In Vitro Diagnostic Testing for Antibiotic Allergy

Exploring the potential and safety of quantum dots in allergy diagnostics

Biomedical investigations in nanotherapeutics and nanomedicine have recently intensified in pursuit of new therapies with improved efficacy. Quantum dots (QDs) are promising nanomaterials that possess a wide array of advantageous properties, including electronic properties, optical properties, and engineered biocompatibility under physiological conditions. Due to these characteristics, QDs are mainly used for biomedical labeling and theranostic (therapeutic-diagnostic) agents. QDs can be functionalized with ligands to facilitate their interaction with the immune system, specific IgE, and effector cell receptors. However, undesirable side effects such as hypersensitivity and toxicity may occur, requiring further assessment. This review systematically summarizes the potential uses of QDs in the allergy field. An overview of the definition and development of QDs is provided, along with the applications of QDs in allergy studies, including the detection of allergen-specific IgE (sIgE), food allergens, and sIgE in cellular tests. The potential treatment of allergies with QDs is also described, highlighting the toxicity and biocompatibility of these nanodevices. Finally, we discuss the current findings on the immunotoxicity of QDs. Several favorable points regarding the use of QDs for allergy diagnosis and treatment are noted.

A new pathway for penicillin delabeling in Norway

Background

Penicillin allergy is self-reported by 3-10% of patients admitted to hospital. The label is wrong in 90% of the cases and has severe health implications. Penicillin-delabeling can reverse the negative effects of the label, and pathways adapted to local practice are needed. No tools are available in Norway for penicillin delabeling outside an allergy clinic.

Objective

To create and validate the first penicillin delabeling pathway applicable outside an allergy clinic in Norway.

Methods

An interdisciplinary taskforce created a penicillin allergy delabeling program (PAD) adapted to the Norwegian health care system. This was validated in a prospective, single-center study. Very low-risk and low-risk patients underwent a direct oral penicillin challenge and high-risk patients were referred for allergologic evaluation.

Results

One-hundred forty-nine patients declaring penicillin allergy were included. Seventy-four (50%) were very-low- and low risk patients suitable for a direct oral penicillin challenge resulting in only 1 mild reaction. Sixty high-risk patients were eligible for an oral penicillin challenge after allergologic evaluation; 3 patients reacted non-severely.

Conclusion

We have created and demonstrated feasibility of the first penicillin delabeling program (PAD) applicable in a hospital setting outside an allergy clinic in Norway. Our data suggest this is safe and beneficial, with 49% patients delabeled through a direct oral penicillin challenge, performed without any serious adverse events, and an overall 87% delabeling rate.

Diagnosis and selection of alternative antibiotics in beta-lactams hypersensitivity reactions: Current recommendations and challenges

Beta-lactam (BLM) antibiotics, including amino-penicillin and cephalosporins, are typically the first-choice treatment for bacterial infections. However, adverse reactions to these antibiotics are frequently reported, causing non-allergist physicians to select alternative broad-spectrum antibiotics that can have harmful consequences. Patients with unclear histories of hypersensitivity reactions to BLMs should undergo an allergy workup to establish a firm diagnosis, particularly when different drugs are prescribed simultaneously. However, finding the safest, most precise, and cost-effective methods for confirming BLMs hypersensitivity and selecting the most appropriate alternative BLM is uncertain, particularly in severe delayed reactions. This review aims to provide data and recommendations on the availability and validity of skin tests (STs), drug provocation test (DPT) protocols, based on the latest published literature and guideline. To make the process more practical, we focused on cross-reactivity between BLMs and diagnostic tests. There are two main novel aspects of this document: 1) For T-cell-mediated reactions, patient stratification into high, moderate, and low-risk groups based on the mortality and morbidity of adverse drug reactions. 2) For IgE-mediated reactions, stratification of individuals with isolated limited urticarial without anaphylaxis in a low-risk group and removal of the extensive limitation.

Delabelling multiple antibiotic allergy: Practical issues

With the growing incidence of multi-drug resistant organisms, delabelling incorrect antibiotic allergies has become an integral part of antimicrobial stewardship worldwide. For example, around 90% of penicillin allergy labels are found to be inaccurate following a full allergy work-up, which deprive patients the use of effective first-line penicillin antibiotics and increase the risk of antimicrobial resistance with the use of other extended spectrum non-penicillin antimicrobials. Significant numbers of adult and paediatric patients over time are labelled with multiple penicillin and non-penicillin antibiotic allergies often during inappropriate antimicrobial use, resulting in a label of “multiple antibiotic allergy”. In contrast to delabelling penicillin allergy where oral direct provocation tests can be used for low-risk, mild reactions, and sensitivity/specificity/positive and negative predictive values of skin tests have been demonstrated, diagnostic tests for multiple antibiotic allergy often require the use of a combination of in-vivo and in-vitro tests across different antimicrobial classes for evaluation. Shared decision making with patients and informed consent are also needed when prioritising which drugs to delabel first, balancing the risks, benefits of testing vs. interim use of alternative antibiotics. Similar to delabelling penicillin allergy, the cost-effectiveness of delabelling multiple drug allergies is unknown.

