Meta-analysis of ACE inhibitor-induced angioedema identifies novel risk locus.

BACKGROUND: Angioedema is a rare but potentially life-threatening adverse drug reaction in patients receiving angiotensin-converting enzyme inhibitors (ACEis). Research suggests that susceptibility to ACEi-induced angioedema (ACEi-AE) involves both genetic and nongenetic risk factors. Genome- and exome-wide studies of ACEi-AE have identified the first genetic risk loci. However, understanding of the underlying pathophysiology remains limited. OBJECTIVE: We sought to identify further genetic factors of ACEi-AE to eventually gain a deeper understanding of its pathophysiology. METHODS: By combining data from 8 cohorts, a genome-wide association study meta-analysis was performed in more than 1000 European patients with ACEi-AE. Secondary bioinformatic analyses were conducted to fine-map associated loci, identify relevant genes and pathways, and assess the genetic overlap between ACEi-AE and other traits. Finally, an exploratory cross-ancestry analysis was performed to assess shared genetic factors in European and African-American patients with ACEi-AE. RESULTS: Three genome-wide significant risk loci were identified. One of these, located on chromosome 20q11.22, has not been implicated previously in ACEi-AE. Integrative secondary analyses highlighted previously reported genes (BDKRB2 [bradykinin receptor B2] and F5 [coagulation factor 5]) as well as biologically plausible novel candidate genes (PROCR [protein C receptor] and EDEM2 [endoplasmic reticulum degradation enhancing alpha-mannosidase like protein 2]). Lead variants at the risk loci were found with similar effect sizes and directions in an African-American cohort. CONCLUSIONS: The present results contributed to a deeper understanding of the pathophysiology of ACEi-AE by (1) providing further evidence for the involvement of bradykinin signaling and coagulation pathways and (2) suggesting, for the first time, the involvement of the fibrinolysis pathway in this adverse drug reaction. An exploratory cross-ancestry comparison implicated the relevance of the associated risk loci across diverse ancestries.

S3 guideline: Diagnosis and treatment of epidermal necrolysis (Stevens-Johnson syndrome and toxic epidermal necrolysis) - Part 2: Supportive therapy of EN in the acute and post-acute stages.

Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) are rare, predominantly drug-induced, acute life-threatening diseases of skin and mucosae. SJS and TEN are nowadays considered as variants of one disease entity with varying degrees of severity called epidermal necrolysis (EN). EN is associated with high morbidity and mortality and constitutes a major disease burden for affected patients. The guideline "Diagnosis and treatment of epidermal necrolysis (Stevens-Johnson syndrome and toxic epidermal necrolysis)" was developed under systematic consideration of existing scientific literature and in a formal consensus process according to regulations issued by the Association of Scientific Medical Societies in Germany (AWMF) to establish an evidence-based framework to support clinical decision-making. The interdisciplinary guideline commission consisted of representatives from various specialist societies and of patient representatives. The guideline is aimed at specialists in the fields of dermatology, ophthalmology, plastic surgery, intensive care, and pediatrics in hospitals and offices, as well as other medical specialties involved in the diagnosis and treatment of EN. The guideline is also aimed at patients, their relatives, insurance funds, and policymakers. The second part is concerned with the topics of supportive therapy in the acute phase of EN and outpatient follow-up treatment.

S3 guideline: Diagnosis and treatment of epidermal necrolysis (Stevens-Johnson syndrome and toxic epidermal necrolysis) - Part 1: Diagnosis, initial management, and immunomodulating systemic therapy.

Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) are rare, predominantly drug-induced, acute, life-threatening diseases of skin and mucosae. SJS and TEN are nowadays considered variants of one disease entity with varying degrees of severity called epidermal necrolysis (EN). EN is associated with high morbidity and mortality and constitutes a major disease burden for affected patients. The guideline "Diagnosis and treatment of epidermal necrolysis (Stevens-Johnson syndrome and toxic epidermal necrolysis)" was developed under systematic consideration of existing scientific literature and in a formal consensus process according to regulations issued by the Association of Scientific Medical Societies in Germany (AWMF) to establish an evidence-based framework to support clinical decision-making. The interdisciplinary guideline commission consisted of representatives from various specialist societies and patient representatives. The guideline is aimed at specialists in the fields of dermatology, ophthalmology, plastic surgery, intensive care, and pediatrics in hospitals and offices, as well as other medical speciallved in the diagnosis and treatment of EN. The guideline is also aimed at patients, their relatives, insurance funds, and policymakers. This first part focuses on the diagnostic aspects, the initial management as well as the immunomodulating systemic therapy.

