Trends in the serovar and antimicrobial resistance in clinical isolates of iSalmonella enterica/i from cattle and pigs between 2002 and 2016 in Japan

摘要

titleAbstract/titlesectiontitleAims/titlepGiven the significance of iSalmonella enterica/i in both human and animal health, and a recent global dissemination of iSalmonella/i 4,5,12:i:‐, changes in the prevalent serovars and antimicrobial resistance in clinical isolates of iSalmonella/i from cattle and pigs were investigated in Japan./p/sectionsectiontitleMethods and Results/titlepThe serovars and antimicrobial susceptibilities of 1605 iSalmonella enterica/i isolated from cattle (in/i = 894) and swine (in/i = 711) between 2002 and 2016 were examined. The most common serovar among all samples was iSalmonella/i Typhimurium. However, its monophasic variant with antigenic structure iS./i 4,5,12:i:‐, which was first detected in cattle in 2006 and swine in 2010, has been rapidly increasing in incidence and resistance. Resistance rates to cefotaxime and ciprofloxacin were generally low (10 in the cattle isolates and 5 in the swine isolates); however, isolates resistant to more than five antimicrobials, which often include these antimicrobials, were recently detected in iSalmonella/i Dublin, iS/i. 4,5,12:i:‐, iS/i. Typhimurium, iSalmonella/i Newport, iSalmonella/i Choleraesuis and iSalmonella/i 6,7:c:‐. Among them, two iS/i. 4,5,12:i:‐ isolates possessed extended‐spectrum β‐lactamase‐encoding genes; ibla/isubSHV‐12/sub or ibla/isubCTX‐M‐55/sub, respectively, while all the five iS/i. Typhimurium isolates possessed AmpC‐type β‐lactamase gene of ibla/isubCMY‐2/sub./p/sectionsectiontitleConclusions/titlepiS./i 4,5,12:i:‐ has been rapidly increasing and exhibiting a remarkable change in antimicrobial resistance in Japan. Considering certain serovars are characterized by multidrug resistance including medically important antimicrobials, continuous monitoring and appropriate measures are required to protect public health and veterinary husbandry./p/sectionsectiontitleSignificance and Impact of the Study/titlepThis study presents a trend in the serovars and antimicrobial resistance in clinical isolates of iSalmonella/i from cattle and pigs in Japan, and showed that there were certain types of iSalmonella/i serovars depending on the animal origin which needs more attention./p/section