Salmonella serovars in a tertiary hospital in Turkey, 2015-2017: molecular epidemiology, antimicrobial resistance and molecular characteristics of resistance mechanisms.

Background: Increase in antimicrobial resistance poses a global threat for treatment of Salmonellosis.

Objectives: In this study, serovar distribution, antimicrobial susceptibility, resistance genes, and clonal diversity were characterized in clinical Salmonella isolates.

Methods: In this study, serovar distribution of clinical Salmonella isolates was characterized by the Kauffman-White scheme. The antimicrobial susceptibility was determined by the broth microdilution method. Resistance genes and clonal diversity were investigated by PCR and PFGE.

Results: The serovars were Salmonella enterica serovar Enteritidis (n=92), Salmonella enterica serovar Typhimurium (n=14), and others (n=25). Resistance to ciprofloxacin, ceftriaxone, trimethoprim-sulfamethoxazole, azithromycin, meropenem, and colistin were 13.3%, 2.2%, 5.2%, 3.0%, 0%, 29.6%, respectively. Two ESBL-positive isolates carried TEM-type β-lactamases. Carbapenemases, mcr-1 and mcr-2 could not be detected. Colistin-resistant S. Enteritidis isolates were grouped in 4 pulsotypes [A1 (n=12), A2 (n=2), A3 (n=13) and B (n=1)]. All except one (B) were found closely related.

Conclusions: A relative decrease in resistance to trimethoprim-sulfamethoxazole was detected with time. Trimethoprim-sulfamethoxazole and azithromycin can be good alternatives to the widely-used ciprofloxacin and third-generation cephalosporins. High resistance of colistin and ciprofloxacin may be due to the extensive use of antibiotics in poultry, which highlights the significance of one health concept.