In Vivo and Ex Vivo Evaluations of Bacteriophages e11/2 and e4/1c for Use in the Control of Escherichia coli O157:H7

Abstract

This study investigated the effect of bacteriophages (phages) e11/2 and e4/1c against Escherichia coli O157:H7 in an ex vivo rumen model and in cattle in vivo. In the ex vivo rumen model, samples were inoculated with either 10 3 or 10 6 CFU/ml inoculum of E. coli O157:H7 and challenged separately with each bacteriophage. In the presence of phage e11/2, the numbers of E. coli O157:H7 bacteria were significantly (P < 0.05) reduced to below the limit of detection within 1 h. Phage e4/1c significantly (P < 0.05) reduced E. coli O157:H7 numbers within 2 h of incubation, but the number of surviving E. coli O157:H7 bacteria then remained unchanged over a further 22-h incubation period. The ability of a phage cocktail of e11/2 and e4/1c to reduce the fecal shedding of E. coli O157:H7 in experimentally inoculated cattle was then investigated in two cattle trials. Cattle (yearlings, n ‫؍‬ 20 for trial one; adult fistulated cattle, n ‫؍‬ 2 for trial two) were orally inoculated with 10 10 CFU of E. coli O157:H7. Animals (n ‫؍‬ 10 for trial one; n ‫؍‬ 1 for trial two) were dosed daily with a bacteriophage cocktail of 10 11 PFU for 3 days postinoculation. E. coli O157:H7 and phage numbers in fecal and/or rumen samples were determined over 7 days postinoculation. E. coli O157:H7 numbers rapidly declined in all animals within 24 to 48 h; however, there was no significant difference (P > 0.05) between the numbers of E. coli O157:H7 bacteria shed by the phage-treated or control animals. Phages were recovered from the rumen but not from the feces of the adult fistulated animal in trial two but were recovered from the feces of the yearling animals in trial one. While the results from the rumen model suggest that phages are effective in the rumen, further research is required to improve the antimicrobial effectiveness of phages for the elimination of E. coli O157:H7 in vivo.

Bacteriophages and Their Role in Food Safety

“…Also, a cocktail of phages CEV1 and CEV2 were reported to lead to more than 99.9% of reduction of E. coli in sheep guts [36]. However, although reductions of E. coli levels in different organs have been described, phages still fail in reducing fecal shedding [29, 35], and only in one published work the authors managed to reduce fecal shedding duration by 14 days [28]. In 2008, Niu and colleagues investigated two different sampling techniques: fecal grab and rectoanal mucosal swab for surveillance of E. coli O157 : H7 [42] and to study the role of phage as a mitigation strategy.…”

Virulent Bacteriophages Can Target O104:H4 Enteroaggregative Escherichia coli in the Mouse Intestine

“…Several studies have reported the use of bacteriophages to target enterotoxigenic, enteropathogenic, and commensal Escherichia coli strains (7). They reported a decrease in diarrheal symptoms (21,40,41), a decrease in the concentration of the bacterium in the intestine (10,(33)(34)(35), an increase in the rate of natural bacterial clearance (9,39,42), or even no decrease in the bacterial concentration at all (16,47). These data indicate that, within the scope of the intestinal microbiota, detailed investigations are required of the interactions between individual bacteriophages and their bacterial hosts, even within a single given bacterial species.…”

Isolation, characterization and complete genome sequence of PhaxI: a phage of Escherichia coli O157 : H7

“…Longer bacterial killing times in milk could be due to the presence of other interacting proteins, components and ions which can affect adsorption of phage to the host. From the O157 phages, several such as CEV1, CEV2, KH1, SH1, e11/2 and e4/1c were tested in animals (Raya et al, 2006(Raya et al, , 2011Rivas et al, 2010;Sheng et al, 2006).…”