Molecular characterization of virulence and antibiotic resistance genes and genotyping of Listeria monocytogenes isolated from cheese, beef, chicken, and milk

The current study was conducted to detect Listeria monocytogenes, associated antibiotic resistance and virulence genes possessed by these strains, and the genotype of identified isolates from milk, cheese, beef, and chicken. Accordingly, 203 samples (53 milk samples, 52 cheese samples, 48 beef samples, and 50 chicken samples) were collected from local markets in Al-Qadisiyah Province, Iraq. These samples were used for conventional and selective cultivation and biochemical studies. Eight isolates were molecularly detected using the PCR and sequencing based on the 16S rRNA gene. All the physically detected isolates were recruited for antibiotic resistance tests. Furthermore, all isolates were exposed to the detection of virulence genes, which included actin assembly inducing protein (actA), listeriolysin (hlyA), invasive associated protein (iap), internalin A (inlA), and phospholipase C (plcA). Random amplified polymorphism DND-polymerase chain reaction (RAPD-PCR) was utilized to genotype these isolates. The cultivation revealed the identity of 63 isolates (16 milk, 14 cheese, 16 beef, and 17 chicken). The molecular detection confirms the identity of the eight tested isolates. Various antibiotic and pattern resistance profiles were detected for the isolates, which included the highest resistance rates, which reached up to 100% and 94% in penicillin and ampicillin, respectively. The virulence genes that reached up to 94% were identified in all isolates. The sequencing findings demonstrated strong alignment with world isolates from the GeneBank. The data here reveal the vital presence of Listeria monocytogenes in food products, which pose high health risks to consumers.