472 Heterogeneity of the Ige Response to Allergenic Determinants of Cefotiam in Serum Samples From Patients with Cefotiam-induced Occupational Allergy

BACKGROUND: Exposure to cefotiam could cause IgE-mediated occupational allergies in hospital personnel. However, the clinically available serologic test has not been widely accepted, and the antigenic determinant of this drug is unclear. We investigated patterns of the IgE response to cefotiam in patients with occupational allergies to cefotiam. METHODS: A total of 161 health care workers and 86 nonatopic healthy controls, never exposed to antibiotics, were recruited from a single tertiary hospital and the general population. A questionnaire regarding work-related symptoms associated with cefotiam was administered. Serum specific IgE antibodies to cefotiam-human serum albumin (HSA) conjugate was measured by enzyme-linked immunosorbent assay (ELISA). Patients with work-related symptoms to cefotiam and positive specific IgE antibody to cefotiam were selected and ELISA inhibition studies were performed using sera of these patients. The inhibitors included various concentrations of free and conjugated cefotiam, ceftriaxone, ceftizoxime, and HSA alone. RESULTS: Four patients showed work-related upper respiratory symptoms and high levels of serum specific IgE to cefotiam-HSA conjugate compared to controls. Significant inhibition patterns to free cefotiam and cefotiam-HSA conjugate were noted in patient 1 on ELISA inhibition testing, while minimal inhibitions to the other cephalosporins, both free and conjugated, were noted. In the other 3 patients, significant dose-dependent inhibitions were noted with additions of cefotiam-HSA conjugate, while minimal inhibitions were noted with free cefotiam. Among the patients, patient 2 showed minimal inhibitions with the other cephalosporins, both free and conjugated, while patient 3 and 4 showed marked dose-dependent inhibition with ceftriaxone-HSA and ceftizoxime-HSA respectively. CONCLUSIONS: The specific IgE response to cefotiam-HSA conjugate in patients with occupational allergies occurs against the hapten or new allergenic determinant in which heterogeneity of the antigenic determinant were noted depending on the individual.