How to Manage Antibiotic Allergy in Cystic Fibrosis? Epidemiologic, Diagnostic, and Therapeutic Aspects

Abstract

Cystic fibrosis (CF) is a complex genetic disease with high mortality, of which 85% is a result of lung disease characterized by serious endobronchial infections. Antibiotic therapy is one of the main treatments of CF, both during acute exacerbations and as chronic maintenance medications, contributing to a prolonged survival. Since neonatal CF screening programs have been implemented universally and the longevity of patients with CF steadily increases, antibiotic hypersensitivity reactions (HSRs) are becoming more important. HSR to antibiotics in CF has been reported since the 1980s and was estimated to occur up to three times more frequently in these patients, probably owing to high rates of antibiotic exposure and boosting stimuli such as infections and inflammation. However, recent studies including large groups of CF patients with a suspicion of antibiotic allergy have used diagnostic algorithms including skin tests and drug provocation tests and showed that true incidence was much lower. The mechanism of the reactions and the clinical presentations are not different in CF than in the general population. Both the immediate and nonimmediate type HSRs are seen, and among the latter, drug fever and drug-induced hemolytic anemia are distinctive presentations. Beta-lactam (BL) agents are the most common cause, with higher rates for ureidopenicillins (piperacillin, mezlocillin, and piperacillin/tazobactam) and cephalosporins (especially ceftazidime), intermediate rates for carbapenems, and lowest rates for aztreonam, and also HSRs to aminoglycosides, macrolides, and quinolones are encountered. Since the available choices for antibiotic therapy are limited due to relevant organisms, management becomes a challenge. It is essential to evaluate the patients according to the mechanism of the HSR and determine the risk of repeat administration of the culprit drug and also safety of alternative drugs with prior skin and provocation tests. The chemical structure and side chains must be taken into account when selecting a safe alternative drug. Contrary to what was previously thought, recent data on cross-reactions between BL antibiotics showed that some BLs can be an option of treatment for patients allergic to other BLs. Desensitization is a useful procedure in immediate and some delayed reactions, if a suitable alternative antibiotic is not available.