Retrospective analysis of antibiotic resistance profiles and frequency of resistance genes in clinical Stenotrophomonas maltophilia isolates

Stenotrophomonas maltophilia is an opportunistic pathogen that can cause infections especially in hospital settings and in immunocompromised individuals. Due to its resistance to many broad-spectrum antibiotics, treatment options that can be used in clinical practice are limited. This study aims to evaluate the susceptibility profiles of S. maltophilia isolates to antimicrobial agents commonly used in treatment and to investigate the presence of different classes of integrons and sul genes responsible for resistance. The study included 100 S. maltophilia isolates from various clinical samples sent to Balıkesir University Health Practice and Research Hospital Medical Microbiology Laboratory between 2017 and 2023. The BD Phoenix™ M50 Automated System was used for bacterial identification and antibiotic sensitivity testing. The susceptibility of isolates to trimethoprim-sulfamethoxazole was also studied by disk diffusion method. All isolates were investigated for sul1, sul2 genes and integron-associated integrase genes by polymerase chain reaction. The susceptibility rates of isolates to trimethoprim-sulfamethoxazole, levofloxacin and ceftazidime were determined as 96%, 66% and 38%, respectively. Polymerase chain reaction results showed, intI1 and sul1 genes were found to be positive together in two isolates resistant to trimethoprim-sulfamethoxazole, while sul1 and sul2 genes were found in two separate isolates sensitive to trimethoprim-sulfamethoxazole. The intI2 gene was not detected in any isolate. This study addresses the clinically important problems of S. maltophilia infections, which are increasingly difficult to treat due to intrinsic and acquired resistance mechanisms. By providing valuable information on antimicrobial susceptibility and resistance profiles of S. maltophilia isolates, it contributes to national data and guides efforts to control resistance and promote rational antibiotic use.