Analysis on serotypes and antibiotic resistance characteristics of food-borne Salmonella strains in Guizhou Province from 2016 to 2018

Abstract

Objective To analyze the serotype distribution and antibiotic resistance characteristics of food-borne Salmonella strains isolated from food and patients with gastroenteritis in Guizhou Province from 2016 to 2018. Methods Serotypes of the strains were characterised using slid agglutination method with Salmonella antisera. Minimal inhibitory concentrations (MIC) of antibiotics were determined by the broth microdilution method. Microsoft Excel 2007 and SPSS18.0 were used for statistical analysis. Results A total of 170 strains of food-borne Salmonella were detected in food and patients with gastroenteritis in Guizhou Province from 2016 to 2018. Thirty-five serotypes were identified and 6 were found in both food and patients. The main serotypes in food were Salmonella Typhimurium (16.67%) and Salmonella Stanley (8.33%), and the predominant serotypes in patients were Salmonella Typhimurium (41.79%), Salmonella Enteritidis (16.42%) and Salmonella London (8.96%). The rate of resistance to ampicillin, chloramphenicol, tetracycline, ciprofloxacin, nalidixic and trimeth-sulfame were 27.78%-33.33% among the isolates from food, and 22.22%-25.00% to gentamicin, cefocime and ampicillin/sulbatan. Among the isolates from patients, the highest resistance was to ampicillin (55.97%), followed by that to tetracycline (49.25%), ampicillin/sulbatan (44.03%), nalidixic acid (41.04%) and cefazolin (37.31%), and 20.90%-30.60% strains were resistant to chloramphenicol, ciprofloxacin, gentamicin, cefotaxime and ampicillin/sulbatan. There were 25.00% isolates from food and 25.37% isolates from patients resistant to at least 6 antibiotics, and the main multi-resistant pattern was ampicillin-tetracyline-nalidixic-cephalosporin antibiotics (partial). Conclusions There were many kinds of serotypes of food-borne Salmonella in Guizhou Province from 2016 to 2018 and the predominant types were Salmonella Typhimurium, Salmonella Enteritidis and Salmonella London. Drug resistance was common in the strars and some multidrug resistant strains were detected. Key words: Food-borne Salmonella; Serotype; Drug resistance