Determining Non-Irritating Concentration for Intradermal Skin Test with Commonly Prescribed Antibiotics in Korean Adults

Rationale: Although the data on validity of skin test with drugs expect for penicillin is still scarce, positive skin reaction at non-irritating concentrations with relevant history is generally accepted for diagnosis of drug allergy. In this study, we intended to exam the maximal non-irritant drug concentrations for intradermal skin test in Korean adults.

Methods: Sixty one healthy volunteers were recruited. Seventeen parenteral antibiotics including beta-lactams and fluoroquinolones were evaluated. Skin tests were performed by two steps with antibiotics as following; A) Intradermal skin test by using full strength concentration of each drug and, if the result was positive, serially diluted concentration till the result was negative; B) Confirming the concentration on step A in 20 more subjects. All subjects were allowed to participate in multiple testing using different drugs.

Results: The mean age of the subjects is 35.0 and females are more than males (77%). Both previous drug concentrations based on literatures and the results of this study are reproducible in ampicillin/sulbactam, aztreonam, ciprofloxacin, clindamycin, nafcillin and penicillin G. Only ceftriaxone among the cephalosporins showed the same result as the previous value. In addition, the discrepancy between previous known concentrations and the values of this study is more 10-fold and over in azithromycin, levofloxacin, meropenem, piperacillin/tazobactam, SMT/TMP, and vancomycin. Inter-individual variability of the skin test results using cefotetan, azithromycin, and vancomycin was more than 100-fold range.

Conclusions: To improve the reliability of skin test, study with the numerous subjects would be necessary to standardize non-irritating drug concentration for skin test.