The Immediate and Delayed Maximal Nonirritating Skin Testing Concentrations of ß-Lactam Antibiotics.

BACKGROUND: Maximal skin testing (ST) nonirritant concentrations (NICs) are consistent for penicillin and aminopenicillin among guidelines. However, there is variability among guidelines for maximal ST NICs of cephalosporins. OBJECTIVE: To determine maximal immediate and delayed ST NICs of 15 ß-lactams in ß-lactam-tolerant and ß-lactam-naïve participants. METHODS: We performed a single-center, nonrandomized prospective study between September 2019 and January 2022 in adult participants. Participants received skin prick testing (SPT) and intradermal test (IDT) injections at 6 increasing concentrations of 1 or more ß-lactams. A concentration was considered irritant when more than 5% of participants had a positive test. A positive test was defined as a wheal ≥3 mm compared with negative control accompanied by a ≥5 mm flare for SPT/IDT and induration ≥5 mm with associated erythema at 48 hours for delayed readings (dIDT). Sensitivity analyses using 3 alternative IDT positive criteria were conducted. RESULTS: A total of 747 participants with a median age of 64 (interquartile range: 54-72) years (52% male, 85% White, and 92% non-Hispanic) underwent 20,858 skin tests. All undiluted SPT concentrations were nonirritant. We found the following maximal IDT/dIDT NICs (mg/mL): ampicillin (41.6/125), ampicillin-sulbactam (93.8/187.5), aztreonam (6.3/25), cefazolin (55/165), cefepime (35/140), cefoxitin (45/90), ceftaroline (7.5/15), ceftriaxone (58.3/175), cefuroxime (55/110), ertapenem (16.6/50), imipenem-cilastin (6.3/25), meropenem (8.3/25), nafcillin (31.3/62.5), oxacillin (20.9/83.5), and piperacillin-tazobactam (112.5/225). dIDTs were almost all completely nonirritant close to or at undiluted concentrations. There were no differences when we applied 3 IDT positivity criteria to our raw data. CONCLUSIONS: Our results suggest that SPTs with undiluted stock ß-lactam antibiotic concentrations are nonirritant. Compared with previously published nonirritant concentrations, we propose a 2- to 50-fold increase to the maximal IDT and dIDT NICs of 15 ß-lactam antibiotics. When performing dIDTs, a higher concentration should be used rather than the same IDT concentration.

Penicillin Allergy: Mechanisms, Diagnosis, and Management.

Allergy to penicillin can occur via any of the 4 types of Gel-Coombs hypersensitivity reactions, producing distinct clinical histories and physical examination findings. Treatments include penicillin discontinuation, and depending on the type of reaction, epinephrine, antihistamines, and/or glucocorticoids. Most beta-lactams may be safely used in penicillin-allergic patients, with the possible exception of first-generation and second-generation cephalosporins. Penicillin testing includes skin testing, patch testing, and graded challenge. The selection of the type of testing depends on the clinical setting, equipment availability, and type of hypersensitivity reaction. Desensitization may be used in some cases where treatment with penicillins is essential.

Safety of Direct Drug Provocation for the Evaluation of Penicillin Allergy in Low-Risk Adults.

BACKGROUND: About 10% of patients have a penicillin allergy label, but less than 5% of them are actually allergic. Unnecessary penicillin avoidance is associated with serious medical consequences. Given the growing number of these labels, it is imperative that our diagnostic strategy for penicillin allergy be as efficient as possible. The validity of traditionally used skin tests (STs) has been questioned, whereas drug provocation testing (DPT), the criterion standard, without previous ST appears very safe in most cases. OBJECTIVE: To evaluate the safety of direct DPT without consideration for ST results and the validity of ST in the diagnosis of penicillin allergy. METHODS: In this prospective cohort study without a control group, we recruited patients consulting an allergist for penicillin allergy. Patients underwent ST followed by DPT regardless of ST results. Patients with anaphylaxis to penicillin within the past 5 years or a severe delayed reaction were excluded, as were those with significant cardiorespiratory comorbidity. RESULTS: None of the 1002 recruited patients had a serious reaction to DPT. Ten (1.0%) had a mild immediate reaction, of whom only 1 (0.1%) was considered likely IgE-mediated. The positive and negative predictive values of ST for an immediate reaction were 3.6% and 99.1%, respectively. CONCLUSIONS: In a low-risk adult population reporting penicillin allergy, ST has very poor positive predictive value. Direct DPT without ST is safe and appears to be an ideal diagnostic strategy to remove penicillin allergy labels that could be implemented in first-line practice.

