Positive Skin Test or Specific IgE to Penicillin Does Not Reliably Predict Penicillin Allergy

Clinical Relevance of Specific IgE in Penicillin Allergy Investigation

INTRODUCTION

Patients with immediate type allergic reactions to penicillins are at risk of anaphylaxis on reexposure. Diagnostic gold standard is drug provocation test (DPT) if allergy is not diagnosed by other means, such as skin testing or in vitro testing with measurement of specific IgE. Specific IgE testing carries low risk for the patient and blood sampling can be performed in primary care, but it is reported to have low sensitivity. The aim of this study was to evaluate if clinical characteristics of patients with suspected allergic reactions to penicillin and elevated specific IgE to penicillins, differed from patients without specific IgE, to identify predictors for elevated specific IgE to penicillins.

METHODS

Levels of specific IgE to five penicillins (penicillin G, penicillin V, amoxicillin, ampicillin, and penicillin minor determinants) were available for 9,100 patients. Using multiple logistic regression, clinical data from 430 patients in this group who had elevated specific IgE to one or more penicillins were compared to data from 4,094 patients without specific IgE to penicillins, who had undergone DPT with a penicillin.

RESULTS

In total 5.2% of patients had elevated specific IgE to one or more penicillins. Significantly more patients with elevated specific IgE had a history of immediate type reactions (<2 h) (OR = 4.34, p < 0.001); circulatory symptoms (OR = 1.63, p = 0.03) or angioedema (OR = 1.46, p = 0.005). Also, significantly more patients with elevated specific IgE had been treated with adrenaline (OR = 2.21, p = 0.005), steroids (OR = 1.76, p < 0.001), or antihistamines (OR = 1.83, p < 0.001).

CONCLUSION

A history of an immediate type reaction requiring treatment, combined with elevated specific IgE to one or more penicillins is suggestive of an IgE mediated penicillin allergy and further allergy investigations may not be needed. Specific IgE to penicillins may be used early in allergy investigation of patients with severe immediate type reactions to penicillins.

The Burden of Self-Reported Antibiotic Allergies in Health Care and How to Address It: A Systematic Review of the Evidence

BACKGROUND

Antibiotics are the first-line treatment for bacterial infections; however, overuse and inappropriate prescribing have made antibiotics less effective with increased antimicrobial resistance. Unconfirmed reported antibiotic allergy labels create a significant barrier to optimal antimicrobial stewardship in health care, with clinical and economic implications.

OBJECTIVE

A systematic review was conducted to summarize the impact of patient-reported antibiotic allergy on clinical outcomes and various strategies that have been employed to effectively assess and remove these allergy labels, improving patient care.

METHODS

The review was undertaken using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A critical appraisal was conducted on all studies and a narrative synthesis was performed to identify themes.

RESULTS

Four themes emerged: the prevalence of antibiotic allergy, impact of antibiotic allergy on antimicrobial prescribing, impact of antibiotic allergy on clinical outcomes, and delabeling strategies to improve clinical outcomes. Of the 32 studies, including 1,089,675 participants, the prevalence of reported antibiotic allergy was between 5% and 35%. Patients with a reported antibiotic allergy had poorer concordance with prescribing guidelines in 30% to 60% of cases, with a higher use of alternatives such as quinolone, tetracycline, macrolide, lincosamide, and carbapenem and lower use of beta-lactam antibiotics. Antibiotic allergy delabeling was identified as an intervention and recommendation to advance the state of the science.

CONCLUSIONS

There is substantial evidence within the literature that antibiotic allergy labels significantly impact patient clinical outcomes and a consensus that systematic assessment of reported antibiotic allergies, commonly referred to as delabeling, improves the clinical management of patients.

