Tolerance of axenically cultured Entamoeba histolytica and Giardia lamblia to a variety of antimicrobial agents.

Twelve antimicrobial agents were tested for use in axenic cultures of Entamoeba histolytica and Giardia lamblia. Ten did not inhibit parasite growth at concentrations of at least two-fold above the effective antibacterial or antifungal levels. We have found the combination of piperacillin (500 micrograms/ml) plus amikacin (125 micrograms/ml) to be useful in axenization of a new strain of E. histolytica, eradication of multiply drug-resistant contaminants in cultures and prevention of bacterial growth in experiments with non-sterile components.