Evaluation and Updated Classification of Acute Hypersensitivity Reactions to Nonsteroidal Anti-Inflammatory Drugs (NSAIDs): NSAID-Exacerbated or -Induced Food Allergy

BACKGROUND

There are hypersensitivity reactions (HRs) to foods in which nonsteroidal anti-inflammatory drugs (NSAIDs) act as aggravating factors (NSAID-exacerbated food allergy [NEFA]) or cofactors (NSAID-induced food allergy [NIFA]), often misdiagnosed as HRs to NSAIDs. Urticarial/angioedematous and/or anaphylactic reactions to two or more chemically unrelated NSAIDs do not meet current classification criteria. However, they may be considered part of a cross-reactive type of acute HR, which is NSAID-induced urticaria/angioedema with or without respiratory or systemic symptoms of anaphylaxis.

OBJECTIVE

To evaluate patients reporting acute HRs to NSAIDs and classify them according to updated criteria.

METHODS

We prospectively studied 414 patients with suspected HRs to NSAIDs. For all whom met these criteria, NEFA/NIFA was diagnosed: (1) mild reactions to (NEFA) or tolerance of (NIFA) the suspected foods without taking NSAIDs; (2) cutaneous and/or anaphylactic reactions to the combination foods plus NSAIDs; (3) positive allergy tests to the suspected foods; and (4) negative drug challenges (DCs) with the NSAIDs involved.

RESULTS

A total of 252 patients were given the diagnosis of NSAID hypersensitivity (60.9%), 108 of whom had NSAID-induced urticaria/angioedema with or without respiratory or systemic symptoms of anaphylaxis. We excluded NSAID hypersensitivity in 162 patients (39.1%) who tolerated DCs with the suspected NSAIDs, nine of whom received a diagnosis of NEFA, and 66 of NIFA. Pru p 3 was implicated in 67 of those 75 patients who received a diagnosis of NEFA or NIFA.

CONCLUSIONS

NEFA and NIFA account for about 18% of patients reporting HRs to NSAIDs, in which Pru p 3 is the main responsible food allergen. Therefore, patients with cutaneous and/or anaphylactic reactions to NSAIDs should be carefully questioned about all foods ingested within 4 hours before or after NSAID exposure, and targeted food allergy tests should be considered in the diagnostic workup of these patients. If testing is positive, DCs with the suspected NSAIDs should also be considered.

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.

Detection of Serum-Specific IgE by Fluoro-Enzyme Immunoassay for Diagnosing Type I Hypersensitivity Reactions to Penicillins

Diagnosis of type I hypersensitivity reactions (IgE-mediated reactions) to penicillins is based on clinical history, skin tests (STs), and drug provocation tests (DPTs). Among in vitro complementary tests, the fluoro-enzyme immunoassay (FEIA) ImmunoCAP^® (Thermo-Fisher, Waltham, MA, USA) is the most widely used commercial method for detecting drug-specific IgE (sIgE). In this study, we aimed to analyze the utility of ImmunoCAP^® for detecting sIgE to penicillin G (PG) and amoxicillin (AX) in patients with confirmed penicillin allergy. The study includes 139 and 250 patients evaluated in Spain and Italy, respectively. All had experienced type I hypersensitivity reactions to penicillins confirmed by positive STs. Additionally, selective or cross-reactive reactions were confirmed by DPTs in a subgroup of patients for further analysis. Positive ImmunoCAP^® results were 39.6% for PG and/or AX in Spanish subjects and 52.4% in Italian subjects. When only PG or AX sIgE where analyzed, the percentages were 15.1% and 30.4%, respectively, in Spanish patients; and 38.9% and 46% in Italian ones. The analysis of positive STs showed a statistically significant higher percentage of positive STs to PG determinants in Italian patients. False-positive results to PG (16%) were detected in selective AX patients with confirmed PG tolerance. Low and variable sensitivity values observed in a well-defined population with confirmed allergy diagnosis, as well as false-positive results to PG, suggest that ImmunoCAP^® is a diagnostic tool with relevant limitations in the evaluation of subjects with type I hypersensitivity reactions to penicillins.

Next-generation sequencing and genotype association studies reveal the association of HLA-DRB3*02:02 with delayed hypersensitivity to penicillins

BACKGROUND

Nonimmediate (delayed)-allergic reactions to penicillins are common and some of them can be life-threatening. The genetic factors influencing these reactions are unknown/poorly known/poorly understood. We assessed the genetic predictors of a delayed penicillin allergy that cover the HLA loci.

METHODS

Using next-generation sequencing (NGS), we genotyped the MHC region in 24 patients with delayed hypersensitivity compared with 20 patients with documented immediate hypersensitivity to penicillins recruited in Italy. Subsequently, we analyzed in silico Illumina Immunochip genotyping data that covered the HLA loci in 98 Spanish patients with delayed hypersensitivity and 315 with immediate hypersensitivity compared to 1,308 controls.

RESULTS

The two alleles DRB3*02:02:01:02 and DRB3*02:02:01:01 were reported in twenty cases with delayed reactions (83%) and ten cases with immediate reactions (50%), but not in the Allele Frequency Net Database. Bearing at least one of the two alleles increased the risk of delayed reactions compared to immediate reactions, with an OR of 8.88 (95% CI, 3.37-23.32; p < .0001). The haplotype (ACAA) from rs9268835, rs6923504, rs6903608, and rs9268838 genetic variants of the HLA-DRB3 genomic region was significantly associated with an increased risk of delayed hypersensitivity to penicillins (OR, 1.7; 95% CI: 1.06-1.92; p = .001), but not immediate hypersensitivity.

CONCLUSION

We showed that the HLA-DRB3 locus is strongly associated with an increased risk of delayed penicillin hypersensitivity, at least in Southwestern Europe. The determination of HLA-DRB3*02:02 alleles in the risk management of severe delayed hypersensitivity to penicillins should be evaluated further in larger population samples of different origins.

Effectiveness and safety of dupilumab in patients with chronic rhinosinusitis with nasal polyps and associated comorbidities: a multicentric prospective study in real life

BACKGROUND

Biologics are currently one of the main treatment options for a number of diseases. The IgG4 monoclonal antibody dupilumab targets the Interleukin-4 receptor alpha chain, thus preventing the biological effects of the cytokines IL-4 and IL-13, that are essential for the Th2 response. Several controlled trials showed that dupilumab is effective and safe in patients with atopic dermatitis (AD), severe asthma and chronic rhinosinusitis with nasal polyps (CRSwNP), thus resulting in approval by regulatory agencies. Aim of the study was to evaluate the efficacy and safety of dupilumab in adult patients with CRSwNP stratified by common overlapping comorbid conditions.

