Title |
Contribution of EmrAB efflux pumps to colistin resistance in Acinetobacter baumannii |
Author |
Ming-Feng Lin1, Yun-You Lin2, and Chung-Yu Lan2,3* |
Address |
1Department of Medicine, National Taiwan University Hospital Chu-Tung Branch, Hsin-Chu County, Taiwan, 2Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsin-Chu City, Taiwan, 3Department of Life Science, National Tsing Hua University, Hsin-Chu City, Taiwan |
Bibliography |
Journal of Microbiology, 55(2),130-136, 2017,
|
DOI |
10.1007/s12275-017-6408-5
|
Key Words |
efflux pump, colistin, antimicrobial resistance,
Acinetobacter baumannii |
Abstract |
Efflux pumps play an important role in antimicrobial resistance
for Acinetobacter baumannii. However, the function of
the Emr pump system and the relationship between Emr and
drug resistance has not been characterized in A. baumannii.
In this study, four possible groups of emr-like genes were
found by searching a genome database. Among them, A1S_
1772 (emrB) and A1S_1773 (emrA) were demonstrated to be
co-transcribed as a single operon. Moreover, during osmotic
stress, A1S_1772 showed the largest change in gene expression
compared to the other emrB-like genes, and deletion of
A1S_1772 (AB ΔemrB) significantly slowed cell growth in
20% sucrose. Using a phenotypic microarray analysis, the AB
ΔemrB mutant was more susceptible to colistin and nafcillin,
paromomycin, spiramycin, and D,L-serine hydroxmate than
the wild type. The spot assay, time kill assay and minimal
inhibition concentration determination also indicated that
the wild type could tolerate colistin better than the AB ΔemrB
mutant. Finally, the increased expression levels of all emrBlike
genes, including A1S_0775, A1S_0909, A1S_1772, and
A1S_1799, in colistin resistance-induced A. baumannii further
supported the possible involvement of the emrB genes
in A. baumannii colistin resistance. Together, the Emr pump
systems in A. baumannii contribute to adaptation to osmotic
stress and resistance to colistin. |