Geographical variation in antimicrobial resistant Salmonella Schwarzengrund from chicken meat in Japan

Chicken meat is a major source of foodborne salmonellosis. In Japan, fluoroquinolones and third-generation cephalosporins are the first- and second-choice treatments for Salmonella gastroenteritis, respectively. We investigated the prevalence and antimicrobial resistance of Salmonella in 154 chicken meat products from Hokkaido (42), Tohoku (45), Kanto (5), and Kyushu (62), Japan. Salmonella was isolated from 133 products (86.4%). High resistance rates were observed for streptomycin (56.5%), tetracycline (50.7%), and kanamycin (47.8%), while all isolates were susceptible to cefazolin, cefotaxime, gentamicin, ciprofloxacin, colistin, and chloramphenicol. The most common serovar, Salmonella Schwarzengrund (83.3%), showed clear regional differences in multidrug resistance: 100% in Kyushu, 41.5% in Tohoku, and 0% in Hokkaido. These findings highlight significant geographical variation in antimicrobial resistance among Salmonella Schwarzengrund isolates.