Beta-Lactam Allergy De-labeling in a Pediatric Hospital.

OBJECTIVE: To assess the ability to de-label pediatric patients of their beta-lactam allergy by using a newly implemented institutional protocol and to identify potential barriers to the de-labeling process. METHODS: All patients with reported allergies to prespecified beta-lactam antibiotics were eligible for a -beta-lactam allergy interview. Following the interview, patients were grouped into 4 risk categories-no risk, low risk, moderate risk, and high risk-and assessed for intervention eligibility. Potential interventions included de-labeling based on the interview alone or proceeding to an oral amoxicillin challenge with or without penicillin allergy skin testing. RESULTS: Of the 62 patients eligible for beta-lactam allergy interviews, 40% (n = 25) were de-labeled. Among de-labeled patients, 60% (n = 15) were de-labeled on the basis of the interview alone. Additionally, no failures were documented in patients who underwent an oral amoxicillin challenge or penicillin skin testing. Barriers to performing oral amoxicillin challenges or penicillin skin testing included concomitant systemic steroid or antihistamine use, refusal of intervention, and insufficient resources to perform penicillin skin testing. CONCLUSIONS: There was a high frequency of patients de-labeled of their beta-lactam allergies in this study. Increased education to patients, parents, and providers on the de-labeling process, as well as increased personnel available to coordinate and perform de-labeling interventions, may result in more beta-lactam allergy de-labeling.

Randomized Multicenter Trial for the Validation of an Easy-to-Administer Algorithm to Define Penicillin Allergy Status in Sexually Transmitted Infection Clinic Outpatients.

BACKGROUND: Approximately 15% of patients in sexually transmitted infection (STI) clinics report penicillin allergies, complicating treatment for syphilis and gonorrhea. Nonetheless, >90% do not have a penicillin allergy when evaluated. We developed and validated an algorithm to define which patients reporting penicillin allergy can be safely treated at STI clinics with these drugs. METHODS: Randomized controlled trial to assess feasibility and safety of penicillin allergy evaluations in STI clinics. Participants with reported penicillin allergy answered an expert-developed questionnaire to stratify risk. Low-risk participants underwent penicillin skin testing (PST) followed by amoxicillin 250 mg challenge or a graded oral challenge (GOC)-amoxicillin 25 mg followed by 250 mg. Reactions were recorded, and participant/provider surveys were conducted. RESULTS: Of 284 participants, 72 (25.3%) were deemed high risk and were excluded. Of 206 low-risk participants, 102 (49.5%) underwent PST without reactions and 3 (3%) had mild reactions during the oral challenge. Of 104 (50.5%) participants in the GOC, 95 (91.3%) completed challenges without reaction, 4 (4.2%) had mild symptoms after 25 mg, and 4 (4.2%) after 250-mg doses. Overall, 195 participants (94.7%) successfully completed the study and 11 (5.3%) experienced mild symptoms. Of 14 providers, 12 (85.7%) completed surveys and 11 (93%) agreed on the safety/effectiveness of penicillin allergy assessment in STI clinics. CONCLUSIONS: An easy-to-administer risk-assessment questionnaire can safely identify patients for penicillin allergy evaluation in STI clinics by PST or GOC, with GOC showing operational feasibility. Using this approach, 67% of participants with reported penicillin allergy could safely receive first-line treatments for gonorrhea or syphilis. Clinical Trials Registration. Clinicaltrials.gov (NCT04620746).

Comparison of intradermal and serum testing for environmental allergen-specific immunoglobulin E determination in a laboratory colony of cats with naturally acquired atopic syndrome.

