Antimicrobial stewardship's new weapon? A review of antibiotic allergy and pathways to 'de-labeling'

Effectiveness of direct delabelling of allergy labels in type A adverse drug reactions to penicillin: a multicentre hospitalwide prospective cohort study

BACKGROUND

Patient-reported penicillin allergy labels (PALs) are associated with adverse patient outcomes and inappropriate antibiotic prescribing. Removal of PALs via direct oral challenge (DOC) is associated with increased penicillin utilization post removal.

OBJECTIVES

To assess the impact of direct delabelling (allergy label removal via medical reconciliation alone) of type A adverse drug reaction (ADR) PALs on inpatient prescribing.

METHODS

From January 2019 to December 2022 at two tertiary hospitals in Melbourne, patients aged ≥18 years with type A ADR PALs, as defined by the validated Antibiotic Allergy Assessment Tool, were offered direct delabelling or single-dose DOC. The primary endpoint was antibiotic use pre- and post-assessment (during index admission and 90 days post assessment). The secondary endpoint was the proportion of patients delabelled in the direct delabelling and DOC cohorts in the electronic medical record at 90 days post assessment.

RESULTS

Allergy labels (n = 4108) were assessed for 488 participants, with 490 individual type A ADR PAL assessments included. Three hundred and thirty-seven patients were directly delabelled, 69 underwent DOC and 84 were not delabelled. There was increased use of any penicillin following direct delabelling (OR 19.19, 95% CI 2.48-148.36) and DOC (OR 56.98, 95% CI 6.82-476.19) during the index admission, higher in the DOC group compared with direct delabelling (OR 2.97, 95% CI 1.39-6.37). Relabelling at 90 days was low with no statistically significant difference between direct delabelling (5/337; 1.5%) and DOC (0/69; 0%).

CONCLUSIONS

Both direct delabelling and DOC of type A ADR PALs increased penicillin usage; however, the impact was greatest with DOC. Most patients remain delabelled at 90 days.

True Rate of Allergy among Pediatric Inpatients with Penicillin Allergy Labels (TRIAL)

Background

Penicillin allergy is a common drug allergy diagnosis in pediatric patients; however, upon appropriate allergy testing, many of these patients are found not to have a true allergy. For patients with a reported allergy, alternative antibiotics are prescribed, which are less effective, more toxic, or more expensive. There is a lack of data evaluating allergies in hospitalized children and comparing allergy assessments conducted by pediatric allergists and pharmacists.

Objective

To estimate the percentage of pediatric patients admitted with reported penicillin allergy who did not have a true penicillin allergy.

Methods

This single-centre prospective cohort study included inpatients between 6 months and 17 years of age, with a documented penicillin allergy, who were admitted to the general pediatric and oncology units of a tertiary care children's hospital between November 2019 and March 2023. The allergy history, evaluation, and risk categorization were performed by pharmacists. The history was reviewed with the allergist, and the patient was then referred, underwent skin testing, or received oral amoxicillin challenge with monitoring for 1 hour.

Results

Thirty patients were included, of whom 29 (97%) had delabelling of their penicillin allergy. Four patients (13%) had delabelling on the basis of history alone, without risk assessment. Twenty-five (83%) of the patients were assessed as having low risk; 24 of these had delabelling following oral challenge, and 1 did not complete the oral challenge because of transfer to another hospital. One patient (3%) was assessed as having moderate risk, with delabelling on the basis of results of skin testing and oral challenge. The pharmacist's and allergist's risk assessments were in agreement in 29 (97%) of the 30 cases.

Conclusions

Pediatric patients, including those with oncologic malignancies, are often mislabelled as having a penicillin allergy. Pharmacists are able to accurately determine true allergy risk and delabel penicillin allergies for pediatric patients in the hospital setting.

How to Define and Manage Low-Risk Drug Allergy Labels

Risk stratification in drug allergy implies that specific risk categories (eg, low, moderate, and high) classify historical drug hypersensitivity reactions. These risk categories can be based on reaction phenotypic characteristics, the timing of the reaction and evaluation, the required reaction management, and individual characteristics. Although a multitude of frameworks have been described in the literature, particularly for penicillin allergy labels, there has yet to be a global consensus, and approaches continue to vary between allergy centers. Immune-mediated drug allergies can sometimes be confirmed using skin testing, but a negative drug challenge is required to demonstrate tolerance and remove the allergy from the electronic health record ("delabel" the allergy). Even for quintessential IgE-mediated drug allergy, penicillin allergy, recent data reveal that a direct oral challenge, without prior skin testing, is an appropriate diagnostic strategy in those who are considered low-risk. Drug allergy pathogenesis and clinical manifestations may vary depending on the culprit drug, and as such, the optimal approach should be based on risk stratification that considers individual patient and reaction characteristics, the likely hypersensitivity reaction phenotype, the drug class, and the patient's clinical needs. This article will describe low-risk drug allergy labels, focusing on β-lactam and sulfonamide antibiotics, nonsteroidal anti-inflammatory drugs, iodinated contrast media, and common chemotherapeutics. This review will also address practical management approaches using currently available risk stratification and clinical decision tools.

Low-risk penicillin allergy delabeling: a scoping review of direct oral challenge practice, implementation, and multi-disciplinary approaches

INTRODUCTION

Penicillin allergy is common, and there is increased clinician interest in direct oral challenge (DOC) as a testing strategy for low-risk penicillin allergy. To aid wider implementation of DOC, consensus definitions of low-risk penicillin allergy phenotypes, and standardized approaches to assessment, DOC procedures, and evaluation, are required.

AREAS COVERED

This review systematically reviews studies that have utilized penicillin DOC in healthcare settings to identify heterogeneity in implementation approaches and synthesize low-risk definitions, procedures, and evaluation.

EXPERT OPINION

Opportunity exists to standardize penicillin DOC procedures in patients with a low-risk penicillin allergy to optimize antimicrobial prescribing and reduce the burden of penicillin allergy. Standardizing the definitions of 'low-risk' and 'positive challenge,' and improving the evaluation of patient safety, alongside the development of a unified approach to the structure of undertaking an oral challenge, is likely to increase uptake and confidence among non-allergist clinicians.

Penicillin Allergy Impact and Management

There is international evidence that penicillin allergies are associated with inferior prescribing and patient outcomes. A host of tools now exist from assessment (risk assessment tools, clinical decision rules) to delabeling (the removal of a beta-lactam allergy via testing or medical reconciliation) to reduce the impact of these "labels" in the hospital and community setting, as a primary antimicrobial stewardship intervention.

Efficacy of a Clinical Decision Rule to Enable Direct Oral Challenge in Patients With Low-Risk Penicillin Allergy: The PALACE Randomized Clinical Trial

Importance

Fewer than 5% of patients labeled with a penicillin allergy are truly allergic. The standard of care to remove the penicillin allergy label in adults is specialized testing involving prick and intradermal skin testing followed by an oral challenge with penicillin. Skin testing is resource intensive, limits practice to specialist-trained physicians, and restricts the global population who could undergo penicillin allergy delabeling.

