Uptake of ciprofloxacin by macrophages.

Ciprofloxacin was concentrated within mouse peritoneal macrophages to between two and three times extracellular values. Uptake was rapid, occurred equally well with dead cells, and was not affected by lowering the pH or by prior ingestion of Staphylococcus aureus. Intracellular staphylococci were killed by extracellular concentrations of ciprofloxacin as low as 0.5 mg/l.