Management of allergy to penicillins and other beta-lactams

Polymorphisms of HLA genes and hypersensitivity to penicillin among patients in a Taiwanese population

Penicillin allergy is a potentially life-threatening condition that is common among patients. However, the genetic associations with penicillin allergy are not yet recognized for prevention or diagnosis, particularly in East Asian populations. We conducted a retrospective case-control study using data from the Taiwan Precision Medicine Initiative and analysing DNA samples to identify eight major MHC Class I and Class II loci. We employed imputation methods for accurate HLA typing and enrolled 17,827 individuals who received penicillin. Logistic regression analyses were utilized to explore associations between HLA genotypes, comorbidities and allergy risk, while simultaneously conducting a subgroup analysis to explore the association between HLA genotypes, comorbidities and the severity of allergic reactions. Our study assigned 496 cases to the penicillin allergy group and 4960 controls to a matched group. The risk of penicillin allergy was significantly higher with HLA-DPB1*05:01 (OR = 1.36, p = .004) and HLA-DQB1*05:01 (OR = 1.54, p = .03), with adjusted p-values of .032 and .24, respectively. Urticaria was identified as a separate risk factor (OR = 1.73, p < .001). However, neither the HLA alleles nor the comorbidities had a significant relationship with the risk of severe penicillin-induced allergy. HLA-DPB1*05:01 was found to be significantly associated with penicillin allergy reactions among the Taiwanese population.

Safety of direct oral provocation test to delabel reported mild beta-lactam allergy in infants

BACKGROUND

Around 10% of people report a drug allergy and avoid some medications because of fear of allergic reactions. However, only after a proper diagnostic workup can some of these reactions be confirmed as allergic or nonallergic hypersensitivities. Beta-lactams (BLs) are the most common medication suspected of being involved in drug hypersensivity reactions (DHRs) in children. Recently, direct oral provocation tests (DPT) with BLs gained popularity within pediatric populations as a tool for delabeling children with suspected BL allergies. This study aimed to evaluate the safety of direct provocation tests in infants with mild cutaneous non-immediate reactions to BLs.

METHODS

The authors retrospectively analyzed the data of 151 infants between 2015 and 2022, referred for evaluating a suspected allergy to BLs that occurred before age 24 months.

RESULTS

The mean age of the children, including 55% male kids, at the suspected reaction was 15.9 months and the mean age at the time of the DPT was 39.6 months. In most cases, antibiotics were prescribed to treat common upper respiratory infections, such as acute otitis (54.3%) and acute tonsillitis (27.2%). Amoxicillin was considered the culprit drug in 62.9% of the cases, and the combination of amoxicillin-clavulanic acid in the case of 33.8% of children. The most frequent associated cutaneous clinical manifestations were maculopapular exanthema in 74.8% and delayed urticaria/angioedema in 25.2%. Of the 151 infants evaluated, parents of 149 infants agreed for a direct DPT, and only three had a positive test (2%). Symptoms resulting from the DPT were mild and easily treatable.

CONCLUSIONS

A direct DPT without prior tests is a safe and effective procedure to delabel BL allergy, even in infants. The authors wish to emphasize the importance of properly validating BL allergy suspicions by promoting appropriate diagnostic procedures in infants as, in most cases, DHRs can be excluded and there is no need for further therapeutic restrictions.

Performance Characteristics of Basophil Activation Tests for Diagnosing Penicillin Allergy: A Meta-Analysis

BACKGROUND

Approximately 10% of the global population identify themselves as penicillin allergic, yet 90% are not truly allergic and could safely tolerate penicillin. There is no simple way to identify these people. Current in vitro diagnostics include specific immunoglobulin E (with a sensitivity of 19% and specificity of 97%) and a basophil activation test (BAT) with undefined sensitivity and specificity.

OBJECTIVE

To define the sensitivity and specificity of BAT in the diagnosis of penicillin allergy METHODS: We searched PubMed and EMBASE from inception to April 2, 2023, for original studies evaluating the performance characteristics of BAT for penicillin allergy in adults. Study selection, data extraction, risk of bias, assessment with QUADAS-2 tool, certainty assessment with Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology were performed independently, in duplicate. Meta-analysis was performed using Reitsma methodology.

RESULTS

Twenty-two studies fulfilled the inclusion criteria. Twelve used the same positive threshold giving a summary point sensitivity 51% (95% confidence interval [95% CI]46%-56%) and specificity 89% (95% CI 85%-93%). Significant risk of bias was identified owing to patient selection. GRADE certainty of evidence rated sensitivity very low due to imprecision and specificity as low. There was great heterogeneity in methods used. Use of 1,000 basophils per test did not improve performance above 500 basophils.

CONCLUSIONS

BAT sensitivity is highly variable across studies and remains too low to be considered as a routine element of clinical practice. BAT specificity is not as good as specific immunoglobulin E in penicillin allergy diagnosis. Significant further work is required in this field before clinical application of BAT in routine practice.

Diagnosis and selection of alternative antibiotics in beta-lactams hypersensitivity reactions: Current recommendations and challenges

Beta-lactam (BLM) antibiotics, including amino-penicillin and cephalosporins, are typically the first-choice treatment for bacterial infections. However, adverse reactions to these antibiotics are frequently reported, causing non-allergist physicians to select alternative broad-spectrum antibiotics that can have harmful consequences. Patients with unclear histories of hypersensitivity reactions to BLMs should undergo an allergy workup to establish a firm diagnosis, particularly when different drugs are prescribed simultaneously. However, finding the safest, most precise, and cost-effective methods for confirming BLMs hypersensitivity and selecting the most appropriate alternative BLM is uncertain, particularly in severe delayed reactions. This review aims to provide data and recommendations on the availability and validity of skin tests (STs), drug provocation test (DPT) protocols, based on the latest published literature and guideline. To make the process more practical, we focused on cross-reactivity between BLMs and diagnostic tests. There are two main novel aspects of this document: 1) For T-cell-mediated reactions, patient stratification into high, moderate, and low-risk groups based on the mortality and morbidity of adverse drug reactions. 2) For IgE-mediated reactions, stratification of individuals with isolated limited urticarial without anaphylaxis in a low-risk group and removal of the extensive limitation.