BACKGROUND: Allergen testing is used to select antigens included in the desensitisation vaccine. Intradermal skin test (IDT) is the gold standard in cats, yet allergen-specific immunoglobulin (Ig)E serological testing (ASIS) is often used. Feline data are lacking regarding the agreement between IDT and ASIS results. HYPOTHESIS/OBJECTIVES: The first objective of the study was to establish a colony of cats with naturally acquired feline atopic syndrome (FAS). Further objectives were to define their hypersensitivity disorder to detail the allergen tests results, and to assess similarity between the allergen tests. ANIMALS: Thirty-five cats with FAS and 10 control cats. MATERIALS AND METHODS: Enrolled cats went through a five phase-screening and quarantine process before joining the colony. An elimination diet trial was performed on all FAS cats. ASIS and IDT were consecutively performed on all cats under sedation. RESULTS: Reactions to 34 allergens were compiled for the 45 cats. Global sensitivity and specificity of ASIS were 34.7% and 78.9%, respectively. Only flea (ICC = 0.26, p = 0.040) and Dermatophagoides pteronyssinus (ICC = 0.48, p < 0.001) allergens had a significant intraclass correlation (weak agreement). Two FAS cats had negative tests including one cat with a concomitant food allergy. CONCLUSIONS AND CLINICAL RELEVANCE: This study depicts the first reported colony of cats with naturally acquired FAS. This is the first feline study to compare and show the poor agreement between allergen tests with a panel of 34 allergens. This colony also harbours two cats with FAS with negative allergen tests. These may represent the first described cats with an intrinsic form of atopic syndrome.

Vitamin B12 Hypersensitivity: A Retrospective Multicenter Study.

BACKGROUND: Vitamin B12 (Vit B12) deficiency affects approximately 20% of those above the age of 60 years in the United Kingdom and United States. If untreated, it leads to detrimental health outcomes. OBJECTIVE: To investigate a cohort of patients with Vit B12 hypersensitivity (VB12H) referred to 3 UK allergy centers and design a pathway for the investigation of VB12H. METHODS: A total of 29 patients seen between 2014 and 2022 underwent skin prick testing (1 mg/mL) with cyanocobalamin (CC) and hydroxycobalamin (HC) and intradermal testing (0.1 and 0.01 mg/mL). Patients with negative skin tests underwent a Vit B12 drug provocation test (DPT) with either the index or the alternative drug. RESULTS: Of 29 patients, 18 (62%) presented with immediate VB12H. Eight experienced anaphylaxis (4 to HC and 4 to CC) and had positive skin tests to the index drug. One patient reacted to oral and 7 patients to injectable Vit B12. Seven patients sensitized to one form of Vit B12-tolerated DPT with an alternative Vit B12. One patient with immediate VB12H reacted to polyethylene glycol (PEG) in oral cobalamin. Of 29 patients, 8 presented with delayed hypersensitivity reaction; 4 patients tolerated the intramuscular index formulation, whereas 2 patients tolerated the per oral formulation. One patient presented with symptoms consistent with symmetrical drug-related intertriginous and flexural exanthema. Three patients were referred because of cobalt allergy. CONCLUSION: Confirmed VB12H is rare. We propose a comprehensive evaluation protocol that includes Vit B12 skin tests and considers PEG allergy in patients presenting with VB12H.

Analysis of the correlation between skin barrier function and age in rosacea patients in Qinghai region.

OBJECTIVE: This study aims at investigating the difference in facial skin barrier function between rosacea patients and the healthy population of different ages in the Qinghai region and its correlation with age, providing a basis for clinical nursing and treatment. METHODS: The data of 216 rosacea patients were collected, and 211 healthy testers were selected as the control group. The skin barrier characteristics of rosacea patients of different ages were evaluated by comparing transepidermal water loss (TEWL), stratum corneum hydration (SCH), sebum content (SC), and pH values between the two groups. Then, the correlation between skin barrier function and age in rosacea patients and the healthy population was analyzed. RESULTS: In all four age groups, the TEWL of the rosacea group was higher than that of the healthy control group, and the epidermal hydration was lower than the healthy control group. In the population aged over 40, the sebum content in rosacea was lower than that in the healthy control group. In the age group of 40-59, the pH value of the rosacea group was higher than the healthy control group. In both the rosacea and the control groups, TEWL was positively correlated with age, and epidermal hydration was negatively correlated with age. The sebum content in rosacea group was negatively correlated with age (p < 0.05). CONCLUSION: As age increases, the facial epidermal function of both rosacea patients and the healthy population declines. Therefore, with increasing age, attention should be paid to enhance the epidermal function to slow down the skin aging process.

