Characterization of antimicrobial resistance of foodborne Listeria monocytogenes.
The objective of this study was to evaluate the susceptibility of 120 Listeria monocytogenes strains isolated from food and food-processing environments to 19 antibiotics currently used in veterinary and human therapy. Susceptibility tests were performed by using the automated VITEK2 system. Apart from penicillin, ampicillin and trimethoprim-sulfamethoxazole, for which clinical breakpoints for Listeria susceptibility testing are defined according to the Clinical and Laboratory Standard Institute (CLSI), in the present study the CLSI criteria for staphylococci were applied. Among the 120 tested strains, 14 (11.7%) displayed resistance to at least one antibiotic. In particular, resistance to one antibiotic was more common than multiple resistance, i.e., 10 (8.3%) isolates were resistant to one antibiotic, 3 (2.5%) to two antibiotics and one (0.8%) to five antibiotics. Resistance to clindamycin was the most common, followed by linezolid, ciprofloxacin, ampicillin and rifampicin, trimethoprim/sulphamethoxazole and, finally, vancomycin and tetracycline. This study shows that L. monocytogenes strains from food and food-processing environments are susceptible to the antibiotics commonly used in veterinary and human listeriosis treatment. Considering that L. monocytogenes is slowly becoming antibiotic resistant, a continued surveillance of emerging antimicrobial resistance of this pathogen is important to ensure effective treatment of human listeriosis. These data are useful in improving background data on antibiotic resistance of strains isolated from food and food environment.
Conter
Mauro
M
Department of Animal Production, Veterinary Biotechnologies, Food Quality and Safety, Parma University, 43100 Parma, Italy. mauro.conter@unipr.it
Paludi
Domenico
D
Zanardi
Emanuela
E
Ghidini
Sergio
S
Vergara
Alberto
A
Ianieri
Adriana
A
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004305:Dose-Response Relationship, Drug; D024881:Drug Resistance, Bacterial; D024901:Drug Resistance, Multiple, Bacterial; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D006801:Humans; D008089:Listeria monocytogenes / Q000187:drug effects*; D008826:Microbial Sensitivity Tests
D000900:Anti-Bacterial Agents