Comparative Action of Selected Amebicidal Agents and Antibiotics against Several Species of Human Intestinal Amebae

Abstract

Summary A series of six agents was tested in vitro against Endamoeba histolytica, E. coli, Dientamoeba fragilis, and Endolimax nana. The agents included emetine, Vioform, carbarsone oxide, a dithio derivative of carbarsone oxide known as C. C. no. 914, prodigiosin and aureomycin. Emetine alone exhibited a distinctly differential amebicidal action, E. histolytica proving at least twenty-five times more susceptible than any other species. Monobacterial cultures tended to be more susceptible than those containing a mixed flora. The broadest activity spectra against all species were exhibited by prodigiosin, carbarsone oxide and C. C. no. 914. Contrary to several published reports, aureomycin was found to have relatively little direct amebicidal activity. From a consideration of the many variables operating during in vitro drug tests, it is concluded that careful control is required of such factors as the inocula, conditions existing in the test medium and criteria for determining amebicidal endpoints. Supplementary tests of terramycin and fumagillin against E. histolytica and E. coli corroborated the claim that fumagillin is the most potent amebicide in vitro yet discovered.