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.
Recently, a long-term (1-year) dog toxicity study has not been a mandatory toxicity study for application of agricultural chemical in the United States (US) and the European Union (EU). This study was conducted to propose a guide for making science-based judgement on the necessity of long-term dog toxicity study, which is one of required toxicity studies at toxicological evaluation in Japanese pesticide regulation system. In order to carry out the proposal we analyzed the results of toxicity studies including subacute (3-month) toxicity study in dogs or toxicity studies in other species in the pesticide evaluation reports published by the Food Safety Commission of Japan (FSCJ), the responsible regulatory body for toxicological evaluation of pesticides in food. In the analysis of evaluation reports of 286 pesticides ADI (acceptable daily intake) of 93 pesticides (32.5%) were established based on dog studies. The ADIs of 74 pesticides among them, however were not considered to have a big influence if the long-term dog toxicity study was omitted. With regard to the other four agents the possibility that the long-term dog study becomes unnecessary was considered by adding detailed examination. With respect to the remaining 15 agents, we could not judge that long-term dog study were unnecessary. The analysis indicated that the dog long term test could be omitted in most cases. On the other hand, it should be considered carefully necessity of the long-term dog study when the toxicological profiles observed in dogs and rats were different, when the toxicity susceptibility in dogs was considered high, when no no-observed-adverse-effect level (NOAEL) is specified in subacute toxicity study in dogs or when bioaccumulation in dogs is concerned. We also noted that the studies already conducted for pesticide registered previously should be used for their hazard evaluation.