The distribution of soil actinomycetes antagonistic to protozoa.

The antibiotic approach to the problem of chemotherapy for protozoan diseases is suggested by the successful treatment of bacterial infections with such substances as penicillin, streptomycin, aureomycin, chloromycetin and terramycin. The general ineffectiveness of these antibacterial agents in treating protozoan diseases (Armstrong et al., 1950; Felsenfeld et al., 1950; Hughes, 1950; Ishihara and Felsenfeld, 1949; Loefer, 1950; Most, 1949; Wyatt and Vandegrift, 1950) recommends the direct use of protozoa as test organisms in a search for antibiotics active against these forms. This is in contrast to the usual procedure wherein antibacterial agents have been isolated and subsequently tested for a coincidental ability to inhibit protozoa. This indirect approach is understandable in view of the diffculties in cultivating parasitic protozoa and the paucity of such species that can be grown in pure culture.