The state and consideration for skin test of β-lactam antibiotics in pediatrics

β-lactam antibiotics are the most frequently used drugs and the most common drugs that cause allergic reactions in pediatrics. The occurrence of some allergic reactions can be predicted by skin testing, especially severe adverse reactions such as anaphylactic shock. Thus, penicillin and cephalosporin skin tests are widely used to predict allergic reactions before medication in pediatrics. However, false-positive results from skin tests were more often encountered in pediatrics than in adults. In fact, many children labeled as allergic to β-lactam are not allergic to the antibiotic, leading to the use of alternative antibiotics, which are less effective and more toxic, and the increase of antibiotic resistance. There has been controversy over whether β-lactam antibiotics should be tested for skin allergies before application in children. Based on the great controversy in the implementation of β-lactam antibiotic skin tests, especially the controversial cephalosporin skin tests in pediatrics, the mechanism and reasons of anaphylaxis to β-lactam antibiotics, the significance of β-lactam antibiotic skin tests, the current state of β-lactam antibiotic skin tests at home and abroad, and the problems of domestic and international skin tests were analyzed to determine a unified standard of β-lactam antibiotic skin tests in pediatrics to prevent and decrease adverse drug reactions, avoid waste of drugs, and a large amount of manpower and material resource consumption.

The effectiveness of interventions that support penicillin allergy assessment and delabeling of adult and pediatric patients by nonallergy specialists: a systematic review and meta-analysis

OBJECTIVES

Penicillin allergy records are often incorrect and may result in harm. We aimed to systematically review the effectiveness and safety of nonallergist health care worker delivery of penicillin allergy delabeling.

METHODS

We searched EMBASE/MEDLINE/CINAHL (Ovid), PsycInfo, Web of Science, and Cochrane CENTRAL from inception to January 21, 2022 and unpublished studies and gray literature. The proportion of patients allergic to penicillin delabeled and harmed was calculated using random-effects models.

RESULTS

Overall, 5019 patients were delabeled. Using allergy history alone, 14% (95% confidence interval [CI], 9-21%) of 4350 assessed patients were delabeled without reported harm. Direct drug provocation testing resulted in delabeling in 27% (95% CI, 18-37%) of 4207 assessed patients. Of the 1373 patients tested, 98% were delabeled (95% CI, 97-99%), and nonserious harm was reported in 1% (95% CI, 0-2%). Using skin testing, followed by drug provocation testing, 41% (95% CI, 24-59%) of 2890 assessed patients were delabeled. Of the 1294 tested patients, 95.0% (95% CI, 90-99%) were delabeled, and the reported harm was low (0%; (95% CI 0-1%).

CONCLUSION

Penicillin allergy delabeling by nonallergists is efficacious and safe. The proportion of assessed patients who can be delabeled increases with the complexity of testing method, but substantial numbers can be delabeled without skin testing.

Addressing the Challenges of Penicillin Allergy Delabeling With Electronic Health Records and Mobile Applications

Allergy labels are common, often incorrect, and potentially harmful. There are many opportunities for clinical decision support (CDS) tools integrated in the electronic health record (EHR) and mobile apps to address the challenges with drug allergy management, including penicillin allergy delabeling (PADL). Effective delabeling solutions must consider multidisciplinary clinical workflow and multistep processes, including documentation, assessment, plan (eg, allergy testing and referral), record update, drug allergy alert management, and allergy reconciliation over time. Developing a systematic infrastructure to manage allergies across the EHR is critical to improve the accuracy and completeness of a patient's allergy and avoid inadvertently relabeling. Improving the appropriateness and relevancy of drug allergy alerts is important to reduce alert fatigue. Using alerts to guide clinicians on appropriate antibiotic use may reduce unnecessary β-lactam avoidance. To date, EHR CDS tools have facilitated non-allergists to provide PADL at the point of care. A mobile app was shown to support PADL and provide specialist support and education. Future research is needed to standardize, integrate, and evaluate innovative CDS tools in the EHR to demonstrate patient safety and clinical utility and facilitate wider adoption.

Comparative Effectiveness, Safety, and Real-World Outcomes of a Nurse-Led, Protocol-Driven Penicillin Allergy Evaluation From the Hong Kong Drug Allergy Delabelling Initiative (HK-DADI)

BACKGROUND

There is a high prevalence of unconfirmed penicillin allergy, which is associated with a multitude of adverse clinical outcomes. With the overwhelming burden of currently incorrect labels and the lack of allergy specialist services, new delabeling strategies are urgently needed.

OBJECTIVE

To assess the effectiveness, safety, and real-world outcomes of a nurse-led, protocol-driven evaluation of penicillin allergy, the Hong Kong Drug Allergy Delabelling Initiative (HK-DADI).

METHODS

Adult patients with suspected penicillin allergy were recruited into HK-DADI. Allergy and postdelabeling outcomes were retrospectively compared between patients evaluated via HK-DADI or traditional allergist evaluation.

RESULTS

A total of 312 completed penicillin allergy evaluation: 84 (27%) and 228 (73%) via HK-DADI and traditional pathways, respectively. Overall, 280 penicillin allergies were delabeled (90%). The delabeling rate between HK-DADI and traditional pathways was similar (90% vs 89%; P = .796). Among patients of the HK-DADI pathway, the delabeling rate was significantly higher among low-risk (LR) compared with non-LR patients (97% vs 77%; P = .010). Skin tests did not add diagnostic value among LR patients. No patients developed severe or systemic reactions during the evaluation. Upon 6- to 12-month follow-up (median, 10 months), 123 patients experienced infective episodes (44%) and 63 used penicillins again after delabeling (23%). This proportion was significantly higher in patients who were delabeled via HK-DADI compared with the traditional pathway (32% vs 19%; P = .026).

CONCLUSIONS

The Hong Kong Drug Allergy Delabelling Initiative, a nurse-led, protocol-driven evaluation, was safe and effective in penicillin allergy delabeling. It led to an even higher rate of future penicillin use after delabeling and mitigated the need for unnecessary skin testing among LR patients.

Beta-lactam allergy and drug challenge test in children: a systematic review and meta-analysis

BACKGROUND

Most cases of beta-lactam allergy in children are likely to be mislabeled. This study aimed to assess the prevalence of true positives, as determined by drug challenge tests, and the rate of false negatives in children with suspected allergies and confirm the safety of the drug challenge test.

METHODS

We conducted a systematic review and meta-analysis according to established procedures. Study participants were children with suspected beta-lactam allergy who underwent a drug challenge. PubMed MEDLINE, Dialog EMBASE, Cochrane Central Register of Controlled Trials, World Health Organization International Clinical Trials Registry Platform, and clinicaltrials.gov were searched from inception until March 5, 2021.

RESULTS

The pooled prevalence of (a) positive results in the first challenge was 0.049 (95% CI, 0.041-0.057; I² = 71%) from 78 studies; (b) serious adverse events was 0.00 (95% CI, 0.00-0.00; I² = 0.0%) from 62 studies; and (c) positive results in the second challenge after the first negative result was 0.028 (95% CI, 0.016-0.043; I² = 38%) from 18 studies.

