Prevalence, species diversity, and antimicrobial resistance profile of Listeria monocytogenes in retail meat and dairy products in Southern Ethiopia

Listeriosis, caused by Listeria monocytogenes (L. monocytogenes), is an important foodborne disease characterized by low incidence but high case fatality rates. Its prevalence varies across regions and is influenced by hygiene practices, food handling, and environmental conditions. In developing countries like Ethiopia, data on L. monocytogenes is often limited due to a lack of awareness. This study aims to assess the prevalence of L. monocytogenes in retail meat and dairy products and evaluate their antimicrobial profiles. A total of 422 food samples were collected from May 2022 to March 2023 using a cross-sectional study design. The Listeria species were isolated and identified using culture-based methods and PacBio sequencing. Antimicrobial susceptibility testing of L. monocytogenes was performed using the standard disk diffusion method on Mueller Hinton agar against six antibiotics commonly used in both veterinary and human medicine. Among the 422 food samples analyzed, 69 (16.4%) tested positive for Listeria species, of which 25 (5.9%) were identified as L. monocytogenes. The highest prevalence was observed in cheese (12.9%, 95% CI: 7.4–21.7%), followed by raw fish (9.8%, 95% CI: 5.0–18.1%) and raw meat (4.7%, 95% CI: 1.8–11.5%). Among the isolated Listeria species, L. monocytogenes (36%) was the most predominant, followed by L. innocua (25%) and L. seeligeri (16%) in the study area. L. monocytogenes isolates were susceptible to gentamicin, vancomycin, sulfamethoxazole, and amoxicillin, while exhibiting the highest resistance rate (100%) to penicillin. This finding indicates the presence of Listeria species in meat and dairy products, with particular concern for L. monocytogenes, which, despite its low prevalence, requires special attention due to its high case fatality rate. Therefore, training in hygienic handling practices for meat and dairy products is essential to minimize the risk of foodborne diseases. Moreover, reducing antibiotic resistance requires regulating and promoting the prudent use of antibiotics in food-producing animals.