Frequency of antiseptic resistance genes and reduced susceptibility to biocides in carbapenem-resistant Acinetobacter baumannii

The aim of this study is to determine the frequency of quaternary ammonium compound-resistant genes, including qacA/B, qacC/D, qacE, qacΔE1, qacG, qacJ, and β-lactamase genes, including blaCTX-M, blaTEM, blaSHV, blaOXA-23, blaVIM, blaIMP, blaNDM and blaGIM in 51 isolates of carbapenem-resistant Acinetobacter baumannii collected over a period of 2 years and to determine the MIC of chlorhexidine and quaternary ammonium compound-based disinfectant benzalkonium chloride. The qac and bla genes were detected by the PCR method. The MICs were determined using the broth microdilution method. The MIC of benzalkonium chloride was in the range of 4 to 64 µg l-1 and chlorhexidine in the range of 4 to 64 µg l-1. The qacΔE1 gene was detected in 96.07 % (49/51) isolates and qacE in 31.37 % (16/51), qacG in 23.52 % (12/51) and qacA/B in 13.72 % (7/51). The qacC/D genes and qacJ were not found in any of these strains in this study. The frequency of bla genes was as follows: 84.31 % (43/51) for blaOXA-23, 33.33 % (17/51) for blaTEM, 27.45 % (14/51) for blaVIM, 19.61 % (10/51) for blaSHV, 17.65 % (9/51) for blaNDM, 11.76 % (6/51) for blaGIM and 7.8 % (4/51) for the blaIMP. The blaCTX-M genes were negative in all the strains. From the study, we concluded that reduced susceptibility to the two disinfectants, as well as qac and bla genes, was prevalent among A. baumannii isolates from the hospital environment. This study may offer hospitals important information about the control of nosocomial infections caused by A. baumannii.