CONCLUSIONS

The prevalence of children with suspected beta-lactam allergy with true-positive results and false-negative results from the drug challenge test was very low. Serious adverse events resulting from drug challenge tests were also very rare.

IMPACT

Most children with suspected beta-lactam allergy were likely to be mislabeled. Serious adverse events caused by the drug challenge test were rare. Few false-negative results were obtained from the drug challenge test.

Drug reintroduction testing and beta-lactam hypersensitivity in children: Protocols and results, a 12-year experience

Introduction: Oral provocation test (OPT) to beta-lactam antibiotics (BL) is a gold standard in allergology investigation. We aimed to demonstrate the contribution of OPT in BL hypersensitivity (HS) indicated as a first step in diagnosis. Methods: We conducted a retrospective study from 2007 to 2019, in a single Tunisian tertiary care academic center. It concerned children with presumed non-severe allergic manifestations to BL, with a reaction that has occurred at least 6 months before the OPT. Results: We identified 35 children for inclusion. After the first OPT, a second OPT with a different BL was performed in case of a positive result of the first one. In 12 cases (34.2%), the OPT elicited a reaction. In eight cases the allergy was to penicillin and in two cases to cephalosporins (cefixim). Cross-reactivity was noted in two cases. Conclusion: An OPT to BL indicated in the first instance in non-severe reaction in children will allow a rapid diagnosis in case of suspicion of HS to BL.

Barriers to paediatric penicillin allergy de-labelling in UK secondary care: a regional survey

BACKGROUND

Incorrect penicillin allergy labels result in the use of inappropriately broad-spectrum antibiotics. De-labelling inaccurate penicillin allergy promotes antimicrobial stewardship and optimises prescribing practices. The objectives were to evaluate paediatric clinicians' knowledge and understanding of penicillin allergy and to identify barriers in tackling incorrect penicillin allergy labels.

METHODS

Paediatric clinicians from across the West Midlands of the UK were surveyed using an online, anonymised questionnaire between 1 August and 30 September 2021. Domains explored were (1) approach to penicillin allergy clinical vignettes, (2) knowledge of the impact of penicillin allergy labels, (3) frequency of allergy-focused history questions and (4) barriers in tackling incorrect penicillin allergy.

RESULTS

Responses were received from 307 paediatric clinicians across 12 hospitals. Sixty-one per cent would not prescribe a penicillin-based antibiotic if a family history of penicillin allergy was reported. There was an overall deficit in taking an allergy-focused history with only 36.5% inquiring about diagnostic confirmation. Absence, or lack of awareness of a referral pathway for antibiotic allergy evaluation (58.6%) and unfamiliarity of the indications for oral provocation testing (55%) were the most common reported barriers to penicillin allergy de-labelling. Fifty-one per cent would rather 'play it safe' than explore penicillin allergy confirmation as it is felt that alternative treatments were readily available.

CONCLUSIONS

The deficiency in antibiotic allergy-focused history among paediatric clinicians highlights the need for better allergy education across all clinical grades. Pragmatic algorithms and clear referral pathways could address barriers faced by non-allergists in de-labelling incorrect penicillin allergy.

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.

Improving drug allergy label accuracy by supervised safety- and protocol-driven evaluation

Introduction: Drug allergies are often self-reported but of unknown accuracy. We carried out a prospective study to examine the utility and safety of formal allergology evaluation, and to identify factors associated with accurate drug allergy labels. Method: All patients who underwent drug allergy evaluation in our clinic during the study period were recruited. Baseline demographics, characteristics of index hypersensitivity reaction and outcomes of evaluation were recorded. Results: A total of 331 patients from March 2019 to June 2021 completed drug allergy evaluation to index drugs of concern. There were 123 (37%) male patients, and the mean age was 49 years (standard deviation 17). There were 170 beta-lactam antibiotics, 53 peri-operative drugs, 43 others, 38 non-steroidal anti-inflammatory drugs, and 27 non-beta-lactam antibiotic evaluations. Index reaction occurred within 5 years in 165 (50%) patients, with latency of less than 4 hours in 125 (38%) patients. The most common index reactions were rash, angioedema and urticaria. There were 57 (17%) evaluations stratified as low risk, 222 (67%) moderate risk, and 52 (16%) high risk based on multidisciplinary consensus. Allergy label was found to be false (negative drug evaluation) in 248 (75%) patients, while 16/237 (7%) skin tests, 44/331 (13%) in-clinic graded challenge, and 23/134 (17%) home prolonged challenges were positive (true drug allergy). The most common evaluation reactions were rash and urticaria. No cases of anaphylaxis were elicited. Conclusion: Seventy-five percent of drug allergy labels are inaccurate. Risk-stratified, protocolised allergy evaluation is safe. Prolonged drug challenge increases the sensitivity of drug allergy evaluation and should therefore be performed when indicated. Keywords: Drug allergy, drug hypersensitivity, graded challenge, prolonged drug provocation, skin testing

Improving antimicrobial stewardship with penicillin allergy testing: a review of current practices and unmet needs

Penicillin allergy, the most frequently reported drug allergy, has been associated with suboptimal antibiotic therapy, increased antimicrobial resistance, increased rates of Clostridioides difficile colonization and infection, as well as extended hospital length of stay and increased cost. Although up to 10% of all patients may report penicillin allergy, most penicillin allergies are not confirmed. As such, most patients with a penicillin allergy can still safely use penicillin and related drugs following a more precise assessment. Herein, we review the current practices and unmet needs in penicillin allergy testing. The diagnostic algorithm is mostly based on a clinical history assessment followed by in vivo testing, i.e. skin test and/or drug challenge. As these tests are labour and resource intensive, there is increased interest in point-of-care penicillin allergy de-labelling solutions incorporated into Antimicrobial Stewardship Programmes including digital assessment tools. These can be locally parameterized on the basis of characteristics of target populations, incidence of specific allergies and local antibiotic usage to perform clinical risk stratification. Safely ruling out any residual risk remains essential and in vivo drug challenge and/or skin testing should be systematically encouraged. Gradual understanding and convergence of the risk stratification of the clinical presentation of penicillin allergy is enabling a wider implementation of this essential aspect of antimicrobial stewardship through digitalized decision tools and in vivo testing. More research is needed to deliver point of care in vitro diagnostic tools to democratize this de-labelling practice, which would be highly beneficial to patient care. This progress, together with better education of patients and clinicians about the availability, efficacy and safety of penicillin allergy testing, will increase the dissemination of penicillin allergy assessment as an important component of Antimicrobial Stewardship Programmes.

