Inactivation of aminoglycosides by beta-lactams of the penicillin and cephalosporin groups

Interaction of carbenicillin with kanamycin, gentamicin, tobramycin, and amikacin, as well as that of cefotaxime with the same aminoglycosides were studied. It was shown that carbenicillin inactivated aminoglycosides in a patient's plasma, urine, rH 5.3-8.44, and in buffer solutions, pH 3.7, 7.5 and 9.25. The inactivation level was the least in acid media. The mechanism of the inactivation was elucidated: opening of the carbenicillin beta-lactam ring occurred at the start.