Testing Strategies For Patients Labeled As Allergic To Fluoroquinolones
Saturday, March 3, 2018
South Hall A2 (Convention Center)
Sarah N. Adams, MD, Elizabeth McKinnon, PhD, Elizabeth J. Phillips, MD FAAAAI

Non-IgE mediated mast-cell activation to fluoroquinolones (FQ) is prevalent and complicates both clinical and skin-test diagnosis of true IgE mediated reactions.


Consecutive patients(n=101) with immediate or accelerated reactions to FQ underwent prick (SPT)/intradermal skin (IDT) (0.005;0.025 mg/ml) testing to ciprofloxacin, levofloxacin, and moxifloxacin followed by single dose 250 mg oral challenge(OC) to the implicated FQ.


3/101 (2.97%) patients had immediate histories consistent with moxifloxacin anaphylaxis. 101/101(100%) were SPT negative. 2/3 patients with anaphylaxis were moxifloxacin IDT positive but negative to ciprofloxacin and levofloxacin at 0.005 mg/ml. Of 98/101 who were IDT 0.005 mg/ml negative to all FQ, 56/56(100%) of patients who underwent single dose OC to >1 FQ were tolerant, and 19/56 (34%) subsequently tolerated a therapeutic course of >1 FQ (5-41 days; median duration 12 days). Using OC as the gold standard, the performance of 0.005 mg/ml IDT FQ was: negative predictive (NPV) 98.25%(95%CI 91.9-99.6); positive predictive value (PPV) 100%; sensitivity (66.7%); specificity (100%). IDT 0.025 mg/ml was equally sensitive, however was positive in 7 patients who tolerated OC (PPV 22.2%[95%CI 9-45.2%; specificity 87.5%]. 76/101 (75%) of those FQ tested had been labeled as penicillin allergic prior to FQ exposure of which 100% were subsequently negative on penicillin SPT/IDT/OC, suggesting that FQ use is in part driven by history of penicillin allergy.


Negative IDT testing to FQ at 0.005 mg/ml followed by low dose FQ (250 mg) OC may be a useful testing strategy in allergy practice to define patients without true IgE-mediated reactions likely to be FQ tolerant.