METHODS

We performed a multicenter, observational, prospective study enrolling adult patients with severe CRSwNP who had started dupilumab treatment in the context of standard care from January 2021 to October 2021. Data were collected from twentynine Italian secondary care centers for allergy and clinical immunology, all of which were part of the Italian Society of Allergy, Asthma and Clinical Immunology (SIAAIC). A number of efficacy parameters were used. Patient data were compared using the Wilcoxon test for paired data. All statistical analyses were performed with SPSS version 20 (IBM, Armonk, NY, USA).

RESULTS

In total, 82 patients with nasal polyposis were identified. A significant improvement was detected for all the applied efficacy parameters, i.e. 22-item Sino-Nasal Outcome Test (SNOT-22) and bilateral endoscopic nasal polyp score (NPS) scores for CRSwNP, Rhinitis Control Scoring System (RCSS) and Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) scores for allergic perennial rhinitis, Forced Expiratory Volume in the 1st second (FEV1) and Asthma Quality of Life Questionnaire (AQLQ) scores for asthma, Eczema Area and Severity Index (EASI) and Dermatology Life Quality Index (DLQI) scores for AD. A non-significant improvement was also obtained in the Urticaria Activity Score over 7 days (UAS7) for chronic spontaneous urticaria. Treatment with dupilumab was well tolerated.

CONCLUSIONS

These data suggest that dupilumab treatment in patients suffering from CRSwNP and associated comorbidities may be suitable. Such outcome, although confirmation by trials is warranted, suggests the possibility to treat different disorders with a single therapy, with favorable effects especially under the cost-effectiveness aspect.

COVID-19 disease in clinical setting: impact on gonadal function, transmission risk, and sperm quality in young males

OBJECTIVES

We want to evaluate the possible presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in semen samples and semen quality, looking for a possible relationship between the infectious disease and fertility.

METHODS

In this prospective study, we enrolled 15 consecutive men (age 18-50 years) with positive oropharyngeal swab to SARS-CoV-2 and classified, according to WHO criteria, in mild to moderate disease. A semen sample was collected to detect SARS-CoV viral RNA by the automated Real-Time PCR ELITe InGenius^® system and the GeneFinder^TM COVID-19 Plus RealAmp Kit assay (ELITechGroup, France). Analysis of semen characteristics was performed according to WHO laboratory manual 5th ed. for the examination and processing of human semen. Blood samples for the dosage of hormonal assay, procalcitonin, interleukin 6, C-reactive protein were obtained.

RESULTS

SARS-CoV-2 RNA has not been detected in semen samples from any of the subjects analysed. Sperm analysis exhibited abnormal seminal values in 14 out of 15 patients (93.3%). Furthermore, no difference was detected regarding sperm quality between mild and moderate SARS-CoV-2 patients. No alteration in the inflammatory indices was observed in the studied population, as well gonadotropins and testosterone levels.

CONCLUSIONS

COVID patients studied exhibits alteration of the seminal fluid both in microscopic and macroscopic characteristics such as hypoposia and increased viscosity, which have not been detected in previous studies. The presence of viral RNA within the seminal fluid was excluded.

Urticaria: The 1-1-1 Criterion for Optimized Risk Atratification in β-Lactam Allergy Delabeling

BACKGROUND

A spurious label of β-lactam allergy compromises antibiotic stewardship. Delabeling protocols based on direct challenges (ie, not preceded by allergy tests) can be applied in low-risk patients.

OBJECTIVE

This study aims at determining the significance of the characteristics of urticaria in the risk stratification for delabeling.

METHODS

The characteristics of urticarial eruptions that had occurred during therapeutic courses with a β-lactam, namely the time interval between the exposure and onset, the dose (first or subsequent) after which urticaria appeared, and the duration of the eruption, were correlated to the results of a systematic allergy workup (skin tests, specific IgE measurements, and challenges). Data from 410 patients enrolled in 3 allergy centers (Rome and Troina, Italy, and Antwerp, Belgium) were analyzed. A multivariable logistic regression was performed, which included appearance within 1 hour after the first dose and regression within 1 day: a model that can be summarized as the "1-1-1" urticaria criterion.

RESULTS

An urticarial eruption that had appeared within 1 hour after the first dose and had regressed within 1 day was more frequently reported in the group with a positive allergy workup, with odds ratios of 17 (95% confidence interval [CI]: 9-31), 11 (95% CI: 6-20), and 48 (95% CI: 14-157), respectively (P < .005). The 1-1-1 criterion displayed a sensitivity and specificity of 85%, and a negative predictive value and a positive predictive value of 80% and 90%, respectively.

CONCLUSION

Patients with urticaria meeting the 1-1-1 criterion should be considered at high risk and referred for an allergy workup with skin testing and specific IgE measurement before challenging.

Practice parameters for diagnosing and managing iodinated contrast media hypersensitivity

Immediate and nonimmediate hypersensitivity reactions to iodinated contrast media (ICM) have been reported to occur in a frequency of about 0.5%-3% of patients receiving nonionic ICM. The diagnosis and management of these patients vary among guidelines published by various national and international scientific societies, with recommendations ranging from avoidance or premedication to drug provocation test. This position paper aims to give recommendations for the management of patients with ICM hypersensitivity reactions and analyze controversies in this area. Skin tests are recommended as the initial step for diagnosing patients with immediate and nonimmediate hypersensitivity reactions; besides, they may also help guide on tolerability of alternatives. Re-exposition or drug provocation test should only be done with skin test-negative ICMs. The decision for performing either re-exposition or drug provocation test needs to be taken based on a risk-benefit analysis. The role of in vitro tests for diagnosis and pretreatment for preventing reactions remains controversial.

β-Lactam Allergy and Cross-Reactivity: A Clinician's Guide to Selecting an Alternative Antibiotic

β-Lactams which include penicillins, cephalosporins, carbapenems, and monobactams are the most common antibiotic classes reported to cause allergic reactions to drugs. This review is mainly about published studies assessing the cross-reactivity among β-lactams in penicillin- or cephalosporin-allergic subjects by carrying out diagnostic tests with alternative β-lactams and, if appropriate, graded challenges. Several studies demonstrated that cross-reactivity connected with the β-lactam ring, causing positive responses to allergy tests with all β-lactams, is infrequent in subjects with an IgE-mediated allergy and anecdotal in those with a T-cell-mediated allergy. Identities or similarities of β-lactam side-chain structures are mainly responsible for cross-reactivity among these antibiotics. For example, in aminopenicillin-allergic subjects, cross-reactivity with aminocephalosporins could possibly be over 30%. On the other hand, in a few prospective studies of penicillin-allergic individuals, less than 1% of cases show a cross-reactivity between penicillins and both aztreonam and carbapenems. Particular patterns of allergy-test positivity observed in some studies that assessed cross-reactivity among β-lactams seem to indicate that prior exposures may be responsible for coexisting sensitivities. Therefore, pre-treatment skin tests with the related β-lactams are suggested before administering them via graded challenges to β-lactam-allergic patients who need alternative β-lactams.