Objective

To determine whether a direct oral penicillin challenge is noninferior to the standard of care of penicillin skin testing followed by an oral challenge in patients with a low-risk penicillin allergy.

Design, Setting, and Participants

This parallel, 2-arm, noninferiority, open-label, multicenter, international randomized clinical trial occurred in 6 specialized centers, 3 in North America (US and Canada) and 3 in Australia, from June 18, 2021, to December 2, 2022. Eligible adults had a PEN-FAST score lower than 3. PEN-FAST is a prospectively derived and internationally validated clinical decision rule that enables point-of-care risk assessment for adults reporting penicillin allergies.

Interventions

Patients were randomly assigned to either direct oral challenge with penicillin (intervention arm) or a standard-of-care arm of penicillin skin testing followed by oral challenge with penicillin (control arm).

Main Outcome and Measure

The primary outcome was a physician-verified positive immune-mediated oral penicillin challenge within 1 hour postintervention in the intention-to-treat population. Noninferiority was achieved if a 1-sided 95% CI of the risk difference (RD) did not exceed 5 percentage points (pp).

Results

A total of 382 adults were randomized, with 377 patients (median [IQR] age, 51 [35-65] years; 247 [65.5%] female) included in the analysis: 187 in the intervention group and 190 in the control group. Most patients had a PEN-FAST score of 0 or 1. The primary outcome occurred in 1 patient (0.5%) in the intervention group and 1 patient (0.5%) in the control group, with an RD of 0.0084 pp (90% CI, -1.22 to 1.24 pp). The 1-sided 95% CI was below the noninferiority margin of 5 pp. In the 5 days following the oral penicillin challenge, 9 immune-mediated adverse events were recorded in the intervention group and 10 in the control group (RD, -0.45 pp; 95% CI, -4.87 to 3.96 pp). No serious adverse events occurred.

Conclusions and Relevance

In this randomized clinical trial, direct oral penicillin challenge in patients with a low-risk penicillin allergy was noninferior compared with standard-of-care skin testing followed by oral challenge. In patients with a low-risk history, direct oral penicillin challenge is a safe procedure to facilitate the removal of a penicillin allergy label.

Trial Registration

ClinicalTrials.gov Identifier: NCT04454229.

Drug Hypersensitivity Reactions

Drug hypersensitivity reactions are a diverse group of reactions mediated by the immune system after exposure to a drug. The Gell and Coombs classification divides immunologic DHRs into 4 major pathophysiologic categories based on immunologic mechanism. Anaphylaxis is a Type I hypersensitivity reaction that requires immediate recognition and treatment. Severe cutaneous adverse reactions (SCARs) are a group of dermatologic diseases that result from a Type IV hypersensitivity process and include drug reaction with eosinophilia and systemic symptom (DRESS) syndrome, Stevens-Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN), and acute generalized exanthematous pustulosis (AGEP). Other types of reactions are slow to develop and do not always require rapid treatment. Emergency physicians should have a good understanding of these various types of drug hypersensitivity reactions and how to approach the patient regarding evaluation and treatment.

Oral challenge vs routine care to assess low-risk penicillin allergy in critically ill hospital patients (ORACLE): a pilot randomised controlled trial

BACKGROUND

Self-reported penicillin allergies are highly prevalent in hospitalised patients and are associated with poor health and health service outcomes. Critically ill patients have historically been underrepresented in prospective delabelling studies in part due to concerns around clinical stability and reliability of penicillin skin testing. Allergy assessment tools exist to identify low-risk penicillin allergy phenotypes and facilitate direct oral challenge delabelling. PEN-FAST is a clinical decision rule that has been validated to predict true penicillin allergy in a cohort of non-critically ill patients. There is however limited evidence regarding the feasibility, safety and efficacy of direct oral challenges and the use of delabelling clinical decisions rules in the intensive care setting.

METHODS

Critically ill patients in the intensive care unit (ICU) with low-risk penicillin allergy phenotypes (PEN-FAST score < 3) will be randomised 1:1 to direct oral penicillin challenge (single dose 250 mg oral amoxicillin or implicated penicillin) or routine care, followed by a 2-h observation period. Patients will receive a second oral challenge/observation prior to hospital discharge (with subsequent observation for 2 h). An assessment for antibiotic-associated adverse events will also be undertaken at 24 h and 5 days post each challenge/observation and again at 90 days post-randomisation. The primary outcome measures are feasibility (proportion of eligible patients recruited and protocol compliance) and safety (proportion of patients who experience an antibiotic-associated immune-mediated adverse event or serious adverse event).

DISCUSSION

We will report the feasibility and safety of point-of-care penicillin direct oral challenge in this first randomised controlled trial of low-risk penicillin allergy in critically ill hospitalised patients. Upon completion of the project, important findings will inform the design of planned large prospective multi-centre clinical trials in Australian and international ICUs, further examining safety and efficacy and exploring antimicrobial prescribing-related outcomes following penicillin oral challenge.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry Registration Number: ACTRN12621000051842 Date registered: 20/01/2021 https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=379735&isReview=true.

Study protocol for PREPARE: a phase II feasibility/safety randomised controlled trial on PeRiopErative Penicillin AlleRgy TEsting

INTRODUCTION

Patient-reported antibiotic allergy labels (AALs) are common. These labels have been demonstrated to have a negative impact on use of appropriate antibiotics and patient-related health outcomes. These patients are more likely to receive suboptimal antibiotics, have increased rates of surgical site infections and are more likely to be colonised with multidrug-resistant organisms. Increasing recognition that antibiotic allergy forms a key part of good antimicrobial stewardship has led to calls for greater access to antibiotic allergy assessment.PREPARE is a pilot randomised controlled trial of beta-lactam allergy assessment and point of care delabelling in perioperative patients utilising a validated antibiotic allergy assessment tool that has been repurposed into a smartphone application. The aim of the study is to assess the feasibility and safety of this approach in the perioperative outpatient setting.

METHODS AND ANALYSIS

Adult participants requiring elective surgery and are likely to require prophylactic intravenous antibiotics will be recruited. During the intervention phase, participants will be randomised to the intervention or control arm, with control patients receiving usual standard of care. Those randomised to intervention undertake a risk assessment via the smartphone application, with those deemed low risk proceeding to direct oral provocation with either a penicillin or cephalosporin. Study outcomes will be evaluated in the postintervention phase, 30 and 90 days after surgery.Feasibility of intervention delivery and recruitment will be reported as proportions with respective 95% CIs. Participants who experience an antibiotic adverse event will be reported by group with respective 95% CIs and compared using modified Poisson regression model with robust SE estimation.

ETHICS AND DISSEMINATION

This protocol has received approval from the Austin Health human research and ethics committee, Heidelberg, Victoria, Australia (HREC/17/Austin/575). Results will be disseminated via publication in peer-reviewed journals as well as presentation at international conferences.

TRIAL REGISTRATION NUMBER

ACTRN12620001295932.

