Prevalence and Antimicrobial Resistance of Salmonella serotypes Isolated from Poultry Meat in Japan

The prevalence and antimicrobial susceptibility of Salmonella in 512 poultry meat samples collected from retail stores and poultry-processing plants in Japan between 2015 and 2016 were investigated. The results showed that 55.9% of poultry meat samples were contaminated with Salmonella, with nine different serotypes represented. The most frequent serovar was Salmonella enterica serovar Infantis, followed by S. Schwarzengrund, together accounting for 78.2% of the isolates. High antimicrobial resistance rates were observed against tetracycline (80.9% S. Infantis and 83.9% S. Schwarzengrund), streptomycin (53.4% S. Infantis and 76.8% S. Schwarzengrund), and kanamycin (33.6% S. Infantis and 82.1% S. Schwarzengrund). All tested isolates were susceptible to colistin and ciprofloxacin. In addition, a high proportion (65.6% of S. Infantis, 85.7% of S. Schwarzengrund) of Salmonella isolates were resistant to two or more antimicrobials, and 22 and 17 different resistance patterns were observed in the two strains, respectively. The predominant antibiotic resistance patterns were streptomycin-tetracycline (32/131, 24.4% of S. Infantis) and streptomycin-kanamycin-tetracycline-sulfamethoxazole/trimethoprim (43/112, 38.4% of S. Schwarzengrund). These data indicate that multidrug-resistant S. Infantis and S. Schwarzengrund have spread among poultry meat in Japan.