Old dog begging for new tricks: current practices and future directions in the diagnosis of delayed antimicrobial hypersensitivity

Cross-reactivity among and between macrolides, lincosamides, and streptogramins: Study on the French pharmacovigilance database

BACKGROUND

Hypersensitivity reactions (HSR) are reported for the macrolides, lincosamides, and streptogramins (MLS) antibiotic family. Data about cross-reactivity among and between MLS remain scarce or controversial.

OBJECTIVES

The aim of this study was to provide an overview of hypersensitivity cross-reactions among MLSs based on data extracted from the French National Pharmacovigilance Database (FPVD).

METHODS

Cases of HSR to MLSs reported between January 1985 and December 2019 were extracted from the FPVD using standardized MedDRA queries (SMQ). Cases including an allergological test involving multiple MLSs and giving at least one positive result were included.

RESULTS

Of the 8394 cases reviewed, 149 were included. HSR mainly involved pristinamycin (n = 83; 53.2%) and spiramycin (n = 31; 19.9%). HSR to MLS was immediate in 54 cases and delayed in 94 cases. Skin tests represented the majority of the allergological tests performed (n = 728; 84.7%), followed by reintroduction tests (n = 79; 9.2%). Eighty-six cross-reactivities among MLS were identified in 62 cases (41.6%). All the 25 explorations performed for streptogramins showed cross-reactivities, but only 30/253 among macrolides (11.9%). Cross-reactivities between the three MLS were observed in 31/322 (9.6%) of the allergological explorations.

CONCLUSION

This study highlights the possibility of cross-reactivity among and between MLSs. Dermatologists and allergologists managing patients with HSR to MLSs should be aware of a risk of cross-reactivity among the macrolides and between the different classes of MLS and to perform MLSs allergological testing before recommending an alternative antibiotic, especially in severe drug hypersensitivity from the MLS family.

Study protocol: Australasian Registry of Severe Cutaneous Adverse Reactions (AUS-SCAR)

INTRODUCTION

Severe cutaneous adverse reactions (SCAR) are a group of T cell-mediated hypersensitivities associated with significant morbidity, mortality and hospital costs. Clinical phenotypes include Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS) and acute generalised exanthematous pustulosis (AGEP). In this Australasian, multicentre, prospective registry, we plan to examine the clinical presentation, drug causality, genomic predictors, potential diagnostic approaches, treatments and long-term outcomes of SCAR in Australia and New Zealand.

METHODS AND ANALYSIS

Adult and adolescent patients with SCAR including SJS, TEN, DRESS, AGEP and another T cell-mediated hypersensitivity, generalised bullous fixed drug eruption, will be prospectively recruited. A waiver of consent has been granted for some sites to retrospectively include cases which result in early mortality. DNA will be collected for all prospective cases. Blood, blister fluid and skin biopsy sampling is optional and subject to patient consent and site capacity. To develop culprit drug identification and prevention, genomic testing will be performed to confirm human leukocyte antigen (HLA) type and ex vivo testing will be performed via interferon-γ release enzyme linked immunospot assay using collected peripheral blood mononuclear cells. The long-term outcomes of SCAR will be investigated with a 12-month quality of life survey and examination of prescribing and mortality data.

ETHICS AND DISSEMINATION

This study was reviewed and approved by the Austin Health Human Research Ethics Committee (HREC/50791/Austin-19). Results will be published in peer-reviewed journals and presented at relevant conferences.

TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry (ACTRN12619000241134).

Delabeling Delayed Drug Hypersensitivity: How Far Can You Safely Go?

Delayed immune-mediated adverse drug reactions (IM-ADRs) are defined as reactions occurring more than 6 hours after dosing. They include heterogeneous clinical phenotypes that are typically T-cell-mediated reactions with distinct mechanisms across a wide spectrum of severity from benign exanthems through to life-threatening cutaneous or organ-specific diseases. For mild reactions such as benign exanthem, considerations for delabeling are similar to immediate reactions and may include a graded or single-dose drug challenge with or without preceding skin or patch testing. Evaluation of challenging cases such as the patient who is on multiple drugs at the time a severe delayed IM-ADR occurs should prioritize clinical ascertainment of the most likely phenotype and implicated drug(s). Although not widely available and validated, procedures such as patch testing, delayed intradermal skin testing, and laboratory-based functional drug assays or genetic (human leukocyte antigen) testing may provide valuable information to further help risk stratify patients and identify the likely implicated and/or cross-reactive drug(s). The decision to use a drug challenge as a diagnostic or delabeling tool in a patient with a severe delayed IM-ADR should weigh the risk-benefit ratio, balancing the severity and priority for the treatment of the underlying, and the availability of alternative efficacious and safe treatments.

