Investigation of prevalence, serotyping, and antibiotic resistance of Listeria monocytogenes in samples of meat, milk, and cheese from eastern Turkey

Abstract

The aim of the present study was to investigate Listeria monocytogenes contamination in ground meat purchased from local butchers and raw cow milk and tulum cheese samples sold in public markets to identify serotypes of the obtained isolates and examine their antibiotic-resistance profiles. We microbiologically tested 300 samples of different origins for the presence of L. monocytogenes and confirmed the isolates found using matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) and polymerase chain reaction, (PCR) after which they were serotyped and tested for antibiotic resistance against 8 antimicrobial agents using the disk diffusion method. L. monocytogenes was identified in 18 (6%) all of the collected samples. The serotypes of the 18 L.monocytogenes isolated in our study were 1/2b (3b) in 9 (50%), 1/2c (3c) in 4 (22.2%), 4b (4e, 4e) in 3 (16.7%), and 1/2a (3a) in 2 (11.1%) of the isolates. All isolates were found to be sensitive to ampicillin, erythromycin, gentamicin, chloramphenicol, penicillin, tetracycline, vancomycin, and sulfamethoxazole/trimethoprim. Although the isolates were sensitive to all commonly used antibiotics and given that L. monocytogenes serotypes were isolated in the examined samples, this pathogen should be closely monitored and its prevalence should be controlled using precautionary measures.