Beta-lactam-induced immediate hypersensitivity reactions: A genome-wide association study of a deeply phenotyped cohort

BACKGROUND

β-lactam antibiotics are associated with a variety of immune-mediated or hypersensitivity reactions, including immediate (type I) reactions mediated by antigen-specific IgE.

OBJECTIVE

We sought to identify genetic predisposing factors for immediate reactions to β-lactam antibiotics.

METHODS

Patients with a clinical history of immediate hypersensitivity reactions to either penicillins or cephalosporins, which were immunologically confirmed, were recruited from allergy clinics. A genome-wide association study was conducted on 662 patients (the discovery cohort) with a diagnosis of immediate hypersensitivity and the main finding was replicated in a cohort of 98 Spanish cases, recruited using the same diagnostic criteria as the discovery cohort.

RESULTS

Genome-wide association study identified rs71542416 within the Class II HLA region as the top hit (P = 2 × 10^-14); this was in linkage disequilibrium with HLA-DRB1∗10:01 (odds ratio, 2.93; P = 5.4 × 10^-7) and HLA-DQA1∗01:05 (odds ratio, 2.93, P = 5.4 × 10^-7). Haplotype analysis identified that HLA-DRB1∗10:01 was a risk factor even without the HLA-DQA1∗01:05 allele. The association with HLA-DRB1∗10:01 was replicated in another cohort, with the meta-analysis of the discovery and replication cohorts showing that HLA-DRB1∗10:01 increased the risk of immediate hypersensitivity at a genome-wide level (odds ratio, 2.96; P = 4.1 × 10^-9). No association with HLA-DRB1∗10:01 was identified in 268 patients with delayed hypersensitivity reactions to β-lactams.

CONCLUSIONS

HLA-DRB1∗10:01 predisposed to immediate hypersensitivity reactions to penicillins. Further work to identify other predisposing HLA and non-HLA loci is required.

SIRM-SIAAIC consensus, an Italian document on management of patients at risk of hypersensitivity reactions to contrast media

Hypersensitivity reactions (HRs) to contrast media (CM) can be distinguished in immune-mediated (including allergic reactions) and non-immune-mediated reactions, even if clinical manifestations could be similar. Such manifestations range from mild skin eruptions to severe anaphylaxis, making it important for radiologists to know how to identify and manage them. A panel of experts from the Società Italiana di Radiologia Medica e Interventistica (SIRM) and the Società Italiana di Allergologia, Asma e Immunologia Clinica (SIAAIC) provided a consensus document on the management of patients who must undergo radiological investigations with CM. Consensus topics included: the risk stratification of patients, the identification of the culprit CM and of a safe alternative by an allergy workup, as well as the use of premedication and the correct procedure to safely perform an elective (i.e., scheduled) or urgent examination. The most important recommendations are: (1) in all patients, a thorough medical history must be taken by the prescribing physician and/or the radiologist to identify at-risk patients; (2) in patients with hypersensitivity reactions to CM, the radiologist must consider an alternative, non-contrast imaging study with a comparable diagnostic value, or prescribe a different investigation with another class of CM; (3) if such options are not feasible, the radiologist must address at-risk patients to a reference centre for an allergy evaluation; (4) if timely referral to an allergist is not viable, it is recommended to use a CM other than the responsible one, taking into account cross-reactivity patterns; in the case of patients with histories of severe reactions, the presence of an anesthesiologist is also recommended and a premedication is suggested.

Tolerability of Cefazolin and Ceftibuten in Patients with IgE-Mediated Aminopenicillin Allergy

BACKGROUND

Side-chain similarities or identities constitute the predominant factor for cross-reactivity between penicillins and cephalosporins, whereas differences in the side-chain structure seem to account for the absence of such cross-reactivity.

OBJECTIVE

We sought to assess the cross-reactivity between penicillins and 2 cephalosporins (ie, cefazolin and ceftibuten) that have side chains different from those of penicillins, as well as to evaluate the possibility of using these cephalosporins in penicillin-allergic subjects.

METHODS

We conducted a prospective study of 131 consecutive subjects who had suffered 170 immediate reactions (mostly anaphylaxis) to penicillins and had positive skin test results to at least 1 penicillin reagent. All patients underwent skin tests with cefazolin and ceftibuten. Patients with negative results were challenged with them.

RESULTS

One participant had positive skin test results to cefazolin and ceftibuten, as well as to all other reagents tested, including aztreonam and carbapenems. All 129 subjects who underwent challenges with cefazolin and ceftibuten tolerated them. One subject refused cephalosporin challenges.

CONCLUSIONS

Subjects with an IgE-mediated hypersensitivity to penicillins could be treated with cephalosporins such as cefazolin and ceftibuten, which are among the cephalosporins that have side-chain determinants different from those of penicillins. Nevertheless, in patients with such hypersensitivity who need these alternative β-lactams, pretreatment skin tests are advisable because of the possibility of coexisting sensitivities or, much less frequently, of a sensitivity to an antigenic determinant of the common β-lactam ring.

A Multicenter Retrospective Study on Hypersensitivity Reactions to Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) in Children: A Report from the European Network on Drug Allergy (ENDA) Group

BACKGROUND

Diagnosis of hypersensitivity (HS) reactions to nonsteroidal anti-inflammatory drugs (NSAIDs) in children is complex. The real prevalence of NSAID HS remains unknown because a drug provocation test (DPT) is not always performed with the culprit NSAID.

OBJECTIVE

To describe and compare the diagnostic workup among different European centers and to find out the real proportion of NSAID HS by performing a DPT with the culprit drug.

METHODS

We retrospectively collected data from children (0-10 years) and adolescents (10-18 years) with a history of NSAID reactions and who underwent a complete allergy workup including DPTs with the culprit in 6 different pediatric centers: Belgrade, Florence, Geneva, Madrid, Porto, and Rome.

RESULTS

A total of 693 children with a history of NSAID reactions were enrolled, and a total of 526 DPTs were performed with the culprit NSAID. The diagnosis of NSAID HS was confirmed in 19.6% (103 of 526) of children by performing a DPT with the culprit drug. The major differences in the allergy workup among the 6 centers concerned the duration of the DPT and the practical use of skin tests for diagnosing NSAID HS. In addition, the use of acetyl salicylic acid to differentiate single reactor or cross-intolerance patients is not common, except in Spain.