Association between skin barrier development and early-onset atopic dermatitis: A longitudinal birth cohort study.

BACKGROUND: A diagnosis of atopic dermatitis (AD) is common during infancy; however, it is unclear whether differential skin barrier development defines this period and signals disease onset in predisposed individuals. OBJECTIVE: We sought to study (NCT03143504) and assess the feasibility of remote skin testing from birth to monitor skin barrier maturation and model association with an AD diagnosis by age 12 months. METHODS: Biophysical testing and infrared spectroscopy were conducted at the maternity ward and family home. Tape stripping collected samples for desquamatory protease and natural moisturizing factor analysis. The 4 common European filaggrin risk alleles were screened. RESULTS: A total of 128 infants completed the study, with 20% developing mild disease. Significant changes in permeability barrier function, desquamatory protease activity, and molecular composition assessed spectroscopically were observed longitudinally, but only subtle evidence of differential skin barrier development was noted between infant subgroups. Common filaggrin risk alleles were strongly associated with early-onset disease and conferred a significant reduction in natural moisturizing factor and water content by age 4 weeks. Accounting for a family history of atopy, these parameters alongside a greater lipid/protein ratio and reduced chymotrypsin-like activity at birth were associated with AD. Measured in ambient conditions, transepidermal water loss did not signal disease risk at any stage. CONCLUSIONS: Skin barrier dysfunction lacked an acquired modality but was considered proportional to cohort severity and suggests that a portfolio of tests used in a community setting has the potential to improve current AD risk evaluations from birth.

A five-year analysis of latent tuberculosis infection in Queensland, 2016-2020.

Background Australia is aiming to reach tuberculosis pre-elimination targets by 2035. As a low-incidence setting, control efforts will increasingly rely on the management of latent tuberculosis infection (LTBI). We undertook this descriptive analysis to assess the recent trends of LTBI testing in Queensland. Methods Our objective was to describe the features of LTBI testing in Queensland, and to estimate the range of possible annual notifications were it to be made a notifiable condition. We collated both state-wide and region-specific data on tuberculin skin testing (TST) and interferon gamma release assays (IGRA) conducted in Queensland during the five-year period 1 January 2016 - 31 December 2020. We used reports on Medicare-funded TST and IGRA testing in Queensland, as well as tuberculosis notification data, to understand the representativeness of our data and to derive state-wide estimates. Results We analysed 3,899 public TST, 5,463 private TST, 37,802 public pathology IGRA, and 31,656 private pathology IGRA results. The median age of people tested was 31 years; 57% of those tested were female. From our data sources, an annual average of 1,067 positive IGRA and 354 positive TST results occurred in Queensland. Building on this minimum value, we estimate possible latent tuberculosis notifications in Queensland could range from 2,901 to 6,995 per annum. Private laboratory TSTs are estimated to contribute the lowest number of potential notifications (range: 170-340), followed by private laboratory IGRA testing (range: 354-922), public laboratory IGRA testing (range: 706-1,138), and public setting TSTs (range: 1,671-4,595). Conclusion If LTBI were to be made notifiable, these estimates would place it among the ten most notified conditions in Queensland. This has implications for potential surveillance methods and goals, and their associated system and resource requirements.

The role of major and minor determinants in penicillin allergy testing: Time to revisit an old friend?