Safety and value of pretransplant antibiotic allergy delabeling in a quaternary transplant center

BACKGROUND

Self-reported antibiotic allergies, also known as antibiotic allergy labels, are common and may lead to worse patient outcomes. Within immunocompromized patients, antibiotic allergy labels can lead to inappropriate use of antimicrobials and may limit options for prophylactic and therapeutic options in the posttransplant period. While antibiotic allergy delabeling is considered an important aspect of antibiotic stewardship protocols, evidence and awareness of its application in transplant recipients is limited.

METHODS

We describe our experience with an antibiotic allergy delabeling intervention in the pretransplant evaluation period and its impact on posttransplant antimicrobial utilization. This was a retrospective analysis of patients with an antibiotic allergy label who underwent evaluation for solid organ or stem cell transplantation between 2015 and 2020. Patients included in this analysis were those who completed pretransplant antibiotic allergy delabeling through our Drug Allergy Clinic and were retained in care for 6 months after transplant.

RESULTS

Twenty-six of 27 patients underwent pretransplant antibiotic allergy delabeling and safely received the delabeled antibiotic posttransplant. There were no reported side effects to the delabeled antibiotic within 6 months posttransplant. Specific examination of sulfonamide (sulfa)-antibiotic delabeling showed cost savings of $254 to $2910 per patient in the posttransplant period compared to the use of alternative antibiotics for prophylaxis protocol.

CONCLUSION

Antibiotic allergy delabeling prior to transplant is safe, is of high value, and should be considered in the pretransplant evaluation period. More resources are needed for the development of delabeling guidelines and support for broad implementation of pretransplant antibiotic allergy delabeling programs.

Antibiotic Allergy De-Labeling: A Pathway against Antibiotic Resistance

Antibiotics are one of the most frequently prescribed drugs. Unfortunately, they also are the most common cause for self-reported drug allergy, limiting the use of effective therapies. However, evidence shows that more than 90% of patients labeled as allergic to antibiotics are not allergic. Importantly, the label of antibiotic allergy, whether real or not, constitutes a major public health problem as it directly impacts antimicrobial stewardship: it has been associated with broad-spectrum antibiotic use, often resulting in the emergence of bacterial resistance. Therefore, an accurate diagnosis is crucial for de-labeling patients who claim to be allergic but are not really allergic. This review presents allergy methods for achieving successful antibiotic allergy de-labeling. Patient clinical history is often inaccurately reported, thus not being able to de-label most patients. In vitro testing offers a complementary approach but it shows limitations. Immunoassay for quantifying specific IgE is the most used one, although it gives low sensitivity and is limited to few betalactams. Basophil activation test is not validated and not available in all centers. Therefore, true de-labeling still relies on in vivo tests including drug provocation and/or skin tests, which are not risk-exempt and require specialized healthcare professionals for results interpretation and patient management. Moreover, differences on the pattern of antibiotic consumption cause differences in the diagnostic approach among different countries. A multidisciplinary approach is recommended to reduce the risks associated with the reported penicillin allergy label.

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).

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.

New diagnostıc perspectives in the management of pediatrıc beta-lactam allergy

Since overdiagnosis of beta-lactam (BL) allergy is common in the pediatric population, delabeling is a critical part of antimicrobial stewardship. Undesirable consequences of inaccurate BL allergy labeling can be handled by incorporating traditional delabeling or newer risk-based strategies into antibiotic stewardship programs. Conventional assessment of BL allergy relies upon a stepwise algorithm including a clinical history with skin testing followed by drug provocation tests (DPTs). However, a growing number of studies highlighted the suboptimal diagnostic value of skin testing in children. Recently, there has been a paradigm shift in the practice of BL allergy assessment due to recent challenging data which emphasize the safety and accuracy of direct DPTs in children with a suspicion of non-immediate mild cutaneous reactions such as maculopapular eruption, delayed urticaria, and possibly also for benign immediate reactions such as urticaria/angioedema. Identifying low-risk BL allergy patients, in whom skin tests can be skipped and proceeding directly to DPTs could be safe, has become a hot topic in recent years. New risk stratification and predictive modeling studies that have the potential to better predict BL allergy risk status have recently been introduced into the field of drug allergy, particularly in adults. However, in contrast to adults, risk assessment studies in children are rare, and optimal risk definitions are controversial. In the coming years, promising potential methods to elucidate the predictors of BL allergy in children will require multidimensional approaches that may include predictive analytics, artificial intelligence techniques, and point-of-care clinical decision tools.

ESCAPE-Allergy: Evaluating screening for children and adolescents with penicillin allergy

AIM

Penicillin allergy labels are frequently encountered in children and are associated with significant harms. Most children are falsely labelled and can safely tolerate a penicillin but delabelling strategies are underutilised and paediatric-specific resources are lacking. The aim of this study was to evaluate an allergy assessment tool for children in hospital.

METHODS

We evaluated a paediatric-adapted penicillin allergy assessment tool, using an online survey of clinicians in a tertiary paediatric hospital, with 10 hypothetical potential penicillin allergy or adverse reaction cases (including non-allergy reactions). For each case, respondents were asked to use the tool to assign a reaction phenotype and recommend management. We determined the tool's sensitivity, specificity and acceptability to end users.

RESULTS

We evaluated 30 complete survey responses from senior and junior medical staff, nurses and pharmacists. The tool's overall sensitivity was 80.7% (95% confidence interval (CI) 74.2-87.1%) for assigning the correct reaction phenotype and 85.3% (95% CI 79.4-91.3%) for appropriate management. The tool had high sensitivity for identifying immediate hypersensitivity reactions at 95.6% (95% CI 90.2-100%). Most respondents agreed or strongly agreed that they would use the tool in their practice (22/30, 73.3%).

CONCLUSION

This survey evaluated a paediatric-adapted penicillin allergy assessment tool in a tertiary paediatric hospital among multidisciplinary clinician groups. The tool performed well overall and had high safety in identifying immediate hypersensitivity reactions. Further research to support implementation of allergy assessment and delabelling programmes among children is required.

Antimicrobial stewardship in Australia: the role of qualitative research in programme development

Antimicrobial stewardship (AMS) in Australia is supported by a number of factors, including enabling national policies, sectoral clinical governance frameworks and surveillance programmes, clinician-led educational initiatives and health services research. A One Health research programme undertaken by the National Centre for Antimicrobial Stewardship (NCAS) in Australia has combined antimicrobial prescribing surveillance with qualitative research focused on developing antimicrobial use-related situational analyses and scoping AMS implementation options across healthcare settings, including metropolitan hospitals, regional and rural hospitals, aged care homes, general practice clinics and companion animal and agricultural veterinary practices. Qualitative research involving clinicians across these diverse settings in Australia has contributed to improved understanding of contextual factors that influence antimicrobial prescribing, and barriers and facilitators of AMS implementation. This body of research has been underpinned by a commitment to supplementing 'big data' on antimicrobial prescribing practices, where available, with knowledge of the sociocultural, technical, environmental and other factors that shape prescribing behaviours. NCAS provided a unique opportunity for exchange and cross-pollination across the human and animal health programme domains. It has facilitated synergistic approaches to AMS research and education, and implementation of resources and stewardship activities. The NCAS programme aimed to synergistically combine quantitative and qualitative approaches to AMS research. In this article, we describe the qualitative findings of the first 5 years.

