Title |
Mutational inactivation of OprD in carbapenem-resistant Pseudomonas aeruginosa isolates from Korean hospitals |
Author |
Chi Hyun Kim1, Hee Young Kang1, Bo Ra Kim1, Hyejin Jeon1, Yoo Chul Lee1, Sang Hwa Lee2, and Je Chul Lee1* |
Address |
1Department of Microbiology, Kyungpook National University School of Medicine, Daegu 700-422, Republic of Korea, 2Department of Microbiology, Dong-A University, College of Medicine, Busan 602-714, Republic of Korea |
Bibliography |
Journal of Microbiology, 54(1),44-49, 2016,
|
DOI |
10.1007/s12275-016-5562-5
|
Key Words |
carbapenem, OprD protein, efflux pump, sequence
type, international clone |
Abstract |
This study investigated the mechanisms underlying the carbapenem
resistance of bloodstream isolates of Pseudomonas
aeruginosa obtained from two Korean hospitals. Of the 79
P. aeruginosa isolates, 22 and 21 were resistant to imipenem
and meropenem, respectively. The 22 imipenem-resistant
P. aeruginosa isolates were classified into 7 sequence types
(STs) and 13 pulsotypes. Twelve imipenem-resistant isolates
from one hospital were found to belong to the international
clone ST111. Two imipenem-resistant P. aeruginosa ST235
isolates carried the blaIMP-6 gene, but the remaining 20 isolates
did not produce carbapenemases. Mutations in the oprD
gene and a related decrease in gene expression were found
in 21 and 5 isolates, respectively. However, all imipenemresistant
P. aeruginosa isolates showed no significant expression
of OprD in the outer membrane as compared with that
of carbapenem-susceptible PAO1 strain. Overexpression of
genes associated with efflux pumps, including mexB, mexD,
mexF, and mexY, was not found in any imipenem-resistant
isolate. One imipenem-resistant P. aeruginosa isolate overexpressed
the ampC gene. Our results show that the low permeability
of drugs due to the mutational inactivation of OprD
is primarily responsible for carbapenem resistance in bloodstream
isolates of P. aeruginosa from Korean hospitals. |