CONCLUSION

The value of this study is that although different approaches are used around Europe to diagnose NSAID HS, we found that the percentage of confirmed NSAID HS is less than 20%. This highlights the importance of the DPT in confirming or excluding NSAID HS in the pediatric population.

Cross-Reactivity and Tolerability of Cephalosporins in Patients with IgE-Mediated Hypersensitivity to Penicillins

BACKGROUND

Studies performed since 1990 on samples of at least 30 subjects with a documented IgE-mediated hypersensitivity to penicillins have found a rate of positive responses to allergy tests with cephalosporins ranging from 0% to 27%.

OBJECTIVE

We sought to assess the cross-reactivity with cephalosporins and evaluate the possibility of using cephalosporins in penicillin-allergic subjects.

METHODS

We conducted a prospective study of 252 consecutive subjects who had suffered 319 immediate reactions (mostly anaphylaxis) to penicillins and had positive skin tests to at least 1 penicillin reagent. All patients underwent serum specific IgE assays for cefaclor, as well as skin tests with 3 aminocephalosporins (cephalexin, cefaclor, and cefadroxil), cefamandole, cefuroxime, ceftazidime, ceftriaxone, cefotaxime, and cefepime. Patients with negative results for the last 5 cephalosporins were challenged with cefuroxime axetil and ceftriaxone; those with negative results for aminocephalosporins were also challenged with cefaclor and cefadroxil.

RESULTS

Ninety-nine participants (39.3%) had positive allergy tests for cephalosporins. Specifically, 95 (37.7%) were positive to aminocephalosporins and/or cefamandole, which share similar or identical side chains with penicillins. All 244 subjects who underwent challenges with cefuroxime axetil and ceftriaxone tolerated them. Of the 170 patients who underwent aminocephalosporin challenges, 3 reacted to cefaclor and 4 to cefadroxil.

CONCLUSIONS

Cross-reactivity between penicillins and cephalosporins seems to be mainly related to side chain similarity or identity. Subjects with an IgE-mediated hypersensitivity to penicillins could be treated with cephalosporins such as cefuroxime and ceftriaxone that have side-chain determinants different from those of penicillins and are negative in pretreatment skin testing.

Hypersensitivity Reactions to Non-Steroidal Anti-Inflammatory Drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) are one of the leading causes of hypersensitivity reactions to drugs, and they are classified in two groups: those induced by nonspecific immunological mechanisms (non-allergic or cross-intolerance (CI) reactions), or by specific immunological mechanisms (allergic or selective reactions (SR)). The pathogenesis of CI is associated with their pharmacological activity (COX-1 inhibition), with symptoms due to an imbalance in the arachidonic acid pathway, independently of their chemical structure. SRs are mediated by specific IgE- or by a T-cell response and can be induced by a single NSAID or a class of chemically related NSAIDs, with patients tolerating chemically unrelated compounds. NSAIDs hypersensitivity reactions have been classified in five main groups: i) NSAIDs-exacerbated respiratory disease (NERD); ii) NSAIDs-exacerbated cutaneous disease (NECD); iii) NSAIDs-induced urticaria/angioedema (NIUA); iv) Single NSAID-induced urticaria/angioedema or anaphylaxis (SNIUAA); v) Single NSAID-induced delayed reactions (SNIDRs). Although this classification described above is widely accepted by most authors some phenotypes such as blended reactions do not fit. Therefore more research is needed in this topic.

Genetic Predictors of Drug Hypersensitivity

Our knowledge of genetic predisposing factors of drug hypersensitivity reactions (DHRs) is still scarce. The analysis of the genetic basis of these reactions may contribute to dissect the underlying mechanisms. We will outline current knowledge of the genetic predictors of most common DHRs, including reactions to betalactam antibiotics (BLs), nonsteroidal anti-inflammatory drugs (NSAIDs) and biological agents. The predictors of DHRs to BLs are mostly linked to IgE-class switching, IgE pathway and atopy (IL4R, NOD2, LGALS3) in replicated candidate gene studies, and to antigen presentation (HLA-DRA) in the single replicated GWAS performed so far. The HLA-DRA variants are predictors of allergy to penicillins, but not to cephalosporins and they influence also the sensitization against prevalent allergens. The predictors of DHRs against NSAIDs are mostly linked to metabolism of eicosanoids (ALOX5, ALOX5AP, TBXAS1, PTGDR, CYSLTR1). Single nucleotide polymorphisms (SNPs) in genes involved in histamine biosynthesis and antigen presentation, HLA, could also have a role in DHRs against NSAIDs. The intriguing association of DHRs to NSAIDs with atopy should deserve further attention. Predictors of DHRs against asparaginase and other biological agents relate to antigen presentation (HLA-DRB1 and HLA-A alleles, respectively). The potential relationship of genetic predictors of DHRs with pathomechanisms also involved in environmental exposure and atopy highlights the need to perform GWAS in contrasted populations, taking into account world-wide variations of allele frequencies and contrasted situations of environmental exposure.

Non-immediate Cutaneous Reactions to Beta-Lactams: Approach to Diagnosis

Non-immediate cutaneous reactions (i.e., occurring at least 1 h after the initial drug administration), particularly maculopapular exanthemas and urticarial eruptions, are common during beta-lactam treatments. A T cell-mediated pathogenic mechanism has been demonstrated in some cutaneous reactions, such as maculopapular exanthema, fixed drug eruption, acute generalized exanthematous pustulosis, and drug-induced hypersensitivity syndrome. In the diagnostic work-up, patch testing is useful, together with delayed-reading intradermal testing. Patch tests are a simple and safe diagnostic tool, which in the case of severe reactions should be used as the first line of investigation. However, patch tests are less sensitive than intradermal tests, which are preferable in subjects with mild reactions. Lymphocyte transformation or activation tests and enzyme-linked immunosorbent spot assays can be used as complementary tests. In selected cases of mild or moderate reactions, displaying negative results in the aforesaid allergy tests, a graded challenge with the implicated beta-lactam can be performed.

Diagnosing β-Lactam Hypersensitivity

Hypersensitivity reactions to β-lactam antibiotics are commonly reported. They can be classified as immediate or non-immediate according to the time interval between the last drug administration and their onset. Immediate reactions occur within one hour after the last drug administration and are manifested clinically by urticaria and/or angioedema, rhinitis, bronchospasm, and anaphylactic shock; they may be mediated by specific IgEantibodies. Non-immediate reactions occur more than one hour after the last drug administration. The most common manifestations are maculopapular exanthemas; specific T lymphocytes may be involved in this type of manifestation. In the diagnostic evaluation of hypersensitivity reactions to β -lactam antibiotics, the patient's history is fundamental. The allergy examination is based on in vitro and in vivo tests selected on the basis of the clinical features and the type of reaction, immediate or non-immediate. Immediate reactions can be assessed in vitro by serum specific IgE assays and basophil activation tests and in vivo by immediate-reading skin tests and, in selected cases, drug provocation tests (DPTs). Non-immediate reactions can be evaluated mainly by delayed-reading skin tests, patch tests, and DPTs.

