EFFECTS OF BETA-LACTAM ANTIBIOTICS ON INTESTINAL MICROFLORAL AND BILE-ACID METABOLISM IN RATS

Wistar male rats were treated for six days with broad spectrum beta-la ctam antibiotics, latamoxef, and cefotaxime. On the seventh day, the n umber of fecal anaerobic microbes decreased, total fecal bile acids de creased, and bile acid pools increased. Secondary bile acids such as b eta-hyocholic, hyodeoxycholic, lithocholic, and deoxycholic acids decr eased in the feces while the primary bile acids, cholic, beta-murichol ic, and chenodeoxycholic acids, became predominant. Coprostanol, a mic robial metabolite of cholesterol, also disappeared from the feces duri ng the treatment. The cecum enlarged to almost twice the size of that in control rats, whereas the liver weight was not significantly change d. After treatment was stopped, the number of fecal microbes returned to the initial counts within a week, but restoration of bile acid and cholesterol metabolism required at least three weeks.