Tools to improve the diagnosis and management of T-cell mediated adverse drug reactions

Delayed drug T-cell immune-mediated hypersensitivity reactions have a large clinical heterogeneity varying from mild maculopapular exanthema (MPE) to severe cutaneous adverse reactions (SCARs) such as acute generalized exanthematous pustulosis (AGEP), drug reaction with eosinophilia and systemic symptoms (DRESS) and severe skin necrosis and blistering as seen in Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Given the knowledge gaps related to the immunopathogenesis of these conditions, the absence of validated diagnostic tools and the significant associated morbidity and mortality, patients with SCARs often have limited drug choices. We performed a comprehensive review aiming to evaluate in vivo diagnostic tools such as delayed intradermal skin and patch testing and ex vivo/in vitro research assays such as the lymphocyte transformation test (LTT) and the enzyme-linked ImmunoSpot (ELISpot) assay. We searched through PubMed using the terms “drug allergy,” “in vivo” and “ex vivo” for original papers in the last 10 years. A detailed meticulous approach adapted to the various clinical phenotypes is recommended for the diagnostic and management of delayed drug hypersensitivity reactions. This review highlights the current diagnostic tools for the delayed drug hypersensitivity phenotypes.

BSACI guideline for the set-up of penicillin allergy de-labelling services by non-allergists working in a hospital setting

The Standards of Care Committee of the British Society for Allergy and Clinical Immunology (BSACI) and a committee of experts and key stakeholders have developed this guideline for the evaluation and testing of patients with an unsubstantiated label of penicillin allergy. The guideline is intended for UK clinicians who are not trained in allergy or immunology, but who wish to develop a penicillin allergy de-labelling service for their patients. It is intended to supplement the BSACI 2015 guideline "Management of allergy to penicillin and other beta-lactams" and therefore does not detail the epidemiology or aetiology of penicillin allergy, as this is covered extensively in the 2015 guideline (1). The guideline is intended for use only in patients with a label of penicillin allergy and does not apply to other beta-lactam allergies. The recommendations include a checklist to identify patients at low risk of allergy and a framework for the conduct of drug provocation testing by non-allergists. There are separate sections for adults and paediatrics within the guideline, in recognition of the common differences in reported allergy history and likelihood of true allergy.

Oral Challenge without Penicillin Skin Tests in Children with Suspected Beta-Lactam Hypersensitivity

Objective A misdiagnosed “penicillin allergy” is a common problem in childhood. Recently, skipping skin tests (STs) and performing a direct oral challenge test (OCT) have become an increasingly common approach in children with suspected β-lactam (BL) allergy. In our study, we aimed to evaluate the safety and efficacy of OCT without using ST in children who had a history of hypersensitivity reactions with BL antibiotics.

Materials and Methods We retrospectively evaluated direct OCT outcomes in children with both nonimmediate and immediate-type reaction history with BL antibiotics. STs were not performed before the challenge test. The patients were monitored for 4 hours after the challenge and continued using the drug in two divided doses for 3 days at home.

Results In this study, 72 patients were included, with median age of 7 years (interquartile range: 4; min: 1 year to max: 16 years), and of these, 56% were male. Forty-five subjects (63%) reported immediate-type adverse reactions. The most common clinical manifestation was urticaria/angioedema (51%, n: 37) and maculopapular exanthema in 46% (n: 33) of patients, respectively. The most commonly suspected drug was 71% amoxicillin-clavulanate. A 3-day OCT without preceding ST was performed in all patients. Only three patients (4.2%) showed a positive response to the oral drug challenge test. None of these reactions observed was more severe than index reactions.

Conclusion Performing OCT without STs is a safe and convenient method to exclude BL hypersensitivity in the pediatric age group.

Hong Kong Drug Allergy Delabelling Initiative (HK-DADI) consensus statements for penicillin allergy testing by nonallergists

Introduction

Penicillin allergy testing has been traditionally performed by allergists, but there remains a huge deficit of specialists. A multidisciplinary effort with nonallergists would be invaluable to overcome the magnitude of penicillin allergy labels via the Hong Kong Drug Allergy Delabelling Initiative (HK-DADI). These consensus statements (CSs) offer recommendations and guidance to enable nonallergists to screen for low-risk (LR) patients and perform penicillin allergy testing.

Methods

CSs were formulated by the HK-DADI Group using the Delphi method. An agreement was defined as greater than or equal to 80% consensus.

Results

A total of 26 CSs reached consensus after multiple rounds of Delphi. CSs were categorized into risk assessment, skin testing, drug provocation testing (DPT), and post-testing management. For risk assessment, the essentials of allergy history and exclusion criteria were detailed. Patients with only LR features can proceed with testing by nonallergists. Skin tests should be performed prior to DPT. Details regarding the timing, preparation, and interpretation of skin tests were elaborated. DPT remains the gold standard to diagnose genuine allergy or tolerance and should be performed when there is a low pretest probability following negative skin testing. Details of DPT preparations, dosing protocols, and interpretation were elaborated. For post-testing management, inaccurate allergy labels should be delabeled following negative DPT with proper patient counseling.

Conclusion

CSs support penicillin allergy testing by nonallergists in Hong Kong. LR cases can be managed by nonallergists at Spoke Clinics, with training and support of an allergist-led Hub.

Quality Improvement to Engage General Pediatrics in Reducing Inaccurate Penicillin Allergy Labels

OBJECTIVE

To remove inaccurate penicillin allergy labels in the general pediatric clinic setting.

METHODS

From October 2017 through December 2021, this collaborative, quality improvement project used education, feedback, electronic health record alerts, and the introduction of oral amoxicillin challenges in a general pediatric clinic setting with the primary aim of decreasing the proportion of penicillin allergy labeled patients. Control charts were used to track the relationship between interventions and improvements in referral rates to allergy clinic, removal of the allergy label at clinic visits and the overall proportion of clinic patients labeled as PCN allergic.

RESULTS

Referral rates to allergy clinic for penicillin allergy labeled patients increased from a baseline mean of 1.9% to 20.4%. The proportion of PCN allergy labeled patients who had the label removed during a pediatric clinic visit increased from a baseline of 1.1% to 6.6%. The overall proportion of penicillin allergy labeled clinic patients decreased from a baseline of 3.4% to 2.2%.

CONCLUSION

With adequate education and collaboration with allergists, general pediatric practitioners can play a significant role in removing inaccurate penicillin allergy labels. Pediatricians can remove some of the burden placed on allergists by evaluating low risk patients in the primary care setting while referring higher risk patients to the specialist.