Cross-Reactivity among Beta-Lactams

Penicillins and cephalosporins are the major classes of beta-lactam (BL) antibiotics in use today and one of the most frequent causes of hypersensitivity reactions to drugs. Monobactams, carbapenems, oxacephems, and beta-lactamase inhibitors constitute the four minor classes of BLs. This review takes into account mainly the prospective studies which evaluated cross-reactivity among BLs in subjects with a well-demonstrated hypersensitivity to a certain class of BLs by performing allergy tests with alternative BLs and, in case of negative results, administering them. In subjects with either IgE-mediated or T-cell-mediated hypersensitivity, cross-reactivity among BLs, particularly among penicillins and among cephalosporins, as well as between penicillins and cephalosporins, seems to be mainly related to structural similarities among their side-chain determinants. Specifically, in penicillin-allergic subjects, cross-reactivity between penicillins and cephalosporins may exceed 30% when they are administered cephalosporins with identical side chains to those of responsible penicillins. In these subjects, a few prospective studies have demonstrated a rate of cross-reactivity between penicillins and both carbapenems and aztreonam lower than 1%. With regard to subjects with an IgE-mediated hypersensitivity to cephalosporins, in a single study, about 25% of the 98 subjects with such hypersensitivity had positive results to penicillins, 3% to aztreonam, 2% to imipenem/cilastatin, and 1% to meropenem. The cross-reactivity related to the selective recognition of the BL ring by IgE or T lymphocytes, which entails positive responses to all BLs tested, appears to be exceptional. Some studies concerning cross-reactivity among BLs have found patterns of allergy-test positivity which cannot be explained by either the common BL ring or by similar or identical side chains, thus indicating the possibility of coexisting sensitivities to different BLs because of prior exposures to them.

Non-immediate hypersensitivity reactions to beta-lactam antibiotics in children - our 10-year experience in allergy work-up

BACKGROUND

Non-immediate reactions to beta-lactam antibiotics (BL) occur more than one hour after drug administration, and the most common manifestations are maculopapular exanthemas and delayed-appearing urticaria and/or angioedema. Infections can lead to skin eruptions and mimic drug hypersensitivity reactions (DHR), if a drug is taken at the same time. The most of children are labeled as 'drug allergic' after considering only the clinical history.

OBJECTIVE

To diagnose/detect a hypersensitivity or an infection which mimic DHR in children with non-immediate reactions to BL METHODS: A prospective survey was conducted in a group of 1026 children with histories of non-immediate reactions to BL by performing patch tests, skin tests, and in case of negative results, drug provocation tests (DPTs). In 300 children, a study was performed to detect infections by viruses or Mycoplasma pneumoniae.

RESULTS

Urticaria and maculopapular exanthemas were the most reported non-immediate reactions. Only 76 (7.4%) of 1026 children had confirmed non-immediate hypersensitivity reactions to BL. Fifty-seven children had positive delayed-reading intradermal tests (18 of these with a positive patch test). Nineteen children had positive DPT. Sixty-six of 300 children had positive tests for viruses or Mycoplasma pneumoniae and 2 of them had a positive allergy work-up.

CONCLUSIONS

A diagnostic work-up should be performed in all children with non-immediate reactions to BL, to remove a false label of hypersensitivity. Even though only 57 (5.5%) of 1026 children displayed positive responses to delayed-reading intradermal tests to BL, such tests appear to be useful in order to reduce the risk for positive DPTs.

Cross-reactivity and tolerability of aztreonam and cephalosporins in subjects with a T cell-mediated hypersensitivity to penicillins

BACKGROUND

The few studies performed in adults with T cell-mediated hypersensitivity to penicillins have found a rate of cross-reactivity with cephalosporins ranging from 2.8% to 31.2% and an absence of cross-reactivity with aztreonam.

OBJECTIVE

We sought to evaluate the possibility of using cephalosporins and aztreonam in subjects with documented delayed hypersensitivity to penicillins who especially require them.

METHODS

We conducted a prospective study of 214 consecutive subjects who had 307 nonimmediate reactions to penicillins (almost exclusively aminopenicillins) and had positive patch test and/or delayed-reading skin test responses to at least 1 penicillin reagent. To assess cross-reactivity with cephalosporins and aztreonam and the tolerability of such alternative β-lactams, all subjects underwent skin tests with cephalexin, cefaclor, cefadroxil, cefuroxime, ceftriaxone, and aztreonam. Subjects with negative responses were challenged with the alternative β-lactams concerned.

RESULTS

All subjects had negative skin test results to cefuroxime, ceftriaxone, and aztreonam and tolerated challenges. Forty (18.7%) of the 214 subjects had positive skin test responses to at least 1 aminocephalosporin. Of the 174 subjects with negative responses, 170 underwent challenges; 1 reacted to cefaclor.

CONCLUSIONS

These data demonstrate a rate of cross-reactivity between aminopenicillins and aminocephalosporins (ie, cephalexin, cefaclor, and cefadroxil) of around 20%, as well as the absence of cross-reactivity between penicillins and cefuroxime, ceftriaxone, and aztreonam in all subjects with T cell-mediated hypersensitivity to penicillins, almost exclusively aminopenicillins. Therefore these subjects could be treated with cefuroxime, ceftriaxone, and aztreonam. In those who especially require cephalosporin or aztreonam treatment, however, we recommend pretreatment skin tests because negative responses indicate tolerability.

Quality-of-life issues in survivors to anaphylactic reactions to drugs

The aim of this cross-sectional observational study was to explore quality of life and well-being in patients with drug-induced anaphylaxis. Two validated tools were used: the Drug Hypersensitivity Quality-of-Life Questionnaire (DrHy-Q) and the Psychological General Well-Being Index (PGWBI). Sixty-five patients (13 males) underwent data analysis. The mean DrHy-Q score was 62.82 ± 12.1. Mean PGWBI score was 64.03 ± 17.66. DrHy-Q score was significantly correlated with PGWBI total score (r = -0.314; P = 0.011) and with the following domains: Anxiety (r = -0.260; P = 0.036), Depressed mood (r = -0.406; P = 0.001), Positive well-being (r = -0.251; P = 0.004), and General Health (r = -0.352; P = 0.004). Compared with the Italian reference population, patients had a significantly reduced PGWBI total and domain score. Our results highlight for the first time how impaired HRQoL and distress commonly feature in survivors to anaphylactic reactions to drug.

