Investigation of resistance and clonal relatedness among thenosocomial acinetobacter isolates

A total of 135 Acinetobacter strains isolated from 130 hospitalized patients at Inonu University Turgut Ozal Medical Center were studied in January 2005- November 2007. Of the 135 Acinetobacter isolates, 131 (97%) were A baumannii and 4 were A. lwoffi (3%). Antibiotic susceptibilities of Acinetobacter isolates were investigated by Kirby Bauer disk difusion method. Minimal resistance among performed strains were detected in netilmisin (7%), where as maximum resistance were at piperacilline (92%), ceftriaxone (81%) and doxicycline (69%). When we compared resistance profiles in 2005 regarded to 2007, there was no difference in antibiotic resistance to piperacilline, ceftriaxone, gentamycine, doxicycline, trimetophrime/sulfomethoxazole. Resistance rates increased from 47% to 76% for piperacilline-tazobactam, 42% to 77% for cephepime, 0% to 39% for imipenem, 0% to 14% for netilmisin, 18% to 53% for amikacin, 18% to 47% for tobramycin, 24% to 55% for levofloxacin, 18% to 46% for ampicilline/sulbactam. The number of strains that were resistant to three or more antibiotics were 77 (57%), and the number of strains that resistant to all antibiotics except colistin and tigecycline were 23 (17%), and there were 2 (1.5%) strains which resistant to all of antibiotics.Pulsed Field Gel Electrophoresis typing of the 131 strains showed that 82 (62,6%) Acinetobacter strains were in clusters. These strains were in 15 clusters. The number of strains that generated these clusters were between 2-27. The strains genotyped were determined as clonally related with a high rate of 72,3%. Thirty-seven strains of isolates had shown spesific PFGE profiles. It had been determined that there were 64 (%48,9) spesific PFGE pattern among 131 Acinetobacter strains.Key word: Acinetobacter, PFGE, cluster, resistant