Record of strep throat infections in Italy: what is needed to know about penicillin allergy? The point of view from the Italian Society of Pediatric Allergy and Immunology (SIAIP).

Notifications of invasive group A streptococcal (iGAS) infections have significantly increased in many European Countries compared to the previous season. In Italy, there has been an increase in streptococcal pharyngitis and scarlet fever cases since January 2023, which sparked concerns about a GAS epidemic in the pediatric population. This rise may be ascribed to the GAS infection season that began earlier than usual (off-season outbreak) and the increase in the spread of respiratory viruses and viral coinfections that raised the risk of iGAS disease. Moreover, this phenomenon was also facilitated by increased travel after reduced GAS circulation during the COVID-19 pandemic.The increase in cases of GAS disease has raised some critical issues regarding the potential reactions to administering amoxicillin, the first-line antibiotic therapy, many of which have been erroneously labeled as "allergy."For these reasons, the Italian Society of Pediatric Allergy and Immunology (SIAIP) intends to provide simple clinical indications to help pediatricians manage GAS pharyngitis, discerning the allergic from non-allergic drug hypersensitivity.

IFN-γ ELISpot-enabled machine learning for culprit drug identification in nonimmediate drug hypersensitivity.

BACKGROUND: Diagnosing drug-induced allergy, especially nonimmediate phenotypes, is challenging. Incorrect classifications have unwanted consequences. OBJECTIVE: We sought to evaluate the diagnostic utility of IFN-γ ELISpot and clinical parameters in predicting drug-induced nonimmediate hypersensitivity using machine learning. METHODS: The study recruited 393 patients. A positive patch test or drug provocation test (DPT) was used to define positive drug hypersensitivity. Various clinical factors were considered in developing random forest (RF) and logistic regression (LR) models. Performances were compared against the IFN-γ ELISpot-only model. RESULTS: Among the 102 patients who had 164 DPTs, most patients had severe cutaneous adverse reactions (35/102, 34.3%) and maculopapular exanthems (33/102, 32.4%). Common suspected drugs were antituberculosis drugs (46/164, 28.1%) and ß-lactams (42/164, 25.6%). Mean (SD) age of patients with DPT was 52.7 (20.8) years. IFN-γ ELISpot, fixed drug eruption, Naranjo categories, and nonsteroidal anti-inflammatory drugs were the most important features in all developed models. The RF and LR models had higher discriminating abilities. An IFN-γ ELISpot cutoff value of 16.0 spot-forming cells/106 PBMCs achieved 94.8% specificity and 57.1% sensitivity. Depending on clinical needs, optimal cutoff values for RF and LR models can be chosen to achieve either high specificity (0.41 for 96.1% specificity and 0.52 for 97.4% specificity, respectively) or high sensitivity (0.26 for 78.6% sensitivity and 0.37 for 71.4% sensitivity, respectively). CONCLUSIONS: IFN-γ ELISpot assay was valuable in identifying culprit drugs, whether used individually or incorporated in a prediction model. Performances of RF and LR models were comparable. Additional test datasets with DPT would be helpful to validate the model further.

Deconstructing adverse reactions to Amoxicillin-Clavulanic Acid: the importance of time of onset.

BACKGROUND: Amoxicillin-clavulanic acid (AX-CL) is the most consumed betalactam antibiotic worldwide. We aimed to establish the different phenotypes of betalactam allergy in those referring a reaction with AX-CL and to investigate the differences between immediate and non-immediate onset. METHODS: Cross-sectional retrospective study performed at Hospital Clínico San Carlos (HCSC) and Hospital Regional Universitario de Málaga (HRUM) in Spain. Patients reporting reactions with AX-CL who completed the allergy workup between 2017 and 2019 were included. Data of reported reaction and allergy workup were collected. Reactions were classified as immediate and non-immediate with 1hour cut-off point. RESULTS: We included 372 patients (HCSC 208, HRUM 164). There were 90 (24.2%) immediate, 252 (67.7%) non-immediate reactions, and 30 (8.1%) with unknown latency. Allergy to betalactams was ruled-out in 266 (71.5%) and confirmed in 106 patients (28.5%). The final main diagnosis in the overall population were allergy to aminopenicillins (7.3%), to CL (7%), to penicillin (6.5%) and to betalactams (5.9%). Allergy was confirmed in 77.2% and 14.3% of immediate and non-immediate reactions respectively, with a relative risk of 5.06 (95%CI 3.64-7.02) of an allergy diagnosis in those reporting immediate reactions. Only 2/54 patients with late-positive intradermal test (IDT) to CL were diagnosed of CL allergy. CONCLUSION: Allergy diagnosis was confirmed in a minority of the whole study population, but 5 times more frequently in those reporting immediate reactions, making this classification useful in risk stratification. Late-positive IDT for CL has no diagnostic value and its late reading could be retrieved from the diagnosis work-up.

