DETERMINATION of DISINFECTANT RESISTANCE GENES in CLINICAL BACTERIAL ISOLATES

In healthcare settings such as hospitals, bacteria develop resistance to disinfectants, which play a critical role in infection control, through various mechanisms. The presence and expression of efflux pumps are considered one of the key mechanisms of disinfectant resistance. The main objective of this study is to detect the presence of qacA/B, qacC/D, qacE, qacΔE1, qacG, qacH, qacJ, and acrA genes in clinical bacterial isolates and to determine the minimum inhibitory concentrations (MICs) against two different disinfectants: a quaternary ammonium compound and a biguanide. The presence of the related genes was screened in a total of 40 clinical isolates using conventional polymerase chain reaction. Disinfectant susceptibility was determined by the agar dilution method. Species-level identification of the isolates was confirmed by Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) technique. As a result of the screening, 6 isolates (15%), confirmed as E. coli, K. pneumoniae, and P. aeruginosa, were found to possess the qacΔE1 gene. The MIC values for these isolates against benzalkonium chloride and chlorhexidine gluconate were found to be in the range of 32−256 mg/L and 2−16 mg/L, respectively. The findings revealed that there was no direct correlation between the observed MIC values and the presence or absence of biocide resistance genes in the clinical E. coli, K. pneumoniae, and P. aeruginosa isolates studied.