Importance of repeat testing in the diagnosis of penicillin allergy

Resensitization in suspected penicillin allergy

BACKGROUND

The diagnosis of allergic reactions to penicillins (AR-PEN) is very complex as there is a loss of sensitization over time, which leads to negative skin tests (STs) and specific IgE in serum, and even to tolerance to the drug involved. However, STs may become positive after subsequent exposure to the culprit drug (resensitization), with the risk of inducing potentially severe reactions. The exact rate of resensitization to penicillins is unknown, ranging from 0% to 27.9% in published studies.

OBJECTIVES

To analyze the rate of resensitization in patients with suggestive AR-PEN by repeating STs (retest) after an initial evaluation (IE).

MATERIAL AND METHODS

Patients with suspected AR-PEN were prospectively evaluated between 2017 and 2020. They underwent STs, and a randomized group also underwent a drug provocation test (DPT) with the culprit. Only patients with negative STs and/or DPT were included. All included cases were retested by STs at 2-8 weeks.

RESULTS

A total of 545 patients were included: 296 reporting immediate reactions (IRs) and 249 non-immediate reactions (NIRs). Eighty (14.7%) cases had positive results in retest (RT+): 63 (21.3%) IRs and 17 (6.8%) NIRs (p < 0.0001). The rate of RT+ was higher in anaphylaxis compared with all other reactions (45.8% vs 9.1%, p < 0.0001). The risk of RT+ was higher from the fifth week after IE (OR: 4.64, CI: 2.1-11.6; p < 0.001) and increased with the patient's age (OR: 1.02; CI: 1.01-1.04; p = 0.009).

CONCLUSIONS

Due to the high rate of resensitization, retest should be included in the diagnostic algorithm of IRs to penicillins after an initial negative study, especially in anaphylaxis, to avoid potentially severe reactions after subsequent prescriptions of these drugs.

The Combined Use of Chronological and Morphological Criteria in the Evaluation of Immediate Penicillin Reactions: Evidence From a Large Study

BACKGROUND

Immediate hypersensitivity reactions to penicillins are often labeled on the basis of a similar set of symptoms, but a key feature of these reactions that can be reproduced in diagnostic testing may be the timing of a reaction in relation to the dose administration.

OBJECTIVE

To determine whether the timing of a reaction in response to the last dose of a penicillin would predict the results of diagnostic testing.

METHODS

We evaluated 1074 patients by performing skin tests, serum specific IgE assays (ImmunoCAP), and challenges. Patients who were evaluated by us more than 6 months after their reactions and found negative were reevaluated within 2 to 4 weeks.

RESULTS

Patients who had reacted within 1 hour after the first dose, within 1 hour after subsequent doses, more than 1 hour to within 6 hours after the first dose, or more than 1 hour to within 6 hours after subsequent doses were classified as group A (758 individuals), B (92), C (67), or D (157), respectively. Penicillin hypersensitivity was diagnosed in 707 patients (65.8%) by skin tests (407 patients, 57.6%), ImmunoCAP (47, 6.6%), both tests (232, 32.8%), or challenges (21, 3%). A conversion to allergy-test positivity occurred in 7 of 10 patients with anaphylactic reactions and in 1 of 28 patients with other reactions who were reevaluated after negative challenges. The rate of penicillin-allergic patients in groups A, B, C, and D was 85%, 35.9%, 35.8%, and 3.8%, respectively. Only 1 of 107 patients reporting cutaneous reactions lasting more than 1 day had positive results to allergy tests.

CONCLUSIONS

IgE-mediated hypersensitivity can be diagnosed by skin tests in about 70% of subjects who react within 1 hour (eg, patients from groups A and B). This hypersensitivity can be lost over time, as demonstrated by the negativization of allergy tests in follow-up studies. In subjects with anaphylactic reactions, however, it is advisable to not consider this phenomenon definitive. In fact, a conversion to allergy test positivity can be observed in up to 20% of such subjects retested after negative challenges.

