HOW TO TREAT 21 penicillin allergy , he is discharged on amoxicillin / clavulanic acid for 10 days ( the drug timeline appears in figure 10 ).
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HOW TO TREAT 21 penicillin allergy , he is discharged on amoxicillin / clavulanic acid for 10 days ( the drug timeline appears in figure 10 ).
On 24 June , James develops a mild maculopapular erythematous reaction on his arms . Following medical advice , he stops the amoxicillin / clavulanic acid . One day later , he starts metronidazole and ciprofloxacin . His skin reaction becomes widespread , infiltrated , and the erythematous lesions become dark purple . On 30 June he returns to ED because of the skin condition . A repeat absolute eosinophil count is 0.55x10 9 / L ( normal 0.04-0.4x10 9 / L ) and his CRP is 78mg / L ( normal less than 5mg / L ). Oral corticosteroids are started , and the following day both the eosinophil count and CRP drop .
The preliminary diagnostic is a severe MPE or possible case of DRESS with a RegiSCAR score for DRESS of 2 . The main culprits for this are amoxicillin / clavulanic acid ( Naranjo score 5 , probable ), the radiocontrast product ( iohexol ), metronidazole , and ciprofloxacin ( Naranjo score 3 , possible ), knowing that the eruption had worsened with the introduction of these drugs .
Delayed intradermal testing ( IDT ) for benzylpenicilloyl polylysine , penicillin G 1000 and 10,000 , ampicillin , cefuroxime , ciprofloxacin and metronidazole is performed ( see figure 11 ), with normal saline as a negative control . The delayed IDT testing confirms ampicillin as the culprit . James is advised to avoid ampicillin and amoxicillin ( similar R-side chain ) and cephalexin , cefaclor and cefadroxil . He
1 . Which THREE statements regarding drug allergies are correct ? a Adverse drug reactions may be either predictable or idiosyncratic . b The most severe immediate allergic drug reaction is life-threatening anaphylaxis . c Once a severe T-cell-mediated reaction has occurred and is confirmed , lifelong avoidance of the culprit drug is essential . d First-degree family members of patients who experience a SCAR are not required to avoid the eliciting drugs .
2 . Which THREE constitute the minimum information to capture for current and drug reactions ? a Drug and date prescribed . b The name of the prescriber . c Dose , route , frequency of drug course . d Reaction .
3 . Which THREE statements regarding antibiotic allergy are correct ? a Penicillin allergy is the most reported drug allergy . b Careful assessment of an antibiotic allergy is required before assigning the correct management . c Negative skin testing will allow patient delabelling in antibiotic allergy .
Pre-Pen
Penicillin 1,000 U / ml
Penicillin 10,000 U / ml
Ampicillin 25mg / ml
Cefuroxime 9mg / ml
Sodium Chloride 0.9 %
Figure 11 . Delayed intradermal testing .
A . Drug timeline . B . Skin testing .
should also avoid clavulanic acid ( no testing performed ), as co-sensitisation to amoxicillin and clavulanic acid has been described . 91
Following a patient-centred
How to Treat Quiz .
d The removal of an antibiotic allergy leads to reduction in inappropriate antibiotic use , restricted antibiotic use , lengthof-stay and hospital costs .
4 . Which TWO statements regarding antibiotic prescribing in key allergy classes are correct ? a Avoid macrolides in patients with low-risk allergy phenotypes to an individual macrolide . b Do not use non-beta-lactams in patients with high-risk allergy phenotype unless under specialist advice or critical need . c Avoid rechallenge and seek specialist advice in patients reporting phenotypes not consistent with vancomycin infusion syndrome . d Avoid non-antibiotic sulfonamides in those reporting a sulfonamide antibiotic allergy .
5 . Which THREE are features of SJS / TEN ? a High level eosinophilia . b Skin necrosis . discussion , James tolerates an oral challenge with ciprofloxacin and metronidazole , an IV challenge to iohexol , and tolerates cefuroxime and penicillin VK .
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A
B c Serious systemic manifestations . d Blistering of the mucous membranes .
6 . Which TWO statements regarding diagnostic tools in SCAR are correct ? a The ingestion challenge in patients with a history of SCAR is safe . b PT can determine the culprit drug with a high sensitivity in those with SJS / TEN . c The drug ingestion challenge remains the gold standard for determining tolerance . d Wait at least 6-8 weeks after skin resolution or stopping the systemic immunosuppressive treatment before performing in vivo testing .
COMMON DRUG ALLERGIES
7 . Which THREE are features of COX-mediated hypersensitivity ? a NSAID-exacerbated respiratory disease . b Symptoms occur in 24-48 hours . c NSAID-exacerbated urticaria and angioedema . d NSAID-induced cutaneous disease .
