Bacterial counts and prevalence of Salmonella and extended-spectrum β-lactamase producing bacteria in prawn and shrimp imported into Japan

Abstract

The prevalence of Non-typhoidal Salmonella (NTS) and extended-spectrum β-lactamase (ESBL) producing bacteria was assessed in samples of imported prawn and shrimp obtained from retail markets in Japan. The overall prevalence of NTS and ESBL producing bacteria was 4%, and 14%, respectively. We identified 4 NTS isolates, including S. enterica subspecies salamae, and 3 serovars of S. enterica subspecies enterica, including Weltevreden, Abony, and Stanley. ESBL producing bacteria were isolated from 14 of 100 samples, thirteen of which harbored Stenotrophomonas maltophilia and that harbored Chryseobacterium indologenes. Among the S. maltophilia-positive samples, six had been imported from India, five samples came from Indonesia, one sample was from Thailand, and 1 was from Vietnam. These 14 ESBL isolates were susceptible to moxalactam, chloramphenicol, nalidixic acid, ofloxacin, and sulfamethoxazole-trimethoprim; however, all isolates were resistant to carbapenems. These findings indicate that to increase food safety, information regarding contamination by foodborne pathogens including Salmonella should be provided as feedback to the food’s country of origin. Additionally, more detailed studies regarding the epidemiological significance of S. maltophilia and C. indologenes contamination of imported food are needed for both food-exporting and -importing countries.