I read with great interest the article entitled ‘Allergic reactions to β-lactams’ by Rodriquez-Pena et al. Citation[1]. Penicillins remain the drugs of choice for so many conditions, particularly in my specialty of otorhinolaryngology. It is truly unfortunate that many factors, including overlabelling patients as allergic Citation[2], have resulted in the overuse of alternative antibiotics. This has led to microbial resistance and increased heath care costs.
Unfortunately there is no universal protocol to work-up patients with self-proclaimed β-lactam allergy. Skin testing is considered by many who manage allergic disease to be a valuable modality given that it as an in vivo modality. However, in the extensive and comprehensive review of this topic, the authors acknowledge that the number of positive cases after skin testing is somewhat variable. Furthermore, patients with nonanaphylactic reactions (i.e., rash alone) may have a lower prevalence of positive skin test. The tendency to react positively, as reviewed by the authors, can also depend on the reagent tested Citation[3]. Oral challenge may also be necessary to elucidate the in vivo significance of a positive response. The summation of these observations suggests that assessment of β-lactam allergy is best accomplished through some algorithm involving a skin test panel Citation[4] of selected reagents followed by oral challenge. These in vivo modalities would identify the reactions of practical significance without the expense of immunoassay or flow cytometry.
The question still remains of what that algorithm should be: What elements of the patient history necessitate skin testing? What reagents (or panel thereof) will have the highest specificity so that patients testing negatively will not be incorrectly labelled as nonallergic, yet will be sensitive enough so as not to miss those with bona fide allergic reactions? Just as in an environmental allergy workup, where a cost-effective panel is selected to correspond to the prevalence of the various pollens in the particular region, a similar algorithm can be proposed here. This can include statements about the exact roles of oral challenge and in vitro testing. It would be helpful to the readers if the authors suggested such a clinical pathway.
Bibliography
- RODRIGUEZ-PENA R, ANTUNEZ C, MARTIN E et al.: Allergic reactions to β-lactams. Expert Opin. Drug Saf. (2006) 5:31-48.
- LANGLEY JM, HALPERIN SA, BARTOLUSSI R: History of penicillin allergy and referral for skin testing: evaluation of a pediatric allergy testing program. Clin. Invest. Med. (2002) 25:181-184.
- WARRINGTON RJ, SIMONS FE, HO HW, GORSKI BA: Diagnosis of penicillin allergy by skin testing: the Manitoba experience. Can. Med. Assoc. J. (1978) 118:787-791.
- SALKIND AR, CUDDY PG, FOXWORTH JW: The rational clinical examination. Is this patient allergic to penicillin? An evidence-based analysis of the likelihood of penicillin allergy. JAMA (2001) 285:2498-2505.