Distribution of Class I Integron and smqnr Resistance Gene Among Stenotrophomonas maltophilia Isolated from Clinical Samples in Iran.

BACKGROUND: Stenotrophomonas maltophilia (S. maltophilia) is a multiple-antibiotic-resistant opportunistic pathogen that is being isolated with increasing frequency from patients with health-care-associated infections. S. maltophilia is inherently resistant to most of the available antimicrobial agents. Spread of resistant strains has been attributed, in part, to class I integrons. In vitro susceptibility studies have shown trimethoprim-sulfamethoxazole and new floroquinolones as two important agents with activity against these organisms.

METHODS: 150 isolates of S. maltophilia were isolated from clinical samples such as respiratory discharges, sputum, and catheter and hospital environments. These isolates were also subjected to susceptibility testing and polymerase chain reaction for four groups of genes including int encoding integron elements, sulI and sulII encoding trimethoprim-sulfamethoxazole resistance and smqnr encoding quinolone resistance.

RESULTS: The rate of resistance to trimethoprim-sulfamethoxazole was up to 27 (18%) and the highest resistance to quinolone family belonged to ofloxacin (20%) and the lowest rate was for gatifloxacin (16%). The results showed that 14% of isolates contained integron elements concomitantly with sulI and sulII genes.

CONCLUSION: Resistance rate of S. maltophilia to co-trimoxazole and fluoroquinolones and detection of integron elements between isolates in this study showed that this rate corresponded to other data obtained from other studies.