Anaphylaxis from bacitracin and polymyxin B (Polysporin) ointment

Ligands and Signaling of Mas-Related G Protein-Coupled Receptor-X2 in Mast Cell Activation

Mas-related G protein-coupled receptor-X2 (MRGPRX2) is known as a novel receptor to activate mast cells (MCs). MRGPRX2 plays a dual role in promoting MC-dependent host defense and immunomodulation and contributing to the pathogenesis of pseudo-allergic drug reactions, pain, itching, and inflammatory diseases. In this article, we discuss the possible signaling pathways of MCs activation mediated by MRGPRX2 and summarize and classify agonists and inhibitors of MRGPRX2 in MCs activation. MRGPRX2 is a low-affinity and low-selectivity receptor, which allows it to interact with a diverse group of ligands. Diverse MRGPRX2 ligands utilize conserved residues in its transmembrane (TM) domains and carboxyl-terminus Ser/Thr residues to undergo ligand binding and G protein coupling. The coupling likely initiates phosphorylation cascades, induces Ca²⁺ mobilization, and causes degranulation and generation of cytokines and chemokines via MAPK and NF-κB pathways, resulting in MCs activation. Agonists of MRGPRX2 on MCs are divided into peptides (including antimicrobial peptides, neuropeptides, MC degranulating peptides, peptide hormones) and nonpeptides (including FDA-approved drugs). Inhibitors of MRGPRX2 include non-selective GPCR inhibitors, herbal extracts, small-molecule MRGPRX2 antagonists, and DNA aptamer drugs. Screening and classifying MRGPRX2 ligands and summarizing their signaling pathways would improve our understanding of MRGPRX2-mediated physiological and pathological effects on MCs.

Contact Allergy to Polymyxin B Among Patients Referred for Patch Testing

BACKGOUND

Polymyxin B is not included in most standard contact allergen series. The aim of this study was to determine the prevalence of contact sensitization to polymyxin B in a population of patients referred for patch testing.

METHODS

A retrospective cohort study design was used to collect data on 795 patients referred to the contact dermatitis clinic of the McGill University Health Centre, as well as to the office of one of the authors (L.M.), between March 2014 and November 2015. Patients were patch tested to the North American Contact Dermatitis Group baseline series and polymyxin B sulfate 3% in petrolatum.

RESULTS

Out of 795 tested individuals, 18 were allergic to polymyxin B, for a prevalence of 2.3%. The eruptions affected almost all body parts, but mostly the face. The degree of reaction ranged from 1+ to 2+. Isolated reactions to polymyxin B occurred in 9 (50%) patients, whereas reactions to bacitracin and polymyxin B were seen in the other 9. Only 1 patient reacted to bacitracin, polymyxin B, and neomycin (11.1%). Most reactions (12/18) were from past exposure to polymyxin B.

CONCLUSIONS

Allergic reactions to polymyxin B are not rare, and this antibiotic warrants inclusion in the standard patch testing series.

Topical triple-antibiotic ointment as a novel therapeutic choice in wound management and infection prevention: a practical perspective

Triple-antibiotic ointment (TAO) is a safe and effective topical agent for preventing infections in minor skin trauma. The formulation contains neomycin, polymyxin B and bacitracin in a petrolatum base. TAO is active against the most common disease-causing pathogens found in wounds and on the skin and may be an attractive alternative to oral therapy in select circumstances. Resistance to TAO does not develop readily, and safety studies have shown that the risk of allergic sensitivity to TAO is low. Susceptibility profiles of TAO have remained relatively unchanged since its discovery. Prophylaxis or treatment with TAO should be considered as resistant organisms continue to emerge in the community and hospital setting.

Anaphylaxis and toxic epidermal necrolysis or Stevens-Johnson syndrome after nonmucosal topical drug application: fact or fiction?

BACKGROUND

Drug-induced anaphylaxis and toxic epidermal necrolysis (TEN) or Stevens-Johnson syndrome (SJS) represent severe immediate and delayed-type adverse drug reactions (ADRs), respectively. Occurrence of such reactions after topical drug application has only rarely been reported. Hence, we compiled a large number of such cases which we systematically analyzed.

