Usefulness of In Vivo and In Vitro Diagnostic Tests in the Diagnosis of Hypersensitivity Reactions to Quinolones and in the Evaluation of Cross-Reactivity: A Comprehensive Study Including the Latest Quinolone Gemifloxacin

Is a Drug Allergy in a Patient's History Real? Our Experience with Diagnostic Drug Provocation Tests

Background and Objectives: Early-type drug hypersensitivity reactions (DHRs) are observed within the first 1-6 h and most commonly manifest as urticaria and/or angioedema. Detailed anamnesis, skin prick tests (SPTs), intradermal tests (IDTs), and oral/intramuscular/intravenous drug provocation tests (DPTs) can be used to identify the drug responsible. We aimed to evaluate the demographic characteristics, responsible drugs, DHR types, and DPT results used in the diagnosis of drug allergy in patients who presented to our clinic with suspected drug allergies. Materials and Methods: The medical records of patients who presented with a suspicion of an early-type DHR between February 2019 and December 2024 were retrospectively evaluated through the hospital information management system. A total of 188 adults who underwent diagnostic drug testing were included. Results: The diagnosis of drug allergy was confirmed in 51 (27%) patients. In 137 (73%) patients, the diagnosis of drug allergy was excluded after DPTs. In 78 of the 188 patients, there was a DHR to a single suspected drug. The other 110 patients had DHR histories with multiple drugs. The rate of confirmation of a drug allergy from diagnostic tests was higher in those who described a history of multiple drug allergies. Amongst the antibiotics, beta-lactam antibiotics (n = 47) were the most frequently suspected drugs. The rate of positive DPTs (n = 4; 8%) was lower in patients with suspected beta-lactam allergies than other antibiotics (p = 0.002). NSAIDs (n = 60) were the second most common group of suspected drug allergies. With regard to IgE or COX-1-mediated mechanisms, there was no statistically significant difference in DPT positivity among these NSAIDs (p = 0.414). The severity of the initial early-type DHRs were grade 1 (n = 168; 80%), grade 2 (n = 14; 7%), and grade 3 (n = 14; 7%). If the patients had redness, itching, urticaria, angioedema, dyspnea, cyanosis, desaturation, syncope, tachycardia, or hypotension during their initial DHRs, the positive diagnostic drug test rate was statistically significantly higher. However, experiencing diarrhea, nausea, and vomiting were not found to be associated with positive diagnostic drug tests. Drug allergies were confirmed with SPTs or IDTs in all patients in whom adrenaline was used during initial reactions. Conclusions: Contrary to the prevailing notion that drugs (especially beta-lactams) are the predominant cause of allergic reactions, this study demonstrated that the actual prevalence of drug allergies is, in fact, low.

Flow-based basophil activation test in immediate drug hypersensitivity. An EAACI task force position paper

Diagnosing immediate drug hypersensitivity reactions (IDHRs) can pose a significant challenge and there is an urgent need for safe and reliable tests. Evidence has emerged that the basophil activation test (BAT), an in vitro assay that mirrors the in vivo response, can be a complementary test for many drugs. In this position paper, members of Task Force (TF) "Basophil activation test in the evaluation of Drug Hypersensitivity Reactions" from the European Academy of Allergy and Clinical Immunology (EAACI) present the data from a survey about the use and utility of BAT in IDHRs in Europe. The survey results indicate that there is a great interest for using BAT especially for diagnosing IDHRs. However, there are still main needs, mainly in the standardization of the protocols. Subsequently consensus-based recommendations were formulated for: (i) Technical aspects of BAT in IDHRs including type of sample, management of drugs, flow cytometry protocols, interpretation of the results; and (ii) Drug-specific aspects that should be taken into account when performing BAT in relation to betalactams, neuromuscular blocking agents, fluoroquinolones, chlorhexidine, opioids, radio contrast media, chemotherapeutics, biological agents, nonsteroidal anti-inflammatory drugs, COVID vaccine, and excipients. Moreover, aspects in the evaluation of pediatric population have also been considered. All this indicates that BAT offers the clinician and laboratory a complementary tool for a safe diagnostic for IDHRs, although its place in the diagnostic algorithm depends on the drug class and patient population (phenotype, geography, and age). The standardization of BAT is important for generalizing this method beyond the individual laboratory.

