Ciprofloxacin skin testing: A retrospective study

Abstract

RATIONALE: Limited information is available regarding the validity of procedures to diagnose allergic adverse drug reactions (ADRs) associated with fluoroquinolones (FQ). A retrospective study was undertaken to examine the clinical utility of ciprofloxacin (CP) skin testing. MATERIALS AND METHODS: A review of 135 charts from patients seen with suspected FQ associated ADRs between 1996-2001 was con- ducted at the Sunnybrook Drug Safety Clinic. Skin testing (prick and intradermal) was performed to CP (0.0001 mg/ml to 0.1 mg/ml) and levofloxacin (0.0001 mg/ml to 0.1 mg/ml) and oral challenge with CP (250 rag) and/or another FQ was administered following the negative skin tests. RESULTS: False positive reactions were associated with concentrations >0.05 mg/ml. 5/135 (4%) tested positive on the skin testing; 2 to levofloxacin and 3 to CP. 20/135 (15%) were positive on the oral challenge; however, only 9 (7%) subjects had reactions consisting of a rash and/or breathing difficulties within the time frame for an immediate or accelerated reaction (between 0 and 72 hours). The other 11 (8%) false negative reactions were potentially non-allergic (eg, pruritus, lightheadedness). There was a significant relationship between the original reaction history (indicative or non-indicative of immediate hypersensitivity) and positive oral challenge outcomes (true false negative or non-specific reactions) (P=0.0014, 95% CI). The negative predictive value for this test was deter- mined to be 93.1%, which is comparable to the negative predictive value for penicillin, the gold standard for skin testing. CONCLUSIONS: Skin testing should be pursued as a diagnostic tool for suspected allergic ADRs associated with FQ antibiotics.