Urticaria caused by Arcanobacterium haemolyticum: Diagnostic and therapeutic failures

Abstract

We presented a case of seventeen-year-old girl exhibiting mild symptoms of sore throat, a marked urticarial rash and heavy desquamations of the skin on palms and soles. According to the antibiogram and diagnosis of Streptococcus non A non B group obtained in routine laboratory procedure, the patient was treated with penicillin; however, ineffectively. Escalation of urticaria and failure of the initial penicillin therapy shifted the diagnosis towards exanthema toxoalergicum and thus to treatment with corticosteroids and antihistamines, yet with no improvement. The culture was repeated with a new specimen. Diagnosis was made according to the specific pattern in a double CAMP test, and confirmed by the ApiCoryne diagnostic set (BioMerieux). With respect to cultural traits, the isolate mimicked Streptococcus pyogenes, yet developing specific pattern in a double CAMP test that directed our diagnosis towards coryneform microorganisms. The diagnosis of Arcanobacterium haemolyticum was confirmed with 99.9% probability rate and T = 0.75.