Serotype changes and drug sensitivity of Salmonella in Yuyao, Zhejiang, 2007–2018

ObjectiveTo investigate the infection status, serotype changes and drug sensitivity of Salmonella in patients with diarrhea in Yuyao of Zhejiang province and provide reference for prevention and clinical treatment.

MethodsA total of 295 strains of Salmonella isolated from diarrhea patients from 2007 to 2018 were resuscitated, serotyped, and their drug susceptibilities were tested. The detection rates in different years were compared with χ² test.

ResultsThe detection rate of Salmonella was 8.60% in sentinel hospitals in Yuyao from 2007 to 2018, and the ratio of male to female was 1.07∶1. Salmonella could be detected in all age groups, mainly in children under 5 years old, the highest detection rate was in summer (10.20%) and the lowest in winter (1.64%). Thirty nine serotypes were detected, belonging to 10 serogroups, and the first four predominant serotypes were Salmonella 4,5,12:i:- (24.41%), S. typhimurium (15.25%), S. enteritidis (9.83%), and S. stanley (8.14%). The resistance rates of the 295 strains to penicillins, tetracyclines and sulfamethoxazole were high, but they were sensitive to other antibiotics, and the resistance rate to cephalosporins increased significantly during 2014–2018 compared with that during 2007–2013. A total of 107 strains (36.27%) were multi-drug resistant, belonging to predominant serotypes and accounting for 36.27%. In the past 12 years, the detection rate, serotypes and drug resistance of Salmonella changed. The detection rate was low during 2007–2013 (3.08%, 34/1 103), and 14 serotypes were detected, mainly S. typhimurium (38.24%, 13/34) and S. enteritis (20.59%, 7/34). The detection rate was high during 2014–2018 (11.22%, 261/2 307), and 34 serotypes were detected. Salmonella 4,5,12:i:- has replaced S. typhimurium as the first serotype, S. typhimurium ranked second, S. stanley and S. enteritidis ranked third.

ConclusionThe predominant serotypes of Salmonella in Yuyao were mainly Salmonella 4,5,12:i:- and S. typhimurium. The surveillance of multi-drug resistance of Salmonella should be further strengthened.