Inactivation of aztreonam by faecal supernatants of healthy volunteers as determined by HPLC.

The enzymatic inactivation of aztreonam to its biologically inactive open ring form, by faecal enzyme preparations from 12 volunteers, was investigated. The percentage inactivation was determined by a high-performance liquid chromatography assay at months 0, 6 and 24. Faecal enzyme preparations from five volunteers could inactivate aztreonam by more than 50% within 20 h at one or more of these sampling times. Monitoring of aztreonam inactivation over a shorter period of time (14 days) in three of the volunteers showed that aztreonam inactivation cannot be predicted.