Abstract
Background: Benzalkonium Chloride (BC) is widely used in hospitals, industry and cosmetics. Adaptation of Pseu-domonas aeruginosa to BC was increased. This adaptation may lead to the emergence of cross-resistance to other disin-fectants and antibiotics. Little attention has been focused on the resistant mechanisms.
Aim of Study: Examination of mutations in the Quinolone-resistance-Determining Region (QRDR) of GyrA and ParC genes and alterations of Outer-Membrane Proteins (OMPs) in Benzalkonium Chloride (BC)-adapted Pseudomonas aeru-ginosa isolates.
Material and Methods: GyrA and ParC genes of the BC-adapted P. aeruginosa isolate and the wild-type strain ATCC 15442 were amplified by Polymerase-Chain-Reaction (PCR) and sequenced. OMPs of these isolates were also analyzed by Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophore-sis (SDS-PAGE) in the presence and absence of permeabilizer disodium Ethylenediamine-Tetraacetate (EDTA) to investigate the variations.
Results: The results manifested a single mutation in both GyrA (Thr-83-Ile) and ParC (Ser-87-Leu). In SDS-PAGE, one band with molecular weight of 52.23kDa was detected in all samples. Seven bands with molecular weights of 71.44, 38.48, 36.01, 33.03, 26.17, 21.14 and 6.35kDa were stable in both ATCC 15442 and treated isolate. Also, seven bands with molecular weights of 120.83, 90.89, 79.72, 44.58, 28.91, 16.12 and 12.49kDa were newly induced in the treated isolate.
Conclusions: These results revealed that mutations in GyrA and ParC genes, and alteration of OMPs contributed to the adaptation of P. aeruginosa to BC, co-operating with efflux pump over-expression.