Development and Validation of the Anaphylaxis Quality of Life Scale for Adults

BACKGROUND

Anaphylaxis is a severe and potentially life-threatening allergic reaction that can have a detrimental impact on quality of life (QoL). There are no validated scales to measure the impact of anaphylaxis on QoL of adults.

OBJECTIVE

The aim of this study was to develop and assess the reliability and validity of a QoL scale for adults with anaphylaxis (Anaphylaxis Quality of Life Scale for Adults [A-QoL-Adults]).

METHODS

All participants were recruited from a specialist allergy clinic and had a confirmed diagnosis of anaphylaxis (as per the World Allergy Organization diagnostic criteria) to food, drugs, venom, or latex or had spontaneous anaphylaxis. Interviews were conducted with 13 adults; data were analyzed using thematic analysis to extract items for a QoL scale. A prototype QoL scale was then completed by 115 participants alongside validated scales to measure generic QoL (World Health Organization Quality of Life Scale [Brief Version] [WHOQoL BREF]), anxiety and depression (Hospital Anxiety and Depression Scale [HADS]), and stress (Perceived Stress Scale [PSS]).

RESULTS

The A-QoL-Adults scale has 21 items demonstrating excellent internal reliability (Cronbach α = 0.96). Factor analysis produced 3 subscales: Emotional Impact; Social Impact; and Limitations on Life. Each has excellent internal reliability (0.92, 0.92, and 0.91, respectively). Poorer anaphylaxis-related QoL (total A-QoL-Adults score and subscale scores) correlated significantly with poorer general QoL and greater anxiety, depression, and stress (all P < .01 with medium-to-large effect sizes).

CONCLUSIONS

The A-QoL-Adults scale is a reliable measure of QoL in adults with anaphylaxis and shows good construct validity. It will offer health care professionals a means to further understand the impact of anaphylaxis on adult patients and could help direct and monitor allergy management and the need for further psychological intervention.

Standards for practical intravenous rapid drug desensitization & delabeling: A WAO committee statement

Drug hypersensitivity reactions (DHRs) to intravenous drugs can be severe and might leave patients and doctors in a difficult position where an essential treatment or intervention has to be suspended. Even if virtually any intravenous medication can potentially trigger a life-threatening DHR, chemotherapeutics, biologics, and antibiotics are amongst the intravenous drugs most frequently involved in these reactions. Admittedly, suspending such treatments may negatively impact the survival outcomes or the quality of life of affected patients.

Delabeling pathways and rapid drug desensitization (RDD) can help reactive patients stay on first-choice therapies instead of turning to less efficacious, less cost-effective, or more toxic alternatives. However, these are high-complexity and high-risk techniques, which usually need expert teams and allergy-specific techniques (skin testing, in vitro testing, drug provocation testing) to ensure safety, an accurate diagnosis, and personalized management. Unfortunately, there are significant inequalities within and among countries in access to allergy departments with the necessary expertise and resources to offer these techniques and tackle these DHRs optimally.

The main objective of this consensus document is to create a great benefit for patients worldwide by aiding allergists to expand the scope of their practice and support them with evidence, data, and experience from leading groups from around the globe.

This statement of the Drug Hypersensitivity Committee of the World Allergy Organization (WAO) aims to be a comprehensive practical guide on the technical aspects of implementing acute-onset intravenous hypersensitivity delabeling and RDD for a wide range of drugs. Thus, the manuscript does not only focus on clinical pathways. Instead, it also provides guidance on topics usually left unaddressed, namely, internal validation, continuous quality improvement, creating a healthy multidisciplinary environment, and redesigning care (including a specific supplemental section on a real-life example of how to design a dedicated space that can combine basic and complex diagnostic and therapeutic techniques in allergy).

Management of Beta-Lactam Antibiotics Allergy: A Real-Life Study

Beta-lactam allergy is a common problem in everyday medical practice and is recognized as a major public health issue. Carrying this label frequently leads to the avoidance of all beta-lactam antibiotics, favoring the use of other less preferred classes of antibiotics, that are more expensive and associated with more side effects and increased antimicrobial resistance. Therefore, delabeling a beta-lactam allergy is part of antimicrobial stewardship programs. Herein, we retrospectively examined the clinical records of 576 patients who were referred to our center for a label of allergy to beta-lactam antibiotics and were systematically investigated following a standardized algorithm. Our main aim was to evaluate the frequency of confirmed immediate- and delayed-type allergy to commonly prescribed subclasses of beta-lactam antibiotics (penicillin and cephalosporin), as well as the negative predictive value (NPV) and the sensitivity of skin tests. Our secondary aims were to examine the safety of beta-lactam skin testing and drug challenge. We identified that 260 patients reported a history of immediate reactions, 131 of delayed reactions, and 114 of unknown timing or mechanism of reactions. Following assessment and testing, 86 (18.3%) patients had a confirmed allergy to any beta-lactam antibiotics; 63 (13.4%) with an immediate- and 23 (4.9%) with a delayed-type reaction. Most frequently identified confirmed allergy was to penicillins (65 patients), followed by cephalosporins (21 patients). When immediate-type reactions were examined, NPV of skin tests were 96.3% and 100% for penicillins and cephalosporins, respectively. When delayed reactions were considered, NPV were 91.9 and 87.5% for penicillins and cephalosporins, respectively. Evaluation of the safety of skin tests according to the standardized procedure showed that systemic allergic reactions occurred in only 0.7% of skin tests and in 3.1% of drug challenges. Overall, our data indicate that only 18.3% of patients with a beta-lactam allergy label have a confirmed allergy and non-allergic patients can be safely delabeled through allergic workup based on skin tests and drug challenge. This approach supports the policy of saving second-line antibiotics through a standardized allergy workup.

Intradermal testing increases the accuracy of an immediate-type cefaclor hypersensitivity diagnosis

Background

Hypersensitivity reactions to cefaclor have increased in accordance with its frequent use. However, only limited data are available on the diagnostic value of skin tests for these conditions, particularly intradermal tests (IDTs).

Objective

To evaluate the clinical usefulness of IDT compared to the ImmunoCAP test in patients with cefaclor-induced immediate-type hypersensitivity.

Methods

We conducted a retrospective chart review from January 2010 to June 2020 of adult subjects from 2 tertiary hospitals in Korea with a history of suspected immediate-type hypersensitivity to cefaclor, and who had undergone ImmunoCAP and IDT.

