Abstract: Objective To investigate antimicrobial resistance and virulence gene profiles of clinically isolated nontyphoidal Salmonella enterica serovars Braenderup (S. Braenderup). Methods Clinical date of patients with acute diarrhea from two teaching hospitals in our city were collected from April to October of 2012 to 2014. Salmonella from stool samples was screened by culture, and identified by biochemical, PCR and serotype methods. Isolates of S. Braenderup were examined with antibiotic susceptibilities. PCR amplification was used for representative genes of Salmonella pathogenicity islands (SPI) 1-5 and SPI regulator. Results Among 153 non-repetitive NTS isolates in the three years, 8 isolates (5.23%) of S. Breanderup were identified. All 8 isolates were positive with invA gene. The resistance rate to nalidixic acid was 100%, and the same with the intermediate resistance rate to ciprofloxacin and levofloxacin. But they were susceptible to other antimicrobial agents. The 8 isolates were positive with the representative genes of SPI 1-5 and regulators (sitC, hilA, sseL, sifA, mgtC, siiE, sopB and phoP). Conclusion Clinical isolates of S. Braenderup in Tianjin are resistant to fluoroquinolones and harbored genes of SPI 1-5 and regulator, and which can threaten public health. Continuous surveillance and research should be carried out in our city.

Key words: diarrhea, drug resistance, microbial, quinolones, fluoroquinolones, virulence, Salmonella Breanderup