Improving antimicrobial stewardship with penicillin allergy testing: a review of current practices and unmet needs

Penicillin allergy, the most frequently reported drug allergy, has been associated with suboptimal antibiotic therapy, increased antimicrobial resistance, increased rates of Clostridioides difficile colonization and infection, as well as extended hospital length of stay and increased cost. Although up to 10% of all patients may report penicillin allergy, most penicillin allergies are not confirmed. As such, most patients with a penicillin allergy can still safely use penicillin and related drugs following a more precise assessment. Herein, we review the current practices and unmet needs in penicillin allergy testing. The diagnostic algorithm is mostly based on a clinical history assessment followed by in vivo testing, i.e. skin test and/or drug challenge. As these tests are labour and resource intensive, there is increased interest in point-of-care penicillin allergy de-labelling solutions incorporated into Antimicrobial Stewardship Programmes including digital assessment tools. These can be locally parameterized on the basis of characteristics of target populations, incidence of specific allergies and local antibiotic usage to perform clinical risk stratification. Safely ruling out any residual risk remains essential and in vivo drug challenge and/or skin testing should be systematically encouraged. Gradual understanding and convergence of the risk stratification of the clinical presentation of penicillin allergy is enabling a wider implementation of this essential aspect of antimicrobial stewardship through digitalized decision tools and in vivo testing. More research is needed to deliver point of care in vitro diagnostic tools to democratize this de-labelling practice, which would be highly beneficial to patient care. This progress, together with better education of patients and clinicians about the availability, efficacy and safety of penicillin allergy testing, will increase the dissemination of penicillin allergy assessment as an important component of Antimicrobial Stewardship Programmes.

Antibiotic desensitization as a potential tool in antimicrobial stewardship programs: retrospective data analysis and systematic literature review

OBJECTIVES

Antibiotic allergy labels (AAL) are related to worse therapeutic results. Strategies to improve the management of these patients, such as the implementation of antibiotic desensitization, are essential for Antimicrobial Stewardship Programs (ASP). The aim of our study is to evaluate the efficacy and safety of antibiotic desensitization procedures for the management of patients with AAL.

METHODS

A retrospective study from 2015 to 2022 was performed to describe all antibiotic desensitization conducted in our institution, within the framework of ASP. A systematic literature review using electronic databases, such as PubMed, was also done to identify studies describing antibiotic desensitization between 2000 and 2022.

RESULTS

Sixteen antibiotic desensitization protocols were carried out in our institution. In fourteen cases, the desensitization was successfully completed, and the antibiotic could be used to treat the infection. In the systematic review, twenty-two studies were included, with a total of 202 desensitization episodes . In 97% of them, the desensitization was completed successfully. No desensitization-related mortality was observed neither in our cohort nor in literature review.

CONCLUSIONS

Antibiotic desensitization strategies should be considered a safe and effective tool that can be included in ASP for patients with a high risk of or confirmed allergy to penicillin.

Development and initial validation of a modified lymphocyte transformation test (LTT) assay in patients with DRESS and AGEP

Background

The lymphocyte transformation test (LTT) is an in vitro assay used to diagnose drug induced hypersensitivity reactions by detecting the activation and expansion of drug-specific memory T cells to the suspected implicated drug. Traditionally radiolabelled thymidine (3H-thymidine) has been used but requires the handling and disposal of radioactive materials.

Objective

To examine safe alternatives to 3H-thymidine, test assay modifications for improved assay sensitivity and evaluate the modified LTT in patients with DRESS and AGEP.

Methods

Four proliferation detection assays (BRDU, CyQUANT™, MTT and XTT) were screened for LTT sensitivity. XTT the most sensitive and practical was selected for further evaluation Modifications like autologous serum (AS) and regulatory T cell depletion (T-REG) were tested for improved assay sensitivity. Finally, an initial evaluation of the XTT–LTT was performed in 8 patients with DRESS and 2 with AGEP including cytokine testing.

Results

Of the non-radioactive alternatives we tested, XTT a colorimetric assay was the most sensitive and practical to move to evaluation. The addition of AS increased background signal. Depletion of T-REGs improved sensitivity but cell sorting time and risk of contamination limited benefit.

Of eight patients diagnosed with DRESS and 2 with AGEP tested with XTT–LTT assay results showed our assay matched clinical findings of implicated drugs in 8/10 patients when using a stimulation index (SI) ≥ 2 and 8/10 with analysis by ANOVA. All ten patients were correctly diagnosed by either analysis.

Conclusion

XTT appears to be a safe, viable alternative to 3H-thymidine, with high sensitivity and allowing direct cytokine quantification on specific patient cells.

Drugs and the skin: A concise review of cutaneous adverse drug reactions

Drug-induced skin disease or cutaneous adverse drug reactions (CADRs) are terms that encompass the clinical manifestations of the skin, mucosae and adnexa induced by a drug or its metabolites. The skin is the organ most frequently affected by drug reactions, which may affect up to 10% of hospitalized patients and occur in 1-3% of multimedicated patients. Most CADRs are mild or self-resolving conditions; however, 2-6.7% of could develop into potentially life-threatening conditions. CADRs represent a heterogeneous field and can be diagnostically challenging as they may potentially mimic any dermatosis. Currently, there are between 29-35 different cutaneous drug-reaction patterns reported ranging from mild dermatitis to an extensively burnt patient. The most frequently reported are maculopapular rash, urticaria/angioedema, fixed drug eruption and erythema multiforme. Less common but more severe patterns include erythroderma, drug reaction with eosinophilia and systemic symptoms, and Stevens-Johnson syndrome/toxic epidermal necrolysis spectrum. Almost any drug can induce a CADR, but antibiotics, nonsteroidal anti-inflammatory drugs and antiepileptics are the most frequently involved. Different mechanisms are involved in the pathogenesis of CADRs, although in some cases, these remain still unknown. CADRs could be classified in different ways: (i) type A (augmented) or type B (bizarre); (ii) immediate or delayed; (iii) immune-mediated or nonimmune-mediated; (iv) nonsevere or life-threatening; and (v) by their phenotype, including exanthematous, urticarial, pustular and blistering morphology. Recognizing a specific CADR will mostly depend on the ability of the physician to perform a detailed clinical examination, the proper description of the morphology of the skin lesions and supporting laboratory and/or skin biopsy findings.

