TY - JOUR
T1 - Antibiotic combination therapy can select for broad-spectrum multidrug resistance in Pseudomonas aeruginosa
AU - Vestergaard, Martin
AU - Paulander, Wilhelm Erik Axel
AU - Marvig, Rasmus Lykke
AU - Clasen, Julie Brastrup
AU - Jochumsen, Nicholas
AU - Molin, Søren
AU - Jelsbak, Lars
AU - Ingmer, Hanne
AU - Folkesson, Anders
N1 - Copyright © 2015 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.
PY - 2016
Y1 - 2016
N2 - Combination therapy with several antibiotics is one strategy that has been applied in order to limit the spread of antimicrobial resistance. We compared the de novo evolution of resistance during combination therapy with the β-lactam ceftazidime and the fluoroquinolone ciprofloxacin with the resistance evolved after single-drug exposure. Combination therapy selected for mutants that displayed broad-spectrum resistance, and a major resistance mechanism was mutational inactivation of the repressor gene mexR that regulates the multidrug efflux operon mexAB-oprM. Deregulation of this operon led to a broad-spectrum resistance phenotype that decreased susceptibility to the combination of drugs applied during selection as well as to unrelated antibiotic classes. Mutants isolated after single-drug exposure displayed narrow-spectrum resistance and carried mutations in the MexCD-OprJ efflux pump regulator gene nfxB conferring ciprofloxacin resistance, or in the gene encoding the non-essential penicillin-binding protein DacB conferring ceftazidime resistance. Reconstruction of resistance mutations by allelic replacement and in vitro fitness assays revealed that in contrast to single antibiotic use, combination therapy consistently selected for mutants with enhanced fitness expressing broad-spectrum resistance mechanisms.
AB - Combination therapy with several antibiotics is one strategy that has been applied in order to limit the spread of antimicrobial resistance. We compared the de novo evolution of resistance during combination therapy with the β-lactam ceftazidime and the fluoroquinolone ciprofloxacin with the resistance evolved after single-drug exposure. Combination therapy selected for mutants that displayed broad-spectrum resistance, and a major resistance mechanism was mutational inactivation of the repressor gene mexR that regulates the multidrug efflux operon mexAB-oprM. Deregulation of this operon led to a broad-spectrum resistance phenotype that decreased susceptibility to the combination of drugs applied during selection as well as to unrelated antibiotic classes. Mutants isolated after single-drug exposure displayed narrow-spectrum resistance and carried mutations in the MexCD-OprJ efflux pump regulator gene nfxB conferring ciprofloxacin resistance, or in the gene encoding the non-essential penicillin-binding protein DacB conferring ceftazidime resistance. Reconstruction of resistance mutations by allelic replacement and in vitro fitness assays revealed that in contrast to single antibiotic use, combination therapy consistently selected for mutants with enhanced fitness expressing broad-spectrum resistance mechanisms.
U2 - 10.1016/j.ijantimicag.2015.09.014
DO - 10.1016/j.ijantimicag.2015.09.014
M3 - Journal article
C2 - 26597931
SN - 0924-8579
VL - 47
SP - 48
EP - 55
JO - International Journal of Antimicrobial Agents
JF - International Journal of Antimicrobial Agents
IS - 1
ER -