EAACI/ENDA position paper on drug provocation testing

In drug hypersensitivity, drug provocation testing (DPT), also called drug challenge, is the gold standard for investigation. In recent years, risk stratification has become an important tool for adjusting the diagnostic strategy to the perceived risk, whilst still maintaining a high level of safety for the patient. Skin tests are recommended before DPT but may be omitted in low-risk patients. The task force suggests a strict definition of such low-risk patients in children and adults. Based on experience and evidence from studies of allergy to beta-lactam antibiotics, an algorithm on how to adjust DPT to the risk, and when to omit skin tests before DPT, is presented. For other antibiotics, non-steroidal anti-inflammatory drugs and other drugs, skin tests are poorly validated and DPT is frequently necessary. We recommend performing DPT with chemotherapeutics and biologicals to avoid unnecessary desensitization procedures and DPT with skin tests negative contrast media. We suggest DPT with anesthetics only in highly specialized centers. Specifics of DPT to proton pump inhibitors, anticonvulsants and corticosteroids are discussed. This position paper provides general recommendations and guidance on optimizing use of DPT, whilst balancing benefits with patient safety and optimizing the use of the limited available resources.

Ciprofloxacin-Induced Anaphylactic Reaction Followed by Negative Provocation Test in Response to Levofloxacin: A Case Report

Fluoroquinolones are a commonly prescribed class of antibiotics due to their broad spectrum of antimicrobial activity, favorable pharmacokinetic properties, ability to switch from parenteral to oral administration, and global availability. After beta-lactams, they are the second most common antibiotic class associated with drug allergies. The mechanism of fluoroquinolone-induced hypersensitivity reactions has not yet been fully understood, so the true incidence of hypersensitivity reactions remains unknown. Cross-reactivity between fluoroquinolones has been the subject of conflicting and limited clinical research. Due to their similar chemical structure, some argue for close cross-reactivity within the group. However, recent studies have produced contradictory results. We present the case of a young patient who had an anaphylactic reaction to ciprofloxacin but was tolerant to levofloxacin, as determined via a skin prick test followed by a drug provocation test. Our findings support the notion that there is little cross-reactivity between fluoroquinolones. Consequently, exposure to another fluoroquinolone in a hospital setting may be beneficial, particularly for patients who lack adequate antibiotic alternatives. However, additional research on this subject is required.

Direct challenges are the gold standard for most antibiotic allergy evaluations

Antibiotic allergies are frequently encountered in clinical practice, and delabeling of these allergies has individual and public health benefits. This review focuses on the evidence supporting graded challenges without preceding skin testing in adult and pediatric patients to the major groups of antibiotics including penicillins, cephalosporins, sulfamethoxazole, fluoroquinolones, tetracyclines, macrolides, metronidazole, carbapenems, and aztreonam. The cost savings, time savings, and evidence for performing graded challenges outside of an allergy/immunology office are also reviewed for graded challenges to penicillins.

In-Class Cross-Reactivity among Hospitalized Patients with Hypersensitivity Reactions to Fluoroquinolones

Results from this large, multicenter study suggest that patients with a confirmed ciprofloxacin, moxifloxacin, or levofloxacin hypersensitivity reaction are likely to tolerate other fluoroquinolones. Avoiding different fluoroquinolones in patients labeled with a ciprofloxacin, moxifloxacin, or levofloxacin allergy may not always be mandatory. This was a study of patients with a ciprofloxacin, moxifloxacin, or levofloxacin hypersensitivity reaction and a documented electronic medical record administration of a different fluoroquinolone. Numerically, the most common reaction risk occurred with a challenge to moxifloxacin (2/19; 9.5%), followed by ciprofloxacin (6/89; 6.3%), and levofloxacin (1/44; 2.2%).

