Efflux-Mediated Fluoroquinolone Resistance in the Bacteroides fragilis Group

• Published in: Anaerobe 2002, Vol.8 (5), p.277-282
• Main Authors: Herin, Oh, Hedberg, Maria, Edlund, Charlotta
• Format: Article
• Language: English
• Subjects: fluoroquinolone, efflux, Bacteroides fragilis, anaerobe, fluoroquinolone resistance
• ISSN: 1075-9964; 1095-8274; 1095-8274
• DOI: 10.1006/anae.2003.0439

In order to investigate the role of efflux pumps in fluoroquinolone resistance, 35 Bacteroides fragilis group isolates with various resistance patterns against ciprofloxacin, levofloxacin, moxifloxacin and clinafloxacin were studied. The gyrA genotypes were known in all isolates studied. The accumulation of ciprofloxacin with and without carbonyl cyanide m -chlorophenylhydrazone (CCCP) was investigated using a silicon oil based fluorometric assay. Seventeen of 25 multiquinolone-resistant strains had significantly increased ciprofloxacin accumulation in the presence of CCCP compared to the corresponding susceptible type strains. Ten of the resistant isolates with increased efflux had no target mutations at positions 82 or 86 of their GyrA subunits. Strains with highly enhanced efflux were consequently shown to have a significant decrease of quinolone MIC values in the presence of efflux pump inhibitor. The results of the present study propose that high levels of resistance to older as well as newer fluoroquinolones, could be explained by increased activity of efflux pumps in B. fragilis group strains.