New PlasmidMediated Fluoroquinolone Efflux Pump, QepA,

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New Plasmid-Mediated Fluoroquinolone Efflux Pump,
QepA, Found in an Escherichia coli Clinical
Isolate
ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, Sept.
2007, p. 33543360
08/01/02 speaker ???
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Fluoroquinolones (FQs) The most common mechanism
for resistance to FQs among pathogenic microbes
is the mutation of chromosomal genes encoding
DNA gyrase and/or topoisomerase IV. Four
chromosome-dependent efflux systems responsible
for FQ resistance have so far been reported.
the resistance nodulation division family
the major facilitator superfamily (MFS)
the multidrug and toxic compound extrusion
family the ATP-binding cassette family In
the study, Identified a novel FQ resistance
mechanism, QepA, as a plasmid-mediated efflux
pump found in an E. coli clinical isolate from
Japan.
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A novel FQ-resistant gene, qepA, was identified
in a plasmid, pHPA, of E. coli C316, and both
qepA and rmtB genes were mediated by a probable
transposable element flanked by two copies of
IS26.
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(No Transcript)
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The qepA gene encoded a putative protein, QepA,
of 511amino acids. The predicted amino acid
sequence of QepA was found to have probably 14
transmembrane segments (TMS)
Suggested that QepA belongs to the 14-TMS family
transporters of gram-positive Actinomycetales but
not those of gram-negative bacteria.
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The intracellular accumulation of norfloxacin was
decreased in a qepA-expressing E. coli
transformant, but this phenomenon was canceled by
CCCP (carbonyl cyanide m-chlorophenylhydrazone).
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The augmented FQ resistance level acquired by the
probable intergeneric transfer of a gene encoding
a major facilitator superfamily-type efflux pump
from some environmental microbes to E. coli was
first identified. Surveillance of the
qepA-harboring clinical isolates should be
encouraged to minimize further dissemination of
the kind of plasmid-dependent FQ resistance
determinants among pathogenic microbes.