Updating the Dermal Sensitisation Thresholds using an expanded dataset and an in silico expert system.

The Dermal Sensitisation Thresholds (DST) are Thresholds of Toxicological Concern, which can be used to justify exposure-based waiving when conducting a skin sensitisation risk assessment. This study aimed to update the published DST values by expanding the size of the Local Lymph Node Assay dataset upon which they are based, whilst assigning chemical reactivity using an in silico expert system (Derek Nexus). The potency values within the expanded dataset fitted a similar gamma distribution to that observed for the original dataset. Derek Nexus was used to classify the sensitisation activity of the 1152 chemicals in the expanded dataset and to predict which chemicals belonged to a High Potency Category (HPC). This two-step classification led to three updated thresholds: a non-reactive DST of 710 µg/cm2 (based on 79 sensitisers), a reactive (non-HPC) DST of 73 µg/cm2 (based on 331 sensitisers) and an HPC DST of 1.0 µg/cm2 (based on 146 sensitisers). Despite the dataset containing twice as many sensitisers, these values are similar to the previously published thresholds, highlighting their robustness and increasing confidence in their use. By classifying reactivity in silico the updated DSTs can be applied within a skin sensitisation risk assessment in a reproducible, scalable and accessible manner.

Vaccine allergy: evidence to consider for COVID-19 vaccines.

PURPOSE OF REVIEW: Whereas the COVID-19 pandemic has changed our lives worldwide, we hope that vaccination can combat the disease. We propose how to evaluate suspected severe allergic reactions to the vaccines so that as many as possible may be safely vaccinated. RECENT FINDINGS: Rare cases of severe allergic reactions after COVID-19 vaccination have been observed, seemingly at a higher frequency than for other vaccines. Few excipients are likely to have caused these reactions. IgE-mediated reactions to polyethylene glycol (PEG) and its derivatives are the most suspected, albeit hitherto unproven, causes. We suggest to make a diagnosis based on skin tests with PEG and PEG derivatives and that these be considered in relation to the decisions required before the first and the second vaccine dose. A vaccine without these excipients is available, but published data about its side effects are limited. SUMMARY: The underlying immunological mechanisms of the rare severe allergic reactions to the COVID-19 vaccines are poorly understood and need to be clarified. Identifying those who have an undiagnosed allergy to PEG and PEG derivatives is crucial before vaccination, and these substances are found in laxatives, cosmetics and in 30% of all our medications today.

Think Twice before Interpreting the Skin Prick Test as Age, Body Mass Index, and Atopy Affect Reaction Time and Size.

INTRODUCTION: The skin prick test (SPT) is a reliable method to confirm sensitization in IgE-mediated allergic diseases; however, it has been reported to be affected by several personal and environmental factors. Our objective was to determine the factors affecting the skin reactivity to histamine and allergens and investigate whether it differs according to age in terms of reading time. METHODS: A total of 500 patients, aged 4 months-18 years, were enrolled in the study. Wheal and flare reaction sizes were documented as the mean of the longest and the midpoint perpendicular diameter in the 5th, 10th, 15th, and 20th min. Skin reactivity was compared between children >24 and ≤24 months of age. RESULTS: We found larger histamine and allergen wheal sizes in children >24 months than the ones ≤24 months of age (p < 0.001 and p = 0.007, respectively). The duration of maximum histamine reactivity was 15 min for children >24 months whereas 10 min for children ≤24 months of age. The number of children losing their histamine reactivity after 15 and 20 min was significantly higher in the smaller age-group. Multiple regression analysis revealed a larger histamine reactivity in children >24 months of age, having obesity, and having allergen sensitization (p = 0.002, p = 0.003, and p = 0.018, respectively). CONCLUSION: It seems more accurate to evaluate SPT after 10 min in children ≤24 months of age. Cutoff values and ideal measurement time according to individual factors such as age, body mass index, or atopy are needed.

Diagnosis of allergic bronchopulmonary aspergillosis in patients with persistent allergic asthma using three different diagnostic algorithms.