The Evolution of Our Understanding of Penicillin Allergy: 1942-2022

This article reviews our evolving understanding of penicillin hypersensitivity at the 80th anniversary of penicillin's clinical introduction. Penicillin breakdown products covalently bond to serum proteins, leading to classic drug hypersensitivity. Penicillin remains the most frequently reported drug "allergy." Adverse reactions were presumed, in retrospect incorrectly, to implicate a risk for anaphylaxis, and therefore skin testing for IgE became the focus. Skin test positivity may wane over time. This insight has led to the radical conclusion that penicillin hypersensitivity may not be "forever." Atopic background, other drug allergies, family history, gender, and race are apparently not risk factors for penicillin hypersensitivity. Confirmed penicillin hypersensitivity has declined since the 1960s, potentially due to "cleaner" penicillin products and lower dose oral, instead of parenteral, use. Avoiding penicillins, without evaluation, caused unanticipated problems that have been appreciated only recently including longer hospital stays, increased cost of care, suboptimal outcomes from serious infections, and greater toxicities and costs with alternative antibiotics. There are personal and public health advantages with broadly implemented penicillin allergy delabeling based on a reaction history-based risk assessment. Limited skin testing followed by an oral challenge, if negative, for higher-risk histories, and direct oral challenges in lower-risk individuals are currently the reference standard tests to confirm current tolerance.

Skin testing as a biomarker in drug allergy

Despite the significant negative impact drug allergies can have on patient care, the diagnosis is largely based on clinical history, and there are limited diagnostic tests that can be done at the time of a reaction. Biomarkers are needed to improve the diagnosis and the identification of the culprit medication. Skin testing is the most useful biomarker for immediate- and delayed-type reactions available, but it is limited by its low sensitivity. To improve its accuracy and reproducibility, a standardized procedure must be used. For immediate-type reactions, penicillin skin testing is the most widely studied, and it can be used in patients with history of anaphylaxis or recent immunoglobulin E-mediated reaction or for whom there is a significant risk if a reaction were to occur, such as pregnancy. Skin testing is also important in allergy to platinum agents allowing for continued first-line therapy. For delayed-type reactions, patch testing and delayed intradermal testing, used in conjunction with clinical history, can help to improve identification of the culprit medication depending on the type of reaction. Other biomarkers including in vitro testing for specific immunoglobulin E, basophil activation test, lymphocyte transformation test, ELISpot, and genetic factors that increase the likelihood of reaction are under investigation, and they may be most helpful when used in combination with the clinical history and skin testing results.

Is Penicillin Allergy a Risk Factor for Surgical Site Infection After Oral and Maxillofacial Surgery?

PURPOSE

The selection of perioperative antibiotics for prevention of surgical site infection (SSI) is often limited by the presence of a reported penicillin allergy. The purpose of this study was to determine if oral and maxillofacial surgery patients who report allergy to penicillin are at an increased risk of developing SSI.

METHODS

A retrospective cohort study was performed of patients who underwent oral and maxillofacial surgical procedures in the operating room setting at a single institution between 2011 and 2018. The following categories of procedures were investigated: dentoalveolar, orthognathic, orthognathic with third molar extraction, pathology and reconstruction, and temporomandibular joint. The primary predictor and outcome variables were reported penicillin allergy and surgical site infection, respectively. Bivariate and multiple logistic regression analysis were performed. P < .05 was considered to be significant.

RESULTS

The cohort was composed of 2,058 patients of which 318 (15.5%) reported allergy to penicillin. Beta-lactam antibiotics were administered less frequently to penicillin allergic patients perioperatively compared with those without penicillin allergy (7.9 vs 97.1%, P < .001), while clindamycin was more commonly administered (76.4 vs 2.5%, P < .001). Clindamycin was associated with a higher SSI rate compared with beta-lactam antibiotics (5.6 vs 1.4%, P < .001). Penicillin allergy was significantly associated with SSI at an adjusted odds ratio of 2.61 (95% CI 1.51 to 4.49, P = .001). After holding perioperative antibiotic usage equal between the 2 groups, penicillin allergy per se was no longer associated with SSI (P = .901), suggesting that the outcome was mediated by antibiotic selection.

CONCLUSIONS

Penicillin allergy was associated with development of SSI due to receipt of non-beta-lactam antibiotics as perioperative prophylaxis. Formal allergy evaluation should be considered for patients with putative penicillin allergy.

Alleged Allergy to Penicillin and Isolation Issues: Toward New Practices for French Navy?

