Relationship between haemolysis production and resistance to fluoroquinolones among clinical isolates of Escherichia coli.
The activities of ampicillin, amoxycillin-clavulanic acid, gentamicin, tetracycline, nalidixic acid, ciprofloxacin, pefloxacin and trovafloxacin against 207 consecutive clinical isolates of Escherichia coli were determined. Fifty-six (27.3%) isolates were haemolytic. The percentages of resistance to quinolones and tetracycline, but not to other agents, among haemolytic isolates were significantly lower (P < 0.05) than among non-haemolytic isolates. Ciprofloxacin-resistant mutants obtained from ciprofloxacin-susceptible haemolytic isolates still produced haemolysis. It is concluded that most quinolone-resistant clinical isolates of E. coli are non-haemolytic, although haemolysis is produced by quinolone-resistant mutants derived from haemolytic quinolone-susceptible strains.
Martínez-Martínez
L
L
Department of Microbiology, University Hospital Virgen Macarena, School of Medicine, Seville, Spain. lmartin@cica.es
Fernández
F
F
Perea
E J
EJ
D000658:Amoxicillin / Q000494:pharmacology; D000667:Ampicillin / Q000494:pharmacology; D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology; D019818:Clavulanic Acid / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D024841:Fluoroquinolones; D005839:Gentamicins / Q000494:pharmacology; D006460:Hemolysin Proteins / Q000378:metabolism*; D006461:Hemolysis; D006801:Humans; D008826:Microbial Sensitivity Tests; D009268:Nalidixic Acid / Q000494:pharmacology; D009287:Naphthyridines / Q000494:pharmacology; D015366:Pefloxacin / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology
D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D005839:Gentamicins; D006460:Hemolysin Proteins; D009287:Naphthyridines; D019818:Clavulanic Acid; D015366:Pefloxacin; D009268:Nalidixic Acid; D002939:Ciprofloxacin; D000667:Ampicillin; D000658:Amoxicillin; C080163:trovafloxacin; D013752:Tetracycline