Feedlot- and Pen-Level Prevalence of Enterohemorrhagic Escherichia coli in Feces of Commercial Feedlot Cattle in Two Major U.S. Cattle Feeding Areas

Abstract

The objective of this study was to determine feedlot- and pen-level fecal prevalence of seven enterohemorrhagic Escherichia coli (EHEC) belonging to serogroups (O26, O45, O103, O111, O121, O145, and O157, or EHEC-7) in feces of feedlot cattle in two feeding areas in the United States. Cattle pens from four commercial feedlots in each of the two major U.S. beef cattle areas were sampled. Up to 16 pen-floor fecal samples were collected from each of 4-6 pens per feedlot, monthly, for a total of three visits per feedlot, from June to August, 2014. Culture procedures including fecal enrichment in E. coli broth, immunomagnetic separation, and plating on selective media, followed by confirmation through polymerase chain reaction (PCR) testing, were conducted. Generalized linear mixed models were fitted to estimate feedlot-, pen-, and sample-level fecal prevalence of EHEC-7 and to evaluate associations between potential demographic and management risk factors with feedlot and within-pen prevalence of EHEC-7. All study feedlots and 31.0% of the study pens had at least one non-O157 EHEC-positive fecal sample, whereas 62.4% of pens tested positive for EHEC O157; sample-level prevalence estimates ranged from 0.0% for EHEC O121 to 18.7% for EHEC O157. Within-pen prevalence of EHEC O157 varied significantly by sampling month; similarly within-pen prevalence of non-O157 EHEC varied significantly by month and by the sex composition of the pen (heifer, steer, or mixed). Feedlot management factors, however, were not significantly associated with fecal prevalence of EHEC-7. Intraclass correlation coefficients for EHEC-7 models indicated that most of the variation occurred between pens, rather than within pens, or between feedlots. Hence, the potential combination of preharvest interventions and pen-level management strategies may have positive food safety impacts downstream along the beef chain.

Occurrence and characterization of seven major Shiga toxin‐producing Escherichia coli serotypes from healthy cattle on cow–calf operations in South Africa

“…Virulence characterization revealed that the majority of STEC isolates carried mainly stx1 (69%), stx2 (96%), and 62% of STEC isolates carried both stx1 and stx2 simultaneously. This was in agreement with similar studies in the USA that have reported proportions of stx1 ranging from 65.5% to 79.4% (Cull et al, ; Stanford et al, ), 73% to 98.6% for stx2 (Bibbal et al, ; Paddock et al, ) and 52.5% to 53% of STEC isolates carried both stx1 and stx2 genes (Cernicchiaro et al, ; Cull et al, ). STEC isolates harbouring stx2 have been frequently associated with severe disease including HUS in humans in comparison to STEC strains which carry stx1 only or both stx1 and stx2 (Friedrich et al, ; Ostroff et al, ).…”

“…The prevalence of infected cattle per farm ranged from 2.9% to 43.3% consistent with reports from Japan and the United Kingdom which reported similar ranges (Ellis‐Iversen et al, ; Gunn et al, ; Lee, 2017). However, the farms prevalence rates obtained in this study were relatively lower in comparison to studies in Brazil, South Korea and USA cattle farms which reported up to 100% for cattle that tested positive for STEC (Cull et al, ; Dong et al, ; Pereira, Brod, Rodrigues, Carvalhal, & Aleixo, ). We also observed that particular serotypes were confined to specific farms.…”

“…Further H typing revealed that the 241 STEC isolates belonged to 14 hr types (Table 2) Virulence genes (stx1, stx2, eaeA and ehxA) The distribution of major STEC virulence genes was as follows: -Iversen et al, 2007;Gunn et al, 2007;. However, the farms prevalence rates obtained in this study were relatively lower in comparison to studies in Brazil, South Korea and USA cattle farms which reported up to 100% for cattle that tested positive for STEC (Cull et al, 2017;Dong et al, 2017;Pereira, Brod, Rodrigues, Carvalhal, & Aleixo, 2003). We also observed that particular serotypes were confined to specific farms.…”

“…To our knowledge, this is the first study reporting on the prevalence of the seven major STEC serogroups including O157, O26, O45, O145, O121 and O103 that are harboured by cattle on cow–calf operations in South Africa. It is important to note that most of the studies that have previously reported on the presence of these serogroups in cattle populations worldwide have mainly limited their search to STEC serogrouping (O‐typing) without further H‐serotyping (H typing; Cernicchiaro et al, ; Cull et al, ; Lee, Kusumoto, Iwata, Iyoda, & Akiba, ; Mellor et al, ; Paddock et al, ; Stanford et al, ). The current study is among the few which characterized STEC for H types.…”

Shiga Toxin Subtypes of Non-O157 Escherichia coli Serogroups Isolated from Cattle Feces

“…The other non-O157 E. coli serogroups included O6 ( n = 2), O8 ( n = 3), O15 ( n = 1), O22 ( n = 1), O38 ( n = 2), O39 ( n = 3), O74 ( n = 3), O88 ( n = 3), O91 ( n = 2), O96 ( n = 3), O104 ( n = 18), O113 ( n = 3), O116 ( n = 3), O117 ( n = 3), O130 ( n = 4), O141 ( n = 3), O146 ( n = 1), O153 ( n = 1), O163 ( n = 2), O171 ( n = 3), and O172 ( n = 2). Cattle strains were isolated from feces, primarily from commercial feedlots (Renter et al, 2005; Noll et al, 2015; Shridhar et al, 2016; Cull et al, 2017). A few human clinical strains, obtained from Michigan State University (MSU) and the Kansas Department of Health and Environment (KDHE), were also included in the study.…”