Multiepitope Dendrimeric Antigen-Silica Particle Composites as Nano-Based Platforms for Specific Recognition of IgEs

β-lactam antibiotics (BLs) are the drugs most frequently involved in drug hypersensitivity reactions. However, current in vitro diagnostic tests have limited sensitivity, partly due to a poor understanding of in vivo drug–protein conjugates that both induce the reactions and are immunologically recognized. Dendrimeric Antigen-Silica particle composites (DeAn@SiO₂), consisting on nanoparticles decorated with BL-DeAns are promising candidates for improving the in vitro clinical diagnostic practice. In this nano-inspired system biology, the synthetic dendrimer plays the role of the natural carrier protein, emulating its haptenation by drugs and amplifying the multivalence. Herein, we present the design and synthesis of new multivalent mono- and bi-epitope DeAn@SiO₂, using amoxicillin and/or benzylpenicillin allergenic determinants as ligands. The homogeneous composition of nanoparticles provides high reproducibility and quality, which is critical for in vitro applications. The suitable functionalization of nanoparticles allows the anchoring of DeAn, minimizing the nonspecific interactions and facilitating the effective exposure to specific IgE; while the larger interaction area increments the likelihood of capturing specific IgE. This achievement is particularly important for improving sensitivity of current immunoassays since IgE levels in BL allergic patients are very low. Our data suggest that these new nano-based platforms provide a suitable tool for testing IgE recognition to more than one BL simultaneously. Immunochemical studies evidence that mono and bi-epitope DeAn@SiO₂ composites could potentially allow the diagnosis of patients allergic to any of these drugs with a single test. These organic–inorganic hybrid materials represent the basis for the development of a single screening for BL-allergies.

Role of nanostructures in allergy: Diagnostics, treatments and safety

Nanotechnology is science, engineering and technology conducted at the nanoscale, which is about 1-100 nm. It has led to the development of nanomaterials, which behave very differently from materials with larger scales and can have a wide range of applications in biomedicine. The physical and chemical properties of materials of such small compounds depend mainly on the size, shape, composition and functionalization of the system. Nanoparticles, carbon nanotubes, liposomes, polymers, dendrimers and nanogels, among others, can be nanoengineeried for controlling all parameters, including their functionalization with ligands, which provide the desired interaction with the immunological system, that is dendritic cell receptors to activate and/or modulate the response, as well as specific IgE, or effector cell receptors. However, undesired issues related to toxicity and hypersensitivity responses can also happen and would need evaluation. There are wide panels of accessible structures, and controlling their physico-chemical properties would permit obtaining safer and more efficient compounds for clinical applications goals, either in diagnosis or treatment. The application of dendrimeric antigens, nanoallergens and nanoparticles in allergy diagnosis is very promising since it can improve sensitivity by increasing specific IgE binding, mimicking carrier proteins or enhancing signal detection. Additionally, in the case of immunotherapy, glycodendrimers, liposomes, polymers and nanoparticles have shown interest, behaving as platforms of allergenic structures, adjuvants or protectors of allergen from degradation or having a depot capacity. Taken together, the application of nanotechnology to allergy shows promising facts facing important goals related to the improvement of diagnosis as well as specific immunotherapy.

Nanoarchitectures for efficient IgE cross-linking on effector cells to study amoxicillin allergy

BACKGROUND

Amoxicillin (AX) is nowadays the β-lactam that more frequently induces immediate allergic reactions. Nevertheless, diagnosis of AX allergy is occasionally challenging due to risky in vivo tests and non-optimal sensitivity of in vitro tests. AX requires protein haptenation to form multivalent conjugates with increased size to be immunogenic. Knowing adduct structural features for promoting effector cell activation would help to improve in vitro tests. We aimed to identify the optimal structural requirement in specific cellular degranulation to AX using well-precised nanoarchitectures of different lengths.

METHOD

We constructed eight Bidendron Antigens (BiAns) based on polyethylene glycol (PEG) linkers of different lengths (600-12,000 Da), end-coupled with polyamidoamine dendrons that were terminally multi-functionalized with amoxicilloyl (AXO). In vitro IgE recognition was studied by competitive radioallergosorbent test (RAST) and antibody-nanoarchitecture complexes by transmission electron microscopy (TEM). Their allergenic activity was evaluated using bone marrow-derived mast cells (MCs) passively sensitized with mouse monoclonal IgE against AX and humanized RBL-2H3 cells sensitized with polyclonal antibodies from sera of AX-allergic patients.

RESULTS

All BiAns were recognized by AX-sIgE. Dose-dependent activation responses were observed in both cellular assays, only with longer structures, containing spacers in the range of PEG 6000-12,000 Da. Consistently, greater proportion of immunocomplexes and number of antibodies per complex for longer BiAns were visualized by TEM.

CONCLUSIONS

BiAns are valuable platforms to study the mechanism of effector cell activation. These nanomolecular tools have demonstrated the importance of the adduct size to promote effector cell activation in AX allergy, which will impact for improving in vitro diagnostics.

Diagnostic Approach of Hypersensitivity Reactions to Cefazolin in a Large Prospective Cohort

BACKGROUND

Cefazolin is a common trigger of perioperative anaphylaxis. The diagnostic approach is controversial because the optimal concentration for skin testing is uncertain, drug provocation tests (DPTs) are contraindicated in severe reactions, and in vitro tests are not thoroughly validated.

OBJECTIVE

We aimed to characterize a large number of patients reporting cefazolin allergic reactions and to analyze the diagnostic role of in vivo and in vitro tests.

METHODS

We prospectively evaluated patients with suspicion for allergic reactions to cefazolin by clinical history, skin tests (STs), and, if negative, DPT. In a subgroup of patients, basophil activation test (BAT) and radioallergosorbent test were done before allergologic workup was performed and the final diagnosis was achieved.

