Cystic fibrosis and penicillin hypersensitivity

Drug Hypersensitivity Reactions in Patients with Cystic Fibrosis: Potential Value of the Lymphocyte Toxicity Assay to Assess Risk

BACKGROUND

Cystic fibrosis (CF) is a genetic disease characterized by multi-system dysfunction resulting in recurrent lung infections and progressive pulmonary disease. CF patients are at a higher risk for drug hypersensitivity reactions (DHRs) compared to the general population, which has been attributed to the recurrent need for antibiotics and the inflammation associated with CF disease. In vitro toxicity tests such as the lymphocyte toxicity assay (LTA) offer the potential for risk assessment for DHRs. In the current study, we investigated the utility of the LTA test for diagnosis of DHRs in a cohort of CF patients.

METHOD

Twenty CF patients with suspected DHRs to sulfamethoxazole, penicillins, cephalosporins, meropenem, vancomycin, rifampicin, and tobramycin were recruited to this study and tested using the LTA test along with 20 healthy control volunteers. Demographic data of the patients, including age, sex, and medical history, were obtained. Blood samples were withdrawn from patients and healthy volunteers, and the LTA test was performed on isolated peripheral blood monocytes (PBMCs) from those individuals.

RESULTS

Cells from CF patients with DHRs displayed a significant (p < 0.0001) concentration-dependent enhanced cell death upon incubation with the culprit drug compared to cells from healthy volunteers. The positivity rate of the LTA test was over 80% in patients with a medical history and clinical presentation consistent with DHRs.

CONCLUSION

This study is the first to evaluate the use of the LTA test for diagnosis of DHRs in CF patients. According to our results, the LTA test may be a useful tool for diagnosis and management of DHRs in CF patients. Identifying the culprit drug is essential for optimal healthcare for CF patients in the setting of a suspected DHR. The data also provide evidence that accumulation of toxic reactive metabolites could be an important component in the cascade of events leading to the development of DHRs in CF patients. A larger-scale study is needed to confirm the data.

Beta-lactam allergy in adults with cystic fibrosis

BACKGROUND

Allergic reactions to one or more beta-lactam antibiotic can pose a management problem in patients with cystic fibrosis (CF), and may limit antibiotic choice.

METHOD

The aim of this study was to assess the prevalence of allergy to anti-pseudomonal beta-lactam antibiotics in an adult CF centre and to assess variables, which may contribute to the development of allergic reactions. A questionnaire-based interview and a review of medical records were performed.

RESULTS

Of the 150 patients, 54 (36%) had allergic reactions to one or more beta-lactam antibiotics and 20 (19%) had allergic reactions to multiple beta-lactam antibiotics. The proportion of patients allergic to specific beta-lactam antibiotics varied from 10% to 26%. Rates of reactions were highest for penicillins and cephalosporins, intermediate for carbepenems and lowest for aztreonam. Of all reactions, 40% occurred within 24 h of the commencement of an individual antibiotic course. Patients with one or more beta-lactam allergic reactions had received greater cumulative exposure (p<0.0001), were older (p=0.016) and had lower lung function (p=0.037) than patients without a history of beta-lactam allergy. Cystic Fibrosis transmembrane regulator (CFTR) status, gender, peripheral blood eosinophil count and total IgE concentrations were not different in patients with allergic reactions.

CONCLUSIONS

This study demonstrates that the prevalence of allergic reactions to beta-lactam antibiotics is high in adults with CF. Increasing age; cumulative exposure and decreasing FEV(1) were associated with the development of allergy.

Antibiotic allergy in cystic fibrosis

Allergic reactions to antibiotics are more common in cystic fibrosis (CF) than in the general population. This in part is due to the improving survival in adults with CF and the increased use of high dose intravenous antibiotics. While some are immediate anaphylaxis type (IgE mediated) reactions, the majority are late onset and may have non-specific features such as rash and fever. Piperacillin has consistently been found to have the highest rate of reported reactions (30-50%). There is a low risk of cross reactions between penicillins and other non-beta-lactam classes of antibiotics in penicillin skin prick positive patients. Carbapenems should only be used with extreme caution in patients with positive skin prick tests to penicillin. However, aztreonam can be used safely in patients who are penicillin allergic with positive skin prick reactions. The aminoglycosides are a relatively uncommon cause of allergic reactions, but patients who react to one member of the family may cross react with other aminoglycosides. Desensitisation relies on the incremental introduction of small quantities of the allergen and has been used for penicillins, ceftazidime, tobramycin and ciprofloxacin and must be repeated before each course. Personalized cards should be regularly updated for patients who develop allergic reactions. Written instructions on the emergency treatment of allergic reactions should be provided to patients self-administering intravenous antibiotics at home. Further research is required to identify risk factors and predictors for antibiotic allergy.