BACKGROUND: Allergic bronchopulmonary aspergillosis (ABPA) has been reported in various degrees among patients with persistent allergic asthma (PAA). Currently, there is no gold standard approach for diagnosis of ABPA. OBJECTIVES: In the current study, we aimed the evaluation of three different mainly used algorithms as Rosenberg & Patterson (A), ISHAM Working Group (B) and Greenberger (C) for diagnosis of ABPA in 200 patients with underlying PAA. METHODS: All patients were evaluated using Aspergillus skin prick test (SPTAf), Aspergillus-specific IgE (sIgEAf) and IgG (sIgGAf), total IgE (tIgE), pulmonary function tests, radiological findings and peripheral blood eosinophil count. The prevalence rate of ABPA in PAA patients was estimated by three diagnostic criteria. We used Latent Class Analysis for the evaluation of different diagnostic parameters in different applied ABPA diagnostic algorithms. RESULTS: Aspergillus sensitisation was observed in 30 (15.0%) patients. According to algorithms A, B and C, nine (4.5%), six (3.0%) and 11 (5.5%) of patients were diagnosed with ABPA, respectively. The sensitivity and specificity of criteria B and C were (55.6% and 99.5%) and (100.0% and 98.9%) respectively. sIgEAf and sIgGAf showed the high significant sensitivity. The performance of algorithm A, in terms of sensitivity and specificity, was somewhat better than algorithm B. CONCLUSION: Our study demonstrated that the sensitivity of different diagnostic algorithms could change the prevalence rate of ABPA. We also found that all of three criteria resulted an adequate specificity for ABPA diagnosis. A consensus patterns combining elements of all three criteria may warrant a better diagnostic algorithm.

A tuberculin skin test survey among healthcare workers in two public tertiary care hospitals in Bangladesh.

In Bangladesh, there is currently no data on the burden of latent TB infection (LTBI) amongst hospital healthcare workers (HCWs). This study aimed to determine the prevalence of LTBI and compare the prevalence among HCWs in two public tertiary care hospitals. Between September 2018 and August 2019, we conducted a cross-sectional study in two public tertiary care general hospitals. Using a survey and tuberculin skin test (TST), we assessed risk factors for LTBI, adjusting for known and plausible confounders. In addition, a facility assessment was undertaken to understand the implementation of relevant IPC measures. The prevalence of LTBI among HCWs was 42%. HCWs spent a median of 6 hours (SD = 1.76, IQR 2.00) per day and attended an average of 1.87 pulmonary TB patients per week. HCWs did not receive any TB IPC training, the wards lacked a symptom checklist to screen patients for TB, and no masks were available for coughing patients. Seventy-seven percent reportedly did not use any facial protection (masks or respirators) while caring for patients. In the multivariable model adjusting for hospital level clustering effect, TST positivity was significantly higher among HCWs aged 35-45 years (aOR1.36, 95% CI: 1.06-1.73) and with >3 years of service (aOR 1.67, 95% CI: 1.62-1.72). HCWs working in the medicine ward had 3.65 (95% CI: 2.20-6.05) times, and HCWs in the gynecology and obstetrics ward had 2.46 (95% CI: 1.42-4.27) times higher odds of TST positivity compared to HCWs working in administrative areas. This study identified high prevalence of LTBI among HCWs. This may be due to the level of exposure to pulmonary TB patients, and/or limited use of personal protective equipment along with poor implementation of TB IPC in the hospitals. Considering the high prevalence of LTBI, we recommend the national TB program consider providing preventative therapy to the HCWs as the high-risk group, and implement TB IPC in the hospitals.

Patch testing 101, part 1: performing the test.

Understanding the basics of patch testing is essential to caring for patients with contact dermatitis. Several screening or standard series are available, and additional allergens or series may be necessary based on the patient's history. A delayed reading should be performed 72 to 144 hours after patch placement. Certain oral medications, phototherapy, or topical products may interfere with patch test results.

Early Skin Test after Anaphylaxis during Induction of Anesthesia: A Case Report.

BACKGROUND: It is recommended that a skin test be performed 4-6 weeks after anaphylaxis. However, there is little evidence about the timing of the skin test when there is a need to identify the cause within 4-6 weeks. CASE REPORT: A 57-year-old woman was scheduled to undergo surgery via a sphenoidal approach to remove a pituitary macroadenoma. Immediately after the administration of rocuronium, pulse rate increased to 120 beats/min and blood pressure dropped to 77/36 mmHg. At the same time, generalized urticaria and tongue edema were observed. Epinephrine was administered and the surgery was postponed. Reoperation was planned two weeks after the event. Four days after the anaphylactic episode, rocuronium was confirmed to be the cause by the skin prick test. Cisatracurium, which showed a negative reaction, was selected as an alternative agent for future procedures. Two weeks later, the patient underwent reoperation without any adverse events. CONCLUSIONS: The early skin test can be performed if there is a need even earlier than 4-6 weeks after anaphylaxis.

Comparison Of Positivity Of Tuberculin Skin Test With Diagnostic Bcg In Children Suffering From Tuberculosis.

