Molecular analysis of carbapenem resistance among hospital acquired Acinetobacter strains and determination of the clonal relations among the strains

Acinetobacter spp. strains isolated from endotracheal aspirate or sputum samples of hospitalized patients from Internal Medicine or Neurology Department Intensive Care Units between August 2007 ? June 2010 were included to the study.The aim of this study is to determine drug susceptibility patterns of Acinetobacter isolates which cause hospital infections, and OXA type beta lactamases enzymes distribution which is the main cause of carbapenem resistance in clinical isolates of multidrug resistant Acinetobacter strains, and besides the clonal relationship between isolates by means of Arbitrarily Primed PZR (AP-PZR) method.Antibiotic susceptibility of the isolated strains was performed by Kirby Bauer disk diffusion method. In this study, it is found that all strains were susceptible to colistin. When the resistant rates of other 13 antibotics (except colistin) were compared, it is found that netilmicin had the lowest resistant rate (44%) and ciproflaxacin had the highest resistant rate (99%). The resistant rates of imipenem and meropenem was found as 84% and 96 %, respectively.blaOXA-23 genes were examined with PZR method and blaOXA-51 gene specified to Acinetocter baumannii was found positive in 99% of all strains. The ratio of blaOXA-23-like gene and blaOXA-58 gene in carbapenem resistant strains was determined as 75% and 23%, respectively. At least one of the blaOXA-23-like and blaOXA-58 gene was found in 90% of all strains.With the clonal analysis of Acinetobacter strains causing hospital infections by using AP-PZR method, two main clons were determined and named as A and B. It is figured out that B1 (the subtype of B clon) is still found in Internal Medicine Intensive Care Unit as potential hospital infections and it is observed as cross transmission between Intensive Care Units.In this study, high prevalence of OXA type carbapenemases and high resistance rates to ß-lactamases antibiotics were noticable and it is observed that AP-PZR method was very successful to show the clonal relationship in epidemic analysis caused by hospital infections.