The Role of In Vivo and Ex Vivo Diagnostic Tools in Severe Delayed Immune-Mediated Adverse Antibiotic Drug Reactions

BACKGROUND

The use of in vivo and ex vivo diagnostic tools for delayed immune-mediated adverse drug reactions is currently ill defined.

OBJECTIVE

To determine whether the combination of skin testing and/or IFN-γ enzyme-linked immunoSpot assay (ELISpot) can aid diagnosis of these allergy phenotypes.

METHODS

Patients with antibiotic-associated severe delayed immune-mediated adverse drug reaction hypersensitivity, including Stevens-Johnson syndrome and toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms (DRESS), acute generalized exanthematous pustulosis, generalized bullous fixed drug eruption, and severe maculopapular exanthema, were prospectively recruited. In vivo testing was completed to the implicated drug(s), and ex vivo testing was performed with the patient's PBMCs stimulated with the relevant antibiotic concentrations for IFN-γ release ELISpot measurement.

RESULTS

Eighty-one patients met the inclusion criteria, with DRESS (42; 51.9%) accounting for most cases. Among the 63 (78%) who had an ELISpot assay performed, 34 (54%) were positive to at least 1 implicated antibiotic (median spot-forming units/million cells, 99.5; interquartile range, 68-187), with glycopeptide being a strong predictor of positivity (adjusted odds ratio, 6.11; 95% CI, 1.74-21.42). In combination (in vivo and ex vivo), 51 (63%) of those tested were positive to an implicated antibiotic. For DRESS and severe maculopapular exanthema associated with penicillins and cephalosporins, this combination confirmed the culprit agent in 11 of the 12 cases and in 6 of 7 for DRESS associated with glycopeptides.

CONCLUSIONS

This study demonstrates that using in vivo in combination with ex vivo testing can enhance the diagnostic approach in these severe phenotypes by assisting with the identification of possible culprit antibiotics.

An Updated Review of the Diagnostic Methods in Delayed Drug Hypersensitivity

Delayed drug hypersensitivity reactions are clinically diverse reactions that vary from isolated benign skin conditions that remit quickly with no or symptomatic treatment, drug discontinuation or even continued drug treatment, to the other extreme of severe cutaneous adverse reactions (SCARs) that are associated with presumed life-long memory T-cell responses, significant acute and long-term morbidity and mortality. Diagnostic "in clinic" approaches to delayed hypersensitivity reactions have included patch testing (PT), delayed intradermal testing (IDT) and drug challenges for milder reactions. Patch and IDT are, in general, performed no sooner than 4-6 weeks after resolution of the acute reaction at the maximum non-irritating concentrations. Functional in vitro and ex vivo assays have largely remained the province of research laboratories and include lymphocyte transformation test (LTT) and cytokine release enzyme linked ImmunoSpot (ELISpot) assay, an emerging diagnostic tool which uses cytokine release, typically IFN-γ, after the patient's peripheral blood mononuclear cells are stimulated with the suspected drug(s). Genetic markers such as human leukocyte antigen have shown recent promise for both pre-prescription screening as well as pre-emptive and diagnostic testing strategies.

Adverse reactions to vancomycin and cross-reactivity with other antibiotics

PURPOSE OF REVIEW

Glycopeptide antibiotics such as vancomycin are frequently utilized to treat resistant Gram-positive infections such as methicillin-resistant Staphylococcus aureus. The current literature on glycopeptide and lipoglycopeptide structure, hypersensitivity and potential cross-reactivity was reviewed, highlighting implications for safe prescribing.

RECENT FINDINGS

Structurally similar, glycopeptides could theoretically cross-react. Immediate reactions to vancomycin include non-IgE-mediated reactions (e.g. red man syndrome) and IgE-mediated hypersensitivity (e.g. anaphylaxis), sharing clinical features. Vancomycin can activate mast cells via MAS-related G-protein-coupled receptor X2, an IgE-independent receptor implicated in non-IgE reactions. In-vivo and in-vitro testing for suspected IgE-mediated reactions to glycopeptides remain ill-defined. Vancomycin is increasingly recognized to cause severe cutaneous adverse reactions (SCAR), with drug reaction with eosinophilia and systemic symptoms (DRESS) predominantly reported. Vancomycin DRESS has been associated with HLA-A32:-01, with a number needed to prevent of 1 in 74. Data demonstrating cross-reactivity amongst glycopeptides and lipoglycopeptides is limited to case reports/series.

