Prevalence of antibiotic resistance and integrons, sul and Smqnr genes in clinical isolates of Stenotrophomonas maltophilia from a tertiary care hospital in Southwest Iran

Objective(s): Stenotrophomonas maltophilia has emerged as an important opportunistic nosocomial pathogen due to its intrinsic and acquired resistance to a wide range of antimicrobial agents. The present study aimed to investigate the occurrence of antibiotic resistance and resistance mechanisms among clinical isolates of S. maltophilia from Iranian patients. Materials and Methods: This cross-sectional study was performed on 44 S. maltophilia isolates that were recovered from different clinical specimens in 2015 and 2016. Conventional microbiologic methods were used for primary identification of isolates and confirmed by specific polymerase chain reaction (PCR) primers. Minimum inhibitory concentrations (MICs) were determined by the E-test. PCR was applied to determine antibiotic resistance genes. Results: All of S. maltophilia isolates were susceptible to trimethoprim/sulfamethoxazole (TMP/SMX) and colistin. Moreover, the susceptibility rates of isolates toward ceftazidime and ciprofloxacin were 93.2%, and 84.1%, respectively. Class 1 integrons was detected in 24 (54.5%) isolates by the presence of int1 gene. Moreover, the prevalence of antibiotic resistance genes sul1, sul2, and Smqnr were found in 16 (36.4%), 15 (34.1%), and 29 (65.9%) isolates, respectively. Conclusion: In summary, the prevalence of sul and Smqnr genes in integrons-contained isolates point out the significant risk of sulfonamides and fluoroquinolones resistance among clinical isolates of S. maltophilia in our region.