with free-ranging livestock in a natural environment in Spain

“…It seems that the detection of stx 1 alone or in combination with stx 2 is less frequent than the carriage of stx 2 alone. This fact may indicate that in Spain, O157:H7 from wild animals are similar to those of cattle regarding their VFs combination (Cabal et al 2013). However, in other countries, stx 2 was more frequently detected than the other two patterns in cattle (Ateba & Mbewe 2011).…”

“…Oppositely, antimicrobial resistance has been found in Salmonella and indicator E. coli from wildlife and livestock, including resistance to fluoroquinolones and cephalosporines (Navarro-Gonzalez et al 2012, which is of concern for public health. Cabal et al (2013) reported high frequency of antimicrobial resistance in E. coli O157:H7 from healthy cattle in Spain. This suggests that the E. coli O157:H7 strains from wildlife might be genetically different to those in livestock, and that the sources of infection might be different for livestock and wildlife.…”

“…One suspected colony per sample was boiled in 600 ml of double-distilled water and confirmed by polymerase chain reaction (PCR) as E. coli O157:H7 as described previously (Desmarchelier et al 1998;Heininger et al 1999). In addition, a multiplex PCR targeting nine virulence factors characteristic of human pathotypes (virulence factors (VFs): stx 1 , stx 2 , eae, ehxA, heat-stable enterotoxin (ST), heat-labile enterotoxin (LT), bfpA, pInv and aggR) was performed using all isolates as previously described (Cabal et al 2013).…”

Microbiome analysis reveals the abundance of bacterial pathogens in Rousettus leschenaultii guano

“…Cabal et al 42 compared the virulence gene profile of E. coli isolated from cattle, swine and broiler. The results indicated the presence of stx1 and stx2 gene (from both O157:H7 and Non-O157:H7 E. coli serotypes) in cattle and swine42.…”

Antimicrobial Resistance in Indicator Escherichia coli Isolates from Free-Ranging Livestock and Sympatric Wild Ungulates in a Natural Environment (Northeastern Spain)

“…For the comparison of our data with that from intensively reared livestock, Table 2 shows the frequencies of resistant E. coli in cattle from Spain (26).…”