BACKGROUND: Tuberculosis is major public health problem in Pakistan and it is often unrecognized cause of morbidity and mortality in children living in endemic areas. Children with age less than 5 years, and especially those who are immune compromised, are at higher risk of developing tuberculosis following exposure. Tuberculosis in children is usually difficult to diagnose compare to adult patients due to its atypical presentation. Tuberculin skin test and Bacille Calmette-Guerin (BCG) are widely used as diagnostic tests for tuberculosis. It was a Cross sectional study carried out from May 2017 to Nov 2018 in the department of Paediatrics, Ayub Teaching Hospital Abbottabad.. METHODS: Both BCG and tuberculin skin test were performed at the same time by the same doctor. Personal data like age, gender and address, type of tuberculosis, positivity of tuberculin skin test and positivity of diagnostic BCG were recorded. The induration was read 48- 72 hours after administration. RESULTS: As per frequencies and percentages for positivity of tuberculin skin, 51 (67.10%) patients showed positivity for tuberculin skin while 71 (93.42%) patients showed positive results via BCG Test. CONCLUSIONS: In paediatric age group, diagnostic BCG test has got better diagnostic value over Tuberculin Skin Test in diagnosis of tuberculosis.

The use of in vivo and in vitro tests in children with beta lactam allergy.

BACKGROUND: Drug allergies are reactions within the context of drug hypersensitivity reactions, which are caused by immunological mechanisms due to a previously sensitising drug. Beta-lactam antibiotics (BLA) are the leading agents causing drug hypersensitivity reactions in children. The aim of this study is to evaluate the diagnostic importance of in vivo and in vitro diagnostic tests in children with suspected immediate-type BLA hypersensitivity and to investigate the frequency of their use for the final diagnosis. METHODS: Patients admitted to the Outpatient Clinic of Division of Paediatric Allergy and Immunology with suspicion of immediate-type BLA hypersensitivity between December 2014 and December 2018 were investigated. Patients with a history of immediate reactions to BLA were examined by performing drug specific IgE, skin prick tests, intradermal tests and drug provocation tests (DPT). RESULTS: During the study period, 148 patients were admitted to our clinic with suspected immediate-type BLA hypersensitivity. Forty-eight patients completed all assessment steps and were enrolled in the study. It has been shown that 27 patients did not have drug allergy. BLA hypersensitivity was proven in 21 patients by using in vivo test algorithm. More than half of the patients were diagnosed via skin tests with culprit drug. CONCLUSION: Allergy work-up should be performed in patients with immediate reactions to BLA. A skin test can demonstrate BLA hypersensitivity in most patients. Thus, skin tests should be performed prior to the drug provocation test.

Drug Provocation Tests for Assessing Antibiotic Hypersensitivity: Is Shorter Also Better?

BACKGROUND: Suspected antibiotic hypersensitivity in children is a frequent reason for consultation. Skin test performance and drug provocation test (DPT) duration are controversial issues. The objective of this study was to assess the effectiveness of diagnostic tests used in the study of antibiotic hypersensitivity and to estimate an optimal duration for DPT. METHODS: Sixty-two children with a suspected hypersensitivity reaction to antibiotics were studied. Skin tests were performed on all patients. In the case of negative results, DPTs were performed for a duration similar to the time elapsed from the start of treatment until the onset of the reaction. RESULTS: The frequency of antibiotic hypersensitivity in the study population was 8.1% (5 of 62). Only 1 patient showed positive skin tests. The other allergic patients were diagnosed by DPT, which reproduced the reaction within the first 6 hours in all but one of them. CONCLUSIONS: Shortening DPT duration may decrease the sensitivity of the test for the diagnosis of non-IgE-mediated hypersensitivity; however, it should be considered as an opportunity to reduce the resulting microbial resistances.

Skin testing in allergy.

Skin tests are used in addition to a directed history and physical examination to exclude or confirm immunoglobulin E (IgE) mediated diseases, such as allergic rhinitis, asthma, and anaphylaxis, to aeroallergens, foods, insect venoms, and certain drugs. There are two types of skin testing used in clinical practice: percutaneous testing (prick or puncture) and intracutaneous testing (intradermal). Prick testing involves introducing a needle into the upper layers of the skin through a drop of allergen extract that has been placed on the skin and gently lifting the epidermis up. Various devices are available for prick testing. Intracutaneous (intradermal) testing involves injecting a small amount of allergen into the dermis. The release of preformed histamine from mast cells causes increased vascular permeability via smooth-muscle contraction and development of a wheal; inflammatory mediators initiate a neural reflex, which causes vasodilatation, which leads to erythema (the flare). Prick testing methods are the initial technique for detecting the presence of IgE. These may correlate better with clinical sensitivity and are more specific but less sensitive than intradermal testing. Sites of skin testing include the back and the volar aspect of the arm. By skin testing on the arm, the patient can witness the emergence and often sense the pruritus of the skin test reaction. Because more patients are sensitized (have IgE antibodies and positive skin test reactions) than have corresponding symptoms, the diagnosis of allergy can be made only by correlating skin testing results with the presence of clinical symptoms.

