Bacteriophage preparation lytic for Shigella significantly reduces Shigella sonnei contamination in various foods

Abstract

ShigaShield™ is a phage preparation composed of five lytic bacteriophages that specifically target pathogenic Shigella species found in contaminated waters and foods. In this study, we examined the efficacy of various doses (9x105-9x107 PFU/g) of ShigaShield™ in removing experimentally added Shigella on deli meat, smoked salmon, pre-cooked chicken, lettuce, melon and yogurt. The highest dose (2x107 or 9x107 PFU/g) of ShigaShield™ applied to each food type resulted in at least 1 log (90%) reduction of Shigella in all the food types. There was significant (P<0.01) reduction in the Shigella levels in all phage treated foods compared to controls, except for the lowest phage dose (9x105 PFU/g) on melon where reduction was only ca. 45% (0.25 log). The genomes of each component phage in the cocktail were fully sequenced and analyzed, and they were found not to contain any “undesirable genes” including those listed in the US Code for Federal Regulations (40 CFR Ch1). Our data suggest that ShigaShield™ (and similar phage preparations with potent lytic activity against Shigella spp.) may offer a safe and effective approach for reducing the levels of Shigella in various foods that may be contaminated with the bacterium.

Identification and Characterization of T5-Like Bacteriophages Representing Two Novel Subgroups from Food Products

“…Besides the above-cited studies of promising candidate phages to be used as biocontrol agents against pathogenic bacteria, there are already several commercially available phage cocktails aimed at various foodborne enterobacterial pathogens (reviewed by Abedon, 2017 ). However, according to our knowledge except for ShigaShield, which is aimed against Shigellae (Soffer et al, 2017 ), and the Microgen ColiProteus aimed against E. coli and Proteus (McCallin et al, 2013 ), none of the component phages have been sequenced. In order to assess the applicability of a phage either for biocontrol of for therapy, extensive knowledge of its genome is essential, to determine whether the phage carries “undesirable” genes.…”

“…There are already several examples of commercially available phage cocktails to be utilized against various foodborne pathogens. There is a phage cocktail aimed against E. coli O157 to be applied to food surfaces (Carter et al, 2012 ), as well as cocktails against Shigella (Soffer et al, 2017 ), Listeria monocytogenes and Salmonella enterica (reviewed by Abedon, 2017 ). There have also been clinical trials of phage cocktails against diarrheagenic E. coli on human subjects (Sarker et al, 2012 , 2016 ), but these did not yield results regarding the efficacious use of phage cocktails for such infections.…”

Bacteriophage Applications for Food Production and Processing

“…Only one FDA-cleared food safety phage preparation is currently available to target Shigella spp. [ 66 , 69 ]. This five-phage cocktail was granted the GRAS status in 2017 (GRN 672) ( Table 2 ), and it was shown to reduce the levels of Shigella by approximately 1 log in a variety of foods, including melons, lettuce, yogurt, deli corned beef, smoked salmon, and chicken breast meat [ 66 ].…”

The dawn of phage therapy

“…ListShield is the first phage‐based approved product in the United States that targets L. monocytogenes as a food preservative; however, the first phage‐based antimicrobial to get approval in 2005 in agricultural practices was Agriphage from OmniLytics Inc. Some commercial phage‐based antimicrobials against food pathogens are EcoShield against E. coli O157:H7, PhageGuard S (Salmonellex) against Salmonella enterica, ShigaShield against a number of pathogens including Shigella dysenteriae , sonnei , flexneri , and boydii, SalmoLyse (SalmoFresh) for S. enterica, and PhageGuard Lystex (Listex P‐100) against L. monocytogenes. The first phage‐based product to be used in animal feed as a replacement for antibiotics is BioTector against Salmonella species …”