Limited Reimbursement and Underuse of Digital Healthcare Concepts Are Major Barriers to Clinical Allergological Care in Germany.

INTRODUCTION: Allergic diseases represent a broad spectrum of high-prevalence, chronic conditions that remain underdiagnosed and undertreated. The aims of this interdisciplinary, questionnaire-based, non-interventional study were to identify and analyze potential barriers to clinical allergological care in Germany. METHODS: All hospitals listed in the German hospital register involved in the treatment of allergological patients (n = 899) were invited to participate. The study yielded a response rate of 52.1% (n = 468). RESULTS: Overall, 88.5% of clinics agreed that allergological care in Germany needs improvement, especially in terms of reimbursement for diagnostics and therapy. More than 80% of participating clinics reported that the decreased availability of test substances and the time-intensity of allergological testing represent relevant barriers. For dermatology and pulmonology, the former is the strongest barrier, while for pediatric and ENT clinics, time-intensity is regarded as the strongest barrier. The availability of good therapy and appropriate guidelines present no barriers to allergological care. Regarding the use of digital healthcare concepts, a very large majority of clinics (n = 352; 91.4%) do not offer video consultations or the use of health applications in patient care. CONCLUSION: In conclusion, we have identified several structural barriers to allergological care in Germany. Reimbursement and the use of digital healthcare concepts in German clinics providing allergological care need improvement. Based on the results of this study, there is an urgent need for researchers and policymakers to further investigate and support allergology departments in their clinical work and in their implementation of digital healthcare concepts.

Current situation of allergological health care at German hospitals.

BACKGROUND: Allergic medical care in Germany is organized on an interdisciplinary basis. An overview of the current care situation is necessary to manage and improve interdisciplinary cooperation. METHODS: Between January and February 2022, questionnaires were sent online and by mail to chief physicians of inpatient clinical departments to which most allergological diseases are assigned (dermatology, otorhinolaryngology [ENT], pulmonology, pediatrics, environmental/occupational medicine, gastroenterology; n = 899). RESULTS: The response rate was 52.1%. Allergology departments of dermatology, ENT and pulmonology were predominantly located in metropolitan areas (> 100,000 inhabitants), whereas responses of pediatric departments were mostly from smaller towns. 76.8% of the respondents reported existing interdisciplinary treatment plans with other specialties. Pediatric and pulmonology clinics stated disproportionately few interdisciplinary treatment concepts with dermatology and ENT clinics, especially in smaller cities with < 100,000 inhabitants. Diagnosis and therapy of allergic rhinitis were performed in particular by the departments of ENT, asthma mainly by the pulmonology departments. Care of other allergological diseases was most frequently reported by chief physicians of dermatology and pediatrics. CONCLUSIONS: In metropolitan areas, participating departments provide allergology care in a cooperative manner. A large spectrum of care is covered in cooperation with dermatological clinics. In more rural areas, cooperation is rarer; here, mainly pediatric departments provide allergological care, which may explain the more limited range of services compared to metropolitan areas.

S3 Guideline Urticaria. Part 2: Treatment of urticaria - German-language adaptation of the international S3 guideline.

This publication is the second part of the German-language S3 guideline on urticaria. It covers the management of urticaria and should be used together with Part 1 of the guideline on classification and diagnosis. This publication was prepared according to the criteria of the AWMF on the basis of the international English-language S3 guideline with special consideration of health system conditions in German-speaking countries. Chronic urticaria has a high impact on the quality of life and daily activities of patients. Therefore, if causal factors cannot be eliminated, effective symptomatic treatment is necessary. The recommended first-line treatment is to administer new generation, non-sedating H1 antihistamines. If the standard dose is not sufficiently effective, the dose should be increased up to fourfold. For patients who do not respond to this treatment, the second-line treatment in addition to antihistamines in the treatment algorithm is omalizumab and, if this treatment fails, ciclosporin. Other low-evidence therapeutic agents should only be used if all treatments in the treatment algorithm agreed upon by the guideline group fail. Both the benefit-risk profile and cost should be considered. Corticosteroids are not recommended for long-term treatment due to their inevitable severe side effects.

S3 Guideline Urticaria. Part 1: Classification and diagnosis of urticaria - German-language adaptation of the international S3 Guideline.

