Title |
Effect of carbonyl cyanide 3-chlorophenylhydrazone (CCCP) on killing Acinetobacter baumannii by colistin |
Author |
Young Kyoung Park and Kwan Soo Ko* |
Address |
Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 440-746, Republic of Korea |
Bibliography |
Journal of Microbiology, 53(1),53-59, 2015,
|
DOI |
10.1007/s12275-015-4498-5
|
Key Words |
time-kill assay, colistin resistance, efflux pump |
Abstract |
We investigated the effect of cyanide 3-chlorophenylhydrazone
(CCCP) and other efflux pump inhibitors (EPIs) on the
colistin susceptibility in Acinetobacter baumannii. While minimum
inhibitory concentrations (MICs) of colistin in all
colistin-resistant strains decreased significantly with 25 μM
of CCCP and 2,4-dinitrophenol (DNP), phenyl-arginine-β-
naphthylamide (PAβN), and reserpine did not decrease the
colistin MICs. However, CCCP and DNP as well as PAβN
and reserpine did not have a significant effect on the MICs of
the other agents. Efflux pump gene expressions in colistinresistant
strains were not increased compared with those in
colistin-susceptible strains. When only 5X MIC of colistin (5
mg/L) was provided to a colistin-susceptible A. baumannii
strain, the bacterial cell number was reduced by 9 h after exposure
to colistin, but regrowth was observed. When CCCP
was added to colistin, bacterial cells were completely killed
after 24 to 48 h of incubation, which was not due to the toxicity
of CCCP itself. Colistin resistance in A. baumannii may
not be due to efflux pumps. Our present study suggests that
bacterial cells with reduced metabolic activity by CCCP are
more susceptible to colistin in A. baumannii. It may show
the possibility that combined therapy with colistin and other
antimicrobial agents could effective against A. baumannii
infections. |