Skin Testing for the Exploration of Immediate and Delayed Hypersensitivity to Fluoroquinolones: Insights From a Real-Life Cohort Study

<u><b><i></i></b></u> <u><b><i>Background:</i></b></u> Fluoroquinolones (FQ) are the second most frequent antibiotics responsible for hypersensitivity reaction (HSR). Data concerning the interest of allergological work-ups are scarce.<u><b><i>Objectives:</i></b></u> We reported a university center experience of the interest and safety of skin tests (ST) and drug provocation tests (DPT) for the exploration of immediate hypersensitivity reaction (IHR) and delayed HSR (DHR) to FQ.<u><b><i>Materials and Methods:</i></b></u> This retrospective study included patients tested for at least 1 FQ between 2008 and 2023. The primary outcome was the frequency of positive tests for FQ. Secondary outcomes aimed to characterize results, cross-reactivity, and tolerance of the tests.<u><b><i>Results:</i></b></u> Among the 113 patients included (32% in IHR, 68% in DHR), the overall test positivity rate was 27% (29% in DHR, 23% in IHR). Negative predictive value was 85% (80% in DHR, 95% in IHR). The most frequently positive ST was the intradermal test (7%). Allergy was more frequently confirmed for ofloxacin (OFX) (38%). Positive tests were more frequent for fixed drug eruption (67%). Cross-reactivity was detected in 15%, involving OFX and LFX or CPX and OFX. DPT was responsible for nonsevere recurrence of initial HSR for 13% of patients who had DPT and recurrence leading to a short hospitalization for 2% of them. 3% of contacted patients experienced a nonsevere recurrence of HSR in real life.<u><b><i>Conclusion:</i></b></u> This cohort demonstrates the benefit and safety of allergological exploration for FQ allowing subsequent use in 73% of cases.