Prevalence of Escherichia coli O157 and O157:H7-infecting bacteriophages in feedlot cattle feces

Aim: To estimate the distribution and prevalence of both Escherichia coli O157 and O157:H7-infecting bacteriophages within a 50 000 head commercial beef feedlot. Methods and Results: Escherichia coli O157 was detected in ∼27% of the individual samples, distributed across seven of the 10 pens screened. In a simple initial screen to detect O157:H7-infecting phages, none were detected in any pen or individual sample. In contrast, after a series of enrichment procedures O157:H7-infecting phages were detected in every pen and in the majority of the samples from most pens; virulent bacteriophages active against E. coli O157:H7 were detected post-enrichment from 39/60 (65%) of the feedlot samples, and 58/60 (∼97%) contained phage that infected E. coli B or O157:H7. Conclusions: The data we present here indicates that we may be grossly underestimating the prevalence of O157:H7-infecting phages in livestock if we simply screen samples and that enrichment screening is required to truly determine the presence of phages in these ecosystems. Significance and Impact of the Study: Our data suggest that O157:H7-infecting phages may play a role in the ecology and transient colonization of cattle by E. coli O157:H7. Further, this and previous data suggest that before starting in vivo pathogen eradication studies using phage or any other regime, test animals should be enrichment screened for phage to avoid erroneous results.Fil: Oot, Rebecca. The Evergreen State College; Estados UnidosFil: Raya, Raul Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Callaway, Todd R.. College Station. Food and Feed Safety Research Unit. Agricultural Research Service; Estados UnidosFil: Edrington, Tom S.. College Station. Food and Feed Safety Research Unit. Agricultural Research Service; Estados UnidosFil: Kutter, Elizabeth M.. The Evergreen State College; Estados UnidosFil: Brabban, Andrew D.. The Evergreen State College; Estados Unido

Isolation and Characterization of a New T-Even Bacteriophage, CEV1, and Determination of Its Potential To Reduce Escherichia coli O157:H7 Levels in Sheep

Bacteriophage CEV1 was isolated from sheep resistant to Escherichia coli O157:H7 colonization. In vitro, CEV1 efficiently infected E. coli O157:H7 grown both aerobically and anaerobically. In vivo, sheep receiving a single oral dose of CEV1 showed a 2-log-unit reduction in intestinal E. coli O157:H7 levels within 2 days compared to levels in the controls

Characterization of a ViI-like Phage Specific to <it>Escherichia coli </it>O157:H7

<p>Abstract</p> <p>Phage vB_EcoM_CBA120 (CBA120), isolated against <it>Escherichia coli </it>O157:H7 from a cattle feedlot, is morphologically very similar to the classic phage ViI of <it>Salmonella enterica </it>serovar Typhi. Until recently, little was known genetically or physiologically about the ViI-like phages, and none targeting <it>E. coli </it>have been described in the literature. The genome of CBA120 has been fully sequenced and is highly similar to those of both ViI and the <it>Shigella </it>phage AG3. The core set of structural and replication-related proteins of CBA120 are homologous to those from T-even phages, but generally are more closely related to those from T4-like phages of <it>Vibrio, Aeromonas </it>and cyanobacteria than those of the <it>Enterobacteriaceae</it>. The baseplate and method of adhesion to the host are, however, very different from those of either T4 or the cyanophages. None of the outer baseplate proteins are conserved. Instead of T4's long and short tail fibers, CBA120, like ViI, encodes tail spikes related to those normally seen on podoviruses. The 158 kb genome, like that of T4, is circularly permuted and terminally redundant, but unlike T4 CBA120 does not substitute hmdCyt for cytosine in its DNA. However, in contrast to other coliphages, CBA120 and related coliphages we have isolated cannot incorporate ³H-thymidine (³H-dThd) into their DNA. Protein sequence comparisons cluster the putative "thymidylate synthase" of CBA120, ViI and AG3 much more closely with those of <it>Delftia </it>phage φW-14, <it>Bacillus subtilis </it>phage SPO1, and <it>Pseudomonas </it>phage YuA, all known to produce and incorporate hydroxymethyluracil (hmdUra).</p