Aim: Currently the isolation rate of Stenotrophomonas maltophilia which is an opportunistic nosocomial pathogen, is increasing worldwide. It is commonly found in nature and also it can be recovered from oropharynx and sputum in adults. When nosocomial pneumonia with S. maltophilia is associated with obstruction and bacteremia, mortality rate increases. S. maltophilia is usually resistant to most of the β-lactam antibiotics, β-lactam inhibitors and aminoglycosides. Since most of the S. maltophilia strains are susceptible to trimethoprim/sulfamethoxazole, this antibiotic is widely used in the treatment. The aim of this study was to determine the susceptibility rates of S. maltophilia strains isolated in our hospital.

Materials and Methods: This study was conducted in the Medical Microbiology Laboratory of Konya Training and Research Hospital, Turkey between 1 January 2009 and 31 December 2013. Bacterial identification and antimicrobial susceptibility testing was performed by using conventional methods and Phoenix® automated system (Becton Dickinson Sparks, USA).

Results: In this study, 121 S. maltophilia strains isolated from various clinical materials in our hospital were evaluated for antimicrobial susceptibility. In 2009, 13 S. maltophilia strains, in 2010 and 2011, 23, in 2012, 28 and in 2013 34 strains were isolated. Most of the strains were isolated from the intensive care units (51.9%), followed by inpatient clinics (43.4%) and outpatient clinics (4.6%). Most of the S. maltophilia strains were isolated from the respiratory samples such as sputum, pleural fluid and bronchoalveolar lavage. The highest rate of susceptibility was achieved with trimethoprim-sulfamethoxazole (84.8%). Susceptibility rates estimated for levofloxacine and ceftazidime were 76.2% and 22.3%, respectively.

Conclusion: As a conclusion, maintenance of therapy for S. maltophilia infections should be planned based on the results of the antimicrobial susceptibility tests, instead of empirical treatment.