RESULTS

We evaluated 184 patients, 76 of whom were confirmed as allergic (41.3%), 90 were nonallergic (48.9%), and 18 were nonconfirmed (9.8%). All patients reporting anaphylactic shock and most reporting anaphylaxis were confirmed to be allergic (P < .001). Forty allergic patients (52.6%) were confirmed by STs, 22 by DPT (28.9%), and 14 by clinical history (18.4%). All subjects manifesting exanthemas and pruritus were nonallergic. The BAT sensitivity was 66.7% when CD63 and CD203c were combined as activation markers. Six of 8 patients with negative STs and positive DPT had a positive BAT.

CONCLUSIONS

Patients allergic to cefazolin often reported severe immediate-type reactions. Skin tests enabled a diagnosis in half of patients when using cefazolin at 20 mg/mL. Unfortunately, DPT could not be performed in all patients owing to reaction severity, which makes BAT a promising diagnostic tool. Further research is needed to clarify the underlying mechanisms, especially in severe reactions.

In-Vitro Approaches to Predict and Study T-Cell Mediated Hypersensitivity to Drugs

Mitigating the risk of drug hypersensitivity reactions is an important facet of a given pharmaceutical, with poor performance in this area of safety often leading to warnings, restrictions and withdrawals. In the last 50 years, efforts to diagnose, manage, and circumvent these obscure, iatrogenic diseases have resulted in the development of assays at all stages of a drugs lifespan. Indeed, this begins with intelligent lead compound selection/design to minimize the existence of deleterious chemical reactivity through exclusion of ominous structural moieties. Preclinical studies then investigate how compounds interact with biological systems, with emphasis placed on modeling immunological/toxicological liabilities. During clinical use, competent and accurate diagnoses are sought to effectively manage patients with such ailments, and pharmacovigilance datasets can be used for stratification of patient populations in order to optimise safety profiles. Herein, an overview of some of the in-vitro approaches to predict intrinsic immunogenicity of drugs and diagnose culprit drugs in allergic patients after exposure is detailed, with current perspectives and opportunities provided.

Lymphocyte transformation test: History and current approaches

Drug-induced hypersensitivity reactions encompass a variety of different clinical phenotypes ranging from harmless rashes to fatal reactions. They can be classified into allergic (i.e. drug allergy) and non-allergic reactions (i.e. non-allergic hypersensitivity). Drug allergies in turn can either be antibody (e.g. IgE) or T cell-mediated. One of the diagnostic tools for the in vitro detection of drug allergy is the lymphocyte transformation test (LTT) which is based on the activation and expansion of the drug-specific memory T cells following co-incubation of the patient's peripheral mononuclear cells (PMBC) with the suspected drug in vitro. The read-out parameter in the classical LTT is T cell proliferation which can be measured as counts per minute following the addition of radiolabeled thymidine to the cell culture. However, in the course of time different modifications of the classical LTT with regard to the read-out parameters and methods have been proposed. Likewise, variations of the LTT platform itself have been described in the literature. This review article describes the development of the classical LTT and its use in the context of drug allergy detection and summarizes the modifications which have been published over time.

Diagnostic workup including CD203c-based basophil activation test in immediate hypersensitivity due to metronidazole and ornidazole and evaluation of cross-reactivity in between

BACKGROUND

Little is known about the diagnostic approaches for immediate hypersensitivity reactions (IHRs) due to 5-nitroimidazole antibiotics. The aim was to evaluate the usefulness of in vivo tests and basophil activation test (BAT) for the diagnosis of IHRs due to metronidazole and ornidazole and to determine possible cross-reactivity in between.

METHODS

Forty-nine patients with a clear history of IHRs due to these drugs and 20 healthy subjects who were known to tolerate these drugs were included. Skin tests (STs) and single-blind placebo-controlled drug provocation tests (SBPCDPTs) were performed with both drugs whereas BAT was applied only with the culprit drug.

RESULTS

The most and least common reaction types were urticaria/angioedema (34.7%) and anaphylaxis (14.3%), respectively. SBPCDPTs were positive in 15 out of 47 patients, and only 7 had positive STs. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of STs for metronidazole/ornidazole were 33.3%/16.6%, 94.2%/97.3%, 60%/50%, and 84.6%/88.1%, respectively. BAT was positive in 12 out of 15 patients and negative in 10 control subjects, giving a sensitivity rate of 71.4% (CI, 29.0%-96.3%) for metronidazole and 83.3% (CI, 35.8%-99.5%) for ornidazole. The optimal concentration of both drugs for BAT was determined as 5 mg/mL. No cross-reactivity among two drugs was observed according to in vivo tests.

CONCLUSIONS

Our study showed that SBPCDPT and BAT are both useful diagnostic tools for IHRs due to 5-nitroimidazole antibiotics and can be used as supplementary to each other. No cross-reactivity between metronidazole and ornidazole in IHRs exists.

The Role of Benzylpenicilloyl Epimers in Specific IgE Recognition

The high prevalence of allergy to β-lactam antibiotics is a worldwide issue. Accuracy of diagnostic methods is important to prove tolerance or allergy, with skin test considered the best validated in vivo method for diagnosing immediate reactions to β-lactams. Although drug provocation test is the reference standard, it cannot be performed in highly risk reactions or in those with positive skin tests. For skin tests, the inclusion of major and minor determinants of benzylpenicillin (BP) is recommended. Commercial skin test reagents have changed along time, including as minor determinants benzylpenicillin, benzylpenicilloate (BPO), and benzylpenilloate (PO). Major determinants consists of multivalent conjugates of benzylpenicilloyl coupled through amide bond to a carrier polymer, such as penicilloyl-polylysine (PPL) or benzylpenicilloyl-octalysine (BP-OL). The chemical stability of such reagents has influenced the evolution of the composition of the commercial kits, as this requirement is necessary for improving the quality and standardization of the product. In this work, we provide a detailed study of the chemical stability of BP determinants. We observed that those structures suffer from an epimerization process in C-5 at different rates. Butylamine-Benzylpenicilloyl conjugates (5R,6R)-Bu-BPO and (5S,6R)-Bu-BPO were selected as a simple model for mayor determinant to evaluate the role of the different epimers in the immunoreactivity with sera from penicillin-allergic patients. In vitro immunoassays indicate that any change in the chemical structure of the antigenic determinant of BP significantly affects IgE recognition. The inclusion of stereochemically pure compounds or mixtures may have important implications for both the reproducibility and sensitivity of in vivo and in vitro diagnostic tests.

