Deux médicaments de même imputabilité dans une toxidermie (deux cas) : limite des tests épicutanés ?

Abstract

For the first time, 2 cases highlight the fact that, in the event of cutaneous adverse drug reactions under treatment associating 2 drugs, a positive test with one of the 2 does not authorize further readministration of the remaining drug without hospital surveillance. A man had urticaria during treatment with pristinamycin subsequently replaced by ceftriaxon. All the patch-tests with synergistins were positive, whereas patch-tests, prick-tests and intradermal tests with betalactams were negative. The oral challenge with ceftriaxon was positive. A woman taking spiramycin developed a maculopapular rash which was slowly regressive despite substitution with cefixim and corticotherapy. Patch-tests, prick-tests and intradermal tests with macrolides and betalactams were negative. An oral challenge with spiramycin was positive. Sensitization to two antibiotics without shared chemical structures can occur during the same episode of a cutaneous adverse drug reaction, even without prior indication of sensitization to these drug classes. The mechanisms at play in this phenomenon are still debated, but this highlights the fact that reintroduction of any drug suspected at the time of a cutaneous adverse drug reaction must be performed under hospital surveillance, whatever the degree of imputability and even if skin tests with other drugs taken simultaneously were positive.