Clindamycin-induced alterations in intestinal microflora-associated characteristics in rats.

Conventional Sprague-Dawley rats were treated with clindamycin, 40 mg/kg/day and 0.04 mg/kg/day, for 5 days. At a dose of 40 mg/kg/day, microflora-associated characteristics (MACs), such as shape, color, and consistency of feces, proteolytic activity, electrophoretic pattern, and cholesterol and bilirubin metabolism were transformed into values like those found in germfree rats: germfree animal characteristics (GACs). The effect on the proteolytic activity lasted longest. It did not disappear until one or two enemas with cecal contents from intact conventional rats were administered. At a dose of 0.04 mg/kg/day, effects on the proteolytic activity and cholesterol metabolism were seen. With the exception of one rat, the effect on proteolytic activity did not disappear until one or two enemas were given. The results indicate that clindamycin, even in very small daily doses, has a profound and long-lasting influence on many intestinal MACs in rats.