SUMMARY

Further studies and in-vivo/in-vitro diagnostics are required for better differentiation between IgE and non-IgE glycopeptide reactions. Despite its association with vanomycin DRESS, utility of pharmacogenomic screening for HLA-A32: 01 is ill-defined. Although HLA-A32:01 has been associated with vancomycin DRESS, its utility for pharmacogenomic screening is ill defined. Further clinical and immunological cross-reactivity data for glycopeptide/lipoglycopeptide antibiotics is required.

Drug hypersensitivity in HIV infection

PURPOSE OF REVIEW

Immune-mediated adverse drug reactions (IM-ADRs) are many times more common in HIV-infected patients. Usual offending drugs include antiretroviral and antiinfectives, but the burden of specific drug IM-ADRs is population-specific; changing as new and fixed dose combinations enter the market, and drug-resistance patterns demand. This review considers recent literature on epidemiology, mechanisms, clinical management and prevention of IM-ADRs amongst persons living with HIV/AIDS.

RECENT FINDINGS

Epidemiological studies continue to describe high rates of delayed hypersensitivity to known offenders, as well as similar reactions in preexposure prophylaxis. IM-ADRs to oral and injectable integrase strand transfer inhibitors are reported with expanding use. The clinical spectrum and management of IM-ADRs occurring in HIV-infected populations is similar to uninfected; with exceptions such as a recently described severe delayed efavirenz DILI with high mortality. Furthermore, the context can be unique, such as the lower than expected mortality in a Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) cohort from a HIV/TB high burden setting. Programmatic data showing the near complete elimination of Abacavir drug hypersensitivity syndrome following implementation of HLA-B57:01 screening is a stellar example of how prevention is possible with mechanistic insight.

SUMMARY

IM-ADRs remain a challenge in persons living with HIV. The complexities posed by polypharmacy, overlapping drug toxicities, drug interactions, overlap of IM-ADRs with other diseases, limited alternative drugs, and vulnerable patients with advanced immunosuppression with high mortality, necessitate increased use of drug provocation testing, treat-through and desensitization strategies. There is an urgent need for improved diagnostics and predictive biomarkers for prevention, or to guide treat-through, rechallenge and desensitization approaches.

High prevalence of antibiotic allergies in cladribine-treated patients with hairy cell leukemia - lessons for immunopathogenesis and prescribing

The relationship between hematological malignancy and chemotherapy on the prevalence of antibiotic allergy label (AAL) is ill-defined. We performed a multicenter retrospective case-control study comparing AAL rates among cladribine-treated hairy cell leukemia (C-HCL) cases, non-HCL cladribine-treated controls (control-1), and fludarabine-treated controls (control-2). The prevalence of AALs in C-HCL patients was 60%, compared with control-1 (14%, p < .01) and control-2 patients (25%, p < .01). The predominant phenotype was maculopapular exanthem (92%). The drugs implicated in AAL causality in C-HCL patients included beta-lactams (81%), trimethoprim-sulfamethoxazole (58%), and allopurinol (69%). C-HCL patients demonstrate high rates of AAL, potentially due to immune dysregulation, impacting beta-lactam utilization.

Drug-induced liver injury with skin reactions: Drugs and host risk factors, clinical phenotypes and prognosis

While dermatologic manifestations of adverse drug reactions are frequent, drug-induced liver injury is rare. Numerous drugs are implicated in either Drug-Induced Liver Injury or Drug-Induced Skin Injury. However, concomitant Drug-Induced Liver Injury and Drug-Induced Skin Injury are uncommon, not well characterized and appear to be caused by a limited number of drugs. These are often associated with immuno-allergic or hypersensitivity features such as fever, skin rash, blisters or peeling of skin, eosinophilia, lymphadenopathy and mucositis. Liver injury can range from asymptomatic elevation of liver biochemical tests to severe hepatitis and acute liver failure needing liver transplantation. Severe cutaneous adverse reaction, particularly drug reaction with eosinophilia and systemic symptoms is commonly associated with internal organ involvement, the liver being the most frequently involved in approximately 90% of the cases. In Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis, abnormalities in liver biochemistry tests are common but severe liver disease is rare. There is a strong association of Human Leukocyte Antigen genotype with both drug reaction with eosinophilia and systemic symptoms and Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis. It is likely that the delayed immune-mediated reaction triggering skin reaction is also responsible for hepatitis. Drug-specific lymphocytes are found in the organs involved and also in circulating blood, which along with the cytokines and chemokines play a role in pathogenesis. Anti-epileptic drugs, allopurinol, sulfonamides, antibiotics and nevirapine are the top five causes of concomitant liver and skin injury. This review will focus on drug and host factors causing concomitant Drug-Induced Skin Injury and Drug-Induced Liver Injury and discuss the characteristics of liver involvement in patients with severe cutaneous adverse reaction.

