Multidrug-resistant (MDR) Salmonella enterica serovar Agona infections affect public health globally. This investigation aimed to ascertain the antimicrobial resistance profiles and molecular characteristics of Salmonella Agona isolates obtained from food-producing animals. A total of 209 Salmonella Agona isolates were recovered from mostly chickens (139 isolates), pigs (56 isolates), cattle (11 isolates), and ducks (3 isolates) between 2010 and 2020 in South Korea. In addition, these Salmonella Agona isolates were obtained from 25 slaughterhouses nationwide. Furthermore, this serotype suddenly increased in chickens in 2020. Salmonella Agona from chickens showed high resistance (69-83%) to ampicillin, streptomycin, tetracycline, trimethoprim/sulfamethoxazole, and chloramphenicol. Moreover, chicken/duck isolates (83.1%) showed significantly higher levels of MDR than cattle/pig isolates (1.5%). For molecular analysis by pulsed-field gel electrophoresis, infrared spectroscopy biotyping, and multilocus sequence typing in combination, a total of 23 types were observed. Especially two major types, P1-III-2-13 and P1-IV-2-13, comprised 59.3% of the total isolates spreading in most farms. Moreover, Salmonella Agona sequence type (ST)13 was predominant (96.7%) among three different STs (ST13, ST11, and ST292) widely detected in chickens (94.3%) in most farms located nationwide. Taken together, MDR Salmonella Agona in chickens might pose a potential risk to public health through direct contact or the food chain.
Keywords: STs; Salmonella Agona; antimicrobial resistance; biotyping; food animals; pulsotypes.