The lifetime prevalence of urticaria, a severe allergic disease, is almost 20%. It not only limits the quality of life of those affected, but also their general performance at work and in their daily activities. This publication is the first section of the Urticaria Guideline. It covers the classification and diagnosis of urticaria, taking into account the major advances in research into its causes, triggering factors and pathomechanisms. It also addresses strategies for the efficient diagnosis of the different subtypes of urticaria. This is crucial for individual, patient-oriented treatment, which is covered in the second part of the guideline, published separately. This German-language guideline was developed according to the criteria of the AWMF on the basis of the international English-language S3 guideline with special consideration of health system characteristics in the German-speaking countries. This first part of the guideline describes the classification of urticaria, distinguishing spontaneously occurring wheals (hives) and angioedema from forms of urticaria with inducible symptoms. Urticaria is defined as sudden onset of wheals, angioedema, or both, but is to be distinguished from conditions in which wheals occur as a short-term symptom, such as anaphylaxis. The diagnosis is based on (a limited number of) laboratory tests, but especially on medical history. In addition, validated instruments are available to measure the severity, activity and course of the disease.

Ligelizumab for Chronic Spontaneous Urticaria.

BACKGROUND: In the majority of patients with chronic spontaneous urticaria, most currently available therapies do not result in complete symptom control. Ligelizumab is a next-generation high-affinity humanized monoclonal anti-IgE antibody. Data are limited regarding the dose-response relationship of ligelizumab and the efficacy and safety of ligelizumab as compared with omalizumab and placebo in patients who have moderate-to-severe chronic spontaneous urticaria that is inadequately controlled with H1-antihistamines at approved or increased doses, alone or in combination with H2-antihistamines or leukotriene-receptor antagonists. METHODS: In a phase 2b dose-finding trial, we randomly assigned patients to receive ligelizumab at a dose of 24 mg, 72 mg, or 240 mg, omalizumab at a dose of 300 mg, or placebo, administered subcutaneously every 4 weeks for a period of 20 weeks, or a single 120-mg dose of ligelizumab. Disease symptoms of hives, itch, and angioedema were monitored by means of weekly activity scores. The main objective was to determine a dose-response relationship for the complete control of hives (indicated by a weekly hives-severity score of 0, on a scale from 0 to 21, with higher scores indicating greater severity); the primary end point of this response was assessed at week 12. Complete symptom control was indicated by a weekly urticaria activity score of 0 (on a scale from 0 to 42, with higher scores indicating greater severity). Safety was analyzed throughout the trial. RESULTS: A total of 382 patients underwent randomization. At week 12, a total of 30%, 51%, and 42% of the patients treated with 24 mg, 72 mg, and 240 mg, respectively, of ligelizumab had complete control of hives, as compared with 26% of the patients in the omalizumab group and no patients in the placebo group. A dose-response relationship was established. At week 12, a total of 30%, 44%, and 40% of the patients treated with 24 mg, 72 mg, and 240 mg, respectively, of ligelizumab had complete control of symptoms, as compared with 26% of the patients in the omalizumab group and no patients in the placebo group. In this small and short trial, no safety concerns regarding ligelizumab or omalizumab emerged. CONCLUSIONS: A higher percentage of patients had complete control of symptoms of chronic spontaneous urticaria with ligelizumab therapy of 72 mg or 240 mg than with omalizumab or placebo. (Funded by Novartis Pharma; ClinicalTrials.gov number, NCT02477332.).

Identification of novel biomarkers to distinguish bradykinin-mediated angioedema from mast cell-/histamine-mediated angioedema.

BACKGROUND: The pathophysiology of the underlying paroxysmal permeability disturbances in angioedema (AE) is not well understood. METHODS: To identify clinical and laboratory parameters specific for a certain AE subtype, 40 AE patients were prospectively enrolled: 15 hereditary (HAE), 13 ACE-inhibitor induced (ACE-AE), and 12 mast cell-mediated without wheals in chronic spontaneous urticaria (CSU-AE). Ten healthy subjects served as controls. Serum levels of markers indicating activation of the ficolin-lectin pathway, of endothelial cells, or those indicating impairment of vascular integrity or inflammation were assessed by enzyme-linked immunosorbent assay. RESULTS: New routine clinical diagnostic criteria could not be identified, not even for distinguishing bradykinin-mediated (BK-) AE (ie, HAE and ACE-AE) from mast cell-/histamine-mediated CSU-AE. However, FAP-α and tPA were significantly increased in all AE compared to controls. In HAE, FAP- α, tPA, uPAR, pentraxin-3, Tie-2, sE-selectin, and VE-cadherin were significantly increased compared to controls. In HAE compared to CSU-AE and ACE-AE, sE-Selectin, Tie-2, and VE-Cadherin were significantly increased, whereas for Ang-2 the difference was significant compared to CSU-AE only. Tie-2 correlated strongly negatively with C4, C1-INH activity, and C1-INH function. CONCLUSIONS: This study is the first to compare HAE, ACE-AE, and CSU-AE. Although significance is limited by small sample size, Tie-2 was identified as a new promising biomarker candidate for HAE. FAP- α and tPA might serve as a marker for AE in general, whereas sE-selectin and Ang-2 were increased in BK-AE only. Our results add information to the role of endothelial dysfunction and serine proteases in different AE subtypes.