Drug Hypersensitivity Reactions

Drug hypersensitivity reactions are a diverse group of reactions mediated by the immune system after exposure to a drug. The Gell and Coombs classification divides immunologic DHRs into 4 major pathophysiologic categories based on immunologic mechanism. Anaphylaxis is a Type I hypersensitivity reaction that requires immediate recognition and treatment. Severe cutaneous adverse reactions (SCARs) are a group of dermatologic diseases that result from a Type IV hypersensitivity process and include drug reaction with eosinophilia and systemic symptom (DRESS) syndrome, Stevens-Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN), and acute generalized exanthematous pustulosis (AGEP). Other types of reactions are slow to develop and do not always require rapid treatment. Emergency physicians should have a good understanding of these various types of drug hypersensitivity reactions and how to approach the patient regarding evaluation and treatment.

Guidelines on Implementing Antimicrobial Stewardship Programs in Korea

These guidelines were developed as a part of the 2021 Academic R&D Service Project of the Korea Disease Control and Prevention Agency in response to requests from healthcare professionals in clinical practice for guidance on developing antimicrobial stewardship programs (ASPs). These guidelines were developed by means of a systematic literature review and a summary of recent literature, in which evidence-based intervention methods were used to address key questions about the appropriate use of antimicrobial agents and ASP expansion. These guidelines also provide evidence of the effectiveness of ASPs and describe intervention methods applicable in Korea.

The Penicillin Allergy Delabeling Program: A Multicenter Whole-of-Hospital Health Services Intervention and Comparative Effectiveness Study

BACKGROUND

Penicillin allergies are associated with inferior patient and antimicrobial stewardship outcomes. We implemented a whole-of-hospital program to assess the efficacy of inpatient delabeling for low-risk penicillin allergies in hospitalized inpatients.

METHODS

Patients ≥ 18 years of age with a low-risk penicillin allergy were offered a single-dose oral penicillin challenge or direct label removal based on history (direct delabeling). The primary endpoint was the proportion of patients delabeled. Key secondary endpoints were antibiotic utilization pre- (index admission) and post-delabeling (index admission and 90 days).

RESULTS

Between 21 January 2019 and 31 August 2019, we assessed 1791 patients reporting 2315 antibiotic allergies, 1225 with a penicillin allergy. Three hundred fifty-five patients were delabeled: 161 by direct delabeling and 194 via oral penicillin challenge. Ninety-seven percent (194/200) of patients were negative upon oral penicillin challenge. In the delabeled patients, we observed an increase in narrow-spectrum penicillin usage (adjusted odds ratio [OR], 10.51 [95% confidence interval {CI}, 5.39-20.48]), improved appropriate antibiotic prescribing (adjusted OR, 2.13 [95% CI, 1.45-3.13]), and a reduction in restricted antibiotic usage (adjusted OR, 0.38 [95% CI, .27-.54]). In the propensity score analysis, there was an increase in narrow-spectrum penicillins (OR, 10.89 [95% CI, 5.09-23.31]) and β-lactam/β-lactamase inhibitors (OR, 6.68 [95% CI, 3.94-11.35]) and a reduction in restricted antibiotic use (OR, 0.52 [95% CI, .36-.74]) and inappropriate prescriptions (relative risk ratio, 0.43 [95% CI, .26-.72]) in the delabeled group compared with the group who retained their allergy label.

CONCLUSIONS

This health services program using a combination of direct delabeling and oral penicillin challenge resulted in significant impacts on the use of preferred antibiotics and appropriate prescribing.

ANAPHYLAXIS AND PREGNANCY: A SYSTEMATIC REVIEW AND CALL FOR PUBLIC HEALTH ACTIONS

BACKGROUND

Although rare, anaphylaxis during pregnancy implies a risk to both mothers and newborns.

OBJECTIVE

This systematic review is intended to identify key issues in the diagnosis and management of this condition in order to support prevention strategies and decrease the risk of death related to anaphylaxis during pregnancy.

METHODS

We searched MEDLINE, Cochrane, Lilacs, Scielo and Science Direct databases for manuscripts concerning terms "anaphylaxis during pregnancy" without language restrictions. We screened studies, extracted data, and assessed risk of bias independently in duplicate.

RESULTS

We selected 12 articles. Frequency of anaphylaxis during pregnancy is estimated between 1.5 to 3.8 per 100 000 maternities. Only one study provided anaphylaxis mortality data in pregnant women, and the rate of anaphylaxis-related maternal mortality is estimated at 0.05 per 100 000 live births. No standard definition of anaphylaxis severity has been utilized. Forty-nine percent to 74% of anaphylaxis cases were described during caesarean sections. Beta-lactam antibiotics (58%), latex (25%) and anaesthetic agents (17%) were the main culprits. In 17% of papers, causative agents were proven by allergy testing. Seventy two percent of articles proposed the same management and treatment for a clinical episode of anaphylaxis during pregnancy as in non-pregnant patients, and, use of epinephrine in the patient's care during anaphylaxis in pregnancy.

CONCLUSION

Few studies address anaphylaxis during pregnancy, and the majority have been produced by non-allergy specialists. Collaboration between different specialists involved in the care of pregnant women should be established in order to support preventive strategies and reduce avoidable deaths.

Classifying cephalosporins: from generation to cross-reactivity

PURPOSE OF REVIEW

To review the most recent literature studying the classifications, immunochemistry, and crossreactivity of allergy reactions to cephalosporins.

RECENT FINDINGS

Over the last five years, research interest has focused on three areas related to cephalosporin allergy: cross-reactivity among cephalosporins and with other beta-lactams; the incidence of adverse reactions in penicillin allergy patients or in reported penicillin allergy labels; and new cephalosporins structures involved in the immunological recognition.

SUMMARY

Meta-analysis of a substantial number of studies shows that cephalosporins are safer than previously thought. Evidence supports two main conclusions in that regard. First, there is a relatively low percentage of cross-reactivity between cephalosporins and other beta-lactams with penicillins in penicillin allergy patients. Second, there is a very low incidence of allergy reactions in nonselected as well as in selected penicillin allergy patients when cephalosporins are used prior to surgical intervention.On the other hand, few structures have been discovered related to the immune mechanism of cephalosporin allergy reactions, and these are far from being ready to use in clinical practice.

Overview of Beta-Lactam Allergy and the Role of the Pharmacist in Management

Unverified beta-lactam allergies are a substantial public health problem, as the majority of patients labeled as beta-lactam allergic do not have clinically significant allergies that may hinder the use beta-lactam therapy when indicated. Outdated or inaccurate beta-lactam or penicillin allergies can result in serious consequences, including suboptimal antibiotic therapy, increased risk of adverse effects, and use of broader spectrum antibiotics than indicated, which may contribute to antimicrobial resistance. The purpose of this review is to provide an overview of beta-lactam allergy and highlight the role of pharmacists in managing beta-lactam allergies. Studies have shown that pharmacists can play a vital role in allergy assessment, penicillin skin testing, beta-lactam desensitization, evaluation of beta-lactam cross-reactivity and recommending appropriate antibiotic therapy in patients with beta-lactam allergies.