Non-immediate hypersensitivity reactions to iomeprol: Diagnostic value of skin tests and cross-reactivity with other iodinated contrast media.

BACKGROUND: Iodinated contrast media produce non-immediate hypersensitivity reactions (NIHR). The goal of this prospective study was to determine the utility of skin tests and the subsequent tolerance to negative skin-tested iodinated contrasts in patients with NIHR caused by iomeprol. METHODS: Prick and intradermal tests with iomeprol, iopamidol, iopromide, and iobitridol were performed in all patients. IV challenge with the causative contrast (iomeprol in 90%) was made if skin tests were negative. In case of a positive skin test with the causal contrast, or a positive challenge test with it, IV challenge test with an alternative, negative skin-tested contrast was performed in all patients. RESULTS: Skin tests were positive in 47.6% (20/42) of patients with NIHR induced by iomeprol. Of the 66 challenge tests performed with negative skin-tested iodinated contrasts, tolerance was confirmed in 35 (53%): 32 iomeron, 2 iobitridol, 1 iopamidol. Cross-reactivity between iomeprol and iopamidol was 22% (4/20 in patients with positive skin tests and 5/21 in patients with negative skin tests). CONCLUSIONS: Sensitivity of the skin tests was less than 50% NIHRs due to iomeprol, while the negative predictive value of skin tests in patients who tolerated challenges with alternative contrasts (mainly iopamidol) was 53% (35 tolerated out of 66 performed). The cross-reactivity between iomeprol and iopamidol is high.

Simplifying the drug provocation test in non-immediate hypersensitivity reactions to amoxicillin in children: The experience of a tertiary care allergy unit.

BACKGROUND: Mild non-immediate reactions (NIR) to beta-lactams (ßLs) are the most common manifestation of adverse drug reactions in children, and the drug provocation test (DPT) remains the gold standard for diagnosis. However, there are still controversies about the protocol that should be used, especially regarding the administration of doses and the DPT length. OBJECTIVE: This study aimed to evaluate a pediatric population with a history of mild NIR to amoxicillin (AMX) or to amoxicillin-clavulanic acid (AMX/CL) who underwent a diagnostic workup including a DPT with the culprit drug, to understand if a graded DPT or, instead, a single full dose could be the most appropriate way of administration in clinical practice. METHODS: The data of children were retrospectively analyzed for a 5-year period, with demographic and clinical characteristics collected. We reported the allergy workup and the results of the DPT performed with the administration of incremental doses and a prolonged DPT at home for a total of 5 days. RESULTS: Three hundred fifty-four patients were included. Overall, 23/354 (6.5%) DPTs were positive: 11/23 patients showed a reaction after 2-8 h after the last dose on the 1st or 2nd day (1 reacted 30 min after the last dose), 1/23 reacted with urticaria 30 min after the first dose, 11/23 reacted at home on the 5th day of the DPT. CONCLUSION: This paper indirectly suggests that a single therapeutic dose administered on the 1st day of a DPT could be safe in the diagnostic workup of mild NIR to AMX/CL. Moreover, this could be less time-consuming as patients would spend less time in the hospital, also considering the public health restrictions imposed during the COVID-19 pandemic.

Hypersensitivity to Gadolinium-Based Contrast Media.

Gadolinium-based contrast agents (GBCAs) are frequently used in magnetic resonance imaging (MRI) examinations to increase sensitivity in diagnoses. Recently, an increase in the description of hypersensitivity reactions to GBCAs has been detected. We performed research in PubMed, PubMed, SCOPUS, and EMBASE until September 2021, searching for studies regarding immediate and delayed hypersensitivity reactions to gadolinium-based contrast agents in which an allergy study was performed. The initial research identified 149 articles written in English. After excluding articles duplicated and articles that had irrelevant designs, 26 articles were included. Finally, 17 studies concerning immediate reactions, six studies concerning non-immediate reactions, and three concerning both that performed allergy evaluations were selected. In the review, we analyzed the characteristics of immediate and delayed reactions and the results of the allergy study and cross-reactivity. Skin tests seem to have acceptable accuracy, but drug provocation tests are still needed when skin tests are negative o to find alternative agents. Although cross-reactivity patterns are not well established, cross-reactivity seems to exist among macrocyclic agents. Notwithstanding, the number of patients analyzed is low and further studies are required. A management algorithm is suggested.