Biotin-Labelled Clavulanic Acid to Identify Proteins Target for Haptenation in Serum: Implications in Allergy Studies

Clavulanic acid (CLV) and amoxicillin, frequently administered in combination, can be independently involved in allergic reactions. Protein haptenation with β-lactams is considered necessary to activate the immune system. The aim of this study was to assess the suitability of biotinylated analogues of CLV as probes to study protein haptenation by this β-lactam. Two synthetic approaches afforded the labeling of CLV through esterification of its carboxylic group with a biotin moiety, via either direct binding (CLV-B) or tetraethylenglycol linker (CLV-TEG-B). The second analogue offered advantages as solubility in aqueous solution and potential lower steric hindrance for both intended interactions, with the protein and with avidin. NMR reactivity studies showed that both CLV and CLV-TEG-B reacts through β-lactam ring opening by aliphatic amino nitrogen, however with different stability of resulting conjugates. Unlike CLV conjugates, that promoted the decomposition of clavulanate fragment, the conjugates obtained with the CLV-TEG-B remained linked, as a whole structure including biotin, to nucleophile and showed a better stability. This was a desired key feature to allow CLV-TEG-B conjugated protein detection at great sensitivity. We have used biotin detection and mass spectrometry (MS) to detect the haptenation of human serum albumin (HSA) and human serum proteins. MS of conjugates showed that HSA could be modified by CLV-TEG-B. Remarkably, HSA preincubation with CLV excess only reduced moderately the incorporation of CLV-TEG-B, which could be attributed to different protein interferences. The CLV-TEG-B fragment with opened β-lactam was detected bound to the ^404-430HSA peptide of the treated protein. Incubation of human serum with CLV-TEG-B resulted in the haptenation of several proteins that were identified by 2D-electrophoresis and peptide mass fingerprinting as HSA, haptoglobin, and heavy and light chains of immunoglobulins. Taken together, our results show that tagged-CLV keeps some of the CLV features. Moreover, although we observe a different behavior in the conjugate stability and in the site of protein modification, the similar reactivity indicates that it could constitute a valuable tool to identify protein targets for haptenation by CLV with high sensitivity to get insights into the activation of the immune system by CLV and mechanisms involved in β-lactams allergy.

Association Between Allergen Sensitization and Anaphylaxis in Patients Visiting a Pediatric Emergency Department

Background and Objectives: Anaphylaxis, a severe allergic disease, can be triggered by various causes. This study investigated the association between allergic sensitization and anaphylactic symptoms and the severity of anaphylaxis in children. Patients and Methods: A retrospective review of 107 pediatric patients with anaphylaxis was performed between January 1, 2015, and December 31, 2017; 74 patients underwent allergen testing for specific immunoglobulin E. Allergic sensitizations and associations with anaphylactic symptoms and severity were investigated. Results: Overall, 64 (86.5%) patients were sensitized to food or inhalant allergens. In children under 2 years of age, 90.5% were sensitized to food (P = 0.001); in those over 6 years of age, 84.6% were sensitized to inhalant allergens (P = 0.001). Milk sensitization was significantly associated with severe anaphylaxis (P = 0.036). The following symptoms showed significant associations with certain allergen sensitizations: facial edema with food; wheezing with milk; dyspnea with mite, etc. Certain allergen sensitizations presenting as risk factors for anaphylactic symptoms: wheat (adjusted odds ratio [aOR] = 4.644, P = 0.044) and nuts (aOR=3.614, P = 0.041) for wheezing, nuts (aOR=5.201, P = 0.026) for dyspnea, and milk (aOR=4.712, P = 0.048) for vomiting. Conclusion: The allergen sensitization status differed according to the age of the children experiencing anaphylaxis. The severity, symptoms, and signs of anaphylaxis differed depending on the allergen sensitization status.

Diagnostic procedures & practices in drug allergy/hypersensitivity: a survey of 13 Asian countries

BACKGROUND

The issues and challenges in the diagnosis of drug allergy/hypersensitivity among children and adults in Asia are likely to be different from non-Asian countries.

OBJECTIVE

To study the diagnostic modalities used in the evaluation and management of drug allergy/drug hypersensitivity reactions (DHRs) among member societies of the Asia Pacific Association of Allergy, Asthma and Clinical Immunology (APAAACI).

METHODS

A questionnaire comprising 41 questions was circulated electronically to member societies and individual members of APAAACI between January 23, 2020 and March 6, 2020.

RESULTS

Twenty-six respondents from 15 member societies and 1 individual member responded. European DHR guidelines were most commonly used. Skin prick and intradermal testing was used by 100%, with only 60% having access to commercial penicillin skin test reagents. In vitro-specific IgE tests were used by 75%, and basophil activation test by 56.3% for immediate DHR. Patch tests were used by 75% in contrast to lymphocyte transformation tests by 25% for nonimmediate DHR. Drug provocation tests were used by 68.8%, the most common indication being to exclude hypersensitivity where history/symptoms were not suggestive of drug hypersensitivity/allergy (93.3%). Human leukocyte antigen (HLA) genotype testing was mandatory among 25% respondents before new carbamazepine prescriptions, and 8.3% for allopurinol prescriptions.

