Etiology and drug resistance of non-typhi Salmonella in Henan province, 2011-2015

Abstract

Objective: To analyze the serotypes and antibiotic resistance phenotypes of non-typhi Salmonella strains in Henan province from 2011 to 2015. Methods: The stool samples were collected from diarrhea patients, and enriched with SBG enrichment broth and the pathogen isolation was conducted with CHROMAgar selective culture medium at 37 ℃ for 18-24 hours using KIA/MIU biochemical action and API20E biochemical system slab to identify Salmonella strains. The serotypes of all the positive strains were detected with SSI Salmonella typing sera. According to K-B drug susceptibility testing method published by USA clinical and Laboratory Standards Institute (CLSI), the antibiotics resistant phenotype of the positive strains were analyzed. Results: A total of 1 351 strains of non-typhi Salmonella were isolated, in which 811 were from males, 540 were from females. The ratio of men to women was 1.5∶1. Children and young adults were mainly affected. The pathogen isolation was mainly in May-October during a year. The 1 351 strains of non-typhi Salmonlla were divided into 58 serotypes. S. enteritidis, S. typhimurium, S. agona, S. derby, S. indiana, S. senftenberg and S. thompson ranked 1st-7th. The drug-resistance rate of the 1 351 strains was 46.1% to synthetic broad-spectrum penicillin ampicillin (AMP), 19.5% and 21.2% to the three generation cephalosporin ceftazidime (CAZ) and cefotaxime (CTX), 8.8% to the four generation cephalosporins cefepime (FEP), 58.7% to the one generation of quinolones nalidixic acid (NAL), 14.7% to the three generation fluoroquinolone ciprofloxacin (CIP) and norfloxacin (NOR), 25.0% and 35.6% to aminoglycoside antibiotic gentamicin (GEN) and streptomycin (STR), 35.4% to amphenicols (CHL), 31.7% to sulfonamide trimethoprim (TMP) and 37.8% to tetracycline (TET). Totally 879 strains were multidrug resistant (65.1%): 350 strains were resistant to 3-4 kinds of antibiotics (25.9%), 309 strains were resistant to 5-7 kinds of antibiotics (22.9%), 174 strains were resistant to 8-10 kinds of antibiotics (12.9%) and 48 strains were resistant to 11-12 kinds of antibiotics (3.6%). Conclusion: The serotypes of non-typhi Salmonella strains isolated from Henan province varied, some strains were resistant to 12 kinds of antibiotics commonly used in clinical treatment and the multidrug resistance has become serious.