INTRODUCTION

According to the literature, 8% of the population claim to have an allergy to penicillin. Allergy tests show that 90% of these patients tolerate this molecule. Physicians working in the French Navy are faced with situations of real isolation and only have a limited number of antibiotics on board, the majority of which are penicillins. They must anticipate the risks linked to the prescription of antibiotics before the mission. However, there is no French recommendation, either military or civilian, intended for general practitioners clarifying the management and allergy assessments of patients alleging a history of allergy to penicillin. This study is the first to evaluate the professional practices of French military practitioners taking care of these patients. The main objective was to evaluate the proportion of sailors who reported an allergy to penicillin and who have never been referred for a consultation with an allergist, by studying the medical files of all the submariners working on the submersible ballistic nuclear submarines squadron in Brest. The secondary objective was to compare these data with the practices of Navy doctors by means of questionnaires.

MATERIAL AND METHODS

Our work is composed of two parts: monocentric study of the digital and paper medical files of Brest submariners (n = 814) looking for allergist consultation reports in cases alleging an allergy to penicillin, then comparison with a multicentric collection of all Navy doctors' practices collected by an anonymized questionnaire (n = 37 out of 53 practicing at the time of the study).

RESULTS

Forty-seven subjects out of 814 alleged an allergy to penicillin (5.8%). Among them, only 12 (25.5%) had undergone allergy tests, of which 3 (6.4%) were confirmed to be allergic, with no cross-reaction between β-lactam antibiotics. Yet, according to the questionnaire, 25 doctors (67%) report referring their patients to an allergist and 16 (43%) report having had difficulties at sea in connection with the prescription of antibiotics for these patients.

CONCLUSIONS

A study of medical records shows that the allergic risk is not anticipated for 74.5% of patients labeled allergic, despite the difficulties encountered at sea. Standardization of practices within the French Navy is necessary to avoid the prescription of second-line antibiotics, less effective and sometimes unavailable on board, and to improve patient safety in isolation situations. In agreement with French military allergists, we propose, in this article, guidelines for a systematic exploration of allegations of allergy to penicillin in the French Navy.

Drug-specific history, skin and in vitro tests can reduce the need for drug provocation tests in betalactam-hypersensitivity

BACKGROUND

Many patients report questionable drug hypersensitivity reactions (DHR) to betalactam antibiotics. A workup is required for objectivation. Direct drug provocation tests (DPTs) omitting a prior allergy workup are increasingly recommended as the primary diagnostic approach. However, apart from the risk of severe side effects, DPTs often are a scarce resource in overloaded healthcare-systems. We investigated how many cases can be solved by drug-specific history, drug-specific IgE, and skin tests obviating the need for DPT.

METHODS

We conducted a chart review in a retrospective cohort of 932 patients in an allergy outpatient centre from 2016 to 2017. Patients had been submitted to drug-specific history and specific IgE-, skin prick-, intradermal- and patch-tests with early and late readings with a series of penicillins and cephalosporins but DPTs were no option.

RESULTS

Overall, positive in vitro and/or skin tests were found in 96/932 (10.3%) patients. Drug-specific IgE was detected in 40/932 (4.3%) patients, 61/787 (7.8%) patients had positive skin tests. In vitro tests to Pencillin V showed the highest rate of positivity 24/479 (5.0%) and early readings of ampicillin the highest amongst the skin tests (3/49, 6.1%). Immediate skin tests were more often positive than delayed ones (75:45). The combination of all parameters including drug-specific history solved 346/932 (37.1%) cases while 586/932 (62.9%) remained unresolved. Self-reported DHR could be less often confirmed in females and young children (p < 0.05).

CONCLUSIONS

Testing with betalactams applying simple, cheap, and safe skin and blood tests can solve a third of DHR-cases on a high throughput scale.

AllergoOncology: ultra-low IgE, a potential novel biomarker in cancer-a Position Paper of the European Academy of Allergy and Clinical Immunology (EAACI)

Elevated serum IgE levels are associated with allergic disorders, parasitosis and specific immunologic abnormalities. In addition, epidemiological and mechanistic evidence indicates an association between IgE-mediated immune surveillance and protection from tumour growth. Intriguingly, recent studies reveal a correlation between IgE deficiency and increased malignancy risk. This is the first review discussing IgE levels and links to pathological conditions, with special focus on the potential clinical significance of ultra-low serum IgE levels and risk of malignancy. In this Position Paper we discuss: (a) the utility of measuring total IgE levels in the management of allergies, parasitosis, and immunodeficiencies, (b) factors that may influence serum IgE levels, (c) IgE as a marker of different disorders, and d) the relationship between ultra-low IgE levels and malignancy susceptibility. While elevated serum IgE is generally associated with allergic/atopic conditions, very low or absent IgE may hamper anti-tumour surveillance, indicating the importance of a balanced IgE-mediated immune function. Ultra-low IgE may prove to be an unexpected biomarker for cancer risk. Nevertheless, given the early stage of investigations conducted mostly in patients with diseases that influence IgE levels, in-depth mechanistic studies and stratification of malignancy risk based on associated demographic, immunological and clinical co-factors are warranted.

