A minireview on the in vitro and in vivo experiments with anti- Escherichia coli O157:H7 phages as potential biocontrol and phage therapy agents

Abstract

Phage therapy is an old method of combating bacterial pathogens that has recently been taken into consideration due to the alarming spread of antibiotic resistance. Escherichia coli O157:H7 is a foodborne pathogen that causes hemorrhagic colitis and life-threatening Hemolytic Uremic Syndrome (HUS). There are several studies on isolation of specific phages against E. coli O157:H7 and more than 60 specific phages have been published so far. Although in vitro experiments have been successful in elimination or reduction of E. coli O157:H7numbers, in vivo experiments have not been as promising. This may be due to escape of bacteria to locations where phages have difficulties to enter or due to the adverse conditions in the gastrointestinal tract that affect phage viability and proliferation. To get around the latter obstacle, an alternative phage delivery method such as polymer microencapsulation should be tried. While the present time results are not very encouraging the work should be continued as more efficient phage treatment regimens might be found in future.

Bacteriophages specific to Shiga toxin-producing Escherichia coli exist in goat feces and associated environments on an organic produce farm in Northern California, USA

“…A previous study reported that phages belonging to family Myoviridae were the most frequently isolated phage morphology from cattle feces [23]. Additionally, a review article also demonstrated that among more than 60 reported phages isolated from various environmental sources that were lytic against STEC strains, the morphologies of most phages belong to the Myoviridae family [41]. On the other hand, the results of the current study show that the isolated phages belonging to the families Podoviridae and Siphoviridae demonstrated a narrow host range infecting only one STEC serogroup (O45 and O145, respectively).…”

Treatment Strategies for Infections With Shiga Toxin-Producing Escherichia coli

“…One of the first attempts to eliminate STEC from animals (e.g., mice, sheep, and cattle) and food was performed with bacteriophages (e.g., the T-even bacteriophage CEV1, rV5, WV8, WV7, wV11, e11/2, and e4/1c), which have the potential to lyse E. coli O:157:H7 (Raya et al, 2006;Sheng et al, 2006;Abuladze et al, 2008;Rivas et al, 2010;Stanford et al, 2010). To date, a large variety of phages have been isolated and shown to be highly effective in the killing of STEC strains in vitro, but the application of individual bacteriophages in vivo seemed less promising, likely due to the fact that bacterial access of the phages in the gut is reduced, or the intestinal environment is disadvantageous for phage survival and/or replication (Niu et al, 2009;Dini et al, 2016;Sabouri et al, 2017;Wang et al, 2017;Safwat-Mohamed et al, 2018). However, more recently, use of certain phages and phage cocktails including multiple STEC-specific phages for oral or rectal administration to ruminants or for spraying on fruits and vegetables has shown the potential of phage therapy to reduce STEC carriage in domestic animals (Niu et al, 2009;Dini et al, 2016;Sabouri et al, 2017;Wang et al, 2017;Safwat-Mohamed et al, 2018).…”

Bacteriophages to control Shiga toxin-producingE. coli– safety and regulatory challenges

“…Some studies report on the use of phages to control food contamination by targeting the pathogen on living animals prior to their slaughter or by applying them as disinfectants on food processing steps (revised elsewhere [107][108][109]). The inclusion of phages on the food chain will result in their presence on the consumers' table and their gut.…”