Antimicrobial-Resistant Listeria Species Isolated From Beef and Beef Products Sold in Mpumalanga Province, South Africa.

This study determined the antimicrobial resistance profiles of L. monocytogenes and other Listeria spp. isolated from beef and beef products sold in retail outlets across Mpumalanga province, South Africa. A total of 153 isolates were obtained from 30 retail outlets. Standard bacteriological methods and PCR were used for isolation and confirmation, and disc diffusion was used to assess resistance to 16 antimicrobials. All isolates showed resistance to at least one antimicrobial, with MDR observed in 51.5% of L. monocytogenes and 47.5% of Listeria spp. All 33 isolates of L. monocytogenes were susceptible to five antimicrobial agents (penicillin, ampicillin, amoxicillin-clavulanic acid, gentamicin, and trimethoprim-sulfamethoxazole), which are commonly used in the treatment of listeriosis. Resistance prevalence ranged from 3.0% to 100% for L. monocytogenes and from 1.7% to 100% for Listeria spp., with all isolates showing resistance to nalidixic acid. The district location, outlet size, and types of beef and beef products significantly affected resistance patterns. Although all L. monocytogenes isolates were susceptible to five therapeutically important antimicrobials, the high prevalence of resistance, including MDR, in Listeria spp. remains a concern. This is because AMR-Listeria species can transfer resistance genes/plasmids to pathogenic L. monocytogenes, thereby posing both food safety and therapeutic implications.