Management of suspected and confirmed COVID-19 (SARS-CoV-2) vaccine hypersensitivity.

BACKGROUND: Systemic allergic reactions to vaccines are very rare. In this study we assessed the management and outcome of suspected SARS-CoV-2 vaccine hypersensitivity. METHODS: Totally, 334 individuals underwent an allergy work up regarding SARS-CoV-2 vaccination (group A: 115 individuals suspected to be at increased risk for vaccine-related reactions before vaccination and group B: 219 patients with reactions after COVID vaccination). The large majority of the SPT/IDT with the vaccines were negative; however, we identified in 14.1% (n = 47) a possible sensitization to the SARS-CoV-2 vaccine and/or its ingredients defined as one positive skin test. Of the 219 individuals (group B) who experienced symptoms suspicious for a hypersensitivity reaction after vaccination, 214 were reported after the first vaccination with a mRNA vaccine (157 mRNA (Comirnaty®, 38 Spikevax®) and 18 with a vector vaccine (Vaxzevria®), 5 cases were after the second vaccination. RESULTS: The symptom profile in group B was as follows: skin symptoms occurred in 115 cases (n = 59 angioedema, n = 50 generalized urticaria and n = 23 erythema/flush. Seventy individuals had cardiovascular, 53 respiratory and 17 gastrointestinal symptoms. Of the overall 334 individuals, 78 patients tolerated (re)-vaccination (out of skin test positive/negative 7/19 from group A and 17/35 from group B). CONCLUSION: Proven IgE-mediated hypersensitivity to SARS-CoV-2 vaccines is extremely rare and not increased in comparison with reported hypersensitivity to other vaccines. The value of skin tests is unclear and nonspecific reactions, in particular when intradermal testing is applied, should be considered.

Phenotype and risk factors of venom-induced anaphylaxis: A case-control study of the European Anaphylaxis Registry.

BACKGROUND: Venom-induced anaphylaxis (VIA) is a common, potentially life-threatening hypersensitivity reaction associated with (1) a specific symptom profile, 2) specific cofactors, and 3) specific management. Identifying the differences in phenotypes of anaphylaxis is crucial for future management guidelines and development of a personalized medicine approach. OBJECTIVE: This study aimed to evaluate the phenotype and risk factors of VIA. METHODS: Using data from the European Anaphylaxis Registry (12,874 cases), we identified 3,612 patients with VIA and analyzed their cases in comparison with sex- and age-matched anaphylaxis cases triggered by other elicitors (non-VIA cases [n = 3,605]). RESULTS: VIA more frequently involved more than 3 organ systems and was associated with cardiovascular symptoms. The absence of skin symptoms during anaphylaxis was correlated with baseline serum tryptase level and was associated with an increased risk of a severe reaction. Intramuscular or intravenous epinephrine was administered significantly less often in VIA, in particular, in patients without a history of anaphylaxis. A baseline serum tryptase level within the upper normal range (8-11.5 ng/mL) was more frequently associated with severe anaphylaxis. CONCLUSION: Using a large cohort of VIA cases, we have validated that patients with intermediate baseline serum tryptase levels (8-11 ng/mL) and without skin involvement have a higher risk of severe VIA. Patients receiving ß-blockers or angiotensin-converting enzyme inhibitors had a higher risk of developing severe cardiovascular symptoms (including cardiac arrest) in VIA and non-VIA cases. Patients experiencing VIA received epinephrine less frequently than did cases with non-VIA.

Placebo effects in allergen immunotherapy-An EAACI Task Force Position Paper.