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.

Patch tests in nonimmediate cutaneous adverse drug reactions: The importance of late readings on day 4.

BACKGROUND: Patch tests (PTs) with two readings have been used for decades to identify the culprit drug in nonimmediate cutaneous adverse drug reactions (NICADRs), followed more recently by late reading of intradermal tests (IDTs). Some teams tend to perform PTs with only one reading before IDTs or even directly perform IDTs. OBJECTIVES: To evaluate the relevance of a late PT reading on day 4 (D4) in NICADRs. METHODS: We retrospectively selected patients who had a PT for an NICADR between July 2014 and March 2020. RESULTS: During the study period, 328 patients had a PT with available results. Among the 75 positive-PT patients with available data for the two readings, 41 (54.7%) had positive results on D2 and D4 and 34 (45.3%) had negative results on D2 but positive results on D4. No patient had positive results on D2 and negative results on D4. CONCLUSION: This study shows that a D4 reading enhanced the PT-positive results. A positive PT result allows for reducing the number of IDTs, which are more difficult and costly to perform. Our series suggests that a late PT reading at D4 should be performed for exploring NICADRs.

Delayed hypersensitivity reaction after oral intake of non-ionic iodinated contrast medium.

Following intravenous contrast medium (CM) injection, a small proportion of patients acquires hypersensitivity reactions that occur either immediately or non-immediately (delayed). Although it is now claer that even oral applied CMs are able to cause adverse reactions, many radiologists as well as physicians of other disciplines, still believe that CM-application via the gastrointestinal route does not induce hypersensitivity reactions. Since this kind of misinterpretation may harm the patient, education on this topic is still necessary. Therefore, we describe a case who acquired a delayed hypersensitivity reaction following the oral intake of a non-ionic iodinated CM.

Cross-reactivity among iodinated contrast agents: should we be concerned?

BACKGROUND: Although several papers deal with "cross-reactivity" in patients with iodinated contrast medium (ICM) hypersensitivity reactions (HSRs), there is no in-depth knowledge of this phenomenon. To define ICM-groups as potential reaction partners and to identify any potential clinical relevance in patients with ICM-HSRs. METHODS: The literature database PubMed was searched for eligible papers dealing with ICM-allergy and "cross-reactivity". The data presented by the papers was analyzed and individual patient data was extracted for re-evaluation based on a definition for both 'polyvalent reactivity' and 'cross-reactivity' as well as for chemical structure-dependent ICM-groups. RESULTS: Twenty-five original papers (with n=340 extracted patients) formed the study population. Incidences of polyvalent reactivity were non-significantly higher than incidences of cross-reactivity (both range from 0% to 100%). Crossover evaluation in reaction pairings (culprit ICM A with ICM B versus culprit ICM B with ICM A) showed concordance of only 30%. Data support rather non-cross-reactivity (individual reaction pattern) than cross-reactivity constellations. CONCLUSIONS: The obtained results favour an individual reaction pattern, rather than a reactivity driven by chemical structures and so-called cross-reactivity.

Patterns of response and drugs involved in hypersensitivity reactions to beta-lactams in children.

BACKGROUND: Beta-lactams generate different allergenic determinants that induce selective or cross-reactive drug hypersensitivity reactions (DHRs). We aimed to identify the drugs involved, the selectivity of the response, the mechanism, and the value of the different diagnostic tests for establishing a diagnosis in children evaluated for DHRs to beta-lactams. METHODS: Prospective study evaluating children aged under 16 years reporting DHRs to beta-lactams. Reactions were classified as immediate and non-immediate reactions. The workup included sIgE, skin testing, and drug provocation tests (DPTs) for immediate reactions and patch testing and DPTs for non-immediate ones. RESULTS: Of the 510 children included, 133 were evaluated for immediate reactions and confirmed in 8.3%. Skin test/in vitro IgE contributed to diagnosing half of the cases. Selective reactions occurred with amoxicillin (63%), followed by common penicillin determinants (27%) and cephalosporins (0.9%). Among non-immediate reactions (11.4% of the 377 children evaluated), most required DPTs, 52.7% of which were positive at 6-7 days of drug challenge. Selective reactions were identified with amoxicillin (80%), penicillin G (7.5%), cephalosporins (7.5%), and clavulanic acid (5%). Urticaria and maculopapular exanthema were the most frequent entities. CONCLUSIONS: There were few confirmed cases of either type of reaction. Skin testing proved less valuable in non-immediate reactions, over half of which would also have been lost in a short DPT protocol. Selective responders to amoxicillin were more likely to have non-immediate reactions, while clavulanic acid selectivity was exclusive to the non-immediate typology. Over half the cases with DPTs required 6-7 days of treatment for DHR confirmation.

