Glycoside antibiotics alone and combined with tetracyclines for prophylaxis of experimental cryptosporidiosis in neonatal BALB/c mice.

Glycoside antibiotics including the macrolide antibiotics azithromycin, clarithromycin, and erythromycin and the aminoglycoside paromomycin were administered alone or combined with doxycycline, minocycline, or tetracycline to neonatal BALB/c mice experimentally infected with Cryptosporidium parvum. Glycosides at 100 or 200 mg/kg of body weight and tetracyclines at 50 mg/kg of body weight were dissolved in dimethylsulfoxide (DMSO), which was then diluted with phosphate-buffered saline (PBS) and given orally by gavage. Drugs were administered at 0, 24, 48, and 72 hr postinfection (PI) for prophylaxis. Histologic sections of ileum, cecum, and colon from tissues fixed at 96 hr PI were examined microscopically to determine the number of developing parasites and assign a quantitative score based on infectivity. All groups that received glycosides had significantly (P < 0.01) lower scores than controls that received only DMSO/PBS. A range in efficacy was apparent. None or extremely few parasites were found in paromomycin- and azithromycin-treated groups, whereas few to moderate numbers of parasites were found in erythromycin- and clarithromycin-treated groups. The addition of tetracyclines did not consistently result in significantly lower scores.