Drug Allergy Practice Parameter Updates to Incorporate Into Your Clinical Practice

The drug allergy practice parameter was developed to provide guidance on the diagnosis and management of drug hypersensitivity reactions. It was last updated in 2010. With the growth of research and evidence-based data since then, experts came together to update the practice parameter with a focus on sections that the work group deemed to have significant changes (or were not addressed) in the previous practice parameter. This review is a focused update on aspects of the practice parameter deemed to have the greatest impact on clinical practice and includes significant updates on diagnosis of antibiotic allergy including penicillin, cephalosporin, sulfonamide, fluoroquinolone, and macrolide allergies. Other topics include the evolution in our management approach to patients with aspirin/nonsteroidal anti-inflammatory drug allergy, diagnostic testing for delayed drug hypersensitivity and allergy to chemotherapeutics and biologics, and the key consensus-based statements for clinical practice. Specifically, the updated practice parameter helps allergists understand the place of 1- or 2-step drug challenges that are valuable tools often without the need for skin testing in many clinical situations. A proactive approach to delabeling penicillin allergy as well as unnecessary avoidance of safe antibiotic alternatives for patients with proven penicillin allergy is emphasized. New guidance is provided on management of patients with different phenotypes of aspirin and nonsteroidal anti-inflammatory drug hypersensitivity reactions. Approaches to delayed drug hypersensitivity and use of delayed intradermal and patch testing for specific phenotypes are reviewed. Lastly, practical approaches to management of patients with reactions to chemotherapeutics and biologics are discussed.

Immediate hypersensitivity to fluoroquinolones: a cohort assessing cross-reactivity

Background

Fluoroquinolones are the second-most prescribed antimicrobial and are frequently associated with causing hypersensitivity reactions. Existing evidence regarding cross-reactivity of fluoroquinolones is limited, offering clinicians little guidance in understanding the implications of selecting an in-class alternative among patients with histories of allergic reactions to fluoroquinolones. The aim of this study was to compare the frequency of immediate hypersensitivity reactions to either ciprofloxacin, levofloxacin, and/or moxifloxacin among patients with a history of immediate hypersensitivity to a different fluoroquinolone.

Methods

This retrospective chart review included adult patients with a history of an immediate hypersensitivity reaction to ciprofloxacin, levofloxacin, and/or moxifloxacin and a documented prescription for a different fluoroquinolone. The primary outcome was documentation of a hypersensitivity reaction upon second fluoroquinolone exposure.

Results

A total of 321 cases met inclusion criteria. Of these cases, 2.5% experienced an immediate hypersensitivity reaction after second fluoroquinolone exposure to ciprofloxacin, levofloxacin, and/or moxifloxacin. Within the ciprofloxacin, levofloxacin, and moxifloxacin index allergy cohorts, the frequency of cross-reactivity were 2.7%, 2.2%, and 5.3%, respectively.

Conclusion

Our data suggest that patients with a history of immediate hypersensitivity reaction to ciprofloxacin, levofloxacin, and/or moxifloxacin are at low risk of experiencing a cross-reaction when exposed to a different fluoroquinolone. Avoidance of all fluoroquinolones in this patient population may not be warranted.

Ciprofloxacin-induced cutaneous adverse drug events: a systematic review of descriptive studies

OBJECTIVES

Ciprofloxacin (CIPRO) is a fluroquinolone class antibiotic used commonly for the treatment of various acute and chronic bacterial infections. However, recently there is increase in the case reports of CIPRO-induced Cutaneous Adverse Drug Reactions (CADRs). We aim to systematically review all the descriptive studies of CIPRO induced CADRs.

