Quinolones in Intracellular Infections

Intracellular parasites are those which spend most of their lives within host cells. The fluoroquinolones demonstrate favourable intracellular pharmacokinetics for the treatment of intracellular infections; these agents diffuse and accumulate in the phagocytes, mainly in the cytosol, and do not associate with cellular organelles. The fluoroquinolones are generally active against Salmonella spp. in vitro, and have been used successfully in the treatment of typhoid fever, Salmonella bacteraemia in patients with AIDS, and chronic enteric carriage. Fluoroquinolone monotherapy has also been found satisfactory in the treatment of tularaemia and Mediterranean spotted fever. Quinolones, alone or in combination with other agents, have also shown promise in animal models of legionellosis and in limited clinical studies. Quinolones, particularly ciprofloxacin and ofloxacin, have notable antimycobacterial activity. Both agents have been used in combination with other antimycobacterial drugs in the treatment of infections caused by Mycobacterium tuberculosis, M. avium-intracellulare complex, rapidly growing mycobacteria and M. leprae, and deserve consideration as part of a multi-drug regimen in otherwise untreatable mycobacterial infections. Clinical data regarding fluoroquinolone monotherapy in brucellosis indicate unacceptable failure rates which preclude the use of these agents in this indication. The quinolones have some efficacy in genital chlamydial infections, but may have limitations in this indication also. In conclusion, as a result of the in vitro activity of the quinolones and their favourable pharmacokinetics, these agents are now an important part of the armamentarium against intracellular infections.