LACK OF CROSS-REACTIVITY BETWEEN AZTREONAM, A MONOBACTAM ANTIBIOTIC, AND PENICILLIN IN PENICILLIN-ALLERGIC SUBJECTS

IgE or immediate hypersensitivity cross-reactivity between aztreonam (a monobactam) and penicillin [antibacterial agents] was investigated, since this will be an important consideration when therapy is chosen. The maximum concentration of aztreonam reagents not giving false-positive skin tests was determined in normal subjects who were not allergic to penicillin. Subsequently, 41 sugjects with IgE antibody to .gtoreq. 1 penicillin moieties, as determined by positive skin reactions, were tested with the aztreonam reagents. Of these persons, 37 showed no reactivity; 4 showed equivocal tests. Repeat tests in those 4 persons were negative to the aztreonam reagents; their penicillin tests were unchanged. Evidently, there is no cross-reactivity between IgE antibodies to penicillin and aztreonam; a basis for investigating the therapeutic use of monobactams in patients who are allergic to penicillin is provided.