Towards a more precise diagnosis of hypersensitivity to beta-lactams - an EAACI position paper

A recent survey of the European Academy of Allergy and Clinical Immunology (EAACI) Drug Allergy Interest Group (DAIG) on how European allergy specialists deal with beta-lactam (BL) hypersensitivity demonstrated a significant heterogeneity in current practice, suggesting the need to review and update existing EAACI guidelines in order to make the diagnostic procedures as safe and accurate, but also as cost-effective, as possible. For this purpose, a bibliographic search on large studies regarding BL hypersensitivity diagnosis was performed by an EAACI task force, which reviewed and evaluated the literature data using the GRADE system for quality of evidence and strength of recommendation. The updated guidelines provide a risk stratification in BL hypersensitivity according to index reaction(s), as well as an algorithmic approach, based on cross-reactivity studies, in patients with a suspicion of BL hypersensitivity and an immediate need for antibiotic therapy, when referral to an allergist is not feasible. Furthermore, the update addresses availability and concentrations of skin test (ST) reagents, ST and drug provocation test (DPT) protocols, and diagnostic algorithms and administration of alternative BL in allergic subjects. Specifically, distinct diagnostic algorithms are suggested depending on risk stratification of the patient into high and low risk based on the morphology and chronology of the reaction, immediate (ie, occurring within 1-6 hours after the last administered dose) or nonimmediate (ie, occurring more than 1 hour after the initial drug administration), and the reaction severity. Regarding the allergy workup, the main novelty of this document is the fact that in some low-risk nonimmediate reactions ST are not mandatory, especially in children. For DPT, further studies are necessary to provide data supporting the standardization of protocols, especially of those regarding nonimmediate reactions, for which there is currently no consensus.

Beta-lactam hypersensitivity in children with cystic fibrosis: a study in a specialized pediatric center for cystic fibrosis and drug allergy

BACKGROUND

Beta-lactam hypersensitivity (HS) is suspected in 5-12% of the children, but proven in only 10-15% of those children, based on skin and challenge tests results. In contrast, 30-60% of patients with cystic fibrosis (CF) are diagnosed allergic to beta-lactams, based mainly on the clinical history of the patients.

OBJECTIVES

To confirm or rule out a suspected beta-lactam HS in CF children and to determine the prevalences of suspected and confirmed beta-lactam HS in those children.

PATIENTS AND METHODS

Children with CF and suspected beta-lactam HS were explored by means of skin and challenge tests with the suspected and alternate beta-lactams. The results in CF children were compared with those reported in the literature in non- CF children.

RESULTS

Eight of the 701 CF children followed in our center between 1990 and 2011 (1.14%), and 11 other children from other centers were explored for suspected beta-lactam HS. Beta-lactam HS was diagnosed in nine of these children (47.3%). Based on the results in the children followed in our center, the prevalence of beta-lactam HS was 0.71% (5/701) in CF children vs. a mean estimated prevalence of 1-1.5% in the general pediatric population.

CONCLUSION

Our results contrast with those of most previous studies. Although half of the CF children with suspected beta-lactam HS were truly allergic to beta-lactams, the general prevalence of beta-lactam HS in CF children was very low. This may result from tolerance induced by frequent and/or prolonged treatments with beta-lactams.

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

BACKGROUND

Skin testing in duplicate, correlation between case history of immediate and nonimmediate reactions and challenge outcome and prolonged oral treatment with penicillin in the diagnostic evaluation of allergic reactions to β-lactam antibiotics, mimicking real-life situations, have only been addressed in few studies.

METHODS

A total of 342 patients suspected of having β-lactam allergy were investigated according to the European Network for Drug Allergy (ENDA) guidelines and patients found to be negative in the ENDA program were supplemented with a 7-day oral treatment with penicillin. Skin testing with penicillins was performed in duplicate. Patients with case histories of reactions to other β-lactams were also subsequently challenged with the culprit drug.

RESULTS

Nineteen patients were IgE-sensitized to penicillin. Then, intracutaneous tests (ICTs) were performed, in which 35 patients tested positive for allergy, 21 with delayed and 14 with immediate reactions. Only three patients tested positive for the major (PPL) and/or minor (MDM) penicillin determinants, all being positive for penicillin G in ICT. The remaining 291 patients were challenged with penicillin: 10 tested positive in single-dose challenge and 23 tested positive in the 7-day challenge. A total of 17 of 78 patients with a negative penicillin challenge tested positive during challenges with other β-lactams. We found no correlation between case histories of immediate and nonimmediate reactions and reaction time during challenge.

CONCLUSION

The data suggest that case history is often insufficient to discriminate between immediate reactors and nonimmediate reactors. A 7-day challenge with the culprit β-lactam may yield more positive reactions than the accepted one- or 2-day challenge. Interpretation of skin testing should be made with caution.

Drug provocation tests in hypersensitivity drug reactions

PURPOSE OF REVIEW

Drug provocation test (DPT) is necessary to diagnose most drug hypersensitivity reactions (HSRs) due to decreased sensitivity of skin testing even when combined with in-vitro tests in immunonologic drug HSR and limited availability of these tests in nonimmunologic reaction. We review the principles and controversial issues of DPT, and recent studies using DPT as a diagnostic tool.