Penicillin Allergy Delabeling: A Multidisciplinary Opportunity

The penicillin allergy label has been consistently linked with deleterious effects that span the health care spectrum, including suboptimal clinical outcomes, the emergence of bacterial resistance, and increased health care expenditures. These risks have recently motivated professional organizations and public health institutes to advocate for the implementation of penicillin allergy delabeling initiatives; however, the burden of delabeling millions of patients is too expansive for any one discipline to bear alone. This review presents the unique perspectives and roles of various stakeholder groups involved in penicillin allergy diagnosis, assessment, and delabeling; we emphasize opportunities, barriers, and promising areas of innovation. We summarize penicillin allergy methods and tools that have proven successful in delabeling efforts. A multidisciplinary approach to delabeling patients with reported penicillin allergy, bolstered by evidence-based clinical practices, is recommended to reduce the risks that associate with the penicillin allergy label.

Taking a Rational Approach to a Reported Antibiotic Allergy

Up to 10% of hospitalized patients have an antibiotic allergy label in their medical file, most frequently concerning penicillins. However, the vast majority of reported allergies to antibiotics does not represent a "true" allergy but are due to drug intolerance, idiosyncratic reactions or symptoms of the concurrent infectious disease. Since antibiotic allergy labels result in deviation from first-choice antimicrobial therapy, tackling the issue of incorrect antibiotic allergy labelling, already at young age, is a core element of antibiotic stewardship. In this article, we describe the structured approach to the patient with a presumed antibiotic allergy with emphasis on key elements of allergy-specific history taking and the limited risk of cross-allergic reactions between beta-lactam subclasses.

Unconfirmed penicillin allergy labels in the paediatric outpatient setting: A call for research and quality improvement initiatives

Over the last 10 years, the electronic medical record has redefined medical documentation, and physicians rely on accurate records to make clinical decisions. Penicillin allergy labels (PALs) are important pieces of the medical history that guide physicians in selecting specific antibiotic classes for the treatment of infectious diseases. However, most children labelled as penicillin-allergic do not have an IgE-mediated (immediate) allergic reaction to penicillin or its derivatives. In the absence of confirmatory penicillin allergy testing or additional history, these children receive alternative, often broad-spectrum and second-line, antibiotics. Addressing unconfirmed PALs requires an understanding of how and why labels get added to the electronic medical record. This viewpoint highlights the knowledge gaps in paediatric outpatient penicillin allergy labelling and proposes an acronym ('LABEL') that primary care providers and antimicrobial stewards can utilise when designing initiatives to address unconfirmed PALs in the community.

Treating Through Drug-Associated Exanthems in Drug Allergy Management: Current Evidence and Clinical Aspects

In the setting of an acute cutaneous adverse drug reaction there is increasing interest in selected phenotypes and hosts to continue drug therapy, especially in settings in which there are limited therapeutic options. This concept of "treating through," defined as the continued use of a drug in the setting of, in particular maculopapular exanthema, potentially avoids unnecessary drug discontinuation. A review of the recent literature, historical viewpoints, and expert opinion are provided within to form recommendations and algorithms for a "treating-through" approach.

Outcome of drug provocation testing in children with suspected beta-lactam hypersensitivity

Background

Suspicion of beta-lactam (BL) hypersensitivity is often based on parental report. Evaluation is important as incorrect labelling has clinical consequence.

Objective

To describe the outcomes of drug provocation test (DPT) in children with suspected hypersensitivity.

Methods

A retrospective study of patients who completed BL DPT from 1 August 2016 to 31 December 2017 at a paediatric allergy centre in Singapore. Suspected hypersensitivity reactions were classified as immediate (onset ≤1 hour) or delayed (onset > 1 hour). Patients with immediate reactions underwent skin prick test (SPT) followed by DPT if SPT was negative. Patients with delayed reactions underwent DPT directly.

Results

We identified 120 children who reported 121 suspected hypersensitivity reactions. The median age at reaction was 2.0 years (interquartile range [IQR], 1.0–5.0 years) and the median age at DPT was 7.4 years (IQR, 4.2–11.1 years). The timing of suspected hypersensitivity reaction was immediate in 21% (25 of 121), delayed in 66% (80 of 121), and uncertain in 13% (16 of 121). Commonly implicated drugs were amoxicillin in 45% (54 of 121), amoxicillin-clavulanate in 37% (45 of 121), and cephalexin in 8% (10 of 121). Commonly reported symptoms were maculopapular rash 44% (53 of 121), urticaria 34% (41 of 121), and angioedema 22% (27 of 121). All SPTs (n = 26) were negative. There were 118 diagnostic DPTs to index drug and 3 DPTs to alternative drug. A negative challenge result was obtained in 93% (110 of 118) of diagnostic DPTs: 92% (96 of 104) and 100% (14 of 14) of DPTs to penicillin group and cephalosporins respectively. All challenge reactions were mild.

Conclusion

Our study supports the opinion that prior skin tests may not be necessary for children who report nonsevere reactions and directly performing diagnostic DPT is a safe approach in the evaluation of suspected childhood BL hypersensitivity.

The role of a clinical pharmacist in spurious Penicillin allergy: a narrative review

Background A label of penicillin allergy is held by 6-10% of the general population and 15-20% of inpatients. > 90% of these labels are found to be spurious after formal allergy assessment. Carrying an unnecessary label of penicillin allergy is not benign. Such patients may receive second line, more expensive antibiotics, representing a significant impediment to antimicrobial stewardship. Aim of the review To (a) Explain the burden of spurious penicillin allergy, and evaluate the safety of direct oral penicillin challenge in 'low risk' patients (b) appraise the place for a clinical pharmacist-led penicillin allergy de-labelling programme. Method Narrative review. Search engines: PubMed, Google Scholar and Cochrane reviews. Search criteria: English language; search terms: penicillin allergy, antimicrobial stewardship, antimicrobial resistance, clostridium difficile, vancomycin resistant enterococci, risk stratification, clinical pharmacist and direct oral provocation test Results Penicillin allergy labels are associated with: longer hospital stay, higher readmission rates, enhanced risk of surgical site infections, risk of Clostridioides difficile infection and Methicillin resistant Staphylococcus aureus infection, a delay in the first dose of an antibiotic in sepsis and higher healthcare costs. A direct oral penicillin challenge in 'low risk' patients has proven to be safe. Discussion Recent studies including those led by a clinical pharmacist have demonstrated safety of a direct oral penicillin challenge in 'low risk' patients. This intervention needs validation within individual health services. Conclusion Direct oral penicillin challenge reduces the adverse impact of spurious penicillin allergy. A pharmacist-led penicillin allergy de-labelling program needs further validation in prospective multi-centre studies.

