Effect of ciprofloxacin on intracellular organisms: in-vitro and in-vivo studies.

Ciprofloxacin is taken up rapidly by both human neutrophils and mouse peritoneal macrophages. It does not appear to be bound firmly within the cell and can be eluted readily if the extracellular concentration is lowered. Uptake does not depend on an active transport mechanism. Intracellular ciprofloxacin is biologically active reducing the survival of intracellular Staphylococcus aureus and Mycobacterium fortuitum, in vitro. In vivo, ciprofloxacin was effective in treating a murine systemic infection with an intracellular pathogen Salmonella typhimurium. The progress of infection in sensitive mice with no natural immunity was delayed by ciprofloxacin although at the dosage used the mice were not cured. These results suggested that clinical studies in patients infected by intracellular pathogens are warranted and that ciprofloxacin may have an important role in the treatment of this type of infection.