CONCLUSIONS

There was increased use of skin testing for iodinated contrast media hypersensitivity and patch testing for nonimmediate DHR. HLA genotype testing prior to new carbamazepine, allopurinol and abacavir prescriptions remain variable despite strong associations for severe cutaneous adverse reactions with Asian ethnicity. Results of this survey form a useful framework for developing educational and training needs and for improving access to drug allergy diagnostic and treatment modalities across APAAACI member societies.

Neo-antigens for the serological diagnosis of IgE-mediated drug allergic reactions to antibiotics cephalosporin, carbapenem and monobactam

New antigens deriving from -lloyl and -llanyl, major and minor determinants, respectively, were produced for β-lactam antibiotics cefuroxime, cefotaxime, ceftriaxone, meropenem and aztreonam. Twenty β-lactam antigens were produced using human serum albumin and histone H1 as carrier proteins. Antigens were tested by multiplex in vitro immunoassays and evaluated based on the detection of specific IgG and IgE in the serum samples. Both major and minor determinants were appropriate antigens for detecting specific anti-β-lactam IgG in immunised rabbit sera. In a cohort of 37 allergic patients, we observed that only the minor determinants (-llanyl antigens) were suitable for determining specific anti-β-lactam IgE antibodies with high sensitivity (< 0.01 IU/mL; 24 ng/L) and specificity (100%). These findings reveal that not only the haptenisation of β-lactam antibiotics renders improved molecular recognition events when the 4-member β-lactam ring remains unmodified, but also may contribute to develop promising minor antigens suitable for detecting specific IgE-mediated allergic reactions. This will facilitate the development of sensitive and selective multiplexed in vitro tests for drug-allergy diagnoses to antibiotics cephalosporin, carbapenem and monobactam.

Basophil activation testing in occupational respiratory allergy to low molecular weight compounds

PURPOSE OF REVIEW

There is an unmet need for better immunological tests in cases of suspected occupational asthma to many workplace chemicals; here we consider the basophil activation test (BAT), a potential alternative to the detection of specific IgE antibodies.

RECENT FINDINGS

BAT is fairly widely used in general allergy services; and there is increasing experience of its use in the diagnosis of occupational allergy to low molecular weight agents and chemicals including wood dusts, persulphates, antibiotics and latex.

SUMMARY

There is potential for BAT to become a useful tool in the clinical consideration of occupational asthma and of its mechanisms, and even to take a place in a Bayesian-based diagnostic algorithm. Further development will only occur if specialist centres with appropriate facilities, and preferably in collaboration, contemplate its use.

Recent developments and highlights in drug hypersensitivity

Drug hypersensitivity reactions (DHRs) are nowadays the third cause of allergy after rhinitis and asthma with a significant increase in prevalence in both adults and paediatric population with new drugs included as culprit. For this, DHRs represent not only a health problem but also a significant financial burden for affected individuals and health systems. Mislabelling DHRs is showing to be a relevant problem for both, false label of drug allergic and false label of nonallergic. All this reinforces the need to improve accurate diagnostic approaches that allow an appropriate management. Moreover, there is a need for training both, nonallergist stakeholders and patients to improve the reaction identification and therefore decrease the mislabelling. The use of allergy cards has shown to be relevant to avoid the induction of DHRs due to the prescription of wrong medication. Recent developments over the last 2 years and highlights about risk factors, diagnostic approaches, mechanisms involved as well as prevention actions, and management have been reviewed. In these papers, it has been outlined the need for correct diagnosis and de-labelling of patients previously false-reported as allergic, which will improve the management and treatment of patients with DHRs.

BAT in the Diagnosis of Drug Allergy: a Novel Tool in Clinical Daily Practice?

PURPOSE OF REVIEW

The aim of this study is to critically review the relevant literature published on basophil activation test, presenting the current knowledge and future perspectives.

RECENT FINDINGS

Basophil activation test (BAT) results varied accordingly to the class of the drug studied, and have promising results in immediate hypersensitivity reactions to pyrazolone (selective reactors), neuromuscular blockers, beta-lactams, and platinum compounds, all examples of classical IgE-mediated hypersensitivity drug reactions. Currently, BAT is applied in research settings, but based in the results of our review, the test can be considered as a diagnostic tool for daily practice for selected patients and selected drugs, when the test is available, particularly for patients who experienced severe reactions and when diagnosis cannot be stablished by serum-specific IgE and skin testing, in order to avoid unnecessary drug provocations tests.

Efficacy and tolerability of desensitization in the treatment of delayed drug hypersensitivities to anti-tuberculosis medications

BACKGROUND

Delayed drug hypersensitivity to first-line anti-tuberculosis medication is a major challenge in tuberculosis treatment.

OBJECTIVE

This study was performed to investigate the efficacy/tolerability of desensitization therapy in treatment of first-line anti-tuberculosis medication hypersensitivity and the usefulness of immunologic evaluation therein.

METHODS

This study was conducted as a prospective, observational cohort study. Subjects who experienced hypersensitivity reactions, including maculopapular exanthema (MPE) and drug reaction with eosinophilia and systemic symptoms (DRESS), to first-line anti-tuberculosis medications (isoniazid [INH], ethambutol [EMB], rifampin [RFP], and pyrazinamide [PZA]) were enrolled. Patch, intradermal, lymphocyte transformation, and oral provocation tests were performed to determine culprit drugs, which were desensitized with rapid and graded challenge protocols. Breakthrough reactions (BTRs) during or after desensitization were assessed.

RESULTS

In total, 31 desensitization treatments (INH, 8; EMB, 8; RFP, 11; PZA, 4) to 12 patients (8 with MPE and 4 with DRESS) were performed. The overall success rate of desensitization was 80.7%. All the study subjects except one completed the full course of anti-tuberculosis treatment. The overall BTR free rate was 64.5%. Sixteen (80%) treatments for MPE and four (36.4%) for DRESS were BTR free (P = 0.023). Drugs that were positive on any two of three immunologic studies showed significantly high BTR rates (P = 0.014), although this was not correlated with desensitization failure rate.

