Comparison of antibiotic susceptibilities of carbapenem resistant and carbapenem sensitive pseudomonas aeruginosa strains and investigating some carbapenemase genes in carbapenem resistant strains

It was aimed to compare the sensitivity of carbapenem resistant (CRPA) and sensitive P. aeruginosa (CSPA) strains to other antibiotics and to determine the presence of carbapenemase genes in carbapenem resistant strains. Fifty CRPA and 251 CSPA isolated in the same period were included into the study. Antibiotic susceptibilities were determined using the automated system. The presence of carbapenemase genes (blaIMP, blaSPM, blaAIM, blaNDM, blaOXA-48, blaKPC) in CRPA strains were investigated by multiplex polymerase chain reaction method. It was determined that the strains were isolated most frequently from wound (32.6%), urine (30.6%) and sputum (16.9%) samples and from the clinics other than intensive care units. Antibiotics which the strains were most resistant, were netilmicin (41.5%), levofloxacin (36.5%), piperacillin (33.2%) and piperacillin/tazobactam (31.9%). The resistance rates of imipenem and meropenem were found 15,6% and 11,9% respectively. CRPA isolates were found to be more resistant to amikacin, aztreonam, gentamicin, netilmicin, tobramycin, ciprofloxacin, levofloxacin, cefepime, ceftazidime, piperacillin, piperacillin / tazobactam than CSPA (p<0,001). No difference in resistance to colistin was found in CSPA and CRPA strains (p=1). Amikacin, aztreonam, ceftazidime, ciprofloxacin, colistin, cefepime, gentamicin, levofloxacin, netilmycin, piperacillin, tobramycin, piperacillin/tazobactam MIC values of CRPA strains were found to be higher than MIC values of CSPA strains so they were found to be more resistant (p<0,001). The multidrug resistance (MDR) rate was 14.6% and the MDR rate was higher in the CRPA group. the In CRPA strains, among blaIMP, blaVIM, blaSPM, blaNDM, blaKPC, blaAIM and blaOXA genes, blaIMP was found in one strain and blaVIM gene in three strains. In conclusion, carbapenem resistance and MDR rate in our study, were found to be lesser than the rates in our country. It was observed that the rates weren't increased over the years compared to the previous studies in our hospital. It was found that CRPA were also more resistant to other antibiotics than CSPA. IMP and VIM type enzymes were found in our study. Together with other studies conducted in our hospital, this study showed that carbapenemases were not common in P. aeruginosa strains isolated in our hospital. Identifying these enzymes epidemiologically is important in preventing the spread of resistance and detection of genes encoding them will guide the selection of appropriate antibiotics which will be used in treatment.