Antimicrobial resistanceof Listeria monocytogenes serogroups IIa and IVbfrom food and food-production environments in Poland

Abstract

Introduction: Listeria monocytogenes is an important foodborne pathogen responsible for human listeriosis, which isa disease with high hospitalisation and mortality rates. The bacteria are usually susceptible to most antibacterial substances, butresistance to some of them has been recently observed. The present study introduces the evidence on the emergence of antibioticresistance among L. monocytogenes strains isolated from food and food-production environments in Poland. Material andMethods: A total of 283 L. monocytogenes isolates classified into serogroups IIa and IVb which had been recovered from foodand food production environments were tested with 17 antimicrobials. These included those that are recommended for treatmentof severe listeriosis cases in humans. A multiplex PCR was used to identify serogroups, and a microbroth dilution method wasapplied for the determination of antibiotic resistance among the isolates tested. Results: Only 34 (12.0%) strains were susceptibleto all the antimicrobials used in the study. The remaining 249 (88.0%) strains displayed different instances of resistance to theantimicrobials tested, from insusceptibility to one (112 strains; 39.6%) to resistance to four antibacterial substances (6 strains;2.1%). Among them, there were 38 strains (13.4%) with multiresistance patterns. Conclusion: Polish food and its processingenvironments may be a potential source of antimicrobial-resistant L. monocytogenes, which may pose a potential health risk toconsumers in the country.