METHODS

Medline (via PubMed) was searched without any language or date restriction from inception to March 2019 using search terms of "Ciprofloxacin" and "Cutaneous reactions." We included only the descriptive studies, which elucidate the CADRs experienced by the patients following the administration of CIPRO. Two reviewers involved in study selection, data extraction and quality assessment of the included studies. Discrepancies were resolved by consensus between the reviewers.

RESULTS

Thirty-nine studies (out of 446) were found to be eligible for the final inclusion. The dose of CIPRO among the included studies was ranging from 500 to 1,000 mg/day and duration of treatment was between 7 and 10 days. The most common CADRs observed were toxic epidermal necrolysis, Stevens-Johnson syndrome, fixed drug eruptions, bullous fixed drug reaction, acute generalized pustulosis, erythema multiforme, drug rash with eosinophilia and systemic symptoms and erythema nodosum.

CONCLUSIONS

Management of the CIPRO-induced CADRs is recommended with the complete cessation of the CIPRO, followed by supportive management with oral or topical glucocorticoids, emollients, and topical moisturizers. CIPRO is likely to cause CADRs, physicians should be vigilant while prescribing it to the patients.

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.

Mas-related G protein-coupled receptor X2 and its activators in dermatologic allergies

The Mas-related G protein-coupled receptor X2 (MRGPRX2) is a multiligand receptor responding to various exogenous and endogenous stimuli. Being highly expressed on skin mast cells, MRGPRX2 triggers their degranulation and release of proinflammatory mediators, and it promotes multicellular signaling cascades, such as itch induction and transmission in sensory neurons. The expression of MRGPRX2 by skin mast cells and the levels of the MRGPRX2 agonists (eg, substance P, major basic protein, eosinophil peroxidase) are upregulated in the serum and/or skin of patients with inflammatory and pruritic skin diseases, such as chronic spontaneous urticaria or atopic dermatitis. Therefore, MRGPRX2 and its agonists might be potential biomarkers for the progression of cutaneous inflammatory diseases and the response to treatment. In addition, they may represent promising targets for prevention and treatment of signs and symptoms in patients with skin diseases or drug reactions. To assess this possibility, this review explores the role and relevance of MRGPRX2 and its activators in cutaneous inflammatory disorders and chronic pruritus.

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.

Quinolone Allergy

Quinolones are the second most common antibiotic class associated with drug-induced allergic reactions, but data on quinolone allergy are scarce. This review article discusses the available evidence on quinolone allergy, including prevalence, risk factors, diagnosis, clinical manifestations, cross-reactivity, and management of allergic reactions. Although the incidence of quinolone allergy is still lower than beta-lactams, it has been increasingly reported in recent decades, most likely from its expanded use and the introduction of moxifloxacin. Thorough patient history remains essential in the evaluation of quinolone allergy. Many diagnostic tools have been investigated, but skin tests can yield false-positive results and in vitro tests have not been validated. The drug provocation test is considered the test of choice to confirm a quinolone allergy but is not without risk. Evidence regarding cross-reactivity among the quinolones is limited and conflicting. Quinolone allergy can be manifested either as an immediate or delayed reaction, but is not uniform across the class, with moxifloxacin posing the highest risk of anaphylaxis. Quinolone should be discontinued when an allergic reaction occurs and avoided in future scenarios, but desensitization may be warranted if no alternatives are available.

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.

Evaluation of the Potential Risk Factors for Drug-Induced Anaphylaxis in Adult Patients

AIM

To investigate the potential risk factors in patients who have experienced anaphylaxis from drugs.

METHOD

The study included 281 adult patients (median age 40 years; 76.5% female) who experienced immediate types of hypersensitivity reaction to a drug. The patients were divided into an anaphylaxis group and a nonanaphylaxis group. The anaphylaxis group was diagnosed according to the criteria of the World Allergy Organization. Skin testing with culprit drugs was performed. In the nonanaphylaxis group, drug provocation tests were performed with culprit drugs, including aspirin or diclofenac, to determine nonsteroidal anti-inflammatory drug (NSAID) hypersensitivity. Atopy was determined by skin prick tests with the common inhalant allergens. Patients' demographics, clinical features, and baseline tryptase and total IgE levels were compared between the 2 groups.

