Association of resistance to quaternary ammonium compounds and organic acids with genetic markers and their relationship to Escherichia coli serogroup

Citation

Castro, V.S., Fang, Y., Yang, X., Stanford, K. (2023). Association of resistance to quaternary ammonium compounds and organic acids with genetic markers and their relationship to Escherichia coli serogroup. Food Microbiology, [online] 113 http://dx.doi.org/10.1016/j.fm.2023.104267

Plain language summary

Sanitizers and organic acids are routinely used in food processing plants to control pathogens of concern and in the case of beef, Shiga toxin-producing Escherichia coli (STEC). E. coli, as a species, is very versatile and as such a population approach is necessary to examine their resistance to sanitizers and organic acids and the underlining genetic mechanisms. In this work, a large number (n=746) of were compared for their response to sanitizers and lactic acid and a selected population was whole genome sequenced and analyzed. The results show that different subgroups of STEC differ in their response to these treatments and some genetic marker for heat resistance may play a role in acid and sanitizer resistance in E. coli. The findings provide information for better control of STEC in food processing environment.

Abstract

Sanitizer resistance is being extensively investigated due to the potential for bacterial survival and cross-resistance with other antimicrobials. Similarly, organic acids are being used due to their microbial inactivation potential as well as being generally recognized as safe (GRAS). However, little is known about associations of genetic and phenotypic factors in Escherichia coli related to resistance to sanitizers and organic acids as well as differences between “Top 7” serogroups. Therefore, we investigated 746 E. coli isolates for resistance to lactic acid and two commercial sanitizers based on quaternary ammonium and peracetic acid. Furthermore, we correlated resistance to several genetic markers and investigated 44 isolates using Whole Genome Sequencing. Results indicate that factors related to motility, biofilm formation, and Locus of Heat Resistance played a role in resistance to sanitizers and lactic acid. In addition, Top 7 serogroups significantly differed in sanitizer and acid resistance, with O157 being the most consistently resistant to all treatments. Finally, mutations in rpoA, rpoC, and rpoS genes were observed, in addition to presence of a Gad gene with alpha-toxin formation in all O121 and O145 isolates, which may be related to increased resistance of these serogroups to the acids used in the present study.

Publication date

2023-08-01

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