CONCLUSION

Rapid desensitization therapy to multiple anti-tuberculosis medications for delayed drug hypersensitivity was safe and successful. Combination of multiple immunologic evaluations may predict BTR although it needs validation in larger studies.

Eperisone-Induced Anaphylaxis: Pharmacovigilance Data and Results of Allergy Testing

PURPOSE

Eperisone is an oral muscle relaxant used in musculoskeletal disorders causing muscle spasm and pain. For more effective pain control, eperisone is usually prescribed together with nonsteroidal anti-inflammatory drugs (NSAIDs). As such, eperisone may have been overlooked as the cause of anaphylaxis compared with NSAIDs. This study aimed to analyze the adverse drug reaction (ADR) reported in Korea and suggest an appropriate diagnostic approach for eperisone-induced anaphylaxis.

METHODS

We reviewed eperisone-related pharmacovigilance data (Korea Institute of Drug Safety-Korea Adverse Event Reporting System [KIDS-KAERS]) reported in Korea from 2010 to 2015. ADRs with causal relationship were selected. Clinical manifestations, severity, outcomes, and re-exposure information were analyzed. For further investigation, 7-year ADR data reported in a single center were also reviewed. Oral provocation test (OPT), skin prick test (SPT) and basophil activation test (BAT) were performed in this center.

RESULTS

During the study period, 207 patients had adverse reactions to eperisone. The most common ADRs were cutaneous hypersensitive reactions (30.4%) such as urticaria, itchiness or angioedema. Fifth common reported ADR was anaphylaxis. There were 35 patients with anaphylaxis, comprising 16.9% of the eperisone-related ADRs. In the single center study, there were 11 patients with eperisone-induced anaphylaxis. All the patients underwent OPT and all the provoked patients showed a positive reaction. Four of the 11 patients with anaphylaxis also underwent SPT and BAT, which were all negative.

CONCLUSIONS

Incidence of eperisone-induced anaphylaxis calculated from the KIDS-KAERS database was 0.001%. Eperisone can cause hypersensitive reactions, including anaphylaxis, possibly by inducing non-immunoglobulin E-mediated immediate hypersensitivity.

Immune Functional Assays, From Custom to Standardized Tests for Precision Medicine

The immune response is a dynamic system that maintains the integrity of the body, and more specifically fight against infections. However, an unbalanced host immune response is highlighted in many diseases. Exacerbated responses lead to autoimmune and allergic diseases, whereas, low or inefficient responses favor opportunistic infections and viral reactivations. Conflicting situations may also occur, such as in sepsis where inflammation and compensatory immunosuppression make it difficult to deploy the appropriate drug treatment. Until the current day, assessing the immune profile of patients remains a challenge. This is especially due to the inter-individual variability—a key feature of the immune system—which hinders precise diagnosis, prognosis, and therapeutic stratification. Our incapacity to practically interpret the host response may contribute to a high morbidity and mortality, such as the annual 6 million worldwide deaths in sepsis alone. Therefore, there is a high and increasing demand to assess patient immune function in routine clinical practice, currently met by Immune Functional Assays. Immune Functional Assays (IFA) hold a plethora of potentials that include the precise diagnosis of infections, as well as prediction of secondary and latent infections. Current available products are devoted to indirect pathogen detection such as Mycobacteria tuberculosis interferon gamma release assays (IGRA). In addition, identifying the status and the underlying factors of immune dysfunction (e.g., in septic patients) may guide immune targeted therapies. Tools to monitor and stratify the immune status are currently being studied but they still have many limitations such as technical standardization, biomarkers relevance, systematic interpretation and need to be simplified, in order to set the boundaries of “healthy,” “ill,” and “critically ill” responses. Thus, the design of new tools that give a comprehensive insight into the immune functionality, at the bedside, and in a timely manner represents a leap toward immunoprofiling of patients.

Proper Cut-off Levels of Serum Specific IgE to Cefaclor for Patients with Cefaclor Allergy

PURPOSE

Cefaclor, a second-generation oral cephalosporin, is known to cause IgE-mediated hypersensitivity. Assays of serum-specific IgE (sIgE) to cefaclor are commercially available via the ImmunoCAP system (Thermo Fisher Scientific). While serum levels of sIgE >0.35 kU/L are considered indicative of an allergy, some patients with cefaclor allergy show low serum IgE levels. This study aimed to evaluate the proper cut-off levels of sIgE in the diagnosis of immediate hypersensitivity to cefaclor.

MATERIALS AND METHODS

A total of 269 patients with drug allergy history, who underwent assays of sIgE to cefaclor at Ajou University hospital and Dong-A University Hospital, were reviewed retrospectively. Among them, 193 patients exhibited cefaclor-induced immediate hypersensitivity with certain or probable causality of an adverse drug reaction according to the WHO-UMC (the World Health Organization-the Uppsala Monitoring Centre) algorithm, and 76 controls showed delayed hypersensitivity reactions to non-antibiotics.

RESULTS

In total, 126 of the 193 patients (65.3%) experienced anaphylaxis; they had higher serum sIgE levels than patients with immediate hypersensitivity who did not experience anaphylaxis (6.36±12.39 kU/L vs. 4.28±13.61 kU/L, p<0.001). The best cut-off value for cefaclor-induced immediate hypersensitivity was 0.11 kU/L, with sensitivity of 80.2% and specificity of 81.6%. A cut-off value of 0.44 kU/L showed the best sensitivity (75.4%) and specificity (65.7%) for differentiating anaphylaxis from immediate hypersensitivity reactions.

CONCLUSION

Patients with cefaclor anaphylaxis exhibit high serum IgE levels. A cut-off value of 0.11 kU/L of sIgE to cefaclor is proper for identifying patients with cefaclor allergy, and 0.44 kU/L may be useful to detect anaphylaxis.

