Rubaiyat Haque

Sesame allergy in adults: Investigation and outcomes of oral food challenges

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DRESS Syndrome due to benzylpenicillin with cross-reactivity to amoxicillin

Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome carries a 10% mortality and is one of the severe cutaneous adverse reactions, which also includes acute generalized exanthematous pustulosis and Stevens-Johnson syndrome/toxic epidermal necrolysis. DRESS syndrome can present with an extensive maculopapular exanthema, fever, lymphadenopathy, internal organ involvement (ie, renal and hepatic), eosinophilia, and other hematological abnormalities (ie, lymphopenia and atypical lymphocytes). The diagnosis is typically reached using the RegiSCAR (European Registry of Severe Cutaneous Adverse Reaction) validation scoring criteria and can be graded accordingly (ie, possible, probable, or definite case). Treatment involves withdrawal of the likely culprit drug and corticosteroids (ie, topical or oral). Here, we present a novel case of DRESS syndrome due to benzylpenicillin with cross-reactivity to amoxicillin confirmed by delayed intradermal and patch tests. A 40-year old man with a history of coarctation of the aorta underwent extended treatment for Staphylococcus lugdunensis bacteremia associated with aortic vascular graft infection. Following initial antimicrobial treatment, which included vancomycin, gentamicin, and rifampicin for 4 weeks, he was switched onto intravenous benzylpenicillin only. Five weeks later he developed an extensive maculopapular exanthematous eruption, without facial edema or mucosal involvement. He was afebrile with no palpable lymphadenopathy. He developed an eosinophilia (1.5 10/L; normal range, [0.0-0.4] 10/L) with deranged liver function (alanine aminotransferase, 644 IU/ L; normal range, 4-59 IU/L). Renal function was not impaired and there was no other internal organ involvement. Skin biopsy was not performed. Blood cultures revealed no growth. Screening for hepatitis A/B/C/D/E, HIV, Chlamydia, and Mycoplasma was all negative. He was diagnosed with DRESS syndrome on the basis of RegiSCAR validation criteria (total score 1⁄4 4 [probable case], achieved from the following criteria: absence of fever [ 1 point], eosinophilia [2 points], rash extent, >50% body surface area [1 point], organ involvement [1 point], exclusion of other potential causes [1 point]). The benzylpenicillin was stopped 48 hours after onset of the eruption and he was treated with topical corticosteroids, which led to a full recovery after 3 weeks. Before discharge he was started on daptomycin and then switched to cephalexin, which was tolerated well. At our allergy clinic 4 months later, intradermal testing (IDT) was performed with amoxicillin (25 mg/mL [undiluted]; Bowmed Ibisqus, Wrexham, UK), in addition to the diluted (0.9% NaCl) stock solutions of benzylpenicillin (6 mg/mL [1:10 dilution]; Genus Pharmaceuticals, Huddersfield, UK), rifampicin (0.006 mg/mL [1:10,000 dilution]; Sanofi Aventis, Guildford, UK), vancomycin (0.5 mg/ mL [1:100 dilution]; Hospira UK, Maidenhead, UK) and gentamicin (0.4 mg/mL [1:100 dilution]; Sanofi Aventis). Immediate IDT result was negative when read at 15 minutes for all tested drugs. Delayed IDT result to rifampicin, vancomycin, and gentamicin was negative at day 2 (D2) and day 4 (D4) readings. However, delayed IDT result to benzylpenicillin and amoxicillin was positive with focal papules, induration, and infiltrated erythema (20 mm) observed at D4 (with a crescendo effect since D2) (Figure 1). We also performed patch testing using IQ Ultra chambers (Chemotechnique Diagnostics, Vellinge, Sweden) with rifampicin (60 mg/mL [undiluted solution]; Sanofi Aventis), vancomycin (10% aqueous), gentamicin (20% petrolatum [pet]), benzylpenicillin (10% pet), and amoxicillin (10% pet) (Chemotechnique Diagnostics). The patch tests were read on D2 and D4 in accordance with the International Contact Dermatitis Research Group criteria. Patch testing result to rifampicin, vancomycin, and gentamicin was negative at D2 and D4 readings. However, patch testing produced a strong positive reaction (þþ) to benzylpenicillin and a doubtful reaction (?þ) to amoxicillin at D4 (Figure 2), all with crescendo effects since D2. He was diagnosed with DRESS syndrome due to benzylpenicillin on the basis of clear temporal relationship, RegiSCAR scoring, and the dual positive intradermal and patch test results to benzylpenicillin. He was advised to completely avoid all penicillin class antibiotics. DRESS syndrome is a severe potentially life-threatening delayed-type drug reaction with an estimated incidence ranging from 1 in 1000 to 1 in 10,000 drug exposures. Various pathogenic mechanisms have been proposed for DRESS syndrome including viral reactivation (ie, human herpesvirus 6 & 7, EBV, cytomegalovirus), cell-mediated hypersensitivity (ie, CD4þ/ CD8þ T-cellemediated), and genetic associations (ie, HLAB*58:01 with allopurinol). A delayed onset of 2 to 6 weeks after initiation of the causative drug is typical of its clinical course. Although the RegiSCAR validation scoring criteria is frequently used for evaluating suspected DRESS syndrome (or drug-induced hypersensitivity syndrome), there are heterogeneous diagnostic criteria also available such as the Japanese consensus group diagnostic criteria, which also include human herpesvirus 6 reactivation. DRESS syndrome has been previously associated with anticonvulsants, antimicrobials, and anti-inflammatory agents. In a large retrospective literature review of DRESS syndrome, carbamazepine was the most frequently reported causative agent. Other commonly implicated drugs include allopurinol,

Occupational Allergic Contact Dermatitis due to Multiple Tropical Plant Species

FIGURE 1. Clustered erythematous papular lesions (left knee) 48 hours after direct contact with tropical plant(s). A 25-year-old female horticulturist was assessed for a 10-month history of recurrent episodes of severe acute erythematous papulovesicular dermatitis affecting exposed areas of skin, occurring only after contact with various tropical plant species at her workplace. The eruptions typically developed around 48 hours after direct contact with plant leaves or stems at the exact sites of cutaneous exposure and lasted around 7 days before resolving. Multiple short courses of prednisolone were prescribed to treat the eruptions. She worked with tropical plants for 4 years before onset of her first reaction and reported minimal sunlight exposure around the time of eruptions. She became asymptomatic when she was temporarily transferred away from the tropical plant enclosure. She had no history of prior allergic disease. On physical examination, clustered erythematous papular lesions were noted on her left knee (Figure 1) and an erythematous vesiculobullous eruption was noted on her left wrist (Figure 2), which both developed 48 hours after contact with plants. The patient worked with multiple tropical plant species on a regular basis, making exact identification difficult; therefore, she brought samples of 12 labeled tropical plants that were handled around the time of her recurrent skin eruptions for testing. Patch testing was performed using IQ Ultra chambers with the British Standard Series and Plant Series (Chemotechnique Diagnostics, Vellinge, Sweden), and uniformly cut pieces of both fresh leaf and stem from the following 12 tropical plants: Mangifera indica, Abroma augustum, Hibiscus tiliaceus, Banisteriopsis caapi, Heliconia collinsiana, Philodendron radiatum, Allamanda cathartica, Stephanotis floribunda, Macadamia tetraphylla, Aechmea fasciata, Gigantochloa verticillata, and Acalypha hispida.