Exploring the prevalence and antibiotic resistance of Listeria monocytogenes in diverse food commodities across Sikkim, India

Listeria monocytogenes is a foodborne pathogen of significant public health concern, especially due to its ability to survive in a wide range of foods and cause severe illness in vulnerable populations. This study aimed to investigate the prevalence and antibiotic resistance of L. monocytogenes across a variety of food commodities collected from four districts of Sikkim, India, between April 2023 and May 2025. A total of 2,829 samples, including raw meats, cooked foods, fermented products, dairy, street foods, and beverages, were analyzed using standard microbiological methods, followed by confirmation using the VITEK 2 bacterial identification system and PCR assay. The antibiotic susceptibility tests (AST) were done and multiple antibiotic resistance (MAR) index values were calculated. Of these tested samples, 98 (3.46%) were positive for the L. monocytogenes. Cooked items and raw meats showed the highest contamination rates, while traditional fermented foods and street food also contributed substantially. District-wise, South Sikkim had the highest number of positive samples. AST revealed notable resistance to penicillin, ampicillin, erythromycin, and clindamycin, with high susceptibility to tetracycline and trimethoprim-sulfamethoxazole. The MAR index values ranged from 0 to 0.81 with 41 isolates showing higher values above 0.2. Our findings highlight the need for improved hygiene practices, regular surveillance, and cautious use of antibiotics. The study underscores the importance of region-specific food safety strategies, particularly in areas where traditional food practices are deeply rooted in daily life.