Resistance of phages lytic to pathogenic Escherichia coli to sanitisers used by the food industry and in home settings

Abstract

Summary Phages are potentially useful as antimicrobial agents in food‐processing environments, provided they can remain active upon extended storage and in the presence of sanitisers. Survival of six phages lytic against enteropathogenic (EPEC) and shiga‐toxigenic (STEC) Escherichia coli strains was assessed upon storage at 4 °C, −20 °C and −70 °C in phosphate‐buffered‐saline (PBS) and Tris‐magnesium‐gelatine buffer (TMG) for up to 1 year. The phages were also exposed to ethanol, sodium hypochlorite, peracetic acid, quaternary ammonium chloride (biocide A), hydrogen peroxide/peracetic acid/peroctanoic acid (biocide B), p‐toluensulfonchloroamide (biocide D) and alkaline chloride foam (biocide C). Plaque‐forming units remained unchanged when the phages were stored at 4 °C in both buffers tested, but decreased by 3.5 and 5.7 log10 PFU when stored in PBS at −20 and −70 °C, respectively. Moreover, TMG seems to be the most protective suspension medium with decreasing temperature because a 1−log10 PFU reduction was observed at −20 and −70 °C. Incubation in 100% ethanol for 24 h reduced plaque counts only by 2.5 log10 PFU. In 10 ppm of sodium hypochlorite and in biocide B (0.13%), the counts decreased by ~5 and ~6 log10 PFU after 15 min. Finally, biocide A and D reduced counts by 4 and 2–4 log10 PFU after 30 min and 8 h of incubation, respectively. Phages were completely inactivated only by peracetic acid and biocides C and E. Therefore, the phages evaluated might be potentially applied together with classical sanitisers such as ethanol and industrial biocides A, B and D, in disinfection programs against pathogenic STEC and EPEC strains.

Isolation and characterization of a novel Escherichia coli O157:H7-specific phage as a biocontrol agent

“…4c) also showed that KFS-EC was stable in the presence of biocides such as chloroform, ethanol, citric acid, and 0.1% peracetic acid but not sodium hypochlorite and 1% peracetic acid. When compared with DT1, DT2, DT3, DT4, DT5, and DT6 phages infecting E. coli O157:H7, our phage showed better stability in the presence of 100% ethanol and similar stability in the presence of sodium hypochlorite [56]. This means that KFS-EC would be stable and active against E. coli O157:H7 when exposed to various environmental conditions during food processing and storage [37].…”

Nonthermal Plasma–Liquid Interactions in Food Processing: A Review

“…Presently, chemical compounds such as quaternary ammonium salts, chlorine, and acids are being used to protect fresh fruits and vegetable from microbial spoilage and to increase their CRF3-2019-0117 Submitted 5/8/2019, Accepted 9/9/2019 shelf life. However, many pathogens are becoming resistant to these conventional sanitizing compounds (Rodríguez-López, Rodríguez-Herrera, Vázquez-Sánchez, & Lopez Cabo, 2018;Tomat, Balagué, Aquili, Verdini, & Quiberoni, 2018). Further, the efficiency of these chemical sanitizing agents depends on the availability of free chlorine, wash water quality, microbial load, washing time, and presence of other organic and inorganic matter (Murray et al, 2017;Xiang, Kang, et al, 2019).…”

Two Newly Isolated Enterobacter-Specific Bacteriophages: Biological Properties and Stability Studies

“…Likewise, such conditions caused a significant decrease in vB-EcoS-95 phage survival (0.8% active particles) [ 79 ]. Interestingly, Tomat et al (2018) [ 106 ] reported E. coli phages that remained active after 24 h of incubation in 100% ethanol (decrease of titer by 2.5 PFU/mL). Recently, the possible negative effects of the uncontrolled spread of phages in food production processes have also been emphasized [ 107 ].…”