METHODS

All such cases contained in the ADR database of the competent pharmacovigilance authority in Germany and cases reported in literature were identified, evaluated and analyzed with regard to potential risk factors. Since the application of drugs to mucous membranes facilitates their entry to the systemic circulation only cases occurring after non-mucosal topical drug application were considered.

RESULTS

After evaluation 28 anaphylaxis database cases and 48 anaphylaxis literature cases remained for analysis. Application to skin wounds or to skin with impaired barrier function was identified as a risk factor in 10/28 (36%) of the database cases and in 42/48 (88%) of the literature cases. In 9/28 database cases (32%), anaphylaxis was induced by drugs used for their hyperemizing effect and, in 8/28 cases (29%) by antibiotics or antiseptics. In the literature cases, anaphylaxis was induced by antibiotics or antiseptics in 35/48 cases (73%). Only one SJS database case and one TEN literature case remained after case evaluation.

CONCLUSION

Anaphylaxis does occur after non-mucosal topical drug administration. Application of drugs to skin wounds or to skin with impaired barrier function may pose a risk factor for its occurrence. TEN or SJS following non-mucosal topical drug application seems to be extremely rare.

Update on the Use of Antibiotics in Cutaneous Surgery

BACKGROUND

Antibiotics are often prescribed in perioperative settings, including dermatologic surgery. Given the continued evolution in the breadth and complexity of cutaneous procedures performed and inevitable localized or distant infections that occasionally occur, it seems prudent to periodically evaluate findings and recommendations from the literature regarding the use of antibiotics in cutaneous surgery.

MATERIALS AND METHODS

Literature review from English-language sources from the past 30 years, especially focusing on sources from the past 5 to 10 years. Data were examined for a variety of cutaneous surgical procedures, routes of antibiotic administration, and consideration of both cutaneous and distant infections.

RESULTS

The literature suggests that, for most routine skin procedures, antibiotic use is probably not warranted for the prevention of surgical wound infection, endocarditis, and late prosthetic joint infections. During prolonged Mohs procedures, delayed repairs, grafts, takedowns of interpolation flaps, or any procedure that breaches a mucosal surface, the evidence is less clear, and decisions should be made on a case-by-case basis. Topical antibiotics are probably overused, although silver sulfadiazine may have an undeserved negative reputation among dermatologists. Systemic prophylactic antibiotics for laser resurfacing and liposuction appear not to be routinely necessary, although patients with known prior herpes infection likely should receive antiviral prophylaxis. The overall reported infection rates and infectious complications remain low in dermatologic surgery, and antibiotic therapy may be prescribed excessively or inappropriately as a result. CONCLUSION.: Antibiotics continue to be widely used, and through varying routes of administration, in the setting of dermatologic surgery. Prudent use of these agents is indicated in high-risk patients, certain anatomic locations, and the presence of overt infection. Additional studies may help clarify the most appropriate indications, and in which patient populations, in the future.

Contact Dermatitis to Polysporin® Masquerading as a Delayed-Type Hypersensitivity Response to Dye Pigment

Background:

A 15-year-old Hispanic adolescent with multiple amateur India ink tattoos developed a recurrent, eczematous pruritic eruption several weeks after each treatment with the Q-switched ruby laser.

Objective:

To determine if the patient was having an allergic reaction to tattoo dye pigment or an allergic contact dermatitis.

Methods:

Open- and closed-patch testing was performed to Polysporin® ointment, which revealed a 2+ vesicular reaction.

Conclusion:

Delayed-type hypersensitivity responses to contact allergens can very closely mimic the less common allergic reactions to dye pigment from tattoos. Open- and closed-patch testing to topical medications should be performed on any patient suspected of having an allergic reaction to tattoo dye pigment.

A review of pharmacotherapeutics for prosthetic dentistry: Part II

STATEMENT OF PROBLEM

Successful preoperative and postoperative care often depends on systemically administered drugs. The competent and successful practitioner must therefore have a strong background in basic pharmacology, be knowledgeable of pharmacotherapeutics, and keep abreast of the latest advances in medicinal agents.

PURPOSE

The purpose of this article is to review pharmacologic properties of prototype and new drugs that are primarily used to allay anxiety and pain or reduce inflammation and infection. This information should enable clinicians to improve clinical outcomes and make a more knowledgeable assessment and comparison of standard drugs with recently released drugs.