Prevalence and Antibiotic Resistance of Listeria monocytogenes Isolated from Ready-to-Eat Foods in Turkey

The aim of the present study was the determination of the prevalence and antibiotic resistance of L. monocytogenes in ready-to-eat (RTE) foods in Ankara, Turkey. In order to detect and isolate L. monocytogenes from 201 RTE food samples, the EN ISO 11290:1 method was used. All isolates were identified using the polymerase chain reaction. The strains were also confirmed by the detection of the hemolysin gene (hlyA). The overall prevalence of L. monocytogenes was 8.5% among the food samples. Seventeen L. monocytogenes strains were examined by the disk diffusion assay for their resistance to 23 antibiotics. All strains were susceptible to erythromycin, clarithromycin, streptomycin, gentamicin, vancomycin, imipenem, trimethoprim, and chloramphenicol, while all strains were resistant to nalidixic acid, ampicillin, penicillin G, linezolid, and clindamycin. The higher resistance was found against oxacillin (94.1%), kanamycin (76.5%), levofloxacin (70.6%), and teicoplanin (64.7%), followed by amoxicillin/clavulanic acid (53.0%), rifampicin (47.1%), and ciprofloxacin (35.3%). A lower incidence of resistance was observed against tetracycline (5.9%), meropenem (5.9%), and trimethoprim/sulfamethoxazole (17.7%). All isolates were multidrug resistant showing resistance to at least three antibiotic classes. High L. monocytogenes prevalence among analyzed RTE foods represents a high risk for public health. Our findings show a high prevalence of L. monocytogenes in RTE foods in Turkey. More effective control strategies for L. monocytogenes are needed to reduce both prevalence and resistance of L. monocytogenes in Turkish RTE foods.