An Updated Review of the Diagnostic Methods in Delayed Drug Hypersensitivity

Delayed drug hypersensitivity reactions are clinically diverse reactions that vary from isolated benign skin conditions that remit quickly with no or symptomatic treatment, drug discontinuation or even continued drug treatment, to the other extreme of severe cutaneous adverse reactions (SCARs) that are associated with presumed life-long memory T-cell responses, significant acute and long-term morbidity and mortality. Diagnostic "in clinic" approaches to delayed hypersensitivity reactions have included patch testing (PT), delayed intradermal testing (IDT) and drug challenges for milder reactions. Patch and IDT are, in general, performed no sooner than 4-6 weeks after resolution of the acute reaction at the maximum non-irritating concentrations. Functional in vitro and ex vivo assays have largely remained the province of research laboratories and include lymphocyte transformation test (LTT) and cytokine release enzyme linked ImmunoSpot (ELISpot) assay, an emerging diagnostic tool which uses cytokine release, typically IFN-γ, after the patient's peripheral blood mononuclear cells are stimulated with the suspected drug(s). Genetic markers such as human leukocyte antigen have shown recent promise for both pre-prescription screening as well as pre-emptive and diagnostic testing strategies.

Penicillin Allergy De-labeling Results in Significant Changes in Outpatient Antibiotic Prescribing Patterns

Unverified penicillin allergies are common but most patients with a penicillin allergy label can safely use penicillin antibiotics. Penicillin allergy labels are associated with poor clinical outcomes and overuse of second-line antibiotics. There is increasing focus on penicillin allergy "de-labeling" as a tool to improve antibiotic prescribing and antimicrobial stewardship. The effect of outpatient penicillin allergy de-labeling on long-term antibiotic use is uncertain. We performed a retrospective pre- and post- study of antibiotic dispensing patterns, from an electronic dispensing data repository, in patients undergoing penicillin allergy assessment at Auckland City Hospital, New Zealand. Over a mean follow-up of 4.55 years, 215/304 (70.7%) of de-labeled patients were dispensed a penicillin antibiotic. Rates of penicillin antibiotic dispensing were 0.24 (0.18-0.30) penicillin courses per year before de-labeling and 0.80 (0.67-0.93) following de-labeling with a reduction in total antibiotic use from 2.30 (2.06-2.54) to 1.79 (1.59-1.99) antibiotic courses per year. In de-labeled patients, the proportion of antibiotic courses that were penicillin antibiotics increased from 12.81 to 39.62%. Rates of macrolide, cephalosporin, trimethoprim/co-trimoxazole, fluoroquinolone, "other" non-penicillin antibiotic use, and broad-spectrum antibiotic use were all lower following de-labeling. Further, antibiotic costs were lower following de-labeling. In this study, penicillin allergy de-labeling was associated with significant changes in antibiotic dispensing patterns.

Implementation of a pharmacist-led penicillin allergy de-labelling service in a public hospital

BACKGROUND

Inaccurate allergy labelling results in inappropriate antimicrobial management of the patient, which may affect clinical outcome, increase the risk of adverse events and increase costs. Inappropriate use of alternative antibiotics has implications for antimicrobial stewardship programmes and microbial resistance.

METHODS

All adult inpatients labelled as penicillin allergic were identified and screened for eligibility by the study pharmacist. An accurate allergy and medication history was taken. Patients were 'de-labelled', underwent oral challenge or were referred to an immunology clinic, if study criteria were met. All patients included in the study were followed-up 1 year after intervention.

RESULTS

Two hundred and fifty eligible patients with a label of 'penicillin allergy' were identified. The prevalence of reported penicillin allergy at Middlemore Hospital was 11%. We found that 80% of study patients could be 'de-labelled'. Of those, 80% were 'de-labelled' after an interview with the pharmacist alone, 16% had an uneventful oral challenge and 4% were deemed to be inappropriately labelled after referral to an immunology clinic. Appropriately labelled patients accounted for 20% of the study population. Changes to inpatient antibiotic therapy were recommended in 61% of 'de-labelled' patients, of which no patients had adverse events after commencing on penicillin antibiotics. At the 1 year follow-up, 98% of patients who were 'de-labelled' had no adverse events to repeated administration of penicillin antibiotics.

CONCLUSIONS

This study showed that a pharmacist-led allergy management service is a safe option to promote antimicrobial stewardship and appropriate allergy labelling.

Evaluation of a pharmacist-led penicillin allergy de-labelling ward round: a novel antimicrobial stewardship intervention

BACKGROUND

Antibiotic allergy labels (AALs), reported by up to 25% of hospitalized patients, are a significant barrier to appropriate prescribing and a focus of antimicrobial stewardship (AMS) programmes.

METHODS

A prospective audit of a pharmacist-led AMS penicillin allergy de-labelling ward round at Austin Health (Melbourne, Australia) was evaluated. Eligible inpatients with a documented penicillin allergy receiving an antibiotic were identified via an electronic medical report and then reviewed by a pharmacist-led AMS team. The audit outcomes evaluated were: (i) AMS post-prescription review recommendations; (ii) direct de-labelling; (iii) inpatient oral rechallenge referral; (iv) skin prick testing/intradermal testing referral; and (v) outpatient antibiotic allergy clinic assessment.

RESULTS

Across a 5 month period, 106 patients were identified from a real-time electronic prescribing antibiotic allergy report. The highest rate of penicillin allergy de-labelling was demonstrated in patients who were referred for an inpatient oral rechallenge with 95.2% (n = 21) successfully having their penicillin AAL removed. From the 22 patients with Type A reactions, 63.6% had their penicillin AAL removed. We demonstrated a significant decrease in the prescribing of restricted antibiotics (defined as third- or fourth-generation cephalosporins, fluoroquinolones, glycopeptides, carbapenems, piperacillin/tazobactam, lincosamides, linezolid or daptomycin) in patients reviewed (pre 42.5% versus post 17.9%, P = 0.0002).

CONCLUSIONS

A pharmacist-led AMS penicillin allergy de-labelling ward round reduced penicillin AALs and the prescribing of restricted antibiotics. This model could be implemented at other hospitals with existing AMS programmes.

The democratization of de-labeling: a review of direct oral challenge in adults with low-risk penicillin allergy

INTRODUCTION

Penicillin antibiotic allergy labels (AALs) are common and lead to significant negative health and health system outcomes. Direct oral challenge offers a rapid and cost-effective way of removing inaccurate AALs and improving outcomes.

AREAS COVERED

A narrative review (Medline, May 2020) of direct oral challenge in low-risk penicillin allergy in adults is described, and the evidence for the safety and efficacy of this approach in inpatients, outpatients, and special patient groups is presented.

EXPERT OPINION

Whilst the current literature demonstrates the safety and efficacy of direct oral challenge in de-labeling low-risk penicillin allergy in adults, novel approaches are needed to improve access to antibiotic allergy assessment and address the growing global need.

β-Lactam allergy testing and delabeling-Experiences and lessons from Singapore

Background

β‐Lactam allergy is over‐reported and this leads to greater healthcare costs. Allergy testing has inherent risks, yet patients who test negative may continue avoiding β‐lactams.

