Narjess Bostanghadiri - Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran.
Ali Hashemi - Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran

BACKGROUND AND OBJECTIVESStenotrophomonas maltophilia, previously known as Pseudomonas maltophilia, has become nowadays a major opportunistic pathogen in hospitalized or immunocompromised patients worldwide. The present study was to investigate the antimicrobial susceptibility pattern, bioflm production, and the presence of biofilm genes among the S. maltophilia clinical isolates.MATERIALS AND METHODSA total of ۸۵ clinical isolates of S. maltophilia were collected from patients referred to several hospitals. Susceptibility to antibiotics was investigated by disc diffusion method according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI). By the crystal violet staining method, the capability of biofilm formation was examined. The genes associated with biofilm production were investigated by the PCR-sequencing techniques.RESULTS AND DISCUSSIONAll isolates were resistant to doripenem, imipenem, and meropenem. Minocycline, trimethoprim/sulfamethoxazole and levofoxacin exhibited the highest susceptibility of ۱۰۰%, ۹۷.۶۵%, and ۹۵.۲۹%, respectively. The results of crystal violet staining assay showed that all isolates (۱۰۰%) form biofilm. Moreover, ۲۴ (۲۸.۲۳%), ۳۲ (۳۷.۶۵%), and ۲۹ (۳۴.۱۲%) of isolates were categorized as weak, moderate, and strong biofilm producers, respectively. Biofilm genes including rpfF, spgM and rmlA had an overall prevalence of ۸۹.۴۱% (۷۶/۸۵), ۱۰۰% (۸۵/۸۵) and ۸۴.۷۱% (۷۲/۸۵), respectively.CONCLUSIONRational prescribing of antibiotics and implementation of infection control protocols are necessary to prevent further infection and development of antimicrobial resistance. Combination strategies based on the appropriate antibiotics along with anti-biofilm agents can also be selected to eliminate biofilm-associated infections.

Stenotrophomonas maltophilia, Antibiotic resistance, Biofilm, Biofilm formation genes