RECENT FINDINGS

DPT is recommended in the diagnosis of HSR to β-lactams, as well as other drug classes [such as acetylsalicylic acid-NSAIDs (ASA-NSAIDs), non-β-lactams antibiotics, heparin, glucocorticoids, and local anesthetic agents]. In view of the decreased sensitivity of skin testing, limited accessibility to new benzylpenicillin polylysine (PPL)/mixture of minor determinant (MDM) test reagents and limited availability of validated sensitive in-vitro tests, individuals who require DPT to β-lactams are increasing. The negative predictive value of allergologic work-up is very high, ranging from 94 to 98% for β-lactams and those reactions after negative tests are mostly nonimmediate and mild. Finally, DPT is recommended to ascertain tolerability of alternative compound when evaluating cross-reactivity among different classes of β-lactams, NSAIDs and glucocorticoids, and possibly iodinated contrast media.

SUMMARY

DPT is often needed when evaluating patients with suspected drug HSR. More studies regarding standardization of the various protocols are needed in order to increase its acceptance and adoption as a standard practice in the diagnostic algorithm for drug HSR.

Drug re-challenges in cutaneous adverse drug reactions: information and effectiveness in the long-term management of patients

BACKGROUND

In patients with cutaneous adverse drug reactions (CADR), drug skin tests and re-challenge under hospital surveillance (RCH) are helpful. The aim of this study was to determine if patients with negative drug RCH can tolerate subsequent treatments with the same drugs.

PATIENTS AND METHODS

Patients with a negative RCH in the last 10 years answered a telephone questionnaire which was delivered by the same investigator in order to determine if subsequently the patients were able to tolerate the drug with which they had a negative RCH and also to study the reasons why the drugs were not taken again.

RESULTS

Six hundred and thirty-seven RCH were analyzed (349 patients, mean age 47 years), 134 drugs were taken again (group A) and 359 were not (group B). In group A, 12 reactions occurred in 10 patients (9%). In group B, drugs were not taken again because 76% of the patients evaluated for an intolerance to antibiotics or radiocontrast media did not require a new course of these products or because their general practitioner (GP) did not want to prescribe these drugs.

DISCUSSION

Ninety percent of the RCH (88.5% of the patients) with a CADR followed by investigations and a RCH have a good tolerance to subsequent treatment with the RC drug. The mechanisms involved in this intolerance despite negative RCH are discussed.

CONCLUSION

  The provocation test procedure, considered as useful by 88% of the patients, has a good negative predictive value. Furthermore, these investigations need to be accompanied by clear information on the patient and his GP.

Allergy to betalactam antibiotics in children: results of a 20-year study based on clinical history, skin and challenge tests

Studies based on skin and challenge tests have shown that 12-60% of children with suspected betalactam hypersensitivity were allergic to betalactams. Responses in skin and challenge tests were studied in 1865 children with suspected betalactam allergy (i) to confirm or rule out the suspected diagnosis; (ii) to evaluate diagnostic value of immediate and non-immediate responses in skin and challenge tests; (iii) to determine frequency of betalactam allergy in those children, and (iv) to determine potential risk factors for betalactam allergy. The work-up was completed in 1431 children, of whom 227 (15.9%) were diagnosed allergic to betalactams. Betalactam hypersensitivity was diagnosed in 50 of the 162 (30.9%) children reporting immediate reactions and in 177 of the 1087 (16.7%) children reporting non-immediate reactions (p<0.001). The likelihood of betalactam hypersensitivity was also significantly higher in children reporting anaphylaxis, serum sickness-like reactions, and (potentially) severe skin reactions such as acute generalized exanthematic pustulosis, Stevens-Johnson syndrome, and drug reaction with systemic symptoms than in other children (p<0.001). Skin tests diagnosed 86% of immediate and 31.6% of non-immediate sensitizations. Cross-reactivity and/or cosensitization among betalactams was diagnosed in 76% and 14.7% of the children with immediate and non-immediate hypersensitivity, respectively. The number of children diagnosed allergic to betalactams decreased with time between the reaction and the work-up, probably because the majority of children with severe and worrying reactions were referred for allergological work-up more promptly than the other children. Sex, age, and atopy were not risk factors for betalactam hypersensitivity. In conclusion, we confirm in numerous children that (i) only a few children with suspected betalactam hypersensitivity are allergic to betalactams; (ii) the likelihood of betalactam allergy increases with earliness and/or severity of the reactions; (iii) although non-immediate-reading skin tests (intradermal and patch tests) may diagnose non-immediate sensitizations in children with non-immediate reactions to betalactams (maculopapular rashes and potentially severe skin reactions especially), the diagnostic value of non-immediate-reading skin tests is far lower than the diagnostic value of immediate-reading skin tests, most non-immediate sensitizations to betalactams being diagnosed by means of challenge tests; (iv) cross-reactivity and/or cosensitizations among betalactams are much more frequent in children reporting immediate and/or anaphylactic reactions than in the other children; (v) age, sex and personal atopy are not significant risk factors for betalactam hypersensitivity; and (vi) the number of children with diagnosed allergy to betalactams (of the immediate-type hypersensitivity especially) decreases with time between the reaction and allergological work-up. Finally, based on our experience, we also propose a practical diagnostic approach in children with suspected betalactam hypersensitivity.

