Antibiotic X-63 in experimental candidiasis of mice

X-63, a polyene antibiotic of heptaene series showed activity against experimental infection with Candida albicans in mice, by several routes. The oral, intraperitoneal and intravenous activities ranged between dosages of 3.1--50, 0.06--0.5 and 0.25--0.5 mg/kg, respectively. Seven days treatment by intraperitoneal route caused significant progressive reduction of colony-forming units in kidney homogenates of infected mice, which was comparable to amphotericin B. The regression of infection was further demonstrated histopathologically. In vitro, antibiotic X-63 was similar to nystatin against nine strains of Candida used. It also proved active against amphotericin B-resistant strains of C. albicans, C. tropicalis, C. pseudotropicalis, C. krusei, and C. parakrusei. The use of combined drug therapy in candidiasis has been discussed.