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Penicillin de-labelling in tertiary clinics: Safe and efficacious but incomplete effectiveness

Bourke, J., Pavlos, R., Hollingsworth, P., McLean-Tooke, A., Horimoto, N., O'Brien, V., Edward, E. and Phillips, E. (2012) Penicillin de-labelling in tertiary clinics: Safe and efficacious but incomplete effectiveness. In: ASCIA 23rd Annual Scientific Meeting, 5 - 8 September 2012, Wellington, New Zealand.

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Introduction: Of the 10–15% of the population labelled as penicillin allergic, ≤10% are truly allergic. We examined the safety, effi cacy and post-testing utility of strategies to de-label clinically diagnosed penicillin allergy.

Methods: Records of skin testing (ST) and oral challenges (OC) performed between June 2008–June 2012 were reviewed. Intradermal ST was performed with PPL/MDM (DAP, Diater, Spain), benzylpenicillin, fl ucloxacillin, amoxycillin, cephazolin and ceftriaxone. OC with penicillin VK was done if ST negative or selectively positive with follow-up OC to other beta-lactams. Telephone follow-up aimed to determine patient perception of post-testing recommendations and antibiotic exposure.

Results: 48/294 (16.3%) patients tested had a positive ST to ≥1 ST determinant. 16/48 (33.3%) had a positive reaction to either benzylpenicillin or PPL/MDM but not both. 17/48 (35%) patients were ST positive to a single beta-lactam determinant with negative tests to benzylpenicillin, PPL and MDM. 2/237 (0.8%) patients who underwent penicillin VK challenge had mild positive reactions despite negative ST (NPV 99.1%). To-date 247/294 (84%) of penicillin allergy labelled patients have been recommended to tolerate ≥1 beta-lactam antibiotic with some OCs still pending. 143/294 (48.6%) of patients were contacted a median of 21 months following testing of which 49/143 (34.3%) had tolerated a complete course of a beta-lactam antibiotic. Overall 16/16 (100%) of ST positive versus 61/117 (52%) of ST negative patients contacted were following specifi c post-testing recommendations (p < 0.001), and this discrepancy was largely driven by reservation by the patient and/or their GP.

Conclusions: ST/OC is a safe and effi cacious way of de-labelling patients with a clinical history of penicillin allergy. Use of multiple ST determinants maintains a high NPV and identifi es those with a selective beta lactam allergy who may benefi t from further OC to clarify their tolerance of other betalactams. Imperfect adherence to post-testing recommendations suggests a need for better reporting and follow-up communication with the patient and their primary physician.

Item Type: Conference Item
Murdoch Affiliation(s): Centre for Clinical Immunology and Biomedical Statistics
Institute for Immunology and Infectious Diseases
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