Oral and Rectal Administration of Bacteriophages for Control of Escherichia coli O157:H7 in Feedlot Cattle

Abstract

This study compared oral and rectal administration of O157-specific bacteriophages for mitigating the fecal shedding of Escherichia coli O157 by experimentally inoculated steers. Fecal shedding of nalidixic acid-resistant (Nal(R)) E. coli O157:H7 was monitored over 83 days after oral (ORL; 3.3 x 10(11) PFU), rectal (REC; 1.5 x 10(11) PFU), both oral and rectal (O+R; 4.8 x 10(11) PFU), or no (CON; control) treatment with a four-strain O157-specific bacteriophage cocktail in multiple doses. Bacteriophages were enumerated by plaque assay, and NalR E. coli O157:H7 by direct plating on sorbitol MacConkey agar supplemented with cefixime, potassium tellurite, and nalidixic acid. Orally treated steers produced the fewest Nal(R) E. coli O157:H7 culture-positive samples (P < 0.06) compared with REC and O+R steers, but this number was only nominally lower (P = 0.26) than that for the CON steers. The overall mean shedding level (log CFU per gram of feces) was higher for REC steers (P < 0.10) than for steers of the other treatment groups. Despite the shedding of higher mean bacteriophage levels (log PFU per gram of feces) by ORL and O+R than by CON and REC steers, there was no difference (P > 0.05) in the number of E. coli O157-positive samples among treatments. Bacteriophage was isolated from CON steers, indicating that these steers acquired the bacteriophage from the environment and shed the phage at a level similar to that of REC steers (P = 0.39). Continuous bacteriophage therapy may be an efficacious method for mitigating shedding of E. coli O157:H7 in cattle, providing that the host bacterium does not develop resistance. This therapy may be especially advantageous if nontreated cattle can acquire this biocontrol agent from the feedlot environment.

Strain-Dependent Cellular Immune Responses in Cattle following Escherichia coli O157:H7 Colonization

“…While these efforts have been partially successful, food-borne outbreaks have not been eliminated, and environmental transmission remains unmitigated. A range of on-farm interventions have been proposed to reduce bacterial shedding by cattle, including dietary manipulation, phage therapy, antimicrobial treatment, probiotic administration, and vaccination (10)(11)(12)(13)(14)(15). Recent reviews and meta-analyses have identified probiotics and vaccines as the most tractable and efficacious control measures (12,16,17).…”

Escherichia coli O157:H7 Typing Phage V7 Is a T4-Like Virus

“…We have tested several of the phages from the Escherichia coli O157:H7 typing set (1) in an effort to minimize the carriage of this pathogen by animals destined for the food chain (10). In this publication, we describe the host range and genomic and proteomic characteristics of phage V7.…”

Lytic bacteriophages in Veterinary Medicine: a therapeutic option against bacterial pathogens?

“…In contrast, certain antibiotics such as tetracyclines and gentamycin exhibit toxic effects after prolonged administrations, in young individuals or in certain physiological states such as pregnancy. -Possible phage transfer between individuals: this is essentially cross infection of phages from treated subjects or environments to untreated individuals, which may be potentially useful in agricultural applications (Fiorentin et al 2005, Rozema et al 2009, Loc-Carrillo and Abedon 2011). -Low environmental impact: because of their chemical composition and their narrow host range, phage eliminated after treatment, unlike broad-spectrum antibiotics, in the worst scenario will impact only a small group of environmental bacteria (Loc-Carrillo and Abedon 2011).…”

“…Several studies on phage efficiency for the elimination or reduction in carriage of these intestinal bacteria have been performed (Sheng et al 2006, Rozema et al 2009. Sheng et al (2006) concluded that a continuous phage therapy can be an effective method to reduce E. coli O157: H7 carriage, achieving significant reductions in vivo up to 1.5 log lower compared with the control group.…”