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Ciprofloxacin 0.02 mg / ml
Ci profloxaci n 0.2 mg / ml
Metronidazole 2.5 mg / ml
Case study two
Anna , a healthy 25-year-old woman presents concerned about dysmenorrhea . She used ibuprofen for dysmenorrhea when she was 13 years old and developed facial angioedema . She trialled mefenamic acid , which she tolerated , but this did not manage her pain . A combined OCP resolved the issue . She has been avoiding NSAIDs but tolerates paracetamol . She wants to stop her OCP and is concerned about pain management .
There is a clear history of tolerating alternative COX-1 inhibiting medication following the index reaction , thus the hypersensitivity is likely selective and allergy mediated . Anna should continue to avoid ibuprofen and use all other NSAIDs . She needs to be educated about the presence of ibuprofen in combination medications .
Case study three
Max , a 12-year-old boy with known asthma , presents with his parents wanting to discuss analgesic options . He was given ibuprofen for a simple illness when aged four years . One hour after the dose of ibuprofen , he developed urticaria and wheeze , requiring hospital admission . He has avoided using NSAIDs and is using paracetamol , but this has been inadequate for some recent sports injuries .
Tolerance to other NSAIDs is uncertain , as it is unsure whether this is selective and allergy-mediated anaphylaxis or COX1-mediated
8 . Which TWO statements regarding LA allergy are correct ? a Most adverse reactions to LA are allergic . b LA hypersensitivity is common . c Traditional IgE-mediated allergy can occur with typical symptoms but can be delayed . d Evaluation of LA allergies relies on skin testing , followed by subcutaneous provocation challenge .
9 . Which THREE statements regarding reactions to contrast are correct ? a Most reactions to contrast are severe . b Reactions can occur to iodinated or gadolinium-based contrast . c Mild physiological reactions are transient and can be managed with patient reassurance . d Although most reactions to contrast are mild and self-limiting , suspected allergic reactions warrant investigation .
10 . Which THREE are appropriate management modalities for a Type 1 IgE-mediated allergy ? a Stop the culprit antibiotic . b Topical and short course of oral corticosteroids . c Non-drowsy antihistamines for mild-moderate reactions . d Adrenaline and bronchodilators for severe reactions .
NSAID-exacerbated respiratory disease . The safest course of action is exclusion of all NSAIDs and referral to immunology for provocation testing .
If paracetamol tolerance was not already confirmed , cross-reaction and intolerance to paracetamol is also possible . Up to 34 % of adults with NSAID-exacerbated respiratory disease will react to a standard 1000mg dose of paracetamol , while smaller doses of 650mg appear to be safe . 92 Data in children is lacking .
Highly selective COX-2 inhibitors like celecoxib may also cross-react . Cross reactivity of 25 % has been demonstrated in adults with NSAID-induced cutaneous disease between non-selective and highly selective COX-2 inhibitors . 93 Adults with NSAID-exacerbated respiratory disease do not appear to be at increased risk . 94 Again , data in children is lacking .
CONCLUSION
THE GP is at the forefront of providing advice for adults and children presenting with reactions to medications . Some reactions may be allergic in nature , implying an immune reaction to the medication . It is difficult , either via clinical observation or patient history , even for allergy specialists to distinguish between an allergic reaction or a non-immune mediated reaction , such as a stress-related response , viral rash or side effect . Contemporaneous and detailed documentation of the reaction , the details of the drug prescription and the timeline of symptoms , are necessary for specialists to confidently diagnosis these drug reactions . For severe reactions , including SCAR , seek immediate specialist input via referral to ED .
RESOURCES
• UpToDate : Patient evaluation prior to oral or iodinated intravenous contrast for CT ( subscription required ) bit . ly / 3Mpb5sO
• Therapeutic Guidelines : Antibiotic ( subscription required ) bit . ly / 3IbOCgj
• Australasian Society of Clinical Immunology and Allergy ( ASCIA ) — Drug ( Medication ) Allergy
Health Professional Information bit . ly / 3W0f4zr — ASCIA Consensus Statement for Assessment of Suspected Allergy to Penicillin Allergy bit . ly / 3IcCTON
— Sulfonamide Antibiotic Allergy bit . ly / 42zBABB
— Drug ( Medication ) Allergy Patient Information bit . ly / 3o19DDK
• RegiSCAR Score bit . ly / 3M6O8t9
• Centre for Antibiotic Allergy and Research Antibiotic Allergy Assessment Tool ( AAAT ) bit . ly / 3WK7byb
• Naranjo score bit . ly / 3OerRfI
References Available on request from howtotreat @ adg . com . au