Prevalence, antibiotic resistance, and phylogenetic analysis of Listeria monocytogenes isolated from various sources in Egypt: fish, vegetables, and humans

Listeriosis is a severe infection caused by consuming food contaminated with Listeria monocytogenes, the primary cause of human listeriosis. This study aimed to identify L. monocytogenes phenotypically and genotypically using inlA and hlyA virulence genes, followed by DNA sequence analysis and antimicrobial sensitivity in food resources and human samples. 345 Samples were obtained randomly from different markets and supermarkets in Qena, Egypt, including 115 fish, 25 fish containers, 90 vegetables, 90 diarrheal samples, and 25 hand swabs from patients and fishermen, respectively. L. monocytogenes was confirmed in 11.30% (39/345) and 3.48% (12/345) of the examined samples using culture and conventional PCR methods, respectively. The frequencies of L. monocytogenes in fish, fish containers, vegetables, and humans were 8.70, 3.48; 20, 8; 18.89, 1.11 and 6.09, 4.35% by both methods, respectively, with a statistically significant difference. Although L. monocytogenes predominated in 5-17 and 31-43-year age groups, the age risk factor for patients was statistically insignificant from an epidemiological perspective. Higher incidences were found in females and urban areas 7.27 and 4.76% than in males and rural areas 0 and 3.70%, without a statistically significant difference. The inlA was identified in all isolates, but the hlyA was identified in 41.67%. The highest multiple antibiotic resistance (MAR) index 0.625 was found in a diarrheal swab; all collected isolates were completely resistant to ampicillin. Additionally, 25% of L. monocytogenes stains were multidrug-resistant. According to phylogenetic analysis, the local isolates obtained from samples of tilapia, catfish, fish containers, cauliflower, and humans shared plenty of similarities.