High serum β-lactams specific/total IgE ratio is associated with immediate reactions to β-lactams antibiotics

Total serum IgE result from the combination of specific and non-specific pools. High specific/total IgE ratio may reflect high level of allergen-specific IgE on mast cells. No data regarding its applications to drug allergies is available. One hundred seventy-one patients with a history of immediate reactions to β-lactams, confirmed by positive skin testing, and 122 control subjects tolerant to β-lactams, were studied. CAP System was used for the detection of serum total and specific IgE antibodies. The specific/total IgE ratio was tested for diagnostic accuracy compared with conventional criteria. We finally performed a simulation study to expand our investigation of the performance of the specific/total IgE ratio index in a scenario in which the new CAP detection threshold is lowered further. Specific/total IgE ratio values ≥0.002 were observed more frequently in reactive than in controls. Seventy-four of 80 subjects with values ≥0.002 were allergic to β-lactams, yielding a positive predictive value of 92.5%. The application of specific/total IgE ratio significantly improves the positive likelihood ratio and the overall diagnostic performance. In addition, we showed the capability of this new criterion to identify true reactive patients even among subjects with high levels of total IgE (>200 kU/L). Significant increase in both receiver operator characteristic (ROC) curve and sensitivity were observed in imputed case of the simulation study. The β-lactams-specific/total IgE ratio may be an additional index compared to the common criterion of positivity to a single hapten in the allergological work-up of patients with β-lactams immediate adverse reactions.

A non-synonymous polymorphism in galectin-3 lectin domain is associated with allergic reactions to beta-lactam antibiotics

Genetic predictors of beta-lactam (BL) allergy are mostly related to Immunoglobulin E (IgE) synthesis and atopy. Despite this context, little attention has been devoted to genes of IgE/FcɛRI pathway, such as galectin-3, a β-galactoside-binding lectin, which binds to IgE. We evaluated the association of LGALS3 polymorphisms with BL allergy in 395 Spanish and 198 Italian cases, compared with 310- and 339-matched controls, respectively. The rs11125 predicted BL allergy with an odds ratio of 4.0 in Spanish population (P<0.0001). This association was replicated with an odds ratio of 5.1 in Italian population (P<0.0001); rs11125 predicted also increased serum level of total IgE in Spanish controls. These data are consistent with the predicted deleterious influence of Gln>His substitution produced by rs11125 on galactose-binding activity of galectin-3. In conclusion, LGALS3 is the strongest genetic predictor of BL allergy reported so far. This association reflects the influence of genes of IgE/FcɛRI pathway in this pathology.

Tolerability of aztreonam and carbapenems in patients with IgE-mediated hypersensitivity to penicillins

BACKGROUND

Studies performed on samples larger than 100 subjects with a documented IgE-mediated hypersensitivity to penicillins have demonstrated a cross-reactivity rate of approximately 1% between penicillins and both imipenem and meropenem, whereas a single study found a cross-reactivity rate of 6.2% with aztreonam in 16 such subjects.

OBJECTIVE

To assess the cross-reactivity and tolerability of aztreonam and 3 carbapenems (imipenem-cilastatin, meropenem, and ertapenem) in patients with documented IgE-mediated hypersensitivity to penicillins.

METHODS

A total of 212 consecutive subjects with immediate reactions to penicillins and positive results on skin tests to at least 1 penicillin reagent underwent skin tests with aztreonam and carbapenems; subjects with negative results were challenged with escalating doses of aztreonam and carbapenems.

RESULTS

All subjects displayed negative skin test results to both aztreonam and carbapenems; 211 accepted challenges and tolerated them. Challenges were not followed by full therapeutic courses.

CONCLUSIONS

These data indicate the tolerability of both aztreonam and carbapenems in penicillin-allergic subjects. In those who especially require these alternative β-lactams, however, we recommend pretreatment skin tests, both because rare cases of cross-reactivity have been reported and because negative results indicate tolerability.

Natural evolution of skin-test sensitivity in patients with IgE-mediated hypersensitivity to cephalosporins

There are studies demonstrating that skin-test sensitivity to penicillins can decrease over time and that allergic patients may lose sensitivity if the responsible compounds are avoided. With regard to subjects with IgE-mediated hypersensitivity to cephalosporins, however, such studies are lacking. We evaluated prospectively in a 5-year follow-up 72 cephalosporin-allergic patients. After the first evaluation, patients were classified into two groups according to their patterns of allergologic-test positivity: to both penicillins and cephalosporins (group A), or only to cephalosporins (group B). Skin tests and serum-specific IgE assays were repeated 1 year later and, in case of persistent positivity, 3 and 5 years after the first allergologic examination. Seven (43.7%) of the 16 subjects of group A and 38 (67.8%) of the 56 patients of group B became negative; one was lost to follow-up. Patients of group B became negative sooner and more frequently than group A subjects.

Absence of cross-reactivity to carbapenems in patients with delayed hypersensitivity to penicillins

Studies performed on subjects with IgE-mediated hypersensitivity to penicillins have demonstrated a 1% rate of cross-reactivity between penicillins and both imipenem and meropenem, while a single study found a 5.5% rate of cross-reactivity with imipenem/cilastatin in subjects with T-cell-mediated hypersensitivity to β-lactams, mostly penicillins. We studied 204 consecutive subjects with a well-demonstrated T-cell-mediated hypersensitivity to assess the cross-reactivity with carbapenems and the tolerability of such alternative β-lactams. All 204 subjects underwent skin tests with imipenem/cilastatin and meropenem; 130 of them were skin-tested also with ertapenem. Subjects with negative test results were challenged with these carbapenems. All subjects displayed negative skin tests to carbapenems and tolerated challenges. These data demonstrate the absence of clinically significant T-cell-mediated cross-reactivity between penicillins and carbapenems. Negative delayed-reading skin testing with carbapenems in individuals with documented T-cell-mediated hypersensitivity to penicillins correlates well with subsequent clinical tolerance of therapeutic doses of carbapenems.

Allergy to betalactams and nucleotide-binding oligomerization domain (NOD) gene polymorphisms

BACKGROUND

Polymorphisms of interleukin genes related to IgE production and inflammation are predictors of hypersensitivity to betalactam, but nothing is known on the influence of NOD genes, despite their association with inflammation and atopy.

OBJECTIVE

To evaluate the association of NOD2 and NOD1 polymorphisms with betalactam allergy.

METHOD

We genotyped 3 polymorphisms of NOD2 and 1 of NOD1 in 368 Italian and 387 Spanish patients, compared with 368 and 326 controls, respectively.

RESULTS

CT/TT genotypes of rs2066845 of NOD2 predicted a lower risk in Italy (P = 0.003), while WT/insC genotype of rs5743293 (also in leucine-rich repeat domain) predicted a higher risk in Spain (P = 0.007). G allele of rs2066845 was associated with a higher level of IgE in the Italian population.

