Adverse reactions associated with therapeutic antibiotic use after penicillin skin testing.

BACKGROUND: There is little prospective data on the antibiotics prescribed and the adverse reactions associated with their use after penicillin skin testing.
OBJECTIVE: Provide data on antibiotic use and new antibiotic "allergy" incidence after penicillin skin testing.
METHODS: All patients who had penicillin skin testing at our Medical Center between 1-1-2000 and 12-31-2004 were followed through 12-31-2009. All therapeutic antibiotic use and all new "allergies" listed in their electronic medical records were reviewed.
RESULTS: There were 1684 study subjects of whom 1191 (70.7%) were female. There were 118 (7.0%) positive to at least one penicillin skin test reagent and 3 (0.2%) were positive only to amoxicillin. The mean follow-up period was 4.5 ± 2.9 years. Subjects were exposed to a mean of 8.2 ± 10.5 therapeutic antibiotic courses during follow-up. The highest new antibiotic "allergy" incidence rates in skin test-negative subjects were noted for penicillins, 2.9%, and sulfonamides, 2.7%, p = 0.9097. Females had higher overall incidences of new antibiotic "allergy," independent of skin test result. Penicillin skin test-negative females treated with penicillin had a nonsignificantly higher new penicillin "allergy" incidence, 3.3% per course versus 1.9% for males, p = 0.0644. Cephalosporins had new antibiotic "allergy" incidence rates not significantly different from tetracyclines, quinolones, macrolides, clindamycin, metronidazole, nitrofurantoin, and other antibiotics.
CONCLUSIONS: Females had higher new antibiotic "allergy" incidence rates. New "allergy" to cephalosporins occurred no more frequently than with non-beta-lactam-antibiotics, independent of skin test result. Sulfonamide antibiotics were associated with the higher rates of new antibiotic "allergy" than cephalosporins.