Results

Overall, 131 subjects diagnosed with cefaclor hypersensitivity were included in the analysis. Fifty-nine patients (59/131, 45.04%) were positive in both IDT and ImmunoCAP. Fifty-four (54/131, 41.22%) and 6 (6/131, 4.58%) subjects showed positive results only with IDT or the ImmunoCAP test, respectively. Twelve subjects (12/131, 9.16%) were negative by both tests but reacted positively in a drug provocation test. The frequency of IDT positivity was similar regardless of the severity of reactions. However, positivity of ImmunoCAP was lower in subjects with mild reactions compared to those with anaphylaxis. Regarding the diagnosis of cefaclor hypersensitivity, the overall sensitivity of IDT and ImmunoCAP was 0.863 and 0.496, respectively while the specificity was 1. The combination of IDT and ImmunoCAP further increased this sensitivity to 0.908.

Conclusion

IDT was more sensitive than ImmunoCAP for the diagnosis of cefaclor allergy, regardless of the severity of the hypersensitivity reaction. Therefore, we recommend a combination of IDT and ImmunoCAP for the diagnosis of cefaclor hypersensitivity.

Outcome of a de-labelling algorithm compared with results of penicillin (β-lactam) allergy testing

Background

Penicillin allergy labels frequently impede guideline-directed treatment with a penicillin or other β-lactam antibiotics. Despite presumed allergy, targeted questioning may indicate a low probability of sensitization and permit reasonably safe administration of the antibiotic in question. In this study, we evaluated a standardized algorithm aiming to differentiate non-allergic patients from those with true allergic β-lactam hypersensitivity.

Methods

We retrospectively applied a de-labelling algorithm in 800 consecutive patients with suspected β-lactam hypersensitivity. All had undergone complete allergy work-up permitting to definitely exclude or diagnose β-lactam allergy between 2009 and 2019.

Results

In 595 (74.4%) out of 800 cases evaluated, β-lactam allergy could be excluded by negative challenge testing. IgE-mediated anaphylaxis was diagnosed in 70 (8.7%) patients, delayed-type hypersensitivity in 135 (16.9%). In 62 (88.6%) anaphylaxis cases, the algorithm correctly advised to use an alternative antibiotic. Accuracy was higher in patients with moderate to severe anaphylaxis (97.7%) compared to those with a history of mild reactions (73.1%). The algorithm correctly identified 122 (90.4%) patients with proven delayed-type hypersensitivity. It permitted de-labelling in 330 (55.5%) out of 595 patients with diagnostic exclusion of penicillin hypersensitivity, but failed to identify the remaining 265 (44.5%) as low-risk cases.

Conclusions

The algorithm detected 89.8% of cases with penicillin (β-lactam) allergy, sensitivity was optimal for moderate to severe anaphylaxis. Study data justify the implementation of a standardized de-labelling algorithm under close supervision in order to permit guideline-directed treatment and reduce the use of broad-spectrum antibiotics as part of an antibiotic stewardship program.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13223-022-00659-1.

Isolierte Zungenschwellung nach Penizillin und negative Allergieabklärung – alles in Butter?

Penizilline können alle Arten spezifischer Immunreaktionen nach der erweiterten Coombs- und Gell-Klassifikation auslösen und zählen zu den häufigsten Ursachen unerwünschter Arzneimittelreaktionen. Das diagnostische Armamentarium umfasst neben den verschiedenen Hauttesten den Nachweis spezifischer IgE gegen allergene Determinanten am Betalaktam-Molekül und ggf. zelluläre Aktivierungsteste. Im Fall negativer Ergebnisse bei den genannten Testen kann ggf. noch die Toleranz im Rahmen eines Provokationstestes nachgewiesen werden. Die Sensitivität der diagnostischen Teste ist – mit Ausnahme des Provokationstests – aber limitiert, und falsch negative Teste sind möglich. Wir präsentieren zwei Fälle mit einer isolierten Zungenschwellung nach Gabe von Amoxicillin bei vollständig negativem, wiederholtem allergologischen Work-up. Bei beiden Patienten konnte die Überempfindlichkeit nur mit einer Reexposition nachgewiesen werden.

Corynebacterium amycolatum infective endocarditis in a patient with severe COVID-19: a case report

Objective. To present a case of successful treatment of a secondary bacterial infection caused by nondiphtheritic corynebacterium in a patient with severe COVID-19 and known beta-lactam intolerance. Materials and Methods. A clinical case of infective endocarditis (IE) caused by Corynebacterium amycolatum in a 74-year-old patient hospitalized with severe COVID-19 is presented. Comorbidity (secondary immune deficiency due to active malignancy, chemotherapy courses; previous heart disease) and the need for immunosuppressive therapy were triggers for infection caused by a rare Gram-positive bacterium which is usually considered as clinically non-significant. The choice of empiric antimicrobial treatment was limited by the patient’s history of beta-lactam intolerance. Results. A multidisciplinary approach to medical care of the patient and alertness to secondary infections helped to diagnose IE in a timely manner and to choose effective antimicrobial therapy. Combination therapy with vancomycin and amikacin helped to make blood flow free from infection. The further switch to oral doxycycline in outpatient settings resulted in the patient recovery from the infection. Conclusions. Under conditions of limited choice of drug therapy, it is critical to have access to modern microbiological diagnostics which make it possible to diagnose rare pathogens. A dialogue between treating physician and clinical pharmacologist helps to choose an empirical and targeted antimicrobial therapy with the best efficacy-safety ratio. There is a need to be alert to secondary infections, including those of atypical locations and courses and caused by rare or opportunistic pathogens.

Adequacy of probabilistic prehospital antibiotic therapy for septic shock

BACKGROUND

Guidelines on sepsis management recommend early recognition, diagnosis and treatment, especially early antibiotic therapy (ABT) administration in order to reduce septic shock (SS) mortality. However, the adequacy of probabilistic prehospital ABT remains unknown.

METHODS

From May 2016 to March 2021, all consecutive patients with SS cared for by a prehospital mICU intervention were retrospectively analyzed.

RESULTS

Among 386 patients retrospectively analyzed, 119 (33%) received probabilistic prehospital ABT, among which 74% received a 3rd generation cephalosporin: 31% cefotaxime and 42% ceftriaxone. No patient had a serious adverse effect related to ABT administration. Overall mortality rate on day-30 was 29%. Among the 119 patients with prehospital ABT, bacteriological identification was obtained for 81 (68%) patients with adequate prehospital ABT for 65 patients (80%) of which 10 (15%) deceased on day-30. Conversely, among the 16 (20%) patients with inadequate prehospital ABT, 9 patients (56%) were deceased on day-30. Prehospital adequate ABT was significantly different between alive and deceased patients on day-30 (p = 4.10^-3). After propensity score matching, a significant association between adequate prehospital ABT administration and day-30 mortality was observed (aOR = 0.09 [0.01-0.47]). Inverse probability treatment weighting with multivariable logistic regression reported a day-30 mortality decrease in the adequate prehospital ABT group: aOR = 0.70 [0.53-0.93].

