Acetylation of fluoroquinolone antimicrobial agents by an Escherichia coli strain isolated from a municipal wastewater treatment plant.
OBJECTIVE
To isolate environmental bacteria capable of transforming fluoroquinolones to inactive molecules.


RESULTS
Bacteria were isolated from the aerobic liquor of a wastewater treatment plant on a medium containing norfloxacin (100 mg l(-1)). Twenty-two isolates were highly resistant (minimal inhibitory concentration: 6.25-200 microg ml(-1)) to five fluoroquinolones and six of them were positive by PCR amplification for the aminoglycoside resistance gene aac(6')-Ib. Of these, only Escherichia coli strain LR09 had the ciprofloxacin-acetylating variant gene aac(6')-Ib-cr; HPLC and mass spectrometry showed that this strain transformed both ciprofloxacin and norfloxacin by N-acetylation. This bacterium also had mutations in the quinolone-resistance determining regions of the gyrA and parC genes.


CONCLUSIONS
An E. coli isolate from wastewater, which possessed at least two distinct fluoroquinolone resistance mechanisms, inactivated ciprofloxacin and norfloxacin by N-acetylation.


CONCLUSIONS
This is the first report of N-acetylation of fluoroquinolones by an aac(6')-Ib-cr-containing bacterium from an environmental source.
Jung
C M
CM
Division of Microbiology, National Centre for Toxicological Research, US FDA, Jefferson, AR, USA.
Heinze
T M
TM
Strakosha
R
R
Elkins
C A
CA
Sutherland
J B
JB
D000107:Acetylation; D000900:Anti-Bacterial Agents / Q000378:metabolism*; D002939:Ciprofloxacin / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D024841:Fluoroquinolones / Q000378:metabolism*; D005798:Genes, Bacterial; D008826:Microbial Sensitivity Tests; D009154:Mutation; D009643:Norfloxacin / Q000494:pharmacology; D014865:Waste Disposal, Fluid
D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D002939:Ciprofloxacin; D009643:Norfloxacin