RESULTS

The median interval between the last reaction in the patient's history and the study evaluation was 7 months (range 1-120 months). In 52.3% of the patients, reactions were defined as anaphylaxis. The most common culprit drugs were NSAIDs (56.9%) and β-lactams (34.7%). The culprit drugs were used parenterally in 13.2% of the patients. 34.9% of the patients had comorbid diseases and 24.6% used additional drugs, the most common being antihypertensives (10%). Atopy was determined in 28.8% and 28.1% of the patients were smokers. The median serum level of baseline tryptase and total IgE was 3.5 µg/L and 77 kU/L, respectively. In 46.3% of the patients, skin tests with culprit drugs were positive and the positivity ratio was higher in the anaphylaxis group (p = 0.002). Anapyhlaxis was more common in patients who were: hypertensive, atopic, using angio-tensin-converting enzyme inhibitors/angiotensin receptor blockers, and received the culprit drug parenterally (p = 0.034, p = 0.04, p = 0.03, p = 0.035, p = 0.013, and p < 0.001). In the multivariate analysis, it was observed that the parenteral usage of the drug and the presence of atopy were significantly higher in the anaphylaxis group (p < 0.001, odds ratio [OR] = 20.05, confidence interval [CI] 4.75-88.64; p = 0.012, OR = 2.1, CI 1.17-3.74). Age, smoking, family history, and serum levels of baseline tryptase and total IgE did not differ between groups.

CONCLUSION

The parenteral route and atopy increase the risk of drug-induced anaphylaxis. IgE-mediated sensitivity to the culprit drug seems to facilitate anaphylaxis.

An unusual dual hypersensitivity reaction to moxifloxacin in a patient

Both immediate and nonimmediate type hypersensitivity reactions (HRs) with a single dose of quinolone in the same patient have not been previously reported. A 47-year-old female patient referred to us because of the history of a nonimmediate type HR to radio contrast agent and immediate type HR to clarithromycin. She experienced anaphylaxis in minutes after the second dose of 50 mg when she was provocated with moxifloxacin. She was treated immediately with epinephrine, fluid replacement and methylprednisole and pheniramine. On the following day she came with macular eruptions, and she was treated with methylprednisolone. The positive patch test performed with moxifloxacin as well as the lymphocyte transformation test proved the T-cell mediated HR. In order to prove the immediate type HR, basophil activation test was performed but was found negative. This case report presents for the first time the 2 different types of HRs in a patient with a test dose of quinolone.

Update on Quinolone Allergy

PURPOSE OF REVIEW

Quinolones are a group of synthetic antibiotics widely use as first-line treatment for many infections. There has been an increase in the incidence of hypersensitivity reactions to quinolones in recent years, likely due to increased prescription. The purpose of this review is to summarize the clinical pictures, the methods used for diagnosing and the management of allergic reactions to quinolones.

RECENT FINDINGS

Allergic reactions to quinolones can be immediate or delayed, being anaphylaxis and maculopapular exanthema respectively the most frequent clinical entities. A precise diagnosis is particularly difficult since clinical history is often unreliable, skin tests can induce false-positive results, and commercial in vitro test are not well validated. Therefore, drug provocation testing is considered the gold standard to establish diagnosis, which is not a risk-free procedure. Cross-reactivity between quinolones is difficult to predict due to the small number of patients included in the few published studies. Moreover, hypersensitivity to quinolones has also been associated with beta-lactam and neuromuscular blocking agent allergies, although further studies are needed to understand the underlying mechanisms. Avoidance of the culprit quinolone is indicated in patients with a diagnosis of hypersensitivity to these drugs. When quinolone treatment is the only therapeutic option available, desensitization is necessary. This review summarizes the complex diagnostic approach and management of allergic reactions to quinolones.