CONCLUSIONS

Among SS cared for by a mICU, probabilistic prehospital ABT is adequate most of the time and associated with a day-30 mortality decrease. Further prospective studies are needed to confirm these results and the weight of prehospital ABT in the prehospital bundle of care for SS.

Immediate and Delayed Hypersensitivity Reactions to Beta-Lactam Antibiotics

Beta-lactam antibiotics are the most commonly reported drug allergy in adults and children. More than 95% of those with reported allergy labels to beta lactams are not confirmed when subjected to allergy testing. Beta lactam antibiotics are associated with a wide spectrum of immediate and delayed drug hypersensitivity reactions. The latency period to symptoms and clinical presentation aids in the causality assessment. Risk stratification based on diagnosis and timing then allows for appropriate management and evaluation. Skin prick testing, intradermal testing and oral challenge are well established for evaluation of immediate reactions. Delayed intradermal testing, patch testing and oral challenge can also be considered for evaluation of mild to moderate delayed reactions. Cross-reactivity between beta-lactams appears to be driven most commonly by a shared R1 side-chain. Standardized algorithms, protocols and pathways are needed for widespread implementation of a pragmatic and effective approach to patients reporting beta lactam allergy.

Transfer of certain beta-lactam antibiotics from cow's milk to fresh cheese and whey

The aim of this study was to investigate the transfer of cephalexin, penicillin-G, and ampicillin & cloxacillin from cow's milk to cheese and whey. For this purpose, raw milk was artificially contaminated to different antibiotic levels and then heat-treated to prepare fresh cheese from it. Antibiotic levels of the milk, whey and cheese were measured with LC-MS/MS. The extent of heat degradation was not sufficient to remove the antibiotic residues from milk. Antibiotic concentrations in whey and fresh cheese were in good accordance with the concentration of the same compound in milk suggesting that contamination of the milk will result in contamination of the product. The investigated antibiotics were transferred less into the cheese curd (1.6-12.5% of the original amount), than into the whey (33.2-74.1%). For penicillin-G even 100% (complete removal) was experienced.

Diagnostic Approach of Hypersensitivity Reactions to Cefazolin in a Large Prospective Cohort

BACKGROUND

Cefazolin is a common trigger of perioperative anaphylaxis. The diagnostic approach is controversial because the optimal concentration for skin testing is uncertain, drug provocation tests (DPTs) are contraindicated in severe reactions, and in vitro tests are not thoroughly validated.

OBJECTIVE

We aimed to characterize a large number of patients reporting cefazolin allergic reactions and to analyze the diagnostic role of in vivo and in vitro tests.

METHODS

We prospectively evaluated patients with suspicion for allergic reactions to cefazolin by clinical history, skin tests (STs), and, if negative, DPT. In a subgroup of patients, basophil activation test (BAT) and radioallergosorbent test were done before allergologic workup was performed and the final diagnosis was achieved.

RESULTS

We evaluated 184 patients, 76 of whom were confirmed as allergic (41.3%), 90 were nonallergic (48.9%), and 18 were nonconfirmed (9.8%). All patients reporting anaphylactic shock and most reporting anaphylaxis were confirmed to be allergic (P < .001). Forty allergic patients (52.6%) were confirmed by STs, 22 by DPT (28.9%), and 14 by clinical history (18.4%). All subjects manifesting exanthemas and pruritus were nonallergic. The BAT sensitivity was 66.7% when CD63 and CD203c were combined as activation markers. Six of 8 patients with negative STs and positive DPT had a positive BAT.

CONCLUSIONS

Patients allergic to cefazolin often reported severe immediate-type reactions. Skin tests enabled a diagnosis in half of patients when using cefazolin at 20 mg/mL. Unfortunately, DPT could not be performed in all patients owing to reaction severity, which makes BAT a promising diagnostic tool. Further research is needed to clarify the underlying mechanisms, especially in severe reactions.

Single-dose prolonged drug provocation test, without previous skin testing, is safe for diagnosing children with mild non-immediate reactions to beta-lactams

INTRODUCTION

Mild non-immediate reactions (NIRs) to beta-lactams (BLs) are the most frequent manifestation of drug allergy in children. The diagnostic approach is complex as the utility of skin tests (STs) and lymphocyte transformation tests (LTTs) is controversial. Drug provocation test (DPT) is the gold standard, although no standardized protocols exist. We aimed to investigate the utility of DPT in a unique dose without previous STs, and LTTs in the diagnosis of NIRs to BLs in children.

METHODS

We prospectively evaluated children 0-14 years old referred to the Regional University Hospital of Málaga during 2017-2020 reporting NIRs to BLs. We performed a DPT with a unique dose followed by regular treatment at home. If positive, STs and LTTs were done after the reaction had disappeared.

RESULTS

We included 194 children, having 24 (12.4%) a positive DPT. The main culprit was AX (70.1%) followed by AX-clavulanic acid (CLV) (26.8%) and the main symptoms maculopapular exanthema (MPE) (49.5%) and delayed-urticaria (48.5%). A decrease (p = 0.013) in the interval of days between drug administration and onset of symptoms was observed in positive DPT compared with the original reaction (3.5 vs 6 days), with no differences in the overall percentage of MPE and delayed-appearing urticaria (p = 0.551). No severe reactions occurred during DPT. Moreover, STs were positive in 13.33% and LTTs in 52.9%.

CONCLUSIONS

Single-dose DPT without previous STs is a safe and useful way to assess NIRs to BLs in children. LTT has shown to be useful, confirming a T-cell mechanism involved in these reactions.

Role of clinical history in beta-lactam hypersensitivity

PURPOSE OF REVIEW

Understand how the clinical history has been used to risk stratify patients reporting a beta-lactam allergy, both in clinical care pathways and predictive models.

RECENT FINDINGS

Drug allergy clinical care pathways have emerged as a safe and effective method of stratifying patients with a reported beta-lactam allergy into risk categories, with 'low-risk' patients able to proceed straight to direct challenges or test doses. These methods have streamlined antibiotic stewardship policies and penicillin allergy de-labeling. However, how to define 'low-risk' has been subject to much debate. New research has developed predictive models that utilize the clinical history to assess a patient's true risk of beta-lactam allergy.