CONCLUSION

The mirrored influence of these NOD2 polymorphisms on betalactam allergy in two populations suggests a link with pathways of inflammation and/or atopy through mechanisms, which need to be clarified.

Lipid transfer proteins: the most frequent sensitizer in Italian subjects with food-dependent exercise-induced anaphylaxis

BACKGROUND

Specific food-dependent exercise-induced anaphylaxis (S-FDEIAn) is a distinct form of food allergy in which symptoms are elicited by exercise performed after ingesting food to which the patient has become sensitised. Non-specific FDEIAn (NS-FDEIAn) is a syndrome provoked by exercise performed after ingesting any food.

OBJECTIVE

We sought to identify the culprit allergenic molecules in patients with FDEIAn, combining 'classic' allergy testing with an allergenic molecule-based microarray approach for IgE detection.

METHODS

All subjects were evaluated who reported at least one episode of anaphylaxis in association with physical exercise performed within 4 h after a meal. We performed skin prick tests (SPT) with commercial food extracts, prick plus prick tests (P + P) with fresh foods (P + P), and serum specific IgE assays by means of both the ImmunoCAP (CAP) and the ISAC 89 microarray system (ISAC).

RESULTS

Among our 82 FDEIAn patients, the most frequent suspected foods were tomato, cereals, and peanut. SPT, P + P, and CAP displayed different degrees of sensitivity. Each test disclosed some positivities not discovered by others. Seventy-nine subjects were positive to at least one food (49 to more than 20), whereas three were negative. All suspected foods were positive to at least one of SPT, P + P, and CAP. When tested using the ISAC, 64 (78%) subjects were positive to Pru p 3 [peach lipid transfer protein (LTP)], 13 were positive to other food allergen molecules, and five displayed negative results to all food allergenic molecules. Overall, 79 patients probably had S-FDEIAn and the other 3 NS-FDEIAn.

CONCLUSIONS

Multiple food hypersensitivity represents a clinical hallmark of a large percentage of FDEIAn patients. The very high prevalence of IgE to the LTP suggests a role of this allergen group in causing S-FDEIAn.

Diagnosing multiple drug hypersensitivity in children

BACKGROUND

Multiple drug hypersensitivity (MDH) has been defined as a hypersensitivity to two or more chemically different drugs. Two types of MDH have been reported: the first one, which develops to different drugs administered simultaneously and the second type, in which sensitizations develop sequentially. In children, studies which diagnose MDH on the basis of positive allergologic tests to 2 or more chemically different drugs are lacking.

METHODS

We conducted a prospective study evaluating children with histories of MDH by skin tests, patch tests, serum-specific IgE assays, and drug provocation tests.

RESULTS

A MDH was diagnosed in 7 (2.5%) of the 279 children evaluated who completed the study. The responsible drugs were β-lactams (penicillins and cephalosporins) in 5 episodes, ibuprofen and anticonvulsants in 3, and erythromycin, fentanyl, methylprednisolone, and cotrimoxazole in 1. Sensitivity to 2 chemically different drugs was diagnosed in 6 children and to 3 drugs in 1 child. Two of the 7 children presented the first type of MDH, whereas 5 displayed the second one.

CONCLUSIONS

MDH can occur in children, even to drugs other than antibiotics. It is crucial to evaluate children with histories of MDH using both in vivo and in vitro allergologic tests, including challenges. In fact, such approach allows the physician to confirm the diagnosis of MDH in a small percentage of children with histories of MDH, as well as to rule it out in the great majority of them.

IgE-mediated hypersensitivity to cephalosporins: cross-reactivity and tolerability of penicillins, monobactams, and carbapenems

BACKGROUND

There have been few studies regarding the cross-reactivity and tolerability of penicillins, aztreonam, and carbapenems in large samples of subjects with cephalosporin allergy.

OBJECTIVE

We sought to evaluate the possibility of using penicillins, monobactams, and carbapenems in subjects with cephalosporin allergy who especially require them.

METHODS

We conducted a prospective study of 98 consecutive subjects who had 106 immediate reactions (mostly anaphylactic shock) to cephalosporins and had positive skin test results for these drugs. To assess the cross-reactivity with penicillins, monobactams, and carbapenems and the tolerability of such alternative β-lactams, all subjects underwent skin tests and serum-specific IgE assays with penicillin reagents, as well as skin tests with aztreonam, imipenem/cilastatin, and meropenem. Subjects with negative test results were challenged with meropenem, imipenem/cilastatin, aztreonam, and amoxicillin.

RESULTS

Positive allergologic test results to penicillins were displayed by 25 (25.5%) subjects, including 1 with positive results to all reagents tested and another with a positive result to aztreonam. Another subject had positive results to both ceftazidime and aztreonam. A reaction to cephalosporins with side-chain structures similar or identical to those of penicillins was a significant predictor of cross-reactivity because of an increased 3-fold risk of positive results on allergologic tests with penicillin determinants. Challenges with alternative β-lactams were tolerated, with the exception of 1 urticarial reaction to imipenem/cilastatin.

CONCLUSIONS

About 25% of subjects with cephalosporin allergy had positive results to penicillins, 3.1% to aztreonam, 2% to imipenem/cilastatin, and 1% to meropenem. In those who especially require alternative β-lactams, pretreatment skin tests are advisable because negative results indicate tolerability of the β-lactam concerned.

The very limited usefulness of skin testing with penicilloyl-polylysine and the minor determinant mixture in evaluating nonimmediate reactions to penicillins

BACKGROUND

The contribution of skin testing with penicilloyl-polylysine (PPL) and the minor determinant mixture (MDM) to the diagnosis of hypersensitivity reactions to penicillins differs greatly according to the type of reaction: immediate (occurring within 1 h after the last drug administration) or nonimmediate (occurring more than 1 h after the last drug administration).

OBJECTIVE

To assess the contribution of skin testing with PPL and MDM to the diagnosis of nonimmediate reactions to penicillins.

METHODS

We evaluated 162 adults who had had 232 nonimmediate reactions to penicillins, mostly aminopenicillins, and presented positive skin and/or patch tests to one or more penicillin reagents: PPL, MDM, benzylpenicillin, ampicillin, and amoxicillin, as well as any responsible penicillins.

RESULTS

A total of 157 subjects (96.9%) displayed patch-test and/or delayed-reading intradermal-test positivity to penicillin reagents, which indicates a cell-mediated hypersensitivity; six of them also presented immediate-reading skin-test positivities. All 157 patients with a cell-mediated hypersensitivity were positive to the responsible penicillins (parent drugs); 16 of them also displayed delayed-reading intradermal-test positivity to MDM. Five (3.1%) of the 162 patients displayed only immediate-reading skin-test positivity (four to PPL and one to amoxicillin). Overall, 158 subjects (97.5%) presented positive responses to the responsible penicillins, while only 9 (5.5%) and 17 (10.5%) were positive to PPL and MDM, respectively.

