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In this contribution, the antimicrobial susceptibility toward 11 antibiotics and four biocides of a panel of 205 Listeria monocytogenes (Lm) strains isolated from different ecological niches (i.e., food, animals and natural environment) was evaluated. The impact of exposure to biocides on the antibiotic susceptibilities of Lm was also investigated. Lm strains isolated from food exhib-ited overall a lower susceptibility (higher minimal inhibitory concentrations, MIC) for ammonium quaternary compounds (QACs) and peracetic acid (PAC) than strains isolated from animals and natural environments. Conversely, the ecological origins of Lm strains did not significantly affect their susceptibilities towards antibiotics. Interestingly, repeated exposure to QACs recurrently led to a decrease in susceptibility toward ciprofloxacin (CIP), a fluoroquinolone antibiotic, largely used in human medicine. Moreover, these lower levels of susceptibility to CIP remained stable in most Lm strains even after subcultures without biocide selection pressure, suggesting an adaptation involving modifications at the genetic level. Results underlined the ability of Lm to adapt to biocides, especially QACs, and the potential link between this adaptation and the selection of resistance toward critical antibiotics such as ciprofloxacin. These data support a potential role of the extensive use of QACs from “farm to fork” in the selection of biocide and antibiotic resistance in pathogenic bacteria such as Lm.

The increase of antibiotic resistance in foodborne bacteria is becoming of the main threat for public health. Increasing number of studies have shown that the exposure to disinfectant biocides as those daily used in the food industry may participate to increase antibiotic resistance in these bacteria. In this contribution, we assessed the antimicrobial susceptibility profiles toward 11 antibiotics and 4 biocides of a panel 206 Listeria monocytogenes strains from different origins. We also investigated the impact of repeated exposure to these biocides on the Lm antibiotic susceptibility. Results revealed that quaternary ammonium compounds (QACs) exposure of Lm strains often led to a decrease of susceptibility toward ciprofloxacin (CIP), a fluoroquinolone antibiotic, largely used in human and veterinary medicine and considered as a critically important antimicrobial. Furthermore, such susceptibility decrease remained stable in most Lm strains even after subcultures without biocide selection pressure suggesting an adaptation involving modifications at the genetic level. The extensive use of QACs in our environments may thus participate to the selection of critical antibiotic resistance in pathogen bacteria such as Lm and thus represent a public health issue. &nbsp

The increase of antibiotic resistance in foodborne bacteria is becoming of the main threat for public health. Increasing number of studies have shown that the exposure to disinfectant biocides as those daily used in the food industry may participate to increase antibiotic resistance in these bacteria. In this contribution, we assessed the antimicrobial susceptibility profiles toward 11 antibiotics and 4 biocides of a panel 206 Listeria monocytogenes strains from different origins.We also investigated the impact of repeated exposure to these biocides on the Lm antibiotic susceptibility. Results revealed that quaternary ammonium compounds (QACs) exposure of Lm strains often led to a decrease of susceptibility toward ciprofloxacin (CIP), a fluoroquinolone antibiotic, largely used in human and veterinary medicine and considered as a critically important antimicrobial. Furthermore, such susceptibility decrease remained stable in most Lm strains even after subcultures without biocide selection pressure suggesting an adaptation involving modifications at the genetic level. The extensive use of QACs in our environments may thus participate to the selection of critical antibiotic resistance in pathogen bacteria such as Lm and thus represent a public health issue. &nbsp

The increase of antibiotic resistance in foodborne bacteria is becoming of the main threat for public health. Increasing number of studies have shown that the exposure to disinfectant biocides as those daily used in the food industry may participate to increase antibiotic resistance in these bacteria. In this contribution, we assessed the antimicrobial susceptibility profiles toward 11 antibiotics and 4 biocides of a panel 206 Listeria monocytogenes strains from different origins. We also investigated the impact of repeated exposure to these biocides on the Lm antibiotic susceptibility. Results revealed that quaternary ammonium compounds (QACs) exposure of Lm strains often led to a decrease of susceptibility toward ciprofloxacin (CIP), a fluoroquinolone antibiotic, largely used in human and veterinary medicine and considered as a critically important antimicrobial. Furthermore , such susceptibility decrease remained stable in most Lm strains even after subcultures without biocide selection pressure suggesting an adaptation involving modifications at the genetic level. The extensive use of QACs in our environments may thus participate to the selection of critical antibiotic resistance in pathogen bacteria such as Lm and thus represent a public health issue.

The increase of antibiotic resistance in foodborne bacteria is becoming of the main threat for public health. Increasing number of studies have shown that the exposure to disinfectant biocides as those daily used in the food industry may participate to increase antibiotic resistance in these bacteria. In this contribution, we assessed the antimicrobial susceptibility profiles toward 11 antibiotics and 4 biocides of a panel 206 Listeria monocytogenes strains from different origins. We also investigated the impact of repeated exposure to these biocides on the Lm antibiotic susceptibility. Results revealed that quaternary ammonium compounds (QACs) exposure of Lm strains often led to a decrease of susceptibility toward ciprofloxacin (CIP), a fluoroquinolone antibiotic, largely used in human and veterinary medicine and considered as a critically important antimicrobial. Furthermore, such susceptibility decrease remained stable in most Lm strains even after subcultures without biocide selection pressure suggesting an adaptation involving modifications at the genetic level. The extensive use of QACs in our environments may thus participate to the selection of critical antibiotic resistance in pathogen bacteria such as Lm and thus represent a public health issue.