Resistance mechanisms and molecular epidemiology of chlorhexidine acetate-resistant Klebsiella pneu-moniae clinical isolates
10.3760/cma.j.issn.0254-5101.2019.03.008
- VernacularTitle:耐醋酸氯己定肺炎克雷伯菌的耐药机制及分子流行病学研究
- Author:
Yizhi ZHANG
1
;
Xiucai ZHANG
;
Siqin ZHANG
;
Yajie ZHAO
;
Guofeng DONG
;
Xiaozhen ZHOU
;
Tieli ZHOU
Author Information
1. 温州医科大学附属第一医院医学检验中心 325000
- Keywords:
Chlorhexidine acetate;
Klebsiella pneumoniae;
Resistance mechanism;
Molecular epi-demiology
- From:
Chinese Journal of Microbiology and Immunology
2019;39(3):202-207
- CountryChina
- Language:Chinese
-
Abstract:
Objective To investigate the chlorhexidine acetate-resistance in Klebsiella pneumoniae ( K. pneumoniae) clinical isolates and to analyze the possible mechanisms and molecular epidemiology of re-sistant isolates. Methods A total of 332 K. pneumoniae clinical isolates were collected in the First Affilia-ted Hospital of Wenzhou Medical University in 2015. Standard agar dilution was used to screen chlorhexidine acetate-resistant isolates. The minimum inhibition concentrations ( MIC) of chlorhexidine acetate to resistant isolates with and without the presence of carbonyl cyanide m-chlorophenyl hydrazone ( CCCP) , which was an efflux pump inhibitor, were analyzed. Efflux pump genes of cepA, qacE and qacΔE1 that carried by and ex-pressed in those isolates were detected by polymerase chain reaction ( PCR) and quantitative real-time PCR ( RT-qPCR) , respectively. The biofilm formation ability was measured by crystal violet staining. The homol-ogy among the chlorhexidine acetate-resistant isolates was investigated with multilocus sequence typing ( MLST) and pulsed-field gel electrophoresis ( PFGE) . Results Twenty-five K. pneumoniae strains were re-sistant to chlorhexidine acetate. The MIC values of chlorhexidine acetate for them were reduced by at least four-fold in the presence of CCCP. Strains carrying the genes of cepA, qacE and qacΔE1 accounted for 100%, 40% and 40%, respectively. The expression of the efflux pump genes in the chlorhexidine acetate-resistant isolates was higher than that in the susceptible isolates. The biofilm formation ability of the chlo-rhexidine acetate-resistant isolates was better than that of the susceptible isolates. Furthermore, negative, weak-positive and positive biofilm formation ability was observed in four ( 16%) , 20 ( 80%) and one (4%) strains, respectively. The results of MLST and PFGE showed that the 25 chlorhexidine acetate-resist-ant isolates belonged to 19 different sequence types ( ST) with diverse PFGE patterns. Conclusions This study suggested that active efflux was the main mechanism of chlorhexidine acetate resistance in K. pneumoni-ae. The 25 chlorhexidine acetate-resistant K. pneumoniae strains possessed different biofilm formation ability and shared low homology.