AIMS: To isolate environmental bacteria capable of transforming fluoroquinolones to inactive molecules. METHODS AND 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. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report of N-acetylation of fluoroquinolones by an aac(6')-Ib-cr-containing bacterium from an environmental source.
AIMS: To isolate environmental bacteria capable of transforming fluoroquinolones to inactive molecules. METHODS AND 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. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report of N-acetylation of fluoroquinolones by an aac(6')-Ib-cr-containing bacterium from an environmental source.
Authors: Dae-Wi Kim; Thomas M Heinze; Bong-Soo Kim; Laura K Schnackenberg; Kellie A Woodling; John B Sutherland Journal: Appl Environ Microbiol Date: 2011-07-01 Impact factor: 4.792
Authors: Minh-Duy Phan; Kate M Peters; Laura Alvarez Fraga; Steven C Wallis; Steven J Hancock; Nguyen Thi Khanh Nhu; Brian M Forde; Michelle J Bauer; David L Paterson; Scott A Beatson; Jeffrey Lipman; Mark A Schembri Journal: Antimicrob Agents Chemother Date: 2021-11-15 Impact factor: 5.938