Diagnosing hypersensitivity reactions to cephalosporins in children

OBJECTIVES

The goals were to evaluate the usefulness of skin tests, patch tests, serum specific IgE assays, and challenges in diagnosing hypersensitivity reactions to cephalosporins and to clarify the pathogenic mechanism of such reactions.

METHODS

Children with immediate manifestations (within 1 hour) underwent immediate-reading skin tests with penicillin reagents and any suspect cephalosporins, serum specific IgE assays, and challenges; some children underwent reevaluations. Children with nonimmediate manifestations (after >1 hour) were assessed with patch tests, delayed-reading skin tests, and challenges.

RESULTS

We evaluated 148 children with hypersensitivity reactions to cephalosporins, mainly cefaclor and ceftriaxone; 105 had experienced nonimmediate manifestations (mostly urticarial eruptions and maculopapular rashes) and 43 immediate manifestations (anaphylactic shock, urticaria and/or angioedema, and erythema). None of the nonimmediate reactors demonstrated positive results in patch tests and/or delayed skin tests; only 1 subject displayed immediate positive responses to penicillin skin-test reagents. Among the 104 patients with negative results, 96 underwent challenges; 95 tolerated the challenges, and 1 reacted to the cefaclor pediatric suspension and tolerated the challenge with a cefaclor capsule. In the first allergologic evaluation, 33 of the 43 children with immediate reactions displayed skin-test positivity. Of the 10 patients with negative results, 7 underwent challenges, followed by therapeutic courses and reevaluations for 4. All challenges and therapeutic courses were tolerated; in the reevaluation, 1 girl demonstrated positive skin-test results for both the responsible cephalosporin and penicillin reagents. Overall, IgE-mediated hypersensitivity was diagnosed for 34 (79%) of 43 subjects.

CONCLUSIONS

Extremely few nonimmediate manifestations associated with cephalosporin therapy are actually hypersensitivity reactions, whereas most immediate reactions to cephalosporins are IgE-mediated. Cephalosporin skin testing is a useful tool for evaluating such reactions.

Preoperative evaluation of patients with history of allergy to penicillin: comparison of 2 models of practice

OBJECTIVE

To study whether allergy consultation and penicillin allergy skin testing affects the selection of antibacterial prophylaxis perioperatively in surgical patients with history of allergy to penicillin (HOAP).

PATIENTS AND METHODS

From January 1 through June 30, 2004, we compared 2 different models of practice at our institution. At the Preoperative Evaluation Clinic (POEC), all patients with HOAP are evaluated by an allergist and undergo skin testing for allergy to penicillin. At other (non-POEC) preoperative evaluation settings (OPES), patients with HOAP do not undergo allergy consultation and penicillin skin testing before surgery. Of the 4889 patients screened at the POEC during the study period, 412 consecutive patients with HOAP were included in the study. Of the 416 patients screened at OPES, 69 consecutive patients with HOAP were studied. Logistic regression was used to assess whether allergy consultation was associated with the choice of antibiotic for antibacterial prophylaxis perioperatively, after adjusting for age, sex, and type of surgery.

RESULTS

Perioperative cephalosporin use was greater among patients screened at POEC vs those screened at OPES (70% vs 39%, P<.001 unadjusted; P=.04 adjusted for age, sex, and type of surgery). Vancomycin use was lower for patients screened at POEC vs those screened at OPES (10% vs 28%, P<.001 unadjusted; P=.03 adjusted).

CONCLUSION

For patients with HOAP, evaluation at the POEC was associated with increased use of cephalosporin and decreased use of vancomycin.