Affiliation:
1. Antimicrobial Agents Research Group, Division of Immunity and Infection, University of Birmingham, Birmingham B15 2TT, United Kingdom
Abstract
ABSTRACT
Comparative reverse transcription-PCR in combination with denaturing high-pressure liquid chromatography analysis was used to determine the levels of expression of
soxS
,
marA
,
acrF
,
acrB
, and
acrD
in multiple-antibiotic-resistant (MAR)
Salmonella enterica
serovar Typhimurium isolates and mutants of
S. enterica
serovar Typhimurium SL1344 with defined deletions. Posttherapy MAR clinical isolates had increased levels of expression of all genes except
soxS. S. enterica
serovar Typhimurium SL1344 Δ
acrB
expressed 7.9-fold more
acrF
than the parent strain. A strain with an
acrF
deletion expressed 4.6-fold more
acrB
. Deletion of
acrB
and/or
acrF
resulted in 2.7- to 4.3-fold more
marA
mRNA and 3.6- to 4.9-fold increases in the levels of expression of
acrD
but had a variable effect on the expression of
soxS
. All mutants were hypersusceptible to antibiotics, dyes, and detergents; but the MIC changes were more noticeable for SL1344 with the
acrB
deletion than for the mutant with the
acrF
disruption. These mutants had different but overlapping phenotypes, and the concentrations of ciprofloxacin accumulated by the mutants were different. These data suggest that
acrB
,
acrF
, and
acrD
are coordinately regulated and that their expression influences the expression of the transcriptional activators
marA
and
soxS
.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology
Cited by
156 articles.
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