The in vitro antimalarial activity of chloramphenicol against Plasmodium falciparum

The minimum inhibitory concentrations, MIC, of chloramphenicol were determined for two isolates of Plasmodium falciparum at 48, 96 and 144 h. The MIC decreased from values greater than 100 micrograms/ml at 48 h to 10.7-12.5 micrograms/ml at 96 h. During 144 h of incubation, concentrations of 0.8-1.6 micrograms/ml were effective in suppressing parasite growth. These results indicate that the multiplication of malaria parasites can be inhibited by clinically achievable concentrations of chloramphenicol provided that exposure to the drug is prolonged over several asexual life cycles. They suggest that undiagnosed falciparum infections may be cured when patients with fever of doubtful origin are treated with 10 to 14 day courses of chloramphenicol. They also raise the possibility that this antibiotic may eventually be used, in combination with a rapidly acting but non-curative drug regimen, to treat patients with falciparum infections in whom the use of tetracyclines is contraindicated, e.g., young children.