[Study on the activities of fluoroquinolones against Staphylococcus aureus and the effect of reserpine on these activities].

Objective: To investigate the activities of fluoroquinolones and the effects of reserpine on the activities of fluoroquinolones against S. aureus.

Methods: The minimal inhibitory concentration (MICs) and the effects of reserpine on MICs of fluoroquinolones against S. Aureus were determined using standard agar dilution method.

Results: Cross resistance to fluoroquinolones was found existing in S. aureus, but there was no remarkable multidrug resistance. The MICs of fluoroquinolones against many of S. aureus could be decreased by reserpine; Obvious decrease in MICs of fluoroquinolones against SA2-16 was observed; The decreasing percentage of MICs of fluoroquinolones against resistant strains was shown not significantly higher than that of sensitive strains. The decreasing percentage of MICs of hydrophilic fluoroquinolones against the strains studied was significantly higher than that of hydrophobic fluoroquinolones.

Conclusions: Cross resistance to fluoroquinolones has been found existing in S. aureus, whereas multidrug resistance is not seen in existence. The efflux of fluoroquinolones is normal in S. aureus; the amount of fluoroquinolones effluxed is related with the resistance of fluoroquinolones in S. aureus.