Associations between HLA-A, -B, and -C alleles and iodinated contrast media-induced hypersensitivity in Koreans.

A common cause of drug hypersensitivity reactions is iodinated contrast media (ICM). ICM-induced hypersensitivity had been considered to be a non-immunological reaction, but evidence for an immunological mechanism has increased recently. Thus, we evaluated whether HLA-A, -B, and -C alleles were associated with ICM-induced hypersensitivity. In total, 126 patients who underwent contrast-enhanced computed tomography studies through outpatient clinics at a tertiary referral hospital between 2008 and 2012 were assessed. Sixty-one patients experienced ICM-induced hypersensitivity and the remainder, 65, were ICM-tolerant patients (control). ICM-induced hypersensitivity patients showed 51 with immediate, 7 with non-immediate, 3 with both or mixed type. HLA-A, -B, and -C genotyping was performed using a PCR sequence-based typing method. Four kinds of ICM were used: iopromide, iohexol, iobitridol, and iodixanol. The most used ICM among the hypersensitivity patients was iopromide. Significant difference in the frequency of HLA-B*58:01 (odds ratios [OR], 3.90; p = 0.0200, 95% confidence interval [CI], 1.16-13.07) was observed between ICM-induced immediate hypersensitivity and control. There were statistically significant differences in the frequencies of the HLA-B*38:02 (OR, 10.24; p = 0.0145; 95% CI, 1.09-96.14) and HLA-B*58:01 (OR, 3.98; p = 0.0348; 95% CI, 1.03-15.39) between iopromide-induced immediate hypersensitivity and control. The mechanism of ICM-induced hypersensitivity remains unknown, but this study showed associations, although weak, with HLA-B*58:01 alleles for ICM-induced immediate hypersensitivity and HLA-B*38:02 and HLA-B*58:01 for iopromide-induced immediate hypersensitivity as risk predictors. Further studies are needed to validate the associations in larger samples and to identify the functional mechanism behind these results.

Safety of direct oral provocation testing using the Amoxicillin-2-step-challenge in children with history of non-immediate reactions to amoxicillin.

BACKGROUND: Previous studies have shown that direct oral provocation tests, without prior skin testing, in children having delayed onset, benign rashes to beta-lactam antibiotic is safe and effective. Although, this test is useful in confirming drug hypersensitivity reactions, there is no standard protocol recommendation of drug provocation tests. This study aimed to evaluate the safety of the direct oral provocation test, using the Amoxicillin-2-step-challenge without prior skin testing, in children with history of non-immediate reactions to amoxicillin. METHODS: The Amoxicillin-2-step-challenge protocol was performed in children with history of non-immediate reactions to amoxicillin. This protocol is composed of 2 doses of amoxicillin, with a 30-min interval; continued for a total of 5 days. All of the patients had not undergone skin testing before the oral provocation test. RESULTS: This study included 54 children, having a median age of 6.6 years, with 70.4% being male. Amoxicillin and amoxicillin-clavulanic acid were reported as the culprit drug in 75.9% and 24.1%, respectively. The index reactions were maculopapular (MP) rash in 79.6% and delayed urticarial rash/angioedema in 20.4%. Five patients (9.3%) had a reaction during the provocation test, all of these patients had delayed urticaria and were treated with oral antihistamine. However, 1 patient developed a fever alongside an MP rash. Laboratory investigation for this patient showed increased atypical lymphocytes and liver enzymes elevation. CONCLUSIONS: Direct oral provocation tests, using the Amoxicillin-2-step-challenge, without prior skin testing, revealed good, immediate safety for the diagnosis of amoxicillin hypersensitivity in children with history of non-immediate reactions to amoxicillin.