Molecular mechanism of colistin resistance in <italic>Klebsiella pneumoniae</italic>

Jie LIN; Yuanbo HOU; Hong LU; Jianming CAO; Lijiang CHEN; Yao SUN; Tieli ZHOU

Return

Molecular mechanism of colistin resistance in Klebsiella pneumoniae

VernacularTitle: 肺炎克雷伯菌多黏菌素耐药机制研究
Author: Jie LIN ¹ ; Yuanbo HOU ² ; Hong LU ³ ; Jianming CAO ⁴ ; Lijiang CHEN ¹ ; Yao SUN ¹ ; Tieli ZHOU ¹
Author Information

1. Laboratory Medicine Center, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China
2. Clinical Laboratory, Sir Run Run Shaw Hospital, Hangzhou 310000, China
3. Department of Clinical Laboratory, Peace Hospital Affiliated to Changzhi Medical College, Changzhi 046000, China
4. School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325000, China
Publication Type:Journal Article
Keywords: Colistin; Klebsiella pneumoniae; Drug resistance mechanism; Two-component regulatory system
From: Chinese Journal of Microbiology and Immunology 2018;38(8):605-610
CountryChina
Language:Chinese
Abstract: Objective:To investigate the molecular mechanism of colistin resistance in Klebsiella pneumoniae (K.pneumoniae).
Methods:Three clinical isolates of colistin-resistant K. pneumoniae (FK1149, FK1920 and FK1934) and three colistin-resistant mutants (FK660R, FK713R and FK729R) were investigated. Resistance genes of pmrAB, phoPQ, mgrB, crrAB, mcr-1 and mcr-2 were detected by PCR and then analyzed by sequencing. PROVEAN platform was used to predict changes in the biological functions of proteins related to drug resistance. Expression of pmrH, pmrC, mgrB and phoP genes was measured using quantitative real-time PCR. LPS silver staining and conjugation assay were performed to analyze the three clinical colistin-resistant isolates.
Results:Amino acid substitutions in PmrA (G53V), PmrB (T157P, R256G), MgrB (F44C) and CrrB (E189K) were detected. ISkpn14 and IS5-like insertion sequences were detected in FK713R and FK729R, respectively. FK1149, FK1920 and FK1934 were negative for mcr genes. Compared with the wild-type strain, expression of pmrH and pmrC genes at the transcriptional level was increased in all investigated isolates. Changes in the expression of phoP and mgrB genes were also observed. A partial deletion of LPS was identified in FK1149.
Conclusion:LPS modification induced by inactivation of PmrAB or MgrB is the main molecular mechanism of colistin resistance in K. pneumoniae isolates in this study. Mutations in PmrA (G53V), MgrB (F44C) and CrrB (E189K) that might be related to colistin resistance are detected for the first time in clinical isolates of K. pneumoniae.