Molecular typing and investigation of carbapenemases in carbapenem resistant acinetobacter baumannii isolates

Acinetobacter baumannii plays an important role in causes of hospital infections and are resistant to most antibiotics, including carbapenems.Aim: It was aimed to investigate the presence and chromosomal or plasmid origin of carbapenemase in carbapenem-resistant A. baumannii strains isolated between December 2008-November 2011. At the end of the study we will introduce whether A. baumannii had originated from the same source or not and seeing the risk of genetically transmission to other bacterias and risk in future for carbapenem resistant bacteria isolation.Method and results: Sixty-five A. baumannii isolates were obtained mostly from patients in intensive care unit (66%) and blood (37%) and endotracheal aspirate samples (25%).Antibiotic susceptibility has been studied to carbapenems with E-test, to other antibiotics with disc diffusion method. The most sensitive antibiotics were found to be tobramycin, netilmicin, polymyxin B and colistin (respectively 98,5%, 98,5%, 98,5% and 96,9% susceptible). The rates of resistance to other antibiotics were very high and the, resistance has been found between 92,3 to 100.0%.AP-PCR was done to investigate the clonal relationship between the isolates; results showed two different patterns with M13 primer, three different patterns with DAF 4 primer.In all isolates chromosomal originated OXA-23 ve OXA-51 enzyme genes were found positive, other enzyme genes were found negative with Multiplex PCR which was done to investigate carbapenemases. Closeness among the isolates was observed with the confirmation of the presence of the viiOXA-23 ve OXA-51 enzymes in the sequencing which is done for positive enzymes.None of the isolates contained plasmids.Conclusion: Isolates are clonal similar according to the typing results and more frequent detection of A. baumannii infections at blood samples in the ICU; we should pay attention to basic infection control measures during interventional procedures to prevent spreading of bacteria from patient to patient.Since isolates do not include plasmids, we think that there is small potential to see carbapenemase resistant bacterias for now.Key words: Acinetobacter baumannii, antibiotic resistance, oxacilinases, metallo-beta-lactamase, PCR.