D3.252 - Azithromycin and Mycoplasma pneumonia: an unusual Stevens-Johnson syndrome case

Stevens-Johnson syndrome (SJS) is a severe type IVc hypersensitivity to medication with epidermal detachment and necrosis with annual incidence of 1-7/1000000. Its early recognition is crucial to prevent further progression and complications.

A 31-year-old female presented with mucocutaneous symptoms consistent with SJS following azithromycin treatment for dyspnea, cough and fever, amidst a nationwide outbreak of Mycoplasma pneumoniae. Approximately 35 hours after initiation of azithromycin the patient reported itchiness in the mouth. The following morning, she noticed painful oral ulcers and swelling of the upper lip. She self-managed with home remedies, but continued azithromycin unaware of its role in the reaction. With quickly progressing symptoms, she was hospitalized. On admission - fever of 39.5°C, large bullous ulceration of oro-labial mucosa with positive Nikolsky's sign, facial angioedema, conjunctival injection with discharge, vulvar edema and pruritus. In the evening - macular rash on the sternum with semi-positive Nikolsky's sign. Laboratory tests showed slight leukocytosis with a left shift, elevated CRP and TNF-α and Mycoplasma pneumoniae IgM, consistent with recent infection. Azithromycin was replaced by levofloxacin. Treatment with systemic dexamethasone 12mg was initiated. Supportive care included bilastine and paracetamol. Over the next seven days angioedema subsided, and mucosal and cutaneous lesions gradually re-epithelialized, leaving depigmented areas. On follow-up HLA-B*15:02 was found positive. Patch testing confirmed the strongest reaction with azithromycin(++) at 48 hours, reducing to(+) at 72 hours, confirming it as the primary trigger. Mild and resolving reactions to clarithromycin and erythromycin suggest partial cross-reactivity within the macrolide class.

1. Dexamethasone therapy was enough to stop the progression of the disease.

2. Patient was unaware that the medication caused her symptoms. Education of patients about early signs of Stevens-Johnson syndrome, potentially would mitigate the severity of the reaction and consequent complications.

3. Initial presentation was atypical with isolated mucosal involvement and concurrent respiratory symptoms.

4. The concurrence of Mycoplasma pneumoniae infection and macrolide hypersensitivity are possible dual-triggers for SJS.