Objective

To evaluate the safety and diagnostic value of β‐lactams allergy testing locally and usage of antibiotics following negative testing.

Methods

We performed a retrospective medical record review and follow‐up survey of patients who underwent β‐lactam testing between 2010 and 2016 at the National Skin Centre, Singapore.

Results

We reviewed the records of 166 patients, with a total of 173 β‐lactam allergy labels. Eighty (46.2%) labels were to penicillin, 75 (43.1%) to amoxicillin/amoxicillin‐clavulanic acid, 11 (6.4%) to cephalexin, and 5 (2.9%) to others. Skin tests were performed in 142 patients and drug provocation tests (DPTs) in 141 patients. Eleven (6.6%) patients defaulted DPTs after skin testing. Out of 166 patients, 22 (13.3%) patients were proven allergic by either skin tests (16) or DPTs (6). Patients who tested positive had nonsevere reactions.

Out of 155 patients who were conclusively evaluated, 133 (85.8%) were not allergic. Of these patients, 30 (22.6%) used the tested β‐lactam subsequently, with one reporting a mild reaction. Fifty‐one (38.3%) patients were uncontactable or uncertain if they consumed a β‐lactam since testing negative. Fifty‐two (39.1%) patients had no re‐exposure (35 had no indication, 17 were fearful of reactions).

Conclusion

Drug allergy testing was safe and removed inappropriate labels.

Clinical Implication

Allergy testing is efficacious, but fears of subsequent rechallenge should be addressed to maximize the effectiveness of allergy delabeling.

Is there a higher prevalence of methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus (VRE) colonization in patients with antibiotic allergy labels?

BACKGROUND

A penicillin allergy label has been associated with significantly higher rates of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) colonization, and correspondingly poorer clinical outcomes. However, there are limited data examining the association between any antibiotic label and colonization rates. We sought to evaluate if there is a relationship between patients with an antibiotic allergy label and prevalence of MRSA or VRE colonization.

METHODS

We retrospectively reviewed all patients with an MRSA surveillance culture between December 15, 2014 and January 31, 2015, or a VRE surveillance culture between January 1, 2013 and January 31, 2015, at a tertiary community-based teaching hospital. Our primary objective was to evaluate the prevalence of MRSA or VRE colonization among patients with and without antibiotic allergies. Bivariate analyses included the χ² test and the Student t test to determine statistical significance for categorical and continuous variables, respectively.

RESULTS

We included a total of 1,053 unique patients screened for MRSA, and 290 unique patients screened for VRE. The rate of MRSA and VRE colonization was 5.8% (62 of 1,053) and 32.4% (94 of 290), respectively, in our cohort. Antibiotic allergies were documented in approximately 1 out of 3 patients, 337 (32%) for the MRSA group and 94 (32%) for VRE group. There was a significant difference in MRSA colonization between patients with and without an antibiotic allergy, 28 of 337 (8.3%) versus 34 of 716 (4.7%) (P = .025), respectively. In contrast, there was no significant difference in antibiotic allergy rates with and without VRE colonization, 34 of 94 (36.2%) versus 92 of 196 (46.9%) (P = .10), respectively.

CONCLUSIONS

An antibiotic allergy label was associated with significantly higher rates of MRSA colonization but no statistical difference with VRE colonization.

Development and Validation of a Penicillin Allergy Clinical Decision Rule

IMPORTANCE

Penicillin allergy is a significant public health issue for patients, antimicrobial stewardship programs, and health services. Validated clinical decision rules are urgently needed to identify low-risk penicillin allergies that potentially do not require penicillin skin testing by a specialist.

OBJECTIVE

To develop and validate a penicillin allergy clinical decision rule that enables point-of-care risk assessment of patient-reported penicillin allergies.

DESIGN, SETTING, AND PARTICIPANTS

In this diagnostic study, a multicenter prospective antibiotic allergy-tested cohort of 622 patients from 2 tertiary care sites in Melbourne, Australia (Austin Health and Peter MacCallum Cancer Centre) was used for derivation and internal validation of a penicillin allergy decision rule. Backward stepwise logistic regression was used to derive the model, including clinical variables predictive of a positive penicillin allergy test result. Internal validation of the final model used bootstrapped samples and the model scoring derived from the coefficients. External validation was performed in retrospective penicillin allergy-tested cohorts consisting of 945 patients from Sydney and Perth, Australia, and Nashville, Tennessee. Patients who reported a penicillin allergy underwent penicillin allergy testing using skin prick, intradermal, or patch testing and/or oral challenge (direct or after skin testing). Data were collected from June 26, 2008, to June 3, 2019, and analyzed from January 9 to 12, 2019.

MAIN OUTCOMES AND MEASURES

The primary outcome for the model was any positive result of penicillin allergy testing performed during outpatient or inpatient assessment.

RESULTS

From an internal derivation and validation cohort of 622 patients (367 female [59.0%]; median age, 60 [interquartile range{IQR}, 48-71] years) and an external validation cohort of 945 patients (662 female [70.1%]; median age, 55 [IQR, 38-68] years), the 4 features associated with a positive penicillin allergy test result on multivariable analysis were summarized in the mnemonic PEN-FAST: penicillin allergy, five or fewer years ago, anaphylaxis/angioedema, severe cutaneous adverse reaction (SCAR), and treatment required for allergy episode. The major criteria included an allergy event occurring 5 or fewer years ago (2 points) and anaphylaxis/angioedema or SCAR (2 points); the minor criterion (1 point), treatment required for an allergy episode. Internal validation showed minimal mean optimism of 0.003 with internally validated area under the curve of 0.805. A cutoff of less than 3 points for PEN-FAST was chosen to classify a low risk of penicillin allergy, for which only 17 of 460 patients (3.7%) had positive results of allergy testing, with a negative predictive value of 96.3% (95% CI, 94.1%-97.8%). External validation resulted in similar findings.

CONCLUSIONS AND RELEVANCE

In this study, PEN-FAST was found to be a simple rule that accurately identified low-risk penicillin allergies that do not require formal allergy testing. The results suggest that a PEN-FAST score of less than 3, associated with a high negative predictive value, could be used by clinicians and antimicrobial stewardship programs to identify low-risk penicillin allergies at the point of care.

A Practical Guide for Managing Antibiotic Allergies in the Emergency Department

Up to 30% of patients report at least one antibiotic allergy, but oftentimes these antibiotic allergies are misdiagnosed. In fact, of the 10% of patients reporting penicillin allergies, 90%-98% are not truly allergic. In an era of increasing antibiotic resistance coupled with a limited number of new antibiotics, evaluating antibiotic allergies is critical in providing optimal patient care. Differentiating adverse drug reactions from antibiotic allergies may seem like a daunting task for clinicians and providers, especially in the emergency department, where decisions are made quickly. However, a systemic approach, including medical record review coupled with patient and/or family interview, is vital in managing patients with antibiotic allergies. Inappropriate, alternative antibiotics are frequently chosen due to patient allergies, and data suggest higher rates of broad-spectrum antibiotic use, antibiotic resistance, and poor outcomes as a result. Herein, we review antibiotic selection in patients reporting antibiotic allergies in the emergency department.

