Importance of repeat testing in the diagnosis of penicillin allergy

Diagnosing Hypersensitivity Reactions to Cephalosporins in Children

“…1 Male 9 48 Ceftriaxone AS Immediate 2 Female 8 9 Cefaclor AS Immediate 3 Male 11 11 Cefaclor UR Immediate 4 Male 7 72 Ceftazidime, ceftriaxone, erythromycin, The rate of resensitization, diagnosed on the basis of conversion to skin-test positivity in patients retested ϳ1 month after negative challenge results followed by full therapeutic courses, observed in the present study (25%; 1 of 4 children) was lower than that found in the aforementioned study of adults (83.3%; 5 of 6 subjects). 8 This resensitization phenomenon has been described in other studies, 13,[15][16][17][18] with frequency rates ranging from 0.9% 15 to 16.6%. 16 Moreover, negative skin-test results were observed for both children and adults with IgE-mediated hypersensitivity to penicillins who were retested after Ն1 year 19,20 ; some subjects tolerated penicillin again.…”

Diagnosis of penicillin allergy revisited: the value of case history, skin testing, specific IgE and prolonged challenge

“…Discrepancies in the results of repeated skin testing in patients have led to the concept of (re‐)sensitization induced by testing . The reports describing a positive skin test result in a previously skin test‐negative patient have used single testing and found that a few percentage of the patients became positive when repeated.…”

Update on the evaluation of hypersensitivity reactions to betalactams

“…Resensitization after allergological tests. In some studies (34–36), resensitization (i.e. a conversion to skin test positivity) has been observed in patients retested about 1 month after a negative allergological test, including DPT, followed by full therapeutic courses, with a frequency ranging from 0.9% (34) to 27.9% (37).…”

“…This phenomenon appears to occur mainly in subjects who have experienced immediate reactions to BLs. However, the aforementioned studies (34–36) evaluated patients with either immediate or nonimmediate reactions. If we just consider patients with immediate reactions, the rate of conversion to skin test positivity could be higher, as has recently been observed in a small number of patients with immediate reactions to cephalosporins (16).…”