Abstract
In an attempt to elucidate the pathophysiological significance of intestinal flora in hepatic encephalopathy, the faecal flora as well as production of toxic substances and drug susceptibility of the isolates from faeces were serially examined in six patients with chronic recurrent hepatic encephalopathy. Significant changes in the faecal flora accompanied with those in toxic substances (ammonia, short-chain fatty acids) and clinical features were observed in three cases who had been administered antimicrobial agents. Administration of antimicrobial agents in the three cases was revealed to be one of the important precipitating factors of hepatic encephalopathy, due mainly to the induction of overgrowth of toxic substance-producing organisms, such as Clostridium species, which produced ammonia and short-chain fatty acids. Moreover, administration of polymyxin B brought about the overgrowth of Morganella morganii, which produced large amounts of ammonia and methanethiol. Clinical use of conventional antimicrobial agents should be carefully decided in patients with hepatic encephalopathy.