Applying non-animal strategies for assessing skin sensitisation report from an EPAA/cefic-LRI/IFRA Europe cross sector workshop, ECHA helsinki, February 7th and 8th 2019.

Four years on since the last cross sector workshop, experience of the practical application and interpretation of several non-animal assays that contribute to the predictive identification of skin sensitisers has begun to accumulate. Non-animal methods used for hazard assessments increasingly are contributing to the potency sub-categorisation for regulatory purposes. However, workshop participants generally supported the view that there remained a pressing need to build confidence in how information from multiple methods can be combined for classification, sub-categorisation and potency assessment. Furthermore, the practical experience gained over the last few years, highlighted the overall high potential value of using the newly validated methods and testing strategies, but also that limitations for certain substance/product classes may become evident with further use as had been the case with other new regulatory methods. As the available information increases, review of the data and collated experience could further determine strengths and limitations leading to more confidence in their use. Finally, the need for a substantial and universally accepted dataset of non-sensitisers and substances of different sensitising potencies, based on combined human and in vivo animal data for validation of methods and test strategies was re-emphasised.

Setting surface wipe limits for skin sensitizers.

Guidance for managing potential dermal exposures has historically been qualitative in nature, for example, in the form of a DSEN notation. We propose a method that can provide quantitative guidance on how to establish and use surface wipe limits for skin sensitizers. The murine local lymph node assay (LLNA) is a validated test that not only identifies potential skin sensitizers but also provides an effective concentration (EC3) value. This provides quantitative dose-response information on induction of skin sensitization that permits estimates of sensitization thresholds and potency. Building upon the previously established correlation between LLNA EC3 values and human repeat insult patch testing no-effect levels, we present a quantitative method for setting surface wipe guidelines using the LLNA EC3. These limits can be used to assign compounds to occupational exposure bands and provide handling guidance for skin sensitizers of varying potency, supporting both exposure assessment and control strategies. A table is included that suggests a band of reasonable surface wipe limits (mg/100 cm2) for potentially all chemical sensitizers. When used in conjunction with a comprehensive industrial hygiene program that includes hazard communication, engineering controls, and personal protective equipment, skin exposure and consequent skin sensitization risks in the workplace can be minimized.

Application of transdermal patches with new skin test reagents for detection of latent tuberculosis.

Introduction. Current intradermal tuberculin skin tests for latent tuberculosis infection (LTBI) based on purified protein derivative (PPD) have poor specificity.Aims. Developing a better skin test antigen as well as a simple skin patch test may improve and facilitate diagnostic performance.Methodology. Defined recombinant antigens that were unique to Mycobacterium tuberculosis (MTB), including two potential latency-associated antigens (ESAT-6 and Rv2653c) and five DosR-encoded latency proteins (Rv1996, Rv2031c, Rv2032, DevR and Rv3716c), were used as diagnostic skin test reagents in comparison with a standard PPD. The performance of the skin tests based on the detection of delayed-type hypersensitivity (DTH) reaction in guinea pigs sensitized to MTB and M. bovis bacille Calmette-Guérin (BCG) vaccine was evaluated.Results. The latency antigens Rv1996, Rv2031c, Rv2032 and Rv2653c and the ESAT-6 protein elicited less reactive DTH skin responses in MTB-sensitized guinea pigs than those resulting from PPD, but elicited no response in BCG-vaccinated guinea pigs. The remaining two latency antigens (DevR and Rv3716c) elicited DTH responses in both groups of animals, as did PPD. The reactivity of PPD in BCG-vaccinated guinea pigs was greater than that of any of the selected skin test reagents. Using stronger concentrations of selected skin test reagents in the patch test led to increased DTH responses that were comparable to those elicited by PPD in guinea pigs sensitized with MTB.Conclusion. Transdermal application of defined purified antigens might be a promising method for LTBI screening.

A review of substances found positive in 1 of 3 in vitro tests for skin sensitization.

