Food contamination with extended-spectrum beta-lactamase (ESBL)-producing bacteria is recognized as one of the public health concerns worldwide. Although fish and fishery products at retail in Japan have relied on the imported materials, no apparent evidences exist on the prevalence and property of genetic transfer in the ESBL-producing bacteria in those food specimens. This study aimed to investigate the prevalence of plasmid-mediated antibiotic-resistant bacteria in imported fishery products. Fifteen fishery products retailed in Japan, imported from Southeast and South Asia during January to March 2020, were examined to detect AmpC/ESBL-producing Escherichia coli, or antibiotic-resistant Vibrio spp. through culture in buffered peptone water (BPW) or alkaline peptone water (APW), followed by selective enrichment on CHROMagar ECC or CHROMagar Vibrio containing cefotaxime/meropenem. A total of 172 strains were finally isolated from 15 samples. 16S rRNA sequencing gene revealed the predominant distribution of Stenotrophomonas maltophilia and E. coli from CHROMagar ECC, and Enterococcus spp. and Vibrio spp. from CHROMagar Vibrio, respectively. Amongst, E. coli, Klebsiella pneumoniae, V. vulnificus, and V. parahaemolyticus were ESBL-producers and harboured CTX-M-15, 55, or 27. Aeromonas caviae and E. coli were AmpC β-lactamase-producers and harboured CMY-8 and CMY-2, respectively. One Enterobacter cloacae complex from one shrimp sample was resistant to meropenem and harboured NDM-1. A gene transfer assay revealed that all isolated ESBLs, except Vibrio spp. and carbapenemase-producing Enterobacter spp., transferred CTX-M or NDM-1 to E. coli ATCC25922 and BL21. Overall, our data indicated the frequent contamination of imported fishery materials with AmpC/ESBL and carbapenemase-producing bacteria, with possible transferability of CTX-M or NDM-1 genes to intestinal E. coli in humans.

Salmonella is one of the most serious food-borne zoonotic pathogens in worldwide. The purpose of this study was to determine the prevalence and antimicrobial resistance of Salmonella isolated from broilers and chicken meat products in several areas in Chugoku and Kyusyu region. The cecal content samples were collected from 185 broilers derived from 37 flocks from 32 farms in Chugoku region and 155 broilers derived from 31 flocks from 28 farms in Kyusyu region. Chicken meat samples (n=20) were collected from the broiler meat processing plant in each region. The antimicrobial susceptibility test of the isolates was performed by broth microdilution testing. Salmonella was prevalent among 87 (47.0%) broilers of 31 flocks from 27 farms in Chugoku region. S. Schwarzengrund is the predominant serovars in the broilers from both regions, and they presented high rates of resistance to antibiotics. In Chugoku and Kyusyu region, S. Schwarzengrund isolates (n=226, and n=177, respectively) were resistant to ampicillin, 0.9 and 0%; cefotaxime, both regions 0%; streptomycin, 100 and 92.1%; kanamycin, 47.3 and 83.6%; tetracycline, 96.5 and 90.4%; nalidixic acid, 0 and 11.3%; and trimethoprim, 97.8 and 84.2%, S. Infantis isolates in Chugoku region (n=43) were resistant to ampicillin, 34.9%; cefotaxime, 32.6%; streptomycin, 100%; kanamycin, 0%; tetracycline, 100%; nalidixic acid, 0%; and trimethoprim, 0%. All isolates were susceptible to gentamicin, chloramphenicol and ciprofloxacin. Our results suggested that there are regional differences in antimicrobial resistance patterns of Salmonella originated from broilers in study region to such as kanamycin.

We found the effect of ethanol, even at low concentrations, on inactivation of SARS-CoV-2 in combination with surfactants. Less than 20% ethanol did not inactivate SARS-CoV-2, whereas high virucidal effects were observed by using 10% ethanol mixed with several surfactants. The present results indicate that the combination of low concentration ethanol and multiple surfactants shows a high virucidal effect as well as a bactericidal effect. The results also provide useful information to prevent the spread of SARS-CoV-2 contamination in the food industry, especially in the food service industry.