THE EFFECT OF QUINOLONES ON THE INTRACELLULAR KILLING OF STAPHYLOCOCCUS-AUREUS IN NEUTROPHIL GRANULOCYTES

The effect of ciprofloxacin, lomefloxacin, fleroxacin and ofloxacin on the intracellular kilting of Staphylococcus aureus in human neutrophi l granulocytes was studied. Each drug was tested in concentrations of 0.25, 1, 4, 16 end 64 times the MIC and the intracellular killing was measured for up to 5 h of incubation. All four quinolones increased th e intracellular killing in a concentration- and time-dependent manner. When compared at concentrations of 4 x MIG, ofloxacin increased the k illing significantly more than the other quinolones. All four quinolon es increased the killing significantly more than the beta-lactam diclo xacillin. All five antibiotics increased the killing significantly rel ative to the control without antibiotics. None of the antibiotics affe cted the viability of the granulocytes or their ability to generate su peroxide anion. In conclusion, the quinolones increased the intracellu lar killing of S. aureus in neutrophil granulocytes.