Listeria monocytogenes is one of the most important foodborne pathogens in human worldwide. In present study, this bacterium was isolated from different animal products and human clinical samples. The isolates were characterized by antibiotic susceptibility tests, serotyping, virulence genes and 16SrRNA sequencing. Out of 1362 investigated samples, Listeria monocytogenes were identified in 48(3.5%) of samples. Seven samples 1.1% were from human, while 41(5.7%) were from food samples. The majority of food isolates were resistant to penicillin, cephalexin, doxycycline, ampicillin and vancomycin; while variable resistance to the other antibiotics was observed. Serotyping of food and human isolates found that 7 of human isolates and 28 of food isolates belonged to serogroup 1/2a (3a). While, 8 isolates from food samples belonged to the serogroup 4b. Five fresh red meat isolates belonged to the serogroup 1/2b. All food and human isolates contained virulence genes actA, hlyA, plcA and iap genes. Phylogenetic analysis based on 16SrRNA sequencing showed that the L. monocytogenes isolated from milk were not closely related to the meat and human isolates. This data suggests that the antibacterial resistant Listeria monocytogenes are widely spread within the animal products rather than the clinical samples. The most common serogroup within the isolated strains was 1/2a (3a). Surprisingly, all isolates found to be virulent strains depending on the virulence genes detection. Therefore, it is highly recommended to apply strict biosecurity measurements on food and food processing environment to avoid or to maintain the spread of the bacterial infection within the area.
Listeria monocytogenes, Multiplex PCR, Virulence factors, antibiotic sensitivity test, Genotyping characterization, serotyping.
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