CONCLUSIONS

The contribution of skin testing with PPL and MDM in diagnosing nonimmediate hypersensitivity reactions to penicillins, especially cell-mediated ones, is very limited. This finding could be useful at a time when PPL and MDM are not available in all countries.

Determining the negative predictive value of provocation tests with beta-lactams

BACKGROUND

The beta-lactam allergic work-up is mostly standardized. However, the negative predictive value of drug provocation tests is not yet well established.

METHOD

A historical-prospective multicentre cohort study was conducted in four centres (one in France, one in Portugal, two in Italy) to assess the negative predictive value of provocation tests with beta-lactams in patients initially tested for a suspicion of drug allergy/hypersensitivity. Patients were contacted at least 6 months after the work-up, between 2003 and 2007. A new allergic work-up was proposed to reacting patients.

RESULTS

Among the 457 patients included, 365 (79.9%) were followed up (159 [79.1%] from France, 153 [82.7%] from Italy and 53 [74.6%] from Portugal). Only 118 (25.8%) were re-exposed to the negatively tested beta-lactam. Nine (7.6%) reported a non-immediate (occurring more than 1 h after drug administration) reaction: five urticaria, three exanthema and one undefined cutaneous reaction. None were severe. Only four accepted a re-challenge, negative in two cases and positive in the two others. The negative predictive value was 94.1% (89.8-98.3) (111 out of 118 patients).

CONCLUSION

Although the negative predictive value of drug provocation tests may not be 100%, none of the false negative patients experienced a life-threatening reaction. This should reassure doctors who might hesitate to prescribe beta-lactams, even in patients with negative allergic work-ups.

Cross-reactive reactions to nonsteroidal anti-inflammatory drugs

INTRODUCTION

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most frequent causes of adverse drug reactions, particularly in patients with asthma and chronic idiophatic urticaria. Many subjects report cutaneous and/or respiratory symptoms and, less frequently, anaphylactic shock after the administration of one (single-reactors) or different (cross-reactors) drugs of this class.

DIAGNOSIS

There are no reliable cutaneous or in vitro tests which allow NSAID hypersensitivity to be identified in patients with cross-reactive reactions; therefore, the challenge test is considered the "gold standard" for establishing or excluding a diagnosis of NSAID hypersensitivity in such patients.

MANAGEMENT

Culprit drugs should always be avoided by patients with suspected or well-established multiple hypersensitivity to NSAIDs. The therapeutic options range from the administration of alternative drugs - such as weak cyclooxygenase (COX)-1 inhibitors and/or preferential or highly selective COX-2 inhibitors to desensitization to the culprit ones.

CONCLUSION

In patients with different NSAID-induced reactions, the challenge test with both culprit drugs and alternative ones is the only method to establish a reliable diagnosis of NSAID hypersensitivity and to find some alternative therapeutic options, respectively. In specific cases, drug desensitization can also be performed. However, further studies are required to improve management of such patients.

Provocation tests in diagnosing drug hypersensitivity

A position paper by the European Network for Drug Allergy (ENDA), the European Academy of Allergology and Clinical Immunology (EAACI) interest group on drug hypersensitivity, defines drug provocation tests (DPTs) as "the controlled administration of a drug in order to diagnose drug hypersensitivity reactions". The DPT is widely considered to be the "gold standard" to establish or exclude the diagnosis of hypersensitivity to a certain substance, as it not only reproduces hypersensitivity symptoms, but also any other adverse clinical manifestation, irrespective of the mechanism. The DPT can be harmful and thus should only be considered after balancing the risk-benefit ratio in the individual patient. The ENDA position paper specifies two main indications for DPTs with the suspected compounds: 1. to exclude hypersensitivity in non-suggestive histories of drug hypersensitivity and in patients with non-specific symptoms, such as vagal symptoms under local anesthesia; 2. to establish a firm diagnosis in suggestive histories of drug hypersensitivity with negative, non-conclusive, or non-available allergologic tests. A positive DPT result optimizes allergen avoidance, while a negative one allows a false label of drug hypersensitivity to be removed. For these reasons, DPTs are often carried out to exclude a diagnosis of hypersensitivity to beta-lactams when other allergologic tests are negative. DPTs are also performed when the sensitivity of allergologic tests for evaluating allergic reactions to certain drugs, such as non-beta-lactam antibiotics, heparins, and glucocorticoids, is limited. On the other hand, DPTs are also performed to diagnose hypersensitivity reactions to nonsteroidal anti-inflammatory drugs in subjects with the cross-reactive pattern, because both skin tests and in vitro diagnostic methods are ineffective in such patients.

Benzylpenicillin skin testing is still important in diagnosing immediate hypersensitivity reactions to penicillins

BACKGROUND

The fact that both Hollister-Stier and Allergopharma ceased the production of penicilloyl-polylysine (PPL) and minor determinant mixture (MDM) in 2004 is severely hampering the diagnosis of beta-lactam hypersensitivity and may produce negative consequences.

OBJECTIVE

To assess the contribution of skin testing with benzylpenicillin to the diagnosis of immunoglobulin E-mediated hypersensitivity to penicillins, in order to determine how much such testing could compensate for PPL and MDM unavailability.

METHODS

We selected patients with histories of immediate reactions to penicillins and positive results to skin tests for one or more penicillin reagents (PPL, MDM, or benzylpenicillin), one or more semi-synthetic penicillins (ampicillin, amoxicillin, or piperacillin), or both.

RESULTS

A total of 300 patients were selected, 105 in the French center and 195 in the Italian centers. Amoxicillin and ampicillin were the main responsible drugs. The most common clinical manifestation was anaphylaxis. The reagents most frequently positive to skin tests were amoxicillin (188, 62.7%), ampicillin (151, 50.3%), and benzylpenicillin (111, 37.0%). Among the 300 subjects, 113 (37.7%) were positive only to semi-synthetic penicillins, 109 (36.3%) to both semi-synthetic penicillins and the classic penicillin reagents, and 78 (26.0%) only to the latter. In the last group, 64 (21.3% of the 300 subjects) were positive only to PPL and/or MDM and 14 (4.7%) to benzylpenicillin, of whom 8 (2.7%) were positive only to the latter.

CONCLUSIONS

Skin testing with benzylpenicillin can partially compensate for PPL and MDM unavailability. Moreover, it can slightly increase the allergologic workup's sensitivity and therefore reduce the number of potentially dangerous challenges.