Pediatric Drug Hypersensitivity

PURPOSE OF REVIEW

Pediatric drug hypersensitivity is a rapidly evolving field. The purpose of this paper is to review the current state of pediatric drug hypersensitivity and highlight new developments in diagnosis and management.

RECENT FINDINGS

This paper will discuss the safety and use of risk stratification to proceed directly to oral challenge without prior skin testing for β-lactam reactions. We review unique aspects of pediatric drug challenges and desensitizations. It is important to accurately diagnose pediatric drug hypersensitivity reactions through a detailed history, physical examination, and available diagnostic testing. Understanding of the underlying mechanism leads to appropriate classification which is necessary to direct management. The decision to perform drug challenge, desensitization, or recommend avoidance of a medication can have a significant impact on a patient's treatment. Utilization of weight-based dose and infusion rate adjustments for current drug challenge and desensitization protocols optimize success.

Adverse Drug Reactions Reported by Healthcare Professionals: Reaction Characteristics and Time to Reporting

We describe adverse drug reaction (ADR) reporting characteristics and factors contributing to length of time to report by healthcare professionals. This is a retrospective study of voluntary reports to an Australian healthcare ADR Review Committee over a 2-year period (2015-2016). Descriptive and univariate models were used for outcomes, employing standardized ADR definitions. Hospital pharmacists reported 84.8% of the 555 ADRs: 70.3% were hospital onset reactions, and 71.7% were at least of moderate severity. Immunologically mediated reactions were most commonly reported (409, 73.7%). The median time to submit an ADR report was 3 (interquartile range 1-10) days. Longer median times to reporting were associated with multiple implicated agents and delayed hypersensitivity reactions, especially severe cutaneous adverse reactions. A total of 650 medications were implicated that involved multiple agents in 165/555 (29.7%) reports. Antimicrobials were the most commonly implicated agents. Immunologically mediated reactions were most commonly associated with antimicrobials and radiocontrast agents (P < .0001, odds ratio [OR] 3.6, 95%CI 2.4-5.5, and P = .04, OR 4.2, 95%CI 1.2-18.2, respectively). Opioids and psychoactive medications were more commonly implicated in nonimmunological reported ADRs (P = .0002, OR 3.9, 95%CI 1.9-7.9, and P < .0001, OR 11.4, 95%CI 4.6-27.8, respectively). Due to the predominant reporting of immunologically mediated reactions, a targeted education program is being planned to improve identification and accuracy of ADR reports, with the overall aim of improved management to ensure quality service provision and patient safety.

The Combined Utility of Ex Vivo IFN-γ Release Enzyme-Linked ImmunoSpot Assay and In Vivo Skin Testing in Patients with Antibiotic-Associated Severe Cutaneous Adverse Reactions

BACKGROUND

For severe cutaneous adverse reactions (SCARs) associated with multiple antibiotics dosed concurrently, clinical causality is challenging and diagnostic approaches are limited, leading to constricted future antibiotic choices.

OBJECTIVE

To examine the combined utility of in vivo and ex vivo diagnostic approaches at assigning drug causality in a cohort of patients with antibiotic-associated (AA)-SCARs.

METHODS

Patients with AA-SCARs were prospectively recruited between April 2015 and February 2017. In vivo testing (patch testing or delayed intradermal testing) was performed to the implicated antibiotic(s) at the highest nonirritating concentration and read at 24 hours through 1 week. Ex vivo testing used patient peripheral blood mononuclear cells (PBMCs) stimulated with a range of pharmacologically relevant concentrations of implicated antibiotics to measure dose-dependent IFN-γ release from CD4+ and CD8+ T cells via an enzyme-linked immunoSpot assay.

RESULTS

In 19 patients with AA-SCARs, combined in vivo and ex vivo testing assigned antibiotic causality in 15 (79%) patients. Ten patients (53%) with AA-SCARs were positive on IFN-γ release enzyme-linked immunoSpot assay, with an overall reported sensitivity of 52% (95% CI, 29-76) and specificity of 100% (95% CI, 79-100), with improved sensitivity noted in acute (within 1 day to 6 weeks after SCAR onset) testing (75%) and in patients with higher phenotypic scores (59%). There was increased use of narrow-spectrum beta-lactams and antibiotics from within the implicated class following testing in patients with a positive ex vivo or in vivo test result.

CONCLUSIONS

We demonstrate the potential utility of combined in vivo and ex vivo testing in patients with AA-SCARs to assign drug causality with high specificity.

Delayed Cutaneous Hypersensitivity Reactions to Antibiotics: Management with Desensitization

Successful desensitization to mild to moderate delayed cutaneous adverse reaction to antibiotics has been described in a limited number of antibiotics and found to be safe. However, there are ample opportunities to standardize protocols for delayed cutaneous adverse reactions to antibiotics.