The placebo (Latin "I will please") effect commonly occurs in clinical trials. The psychological and physiological factors associated with patients' expectations about a treatment's positive and negative effects have yet to be well characterized, although a functional prefrontal cortex and intense bidirectional communication between the central nervous system and the immune system appear to be prerequisites for a placebo effect. The use of placebo raises certain ethical issues, especially if patients in a placebo group are denied an effective treatment for a long period of time. The placebo effect appears to be relatively large (up to 77%, relative to pretreatment scores) in controlled clinical trials of allergen immunotherapy (AIT), such as the pivotal, double-blind, placebo-controlled (DBPC) randomized clinical trials currently required by regulatory authorities worldwide. The European Academy of Allergy and Clinical Immunology (EAACI) therefore initiated a Task Force, in order to better understand the placebo effect in AIT and its specific role in comorbidities, blinding issues, adherence, measurement time points, variability and the natural course of the disease. In this Position Paper, the EAACI Task Force highlights several important topics regarding the placebo effect in AIT such as a) regulatory aspects, b) neuroimmunological and psychological mechanisms, c) placebo effect sizes in AIT trials, d) methodological limitations in AIT trial design and e) potential solutions in future AIT trial design. In conclusion, this Position Paper aims to examine the methodological problem of placebo in AIT from different aspects and also to highlight unmet needs and possible solutions for future trials.

The pseudoallergen receptor MRGPRX2 on peripheral blood basophils and eosinophils: Expression and function.

BACKGROUND: Mas-related G protein-coupled receptor X2 (MRGPRX2) is regarded as a mast cell-specific receptor mediating non-IgE-dependent activation. We aimed to investigate whether human basophils and eosinophils express functional MRGPRX2. METHODS: Flow cytometry, immunocytochemistry, immunofluorescence, Western blot, and RT-PCR were performed in highly purified peripheral blood basophils and eosinophils of atopic and nonatopic donors. To assess functional activity, fluorescent avidin-based degranulation assay, calcium mobilization, cytokine production in supernatants, assessment of viability/apoptosis, and tricolor granulocyte activation test were used. RESULTS: MRGPRX2 was significantly expressed by basophils and eosinophils but not neutrophils. Functional capacity was shown by anti-MRGPRX2 mAb-induced calcium influx and concentration-dependent induction of degranulation. Sequential stimulation in the calcium mobilization assay gave no evidence for desensitization or receptor internalization. Anti-MRGPRX2 mAb significantly promoted survival. Inhibition of apoptosis could be due to released IL-3, IL-5, and GM-CSF found in supernatants. Short-term incubation with IL-3 dose-dependently upregulated MRGPRX2 expression in both, stimulation for 24 hours with anti-IgE, C5a, fMLP, and IL-3 in basophils and by IL-3, IL-5, and IL-33 in eosinophils. Among known mast cell MRGPRX2 agonists ciprofloxacin but not PMX-53 was functional on basophils and eosinophils. In basophils of allergic subjects, tricolor granulocyte activation test using grass pollen demonstrated MRGPRX2 upregulation associated with degranulation and CD63 expression. CONCLUSION: Unraveling the regulation and signaling mechanisms of MRGPRX2 on basophils and eosinophils might enable the development of new therapeutic strategies to prevent or inhibit allergic and nonallergic hypersensitivity. Moreover, addressing MRGPRX2 might have potential for diagnostic purposes in (drug) hypersensitivity.

Secondary prevention measures in anaphylaxis patients: Data from the anaphylaxis registry.

BACKGROUND: Patients with a history of anaphylaxis are at risk of future anaphylactic reactions. Thus, secondary prevention measures are recommended for these patients to prevent or attenuate the next reaction. METHODS: Data from the Anaphylaxis Registry were analyzed to identify secondary prevention measures offered to patients who experienced anaphylaxis. Our analysis included 7788 cases from 10 European countries and Brazil. RESULTS: The secondary prevention measures offered varied across the elicitors. A remarkable discrepancy was observed between prevention measures offered in specialized allergy centers (84% of patients were prescribed adrenaline autoinjectors following EAACI guidelines) and outside the centers: Here, EAACI guideline adherence was only 37%. In the multivariate analysis, the elicitor of the reaction, age of the patient, mastocytosis as comorbidity, severity of the reaction, and reimbursement/availability of the autoinjector influence physician's decision to prescribe one. CONCLUSIONS: Based on the low implementation of guidelines concerning secondary prevention measures outside of specialized allergy centers, our findings highlight the importance of these specialized centers and the requirement of better education for primary healthcare and emergency physicians.

Hypersensitivity reactions to biologics (part I): allergy as an important differential diagnosis in complex immune-derived adverse events.