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.

Safety of direct drug provocation testing in adults with penicillin allergy and association with health and economic benefits

BACKGROUND

Nonprescription of penicillin-containing antibiotics in patients diagnosed with penicillin allergy is associated with morbidity and mortality. Adverse reactions to penicillins comprise type A and B reactions.

OBJECTIVE

To assess the feasibility of penicillin allergy evaluation without penicillin skin testing (PST) for adult patients with type B reactions and the health and economic benefits of this process.

METHODS

Inpatients at an Australian tertiary hospital between April 1, 2017, and April 30, 2018, with a diagnosis of type B penicillin allergy, requiring a penicillin-containing antibiotic for treatment, were included. All patients underwent clinical history review, PST, and drug provocation testing (DPT).

RESULTS

Seventy-one patients were enrolled. Sixty-three reported a history of type B or unknown adverse reactions. No patients had a history of anaphylaxis requiring intubation or epinephrine within the last 10 years or a history suggesting Gell and Coombs type 2, 3, or 4 (severe) hypersensitivity reaction. Seven did not complete DPT because the treating team used a β-lactam antibiotic other than amoxicillin. Fifty-four of 56 remaining patients (96%) completed 3-day DPT to amoxicillin with no adverse reaction. Two experienced mild cutaneous reactions. Penicillin allergy evaluation was significantly associated with reduced length of stay, reduced hospital expenditure on bed and second-line antibiotics, and reduced readmission rates.

CONCLUSION

Penicillin allergy evaluation with DPT without PST may be feasible for all adult patients with a reported history of type B reactions to penicillins who do not have a history of anaphylaxis within the last 10 years or a type 2, 3, or 4 (severe) hypersensitivity reaction.

Management of a surgical patient with a label of penicillin allergy: narrative review and consensus recommendations

Unsubstantiated penicillin-allergy labels are common in surgical patients, and can lead to significant harm through avoidance of best first-line prophylaxis of surgical site infections and increased infection with resistant bacterial strains. Up to 98% of penicillin-allergy labels are incorrect when tested. Because of the scarcity of trained allergists in all healthcare systems, only a minority of surgical patients have the opportunity to undergo testing and de-labelling before surgery. Testing pathways can be modified and shortened in selected patients. A variety of healthcare professionals can, with appropriate training and in collaboration with allergists, provide testing for selected patients. We review how patients might be assessed, the appropriate testing strategies that can be used, and the minimum standards of safe testing.

Penicillin allergy de-labelling ahead of elective surgery: feasibility and barriers

BACKGROUND

Around 10-15% of the in-patient population carry unsubstantiated 'penicillin allergy' labels, the majority incorrect when tested. These labels are associated with harm from use of broad-spectrum non-penicillin antibiotics. Current testing guidelines incorporate both skin and challenge tests; this is prohibitively expensive and time-consuming to deliver on a large scale. We aimed to establish the feasibility of a rapid access de-labelling pathway for surgical patients, using direct oral challenge.

METHODS

'Penicillin allergic' patients, recruited from a surgical pre-assessment clinic, were risk-stratified using a screening questionnaire. Patients at low risk of true, immunoglobulin E (IgE)-mediated allergy were offered direct oral challenge using incremental amoxicillin to a total dose of 500 mg. A 3-day course was completed at home. De-labelled patients were followed up to determine antibiotic use in surgery, and attitudes towards de-labelling were explored.

RESULTS

Of 219 patients screened, 74 were eligible for inclusion and offered testing. We subsequently tested 56 patients; 55 were de-labelled. None had a serious reaction to the supervised challenge, or thereafter. On follow-up, 17 of 19 patients received appropriate antimicrobial prophylaxis during surgery. Only three of 33 de-labelled patients would have been happy for the label to be removed without prior specialist testing.

