Abstract
Two macrolide antibiotics, clarithromycin and roxithromycin, have recently entered the market and are now in frequent clinical use. These antibiotics were inactivated by an inactivating enzyme, macrolide 2′-phosphotransferase [MPH(2′)I], extracted from highly erythromycin-resistant Escherichia coli, and the reaction products were analyzed by ESI-MS. It was demonstrated that the 2′-phosphate derivatives of these macrolides could be detected by analysis of the mixture of MPH(2′)I and adenosine 5′-triphosphate after only a simple sample pretreatment with the addition of 3% acetic acid into water-methanol (1 : 1, v/v).