Background: Skin testing is an important step in evaluation of penicillin allergic reactions. It includes testing to the following: amoxicillin, benzyl penicillin, and products generated in vivo after penicillin administration, the major determinant hapten penicilloyl-polylysine (PPL) and the minor determinant mixture (MDM). Although PPL and MDM are available as a commercial kit, their supply and cost remain problematic. Objective: We aimed to evaluate the performance and utility of PPL and MDM in penicillin allergy testing. Methods: A retrospective audit over a 5-year period was undertaken for those with penicillin testing in a tertiary immunology unit. Results: In all, 214 patients were identified. Of those patients, 151 (70.6%) were female and the average age was 58 years. Unspecified penicillin was the most common index drug (n = 127 [59.3%]), followed by amoxicillin (n =3 [24.8%]) and amoxicillin-clavulanic acid (n = 21 [9.7%]). The result of skin testing was positive in 23 patients (10.7%); skin prick testing was positive in 10 patients (4.7%), and intradermal testing (IDT) was positive in 13 patients (6.1%), the majority of whom had identified amoxicillin or amoxicillin-clavulanic acid as the index drug (n = 22 [95.7%]). The result of testing to PPL and/or MDM was positive with IDT only (n=5 [23.8%]). PPL and MDM positivity coexisted with a positive reaction to amoxicillin IDT in 2 patients, 1 of whom passed an amoxicillin challenge. Additionally, 2 positive tests to PPL were present with a negative result for MDM; of these 2 positive results, 1 was positive to amoxicillin IDT. In only 1 case were the results of testing for MDM and PPL both positive, with negative results to all native ß-lactams tested; the patient tolerated an amoxicillin challenge. Overall, the negative predictive value for both skin prick testing and IDT was 89.5%. Conclusion: Benzyl penicillin and amoxicillin alone may be sufficient for in vivo testing in suspected individuals with penicillin allergy.

Penicillin Allergy Evaluation Should Be Performed Proactively in Patients With a Penicillin Allergy Label.

Penicillin allergy is the most common drug allergy in the US population. A penicillin allergy label is associated with poor patient outcomes including increased hospital length of stay, increased perioperative infections, and overall increased mortality. A penicillin allergy evaluation accurately identifies approximately 9 of 10 patients who, despite reporting a history of penicillin allergy, can receive penicillins safely. Penicillin allergy evaluations should be offered proactively to healthy patients during routine visits, including children and pregnant women, in advance of antibiotic need.

Impact of antimicrobial stewardship interventions on peripartum antibiotic prescribing in patients with penicillin allergy.

BACKGROUND: Beta-lactam antibiotics (eg, penicillins, cephalosporins, and carbapenems) are preferred for group B streptococcus prophylaxis, intra-amniotic infection, and cesarean surgical site infection prophylaxis. Non-beta-lactam alternatives are associated with inferior efficacy and contribute to higher rates of surgical site infection and longer lengths of stay. Most patients who report a penicillin allergy can tolerate penicillins without any adverse reaction. There are low rates of cross-reactivity between penicillins and other beta-lactams, including cephalosporins and carbapenems. Efforts to evaluate penicillin allergy and promote the use of beta-lactams are needed. OBJECTIVE: This study aimed to evaluate whether an antimicrobial stewardship intervention improved the use of first-line antibiotics for peripartum indications in patients with a reported penicillin allergy, following updates to institutional guidelines. STUDY DESIGN: This was a retrospective study of adult patients presenting for vaginal or cesarean delivery at 2 hospitals within a healthcare system. Patients received at least 1 dose of antibiotics for a peripartum indication between May 1, 2018, and October 31, 2018 (preintervention group) and May 1, 2020, to October 31, 2020 (postintervention group). The stewardship intervention bundle, which was implemented between March 2019 and April 2020, included updates to institutional antibiotic guidelines, reclassification of severe penicillin allergy, development of obstetrical prophylaxis and treatment order sets, promotion of allergy referral services, and establishment of a physician champion. The primary outcome was the composite rates of patients with reported penicillin allergy who received a preferred antibiotic for a peripartum indication. The secondary measures included maternal and neonatal outcomes. RESULTS: A total of 192 patients with a history of documented penicillin allergy were evaluated (96 patients in the preintervention group and 96 patients in the postintervention group). Hives were the most commonly reported index symptom in both groups (40/96 [41.7%] vs 39/96 [40.6%]; P=.883). After stewardship interventions, there was a significant increase in the rate of preferred antibiotic use (33/96 [34.3%] vs 81/96 [84.3%]; P<.001). The effect was the greatest in patients with nonsevere allergy (14/76 [18.4%] vs 68/82 [82.9%]; P<.001). There was no difference in the rates of postpartum endometritis, 30-day readmission, 90-day surgical site infection, or neonatal early-onset sepsis between the pre- and postintervention groups. Of note, 1 patient in the postintervention group experienced itching, and another patient developed a rash, both of which resolved with medical management. CONCLUSION: A comprehensive antibiotic stewardship intervention was associated with a 50% increase in the use of preferred antibiotics for peripartum indications in patients with penicillin allergy. Allergic reactions with first-line beta-lactams were minimal and manageable.

