Effects of antibiotics on Plasmodium falciparum in vitro.

Evidence from in vivo experiments and clinical reports in humans has indicated that some antibiotics demonstrate antimalarial activity. Twelve antibiotics have been tested against Plasmodium falciparum in vitro, including cycloheximide, streptomycin, erythromycin, tetracycline, chloramphenicol, clindamycin, actinomycin D, rifampin, nalidixic acid, penicillin G, chlorhexidine, and isoniazid. Inhibitory effects obtained at various drug concentrations in vitro were compared to drug levels reported to be effective against bacteria in vivo. Several antibacterial drugs, including erythromycin, chloramphenicol, clindamycin, rifampin and tetracycline, demonstrated significant antiparasitic effects at concentrations within or near those observed during therapy in vivo; the potency of erythromycin and tetracycline was greater at 96 hours of exposure than at 48 hours.