SUMMARY

The clinical history has long been an essential part of drug allergy evaluation and has proven invaluable within the past decade in the development of drug allergy clinical pathways. Evidence-based predictive models that use the clinical history to assess a patient's true risk of beta-lactam allergy offer tremendous promise, but differ in crucial areas such as the populations they study, the predictor variables they use, and the ultimate accuracy they attain. These models highlight key aspects of the drug allergy history and pave the way for future large-scale research.

Predictive factors of amoxicillin immediate hypersensitivity and validation of PEN-FAST clinical decision rule

BACKGROUND

The challenge of delabeling amoxicillin allergy is an important issue for patients and clinicians, especially when anaphylaxis is reported. A recent study has proposed a clinical decision rule, PEN-FAST, to identify low-risk penicillin allergies.

OBJECTIVE

To validate the PEN-FAST clinical decision rule in a population with high risk of suspected immediate amoxicillin allergy and to identify clinical predictive factors of amoxicillin immediate hypersensitivity.

METHODS

We retrospectively analyzed medical records of patients with a suspected immediate amoxicillin allergy who carried out an allergologic evaluation by a specialist in the Allergy Unit of Strasbourg University Hospital from 2015 to 2020.

RESULTS

A total of 142 adult patients (88 women [62.0%]; median age, 52 [interquartile range, 40.3-62.0] years) were analyzed. Most of them reported anaphylaxis (68.8%). Internal validation of PEN-FAST score revealed a good discrimination with area under the curve of 0.86 (95% confidence interval, 0.79-0.92). A cutoff of less than 3 points for PEN-FAST was used to classify 29 from 142 patients at low risk of allergy, of whom only 2 (6.9%) received positive results of allergy testing. The negative predictive value for successful delabeling was 0.93 (95% confidence interval, 0.77-0.99). Predictive clinical features for immediate amoxicillin hypersensitivity were time since reaction (P < .001), time elapsed between drug intake and first symptom (P < .001), severity grade reaction (P < .001), and treatment or hospitalization required (P < .001).

CONCLUSION

PEN-FAST has been validated to identify low-risk penicillin allergies in our European cohort of patients mainly reporting anaphylaxis. This is the first reported external validation of a penicillin allergy clinical decision rule internationally.

Atezolizumab-induced anaphylactic shock in a patient with hepatocellular carcinoma undergoing immunotherapy: A case report

BACKGROUND

Atezolizumab is a programmed death ligand 1 (PD-L1) inhibitor, and its combination with bevacizumab has been proven an effective immunotherapy for unresectable hepatocellular carcinoma (HCC). Treatment with immune checkpoint inhibitors (ICIs) can lead to hypersensitivity reactions; however, anaphylactic shock is rare. We present a case of life-threatening anaphylactic shock during atezolizumab infusion and performed a relevant literature review.

CASE SUMMARY

A 75-year-old man was diagnosed with HCC recurrence after hepatectomy. He was administered immunotherapy with atezolizumab plus bevacizumab after an allergy to a programmed death-1 (PD-1) inhibitor. The patient showed a sudden onset of dizziness, numbness, and lack of consciousness with severe hypotension during atezolizumab infusion. The treatment was stopped immediately. The patient’s symptoms resolved after 5 mg dexamethasone was administered. Because of repeated hypersensitivity reactions to ICIs, treatment was changed to oral targeted regorafenib therapy.

CONCLUSION

Further research is necessary for elucidating the hypersensitivity mechanisms and establishing standardized skin test and desensitization protocols associated with PD-1 and PD-L1 to ensure effective treatment with ICIs.

Model Based Evaluation of Hypersensitivity Adverse Drug Reactions to Antimicrobial Agents in Children

Drug use in children is-in most cases-supported by extrapolation of data generated from clinical trials in adult populations. This puts children at higher risk of developing adverse drug reactions (ADRs) due to "off-label" use of drugs and dosing issues. Major types of ADRs are drug hypersensitivity reactions, an idiosyncratic type of ADRs that are largely unpredictable and can cause high morbidity and mortality in a hard-to-identify specific population of patients. Lack of a complete understanding of the pathophysiology of DHRs and their unpredictive nature make them problematic in clinical practice and in drug development. In addition, ethical and legal obstacles hinder conducting large clinical trials in children, which in turn make children a "therapeutic orphan" where clear clinical guidelines are lacking, and practice is based largely on the personal experience of the clinician, hence making modeling desirable. This brief review summarizes the current knowledge of model-based evaluation of diagnosis and management of drug hypersensitivity reactions (DHRs) to antimicrobial drugs in the pediatric population. Ethical and legal aspects of drug research in children and the effect of different stages of child development and other factors on the risk of DHRs are discussed. The role of animal models, in vitro models and oral provocation test in management of DHRs are examined in the context of the current understanding of the pathophysiology of DHRs. Finally, recent changes in drug development legislations have been put forward to encourage drug developers to conduct trials in children clearly indicate the urgent need for evidence to support drug safety in children and for modeling to guide these clinical trials.

Antimicrobial anaphylaxis: the changing face of severe antimicrobial allergy

OBJECTIVES

The epidemiology, clinical characteristics and outcomes of antimicrobial-associated anaphylaxis remain ill-defined. We sought to examine antimicrobial anaphylaxis with regard to: (i) the frequency of implicated antimicrobials; (ii) attributable mortality; and (iii) referral for definitive allergy assessment.

METHODS

This was conducted through a national retrospective multicentre cohort study at five Australian tertiary hospitals (January 2010 to December 2015). Cases of antimicrobial anaphylaxis were identified from ICD-10 coding and adverse drug reaction committee databases.

RESULTS

There were 293 participants meeting the case definition of antimicrobial anaphylaxis and 310 antimicrobial anaphylaxis episodes. Of 336 implicated antimicrobials, aminopenicillins (62/336, 18.5%) and aminocephalosporins (57/336, 17%) were implicated most frequently. ICU admission occurred in 43/310 (13.9%) episodes; however, attributable mortality was low (3/310, 1%). The rate of anaphylaxis to IV antibiotics was 3.5 (95% CI=2.9-4.3) per 100 000 DDDs and the rate of hospital-acquired anaphylaxis was 1.9 (95% CI=2.1-3.3) per 100 000 occupied bed-days. We observed overall low rates of hospital discharge documentation (222/310, 71.6%) and follow-up by specialist allergy services (73/310, 23.5%), which may compromise medication safety and antimicrobial prescribing in future.

CONCLUSIONS

This study demonstrated that a high proportion of severe immediate hypersensitivity reactions presenting or acquired in Australian hospitals are secondary to aminopenicillins and aminocephalosporins. Overall rates of hospital-acquired anaphylaxis, predominantly secondary to cephalosporins, are low, and also associated with low inpatient mortality.