Investigation of clonal relatedness among the nosocomial pseudomonas aeruginosa isolates

In this study,our aim was to investigate of clonal relatedness among the nosocomial and enviromental Pseudomonas aeruginosa strains isolated from patients treated in intensive care units of Gazi University Medical School Hospital. A total of 54 Pseudomonas aeruginosa consisting of 50 clinical strains isolated from patients diagnosed with nosocomial infections and four strains from environmental samples between January 2010 - August 2011 from general surgery, anesthesiology and reanimation, pediatric, internal medicine, neurology, chest disease and neurosurgery intensive care units were included in the study. Antibiotic susceptibility tests and identification of Pseudomonas aeruginosa strains (n:54) included in the study were performed with an automated identification system (MicroScan autoSCAN-4, Germany). Clonal relatedness among environmental and nosocomial strains were investigated with Rep-PCR method. Minimal resistance among performed strains were detected in amikacin (12%), where as maximum resistance were at ceftriaxone (100%), cefotaxime (100%) and tazobactam-piperacilline (100%). Resistance rates for other tested antibiotics were; 26% for gentamycine and tobramycin, 30% for ciprofloxacin and levofloxacin, 34% for imipenem and meropenem and 98% for aztreonam and cefepime. Rep-PCR typing of the 52 strains showed that 14 strains were not clonally related to any other strains included in the study. Clonally related strains (n:38) were grouped in 13 clusters. The number of strains that generated these clusters were between 2-6. The strains genotyped were determined as clonally related with a high rate of 73%. It had been determined that there were 27 spesific Rep-PCR patterns among 52 Pseudomonas aeruginosa strains.