Contact allergy to corticosteroids: Is the European baseline series sufficient?

BACKGROUND: Patients are consecutively screened for contact allergy to corticosteroids with budesonide and tixocortol-21-pivalate in the European baseline series. Centres using TRUE Test also include hydrocortisone-17-butyrate. A supplementary corticosteroid patch test series is used in case of suspicion of corticosteroid contact allergy or when a marker of corticosteroid contact allergy is positive. OBJECTIVE: The aims were to evaluate (1) the efficacy of corticosteroids in the TRUE Test and (2) co-sensitization patterns. METHODS: This retrospective study analysed patients patch tested with TRUE Test corticosteroids plus supplementary corticosteroid series in the period 2006-2020 at the Department of Dermatology and Allergy Centre, Odense University Hospital. RESULTS: Of 1852 patients tested, 119 were sensitised to TRUE Test corticosteroids and supplementary testing found additional reactions to other corticosteroids in 19 of 119 patients. TRUE Test corticosteroids gave more positive and stronger reactions compared to allergens in petrolatum/ethanol. Fourteen percent of sensitised patients were co-sensitised to multiple corticosteroid groups. Baeck group 3 corticosteroids accounted for 9 of 16 patients not identified by TRUE Test. CONCLUSIONS: Budesonide, hydrocortisone-17-butyrate, and tixocortol-21-pivalate in combination are sensitive corticosteroid markers. In case of clinical suspicion of corticosteroid contact allergy, patch testing with supplementary corticosteroids is highly recommended.

Updated guidance regarding the risk of allergic reactions to COVID-19 vaccines and recommended evaluation and management: A GRADE assessment and international consensus approach.

This guidance updates 2021 GRADE (Grading of Recommendations Assessment, Development and Evaluation) recommendations regarding immediate allergic reactions following coronavirus disease 2019 (COVID-19) vaccines and addresses revaccinating individuals with first-dose allergic reactions and allergy testing to determine revaccination outcomes. Recent meta-analyses assessed the incidence of severe allergic reactions to initial COVID-19 vaccination, risk of mRNA-COVID-19 revaccination after an initial reaction, and diagnostic accuracy of COVID-19 vaccine and vaccine excipient testing in predicting reactions. GRADE methods informed rating the certainty of evidence and strength of recommendations. A modified Delphi panel consisting of experts in allergy, anaphylaxis, vaccinology, infectious diseases, emergency medicine, and primary care from Australia, Canada, Europe, Japan, South Africa, the United Kingdom, and the United States formed the recommendations. We recommend vaccination for persons without COVID-19 vaccine excipient allergy and revaccination after a prior immediate allergic reaction. We suggest against >15-minute postvaccination observation. We recommend against mRNA vaccine or excipient skin testing to predict outcomes. We suggest revaccination of persons with an immediate allergic reaction to the mRNA vaccine or excipients be performed by a person with vaccine allergy expertise in a properly equipped setting. We suggest against premedication, split-dosing, or special precautions because of a comorbid allergic history.

Suspected perioperative anaphylaxis: are we making the correct diagnosis?

We provide a commentary on aspects of a prospective study of the epidemiology of perioperative anaphylaxis in Japan (Japanese Epidemiologic Study for Perioperative Anaphylaxis [JESPA]). Accurate diagnosis of perioperative anaphylaxis is important for research but essential for clinical safety. We evaluate the diagnostic approach used in the JESPA study and caution against over-reliance on diagnostic tests that lack sensitivity and specificity when clinical data suggest an immediate perioperative hypersensitivity reaction is likely.

Investigating the optimal diagnostic value of histamine for diagnosing perioperative hypersensitivity: a prospective, observational study.

