Correlation of the antiseptic resistance in Acinetobacter baumannii and the antiseptic resistance gene qacE△ 1 located in class Ⅰ integron

摘要

In the past decade, uses of antiseptics and disinfectants in hospitals and other health care centers are rather common, but the chance to develop resistance to antiseptics and disinfectants is also increased. Acinetobacter baumannii is one of the opportunistic bacteria involving in the nosocomial infection . In the present study, the correlation of the antiseptic resistance in A . baumannii and the antiseptic resistance gene qacEΔ1 was investigated by means of determination of MICs. Meanwhile, the MICs of glutaraldehyde, chlorhexidine, benzalkonium bromide, iodophor and trichloroisocyanurate to 80 clinical isolates of A. baumannii were detected by tube dilution assay and the resistance genes intI1 and qacEΔ1 in these isolates were amplified by PCR and verified by DNA sequencer. It was found that the MIC50 for these 5 antiseptics tested were 32, 8, 8, 4 and 1μg/ml respectively, and the detection rates of intI1 and qacEΔ1 gene were 60.0% and 77.6% respectively. In addition, 55% of the 80 isolates simultaneously possessed both intll and qacEΔ1 gene, and the percentage of antiseptic resistance of A . baumannii carring both genes to benzalkonium bromide were higher than that without these two genes, however, there was no significant difference between intll and qacEΔ1 gene. The result in bactericidal efficiency assay indicated that chlorhexidine could still produce rapid and strong bactericidal effect at concentration of 1 MIC after 10 min exposure. These results suggest that the antiseptic resistance of A . baumannii to various antiseptics is correlated with the presence of the antiseptic resistance genes qacEΔ1 in bacteria, thus warning that the increase of the antiseptic resistance should not be ignored and the relative high concentration or prolonged application time is required to achieve a sufficient bactericidal effect.