The challenge of de-labeling penicillin allergy

BACKGROUND

Even though 8%-25% of most populations studied globally are labeled as penicillin allergic, most diagnoses of penicillin allergy are made in childhood and relate to events that are either not allergic in nature, are low risk for immediate hypersensitivity, or are a potential true allergy that has waned over time. Penicillin allergy labels directly impact antimicrobial stewardship by leading to use of less effective and broader spectrum antimicrobials and are associated with antimicrobial resistance. They may also delay appropriate antimicrobial therapy and lead to increased risk of specific adverse healthcare outcomes. Operationalizing penicillin allergy de-labeling into a new arm of antimicrobial stewardship programs (ASPs) has become an increasing global focus.

METHODS

We performed an evidence-based narrative review of the literature of penicillin allergy label carriage, the adverse effects of penicillin allergy labels, and current approaches and barriers to penicillin allergy de-labeling. Over the period 1928-2018 in Pubmed and Medline, search terms used included "penicillin allergy" or "penicillin hypersensitivity" alone or in combination with "adverse events," "testing," "evaluation," "effects," "label," "de-labeling," "prick or epicutaneous," and "intradermal" skin testing, "oral challenge or provocation," "cross-reactivity," and "antimicrobial stewardship".

RESULTS

Penicillin allergy labels are highly prevalent, largely inaccurate and their carriage may lead to unnecessary treatment and inferior outcomes with alternative agents as well as adverse public health outcomes such as antibiotic resistance.

CONCLUSIONS

Operationalizing penicillin allergy de-labeling as an aspect of ASP has become an increasing global focus. There is a need for validated approaches that optimally combine the use of history and ingestion challenge with or without proceeding formal skin testing to tackle penicillin allergy efficiently within complex healthcare systems. At the same time, there is great promise for penicillin allergy evaluation and de-labeling as an individual and public health strategy to reduce adverse healthcare outcomes, improve antimicrobial stewardship, and decrease healthcare costs.

Allergological Study of 565 Elderly Patients Previously Labeled as Allergic to Penicillins

Purpose

Elderly people thought to have an allergy to beta-lactams (BLs) may tolerate the drugs in subsequent exposures due to initial false labeling of allergies, the spontaneous loss of sensitivity to BLs over time or age-related decline in sensitization. As a result, they may be treated with less appropriate antibiotics, causing more side effects and entailing increased costs for health systems. The aim of this investigation was to assess whether patients in the third and fourth age with previously confirmed allergies to BLs had lost sensitization and could tolerate these antibiotics.

Patients and methods

Patients allergic to BLs were divided into group A (aged 60-79 years) and B (aged ≥80 years). Clinical history, skin testing, drug challenge tests (DCT) and evaluation of resensitization were used to classify participants as showing immediate reactions, non-immediate reactions, or tolerance. We compared clinical entities, drugs involved, and final outcome by age group.

Results

Of 1362 cases evaluated, 565 underwent an allergological study. The skin was the most common organ involved. Anaphylaxis and side chain reactions were more frequent in group A (p<0.01), as were positive DCT. Classical benzylpenicillin determinants (benzylpenicilloyl and/or minor determinant mixture) were more frequent triggers in group B (p< 0.01). Resensitization after challenge occurred in very few participants.

Conclusion

The risk for allergy to BLs decreases with age and a history of anaphylaxis by BLs is a predictor of positive results in skin tests (ST). Both immunoglobin E (IgE) and T-cell-mediated responses can disappear in elderly people, who can develop tolerance to these antibiotics. These results are of clinical relevance to patients who need to be treated with antibiotics from this family.

Sulfonamide desensitization in solid organ transplant recipients: A protocol-driven approach during the index transplant hospitalization

Trimethoprim-sulfamethoxazole (TMP-SMX) is the first-line agent for Pneumocystis jiroveci pneumonia (PJP) prophylaxis for solid organ transplant (SOT) recipients because of its efficacy for this indication, extended antimicrobial coverage, and favorable cost. Reported sulfonamide allergy is not uncommon and often results in TMP-SMX avoidance. Desensitization offers an efficacious and cost-effective alternative to TMP-SMX avoidance. Herein, we reviewed our experience with desensitization during the index transplant hospitalization among 52 SOT recipients with history of a non-anaphylactic sulfonamide allergy. Of those enrolled in the desensitization protocol, 92% (48/52) completed the protocol, with nearly 80% (41/52) still on TMP-SMX at 3 months without adverse reaction. Eleven patients discontinued TMP-SMX (7 for allergic reactions and 4 for non-allergic reasons) and switched to pentamidine. A cost savings of $575 per desensitization was calculated based on annual wholesale drug prices, for a total savings of $23 575. Additionally, the protocol did not delay discharge in any patient nor was it associated with any severe allergic reactions. These findings suggest TMP-SMX desensitization is safe and effective in SOT recipients with a history of non-anaphylactic, non-life-threatening sulfonamide hypersensitivity.

Penicillin allergy skin testing as an antibiotic stewardship intervention reduces alternative antibiotic exposures in hematopoietic stem cell transplant recipients

BACKGROUND

Antibiotic allergy de-labeling using penicillin allergy skin testing (PAST) can reduce the use and cost of alternative, non-β-lactam antibiotics in general inpatient populations. This strategy's role in hematopoietic stem cell transplant (HSCT) recipients is unclear.

METHODS

This study aimed to determine the effect of a pre-transplant PAST protocol on antibiotic use, days of therapy (DOT), and cost in an immunocompromised population at a single center from 7/1/2010-2/1/2019. Patients who received chimeric antigen receptor (CAR) T-cell therapy and those who underwent transplantation in the outpatient setting were excluded.

RESULTS

Of 1560 patients who underwent inpatient HSCT during the study period, 208 reported β-lactam allergy (136/844 [16%] pre- and 72/716 [10%] post-implementation; P < .001). PAST was performed on 7% and 54% of HSCT recipients pre- and post-implementation, respectively. Only two positive PAST were noted. There were no adverse reactions to PAST. There were no significant differences in the disease and transplant characteristics between the two groups. Days of therapy and cost of alternative antibiotics significantly decreased post-implementation (mean 788 vs 627 days, P = .01; mean $24 425 vs $17 518, P = .009).

CONCLUSION

Penicillin allergy skin testing adjudicates reported β-lactam allergy in HSCT recipients, lowering use, DOT, and cost of alternative antibiotics and promoting effective formulary agents to treat immunocompromised HSCT recipients.

Beta-Lactam and Sulfonamide Allergy Testing Should Be a Standard of Care in Immunocompromised Hosts

Antibiotic allergies are reported in up to 1 in 4 immunocompromised hosts with significant impacts on antibiotic utilization and patient outcomes. Health services programs focused on de-labeling beta-lactam and sulfonamide allergy labels should be a standard of care in immunocompromised hosts.