CONCLUSION

Rapid access de-labelling, using direct oral challenge in appropriately risk-stratified patients, can be incorporated into the existing surgical care pathway. This provides immediate and potential long-term benefit for patients. Interest in testing is high among patients, and clinicians appear to follow clinic recommendations. Patients are unlikely to accept removal of their allergy label on the basis of history alone.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov: AN17/92982.

The Journal of Allergy and Clinical Immunology: In Practice 2017 Year in Review

An impressive number of clinically impactful studies and reviews were published in The Journal of Allergy and Clinical Immunology: In Practice in 2017. As a service to our readers, the editors provide this Year in Review article to highlight and contextualize the advances published over the past year. We include information from articles on asthma, allergic rhinitis, rhinosinusitis, immunotherapy, atopic dermatitis, contact dermatitis, food allergy, anaphylaxis, drug hypersensitivity, urticarial/angioedema, eosinophilic disorders, and immunodeficiency. Within each topic, epidemiologic findings are presented, relevant aspects of prevention are described, and diagnostic and therapeutic advances are enumerated. Treatments discussed include behavioral therapy, allergen avoidance therapy, positive and negative effects of pharmacologic therapy, and various forms of immunologic and desensitization management. We hope this review will help readers consolidate and use this extensive and practical knowledge for the benefit of patients.

Oral challenge without skin tests in children with non-severe beta-lactam hypersensitivity: Time to change the paradigm?

Suspected allergy to penicillins and cephalosporins is very common in childhood. After a proper evaluation, allergy will be confirmed only in a small portion of them. Intradermal tests are usually part of the allergy workup, but they are painful for children and time-consuming, and their role has been debated. A systematic review found only two studies reporting a positive predictive value of skin tests in children of 36% and 33%, respectively, leading to a high rate of inaccurate diagnosis. Moreover, considering that skin tests are negative in more than 90%-95% of cases, an oral provocation test (OPT) is finally needed to confirm tolerance in most of these children. Positive OPT are rare, and even where children demonstrate reproducible signs on challenge, they rarely constitute immediate or serious symptoms. Therefore, OPT to the index antibiotic without skin tests are increasingly being considered an accepted procedure for children with a suspected mild non-immediate reaction related to a beta-lactam antibiotic. Furthermore, a recent research has taken the same approach including children with suspected mild immediate reactions, with similar safety and positive results. In light of recent evidence highlighted, it is now the time for large and multicentric studies to confirm that OPT with the index antibiotic, without skin tests, are safe and convenient for children with a history of a mild reaction with a beta-lactam antibiotic before it can be recommended in pediatric allergy guidelines.

Is a positive intracutaneous test induced by penicillin mediated by histamine? A cutaneous microdialysis study in penicillin-allergic patients

Background

Diagnostic workup of penicillin allergy comprises skin testing with penicillins, and patients are deemed allergic if skin test is positive. However, the literature suggests that skin test-positive patients may be challenge-negative, indicating that the skin test may be falsely positive.

Objective

To investigate real-time histamine release from a positive intracutaneous test induced by penicillin in patients with positive and negative challenges to penicillin.

Methods

Skin microdialysis was performed in 21 penicillin-allergic patients with positive skin test, 13 non-allergic volunteers serving as negative controls, and 7 grass pollen-allergic patients serving as positive controls. Histamine was measured by microdialysis after skin test with penicillin/grass/NaCl. Penicillin challenge was subsequently performed in 12 of the patients.

Results

Only 10/21 patients (47.6%) were skin test positive at microdialysis. During microdialysis 13 single intracutaneous tests were positive and histamine was detected in 4/13 occurring in four challenge positive patients. Thirteen/21 patients (61.9%) were deemed allergic to penicillin; eight had positive skin test. Two patients with positive skin test were challenge negative. In grass pollen allergic patients, 7/7 had a positive intracutaneous test to grass and all released histamine in the wheals. All 13 negative controls had negative intracutaneous test to penicillin and no histamine release.

Conclusion

Histamine was only detected in the minority of positive intracutaneous tests with penicillin in penicillin-allergic patients. Other mediators may be involved.