Abstract
We measured the susceptibilities of the normal intestinal bacterial flora as well as opportunistic pathogens to the major broad spectrum antibiotics under anerobic conditions as was in intestine. The results showed that oppor-tunistic pathogens were always more resistant to the commonly used antibiotics at that period than the commensal bacterial flora suggesting that abnormal increases of opportunistic pathogens caused by the uses of broad spectrum antibiotics could trigger the opportunistic infections in the immune deficient patients. Thus, the susceptibilities of the commensal bacteria to all antibiotics should be seriously considered for the adequate chemotherapy.