Purpose: Biotechnological substances (BSs) are strongly relied upon to prevent rejection of transplanted organs, and to treat oncological, allergological, and other inflammatory diseases. Allergic reactions to partly foreign biologics can occur due to their potential immunogenicity. The severity of an immune response to a biological drug may range from no clinical significance to a severe, life-threatening anaphylactic reaction.Methods: Detailed searches were performed on Pubmed, Web of Science, and Google Scholar to include all available publications. In addition, the Food and Drug Administration, the European Medicines Agency, and British Columbia Cancer Agency Drug Manual databases were screened for hypersensitivity reaction (HSR), infusion reaction, injection site reaction, urticaria, and anaphylaxis for individual BSs.Results: Treatment with BSs can cause various types of HSR. These are mentioned in the literature with definitions such as allergic reactions, anaphylactoid reactions, anaphylaxis, HSR, infusion reactions, injection site reactions, cytokine release syndrome, and urticaria. Due to the overlap in signs and symptoms in the reported descriptions, it is not always possible to differentiate these reactions properly according to their pathomechanism. Similarly, many data reported as anaphylaxis actually describe severe anaphylactic reactions (grades III or IV).Conclusion: There is an urgent need for a simpler symptom- or system-based classification and scoring system to create an awareness for HSRs to BSs. A better understanding of the pathophysiology of HSRs and increased clinical experience in the treatment of side effects will provide timely control of unexpected reactions. As a result, immunotherapy with BSs will become safer in the future.Cite this as Gülsen A, Wedi B, Jappe U. Hypersensitivity reactions to biologics (part I): allergy as an important differential diagnosis in complex immune-derived adverse events. Allergo J Int 2020; 29:97-125https://doi.org/10.1007/s40629-020-00126-6.

Omalizumab treatment in patients with chronic inducible urticaria: A systematic review of published evidence.

BACKGROUND: Omalizumab, a recombinant anti-IgE antibody, effectively treats chronic spontaneous urticaria. Evidence is lacking in patients with chronic inducible urticarias (CIndUs), which are frequently H1-antihistamine resistant. OBJECTIVE: From the current published literature, we aimed to determine the strength of evidence for omalizumab efficacy and safety in the treatment of CIndUs. METHODS: We performed a PubMed search to identify evidence on omalizumab use in the following 9 CIndU subtypes: symptomatic dermographism, cold urticaria, delayed-pressure urticaria, solar urticaria, heat urticaria, vibratory angioedema, cholinergic urticaria, contact urticaria, and aquagenic urticaria. RESULTS: Forty-three trials, case studies, case reports, and analyses were identified. Our review indicates that omalizumab has substantial benefits in patients with various CIndUs. The evidence is strongest for symptomatic dermographism, cold urticaria, and solar urticaria. Little/no evidence was available on vibratory angioedema and aquagenic and contact urticaria. Our review supports rapid onset of action demonstrated through early symptom control in most cases, sometimes within 24 hours. Many patients gained complete/partial symptom relief and substantially improved quality of life. Adverse events were generally low, with omalizumab being well tolerated by most patients, including children. CONCLUSIONS: A strong body of evidence supports the use of omalizumab in the treatment of patients with therapy-refractory CIndU. More data from randomized controlled studies are warranted.

Generalized reactions during skin testing with clindamycin in drug hypersensitivity: a report of 3 cases and review of the literature.

BACKGROUND: The diagnostic approach to drug hypersensitivity includes a detailed medical history, clinical examination, and skin testing and/or oral challenge with a culprit or alternative drug, depending on the type of reaction and the suspected drugs. Although skin testing is considered to be rather safe, cutaneous and systemic, including fatal, reactions have been described. OBJECTIVES: To report 3 cases with generalized delayed reactions after skin testing with clindamycin, and to review the existing literature. METHODS: Thorough clinical examination, blood tests and prick, intradermal and patch tests were performed in 3 patients. RESULTS: All patients experienced generalized maculopapular exanthema after intradermal and patch testing with clindamycin and amoxicillin in the first patient, and clindamycin alone in the second and third patient. None of the patients showed immediate reactions to skin tests, while positive intradermal reactions after 24 h to amoxicillin and clindamycin were observed in the first patient, and positive intradermal reactions after 24 h to clindamycin were observed in the second and third patients. CONCLUSIONS: Skin testing with clindamycin in the diagnosis of drug hypersensitivity carries some risk of adverse reactions. A stepwise and individual diagnostic work-up, considering potential risk factors, and testing in a specialized centre with emergency equipment available is highly recommended.