There has been significant progress in recent years in the development and application of alternative methods for assessing the skin sensitization potential of chemicals. The pathways involved in skin sensitization have been described in an OECD adverse outcome pathway (AOP). To date, a single non-animal test method is not sufficient to address this AOP so numerous approaches involving the use of 2 or more assays are being evaluated for their performance. The 2 out of 3 approach is a simple approach that has demonstrated very good sensitivity, specificity and overall accuracy numbers for predicting the skin sensitization potential of chemicals. Chemicals with at least two positive results in tests addressing Key events 1-3 are predicted sensitizers, while chemicals with none or only one positive outcome are predicted non-sensitizers. In this report we have thoroughly reviewed the discordant results of 29 chemicals with 1 out of 3 positive results to understand better what led to the results observed and how this information might impact our hazard assessments of these chemicals. We initially categorized each chemical using a weight of evidence approach as positive, negative or indeterminate based on review of available human and animal data as well as what skin sensitization alerts were triggered using two versions of OECD Toolbox and DEREK Nexus. We determined that 4 of the 29 chemicals should be classified as indeterminate and not included in analysis of method performance based on insufficient, borderline and/or conflicting data to confidently categorized the chemicals as allergens or non-allergens. Of the 29 chemicals included in this analysis, 17 were classified as negative and would be correctly identified using a 2 out of 3 approach while 8 chemicals were classified as positive in vivo and would be false-negative with this approach. For some of these chemicals, the outcomes observed can be explained by in vitro borderline results (13 chemicals) or in some instances there is mechanistic understanding of why a chemical is positive or negative in a particular assay (9 chemicals). Thus, when comparing the performance of different defined approaches, one should attempt to only include chemicals which demonstrate clear evidence to be categorize as allergens or non-allergens. Finally, when interpreting the results obtained for an individual unknown chemical it is critical that the in vitro skin sensitization data is reviewed critically and there is a good understanding of the variance and applicability domain limitations for each assay being used.

A practical guide for pharmacists to successfully implement penicillin allergy skin testing.

PURPOSE: The purpose of this article is to offer practical guidance for pharmacists to successfully implement penicillin allergy skin testing (PAST). SUMMARY: Less than 10% of patients labeled as having a penicillin allergy are confirmed as present upon skin testing. This labeling results in use of alternative antibiotics and thus unwanted adverse consequences including potentiated antimicrobial resistance, increased costs, and worse clinical outcomes. Stewardship guidelines recommend PAST to enhance use of first-line agents; however, this was a weak recommendation with low-quality evidence. Recent efforts and subsequent research since publication of guidelines have demonstrated beneficial effects from increasing use of PAST among stewardship programs to improve outcomes. A number of different models exist demonstrating successful implementation of PAST at various healthcare facilities. There are important logistical factors to consider during implementation of PAST such as target population, optimal preparation, leadership structure, resource availability, and state regulations. Pharmacists as leaders of antimicrobial stewardship teams and experts in drug allergies are a natural fit to help implement PAST in healthcare settings to improve overall outcomes. This article offers guidance to institutions considering implementation of PAST. CONCLUSION: PAST is rapidly becoming an effective, long-term antimicrobial stewardship tool to optimize antimicrobial prescribing in both the inpatient and outpatient settings. Pharmacists have demonstrated significant benefit as providers of PAST services in a variety of healthcare settings with a number of different healthcare professionals.

[Diagnostics of alpha-gal syndrome : Current standards, pitfalls and perspectives]. / Diagnostik des α­Gal-Syndroms : Aktuelle Standards, Fallstricke und Perspektiven.

α-Gal syndrome results from sensitization to the carbohydrate epitope galactose-α-1,3-galactose (α­gal). The allergen occurs in mammalian meat and innards, but also in other foods and medical products of animal origin. Allergic reactions generally occur delayed after allergen intake with a latency period, depending on the individual tolerance threshold and the influence of cofactors. Details in the patient's medical history can help to establish the suspected diagnosis of α­gal syndrome. Confirmation of the diagnosis requires the expertise of specialists, experienced with the implementation and interpretation of in vitro and in vivo diagnostic tests. Whereas skin prick testing with commercial whole-meat extracts often does not provide reliable results, allergen-specific IgE (α-gal) is generally detectable in affected patients. Cell-based tests such as the basophil activation test are currently only employed in an experimental setting. To evaluate, whether a sensitization is clinically relevant, an in-patient oral food challenge should be performed, using for example cooked pork or porcine kidney in addition to suspected cofactors.