Controversies in Drug Allergy: Beta-Lactam Hypersensitivity Testing

All beta-lactam use is associated with a certain rate of adverse reactions. Many of these adverse reactions result in an allergy to the beta-lactam being entered into the patient's medical record. Unfortunately, only a small minority of these recorded allergies are clinically significant immunologically mediated drug hypersensitivity. An unconfirmed allergy to beta-lactams is a significant public health risk, because patients so labeled typically do not receive narrow-spectrum penicillins and cephalosporins when clinically indicated. The alternative antibiotics they receive result in poorer clinical outcomes, increased incidence of serious antibiotic-resistant infections, prolonged hospitalizations, and greater health care utilization. There is a wide variation in beta-lactam allergy incidence and prevalence around the world, based in part on the specific beta-lactams used and overused. There is a wide variation in specific protocols used to confirm current tolerance of beta-lactams and remove these inaccurate allergy reports. Harmonizing testing protocols, when possible, may lead to more widespread use of narrow-spectrum beta-lactams, when clinically indicated, and improve patient safety worldwide. Further research is needed to better understand the regional differences in reporting beta-lactam allergy as this relates to regional differences in beta-lactam use and overuse, the frequency of clinically significant immunologically mediated beta-lactam hypersensitivity, and the optimal testing strategies to confirm current tolerance, based on presenting clinical symptoms.

Sulfonamide Drug Allergy

PURPOSE OF REVIEW

We sought to review past and current literature on sulfonamide drug allergy and distill it in a practical manner to assist the clinician, specifically focusing on cross-reactivity and desensitization.

RECENT FINDINGS

There do not appear to be consistent genetic markers to reliably predict features of or the presence hypersensitivity reactions. Recent evidence continues to alleviate early concerns cross-reactivity between sulfonamide antibiotics and non-antibiotics. Sulfonamide drug allergy is frequently encountered by the practicing clinician. For sulfonamide antibiotics, delayed rash is the most common clinical manifestation. There is no current evidence to support avoidance of all non-antibiotic sulfonamides in those with a reported allergy to sulfonamide antibiotics, although certain scenarios require caution. Available evidence supports the cautious reintroduction of sulfonamide antibiotics via desensitization, which is usually well tolerated and should be considered in those with strong indications for trimethoprim-sulfamethoxazole and a reported sulfonamide allergy.

Dendrimeric Antigens for Drug Allergy Diagnosis: A New Approach for Basophil Activation Tests

Dendrimeric Antigens (DeAns) consist of dendrimers decorated with multiple units of drug antigenic determinants. These conjugates have been shown to be a powerful tool for diagnosing penicillin allergy using in vitro immunoassays, in which they are recognized by specific IgE from allergic patients. Here we propose a new diagnostic approach using DeAns in cellular tests, in which recognition occurs through IgE bound to the basophil surface. Both IgE molecular recognition and subsequent cell activation may be influenced by the tridimensional architecture and size of the immunogens. Structural features of benzylpenicilloyl-DeAn and amoxicilloyl-DeAn (G2 and G4 PAMAM) were studied by diffusion Nuclear Magnetic Resonance (NMR) experiments and are discussed in relation to molecular dynamics simulation (MDS) observations. IgE recognition was clinically evaluated using the basophil activation test (BAT) for allergic patients and tolerant subjects. Diffusion NMR experiments, MDS and cellular studies provide evidence that the size of the DeAn, its antigen composition and tridimensional distribution play key roles in IgE-antigen recognition at the effector cell surface. These results indicate that the fourth generation DeAns induce a higher level of basophil activation in allergic patients. This approach can be considered as a potential complementary diagnostic method for evaluating penicillin allergy.

An Updated Review of the Molecular Mechanisms in Drug Hypersensitivity

Drug hypersensitivity may manifest ranging from milder skin reactions (e.g., maculopapular exanthema and urticaria) to severe systemic reactions, such as anaphylaxis, drug reactions with eosinophilia and systemic symptoms (DRESS)/drug-induced hypersensitivity syndrome (DIHS), or Stevens–Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN). Current pharmacogenomic studies have made important strides in the prevention of some drug hypersensitivity through the identification of relevant genetic variants, particularly for genes encoding drug-metabolizing enzymes and human leukocyte antigens (HLAs). The associations identified by these studies are usually drug, phenotype, and ethnic specific. The drug presentation models that explain how small drug antigens might interact with HLA and T cell receptor (TCR) molecules in drug hypersensitivity include the hapten theory, the p-i concept, the altered peptide repertoire model, and the altered TCR repertoire model. The broad spectrum of clinical manifestations of drug hypersensitivity involving different drugs, as well as the various pathomechanisms involved, makes the diagnosis and management of it more challenging. This review highlights recent advances in our understanding of the predisposing factors, immune mechanisms, pathogenesis, diagnostic tools, and therapeutic approaches for drug hypersensitivity.

The Value of In Vitro Tests to DiminishDrug Challenges

Drug hypersensitivity reactions have multiple implications for patient safety and health system costs, thus it is important to perform an accurate diagnosis. The diagnostic procedure includes a detailed clinical history, often unreliable; followed by skin tests, sometimes with low sensitivity or unavailable; and drug provocation testing, which is not risk-free for the patient, especially in severe reactions. In vitro tests could help to identify correctly the responsible agent, thus improving the diagnosis of these reactions, helping the physician to find safe alternatives, and reducing the need to perform drug provocation testing. However, it is necessary to confirm the sensitivity, specificity, negative and positive predictive values for these in vitro tests to enable their implementation in clinical practice. In this review, we have analyzed these parameters from different studies that have used in vitro test for evaluating drug hypersensitivity reactions and estimated the added value of these tests to the in vivo diagnosis.