EFFECT OF AEROBIC AND ANAEROBIC ENVIRONMENTS ON ANTISTAPHYLOCOCCAL ACTIVITIES OF 5 FLUOROQUINOLONES

A previously established in vitro pharmacodynamic system was used to e valuate the antistaphylococcal activities of five fluoroquinolones und er both aerobic and anaerobic conditions, Staphylococcus aureus ATCC 2 9213 was exposed to a 5-mu g/ml concentration of each of the following fluoroquinolones: ciprofloxacin, ofloxacin, temafloxacin, sparfloxaci n, and clinafloxacin, Terminal elimination half-lives of 4, 6, 8, 8, a nd 13 h were simulated for the respective drugs, Each fluoroquinolone was bactericidal under both aerobic and anaerobic conditions, However, the bactericidal activity of each fluoroquinolone was delayed by anae robiosis. This difference in fluoroquinolone activity under aerobic an d anaerobic conditions could not be attributed to any particular param eter or physiochemical property but was most likely caused by a combin ation of factors (e.g., variations in hydrophobicity, intracellular pH , antibiotic concentration, and structure-activity relationships), Flu oroquinolone uptake studies were also performed to investigate the pos sibility of active, energy-dependent transport mechanisms in S. aureus ATCC 29213. Uptake studies indicated that active efflux does occur in S. aureus ATCC 29213.