Antimicrobial Use Guidelines (AMUG) version 21 - UW Health

with aztreonam and other beta-lactams, except ceftazidime (see Section D), is low and it may beused safely in beta-lactam allergic patients. 5,11,21 Also, patients with a history of penicillin allergyare three times more likely to have an adverse reaction to any additional antibiotics (includingcephalosporins and sulfa). 8,22Penicillin is the only drug class with a valid skin test. Degradation products of other antibioticsare not known or commercially available. Under physiologic conditions, penicillin degrades toreactive intermediates that act as haptens. These haptens bind to self-proteins and elicit animmune response. Approximately 95% of penicillin degrades to the penicilloyl moiety which is themajor determinant. The rest degrades to penicilloate and penicillanyl moieties which are theminor determinants. The risk of having an adverse reaction to a penicillin skin test is