Although several guidelines recommend measuring blood tryptase and histamine concentrations to diagnose perioperative anaphylaxis (POA), tryptase measurement is more common. The appropriate timing of blood collection and the diagnostic threshold for histamine measurement are still controversial. To address these issues, histamine concentrations in patients with anaphylaxis and those with anaphylaxis-uncertain were compared in our previous study, the Japanese Epidemiologic Study for Perioperative Anaphylaxis (JESPA). However, because we could not rule out the possibility that the anaphylactic-uncertain group included anaphylactic patients, histamine concentrations were measured in patients who underwent general anesthesia with no complications as controls in the present study. Histamine levels were measured at anesthesia induction (baseline), 30 min (first point), and 2 h (second point) after the start of surgery in 30 control patients. Histamine concentrations in controls were lower than in patients with POA in JESPA at the first and second points. At the first point, a threshold of 1.5 ng/ml resulted in sensitivity of 77% and specificity of 100%. A threshold of 1.1 ng/ml at the second point resulted in sensitivity of 67% and specificity of 87%. Measurement of histamine concentrations within two hours after symptom onset might help diagnose POA.

Penicillin Allergy: Mechanisms, Diagnosis, and Management.

Allergy to penicillin can occur via any of the 4 types of Gel-Coombs hypersensitivity reactions, producing distinct clinical histories and physical examination findings. Treatments include penicillin discontinuation, and depending on the type of reaction, epinephrine, antihistamines, and/or glucocorticoids. Most beta-lactams may be safely used in penicillin-allergic patients, with the possible exception of first-generation and second-generation cephalosporins. Penicillin testing includes skin testing, patch testing, and graded challenge. The selection of the type of testing depends on the clinical setting, equipment availability, and type of hypersensitivity reaction. Desensitization may be used in some cases where treatment with penicillins is essential.

[Allergy to Pfizer-BioNTech® vaccine demonstrated by skin testing]. / Alergia a la vacuna Pfizer-BioNTech® demostrada mediante pruebas cutáneas.

BACKGROUND: The Pfizer-BioNTech® BNT162b2 vaccine, provides 95% effectiveness from the second dose onwards. The reported rate of anaphylaxis to COVID-19 vaccines is 4.7 cases/million doses administered. CASE REPORT: 30-year-old female, health professional, history of allergic rhinitis, asthma, reaction to eye cosmetics and adhesive tape: erythema, edema, and local pruritus. Immediately after application of the first dose of Pfizer-BioNTech vaccine, she presented grade III anaphylaxis. The patient was stratified, phenotyped and skin tests with PEG 3350 were positive. A recommendation was issued not to reapply vaccine containing polyethylene glycol and alternatives were offered. CONCLUSIONS: An adequate risk stratification should be performed before applying mRNA-based COVID-19 vaccines for the first time in at-risk groups. In case of anaphylaxis at the first dose, phenotyping and further study with PEG skin tests should be performed and vaccination alternatives should be offered.

INTRODUCCIÓN: La vacuna Pfizer-BioNTech® BNT162b2 proporciona efectividad del 95% a partir de la segunda dosis. La tasa de anafilaxia reportada de vacunas para COVID-19 es de 4.7 casos por millón de dosis administradas. REPORTE DEL CASO: Paciente femenina de 30 años, profesional de la salud, con antecedentes de rinitis alérgica, asma, reacción a productos cosméticos en los párpados y al pegamento de la cinta adhesiva (eritema, edema y prurito local). Posterior a la aplicación de la primera dosis de la vacuna Pfizer-BioNTechÒ tuvo un evento de anafilaxia grado III. Se estratificó, fenotipificó y efectuaron pruebas cutáneas con PEG-3350, que resultaron positivas. Se sugirió no aplicar la aplicar vacuna de refuerzo que contuviera polietilenglicol y se ofrecieron alternativas de tratamiento. CONCLUSIONES: Es importante efectuar la adecuada estratificación de riesgo antes de aplicar las vacunas para COVID-19 basadas en ARNm por primera vez. En caso de anafilaxia es necesario fenotipificar y ampliar el estudio con pruebas cutáneas con PEG, además de otorgar alternativas de vacunación.