Abstract
Shiga toxin-producing Escherichia coli (STEC) O26:H11 is an emerging foodborne pathogen of growing concern. Since current strategies to control microbial contamination in foodstuffs do not guarantee the elimination of O26:H11, novel approaches are needed. Bacteriophages present an alternative to traditional biocontrol methods used in the food industry. Here, a previously isolated bacteriophage vB_EcoM_VR26 (VR26), adapted to grow at common refrigeration temperatures (4 and 8 °C), has been evaluated for its potential as a biocontrol agent against O26:H11. After 2 h of treatment in broth, VR26 reduced O26:H11 numbers (p < 0.01) by > 2 log10 at 22 °C, and ~3 log10 at 4 °C. No bacterial regrowth was observed after 24 h of treatment at both temperatures. When VR26 was introduced to O26:H11-inoculated lettuce, ~2.0 log10 CFU/piece reduction was observed at 4, 8, and 22 °C. No survivors were detected after 4 and 6 h at 8 and 4 °C, respectively. Although at 22 °C, bacterial regrowth was observed after 6 h of treatment, O26:H11 counts on non-treated samples were >2 log10 CFU/piece higher than on phage-treated ones (p < 0.02). This, and the ability of VR26 to survive over a pH range of 3–11, indicates that VR26 could be used to control STEC O26:H11 in the food industry.
Highlights
Most strains of E. coli are non-pathogenic, a number of strains, such as Shiga toxin-producing E. coli (STEC), can cause severe foodborne disease
Bacteriophage VR26 was tested against a set of 5 pathogenic E. coli, representing different Shiga toxin-producing Escherichia coli (STEC) serotypes: O157:H7, O103:H2, O111:H8, O145:H128, and O26:H11
Phages that display a narrow lytic activity against non-O157 E. coli were described in a study by Litt et al [24], in which three viruses targeting O26:H11 failed to infect isolates representing other STEC serogroups, including O45, O103, O111, O121, and O145
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Escherichia coli (E. coli) is a gram-negative, facultatively anaerobic, rod-shaped bacterium of the genus Escherichia, family Enterobacteriaceae, that is commonly found in the gut of humans and warm-blooded animals [1]. Since the bacterium is routinely shed into the environment through feces, it can contaminate drinking water, irrigation water, and soil. It can be transmitted to humans primarily through the consumption of contaminated foods [2,3]. Most strains of E. coli are non-pathogenic, a number of strains, such as Shiga toxin-producing E. coli (STEC), can cause severe foodborne disease
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