[Cutaneous infections in bullous pemphigoid patients treated with topical corticosteroids]

Potent topical corticosteroids (TCS), such as clobetasol propionate are more efficacious than systemic corticosteroids in the treatment of bullous pemphigoid (BP) and in reducing the rate of systemic infectious complications. However, TCS can have cutaneous side effects, such as atrophy and purpura. The risk of cutaneous infections due to TCS in BP is known but has never been studied, despite prolonged use of high doses. Since we noted three cases of fatal necrotizing fasciitis (NF) in patients treated with TCS for BP over a one-year period in our institution, we decided to analyse the frequency of cutaneous infections in all BP patients hospitalized in our department.

In this retrospective single-centre study, all files of patients presenting BP treated with TCS and hospitalized between April 2008 and April 2009 were reviewed. When the clinical file indicated a cutaneous infectious problem, bacteriological data were requested from the bacteriology laboratory. For each patient, clinical data, history, ongoing treatment, type of cutaneous infectious complication, general symptoms and details of outcome were collected.

In the 30 files studied, we found ten cutaneous infections in nine patients: minor complication (three cases of impetiginisation), moderate complications (two erysipelas, one lymphangitis with sepsis, one flexor tendon phlegmon with cutaneous fistula), and severe complications with a fatal course (three NF, one of which had involved erysipelas of favourable outcome a few months earlier). These cutaneous complications occurred after various treatment times (ten days to two years) and various dosages of TCS (two-three tubes/day to two tubes every two days). Three of the nine patients with cutaneous infections had diabetes, in particular two of the three patients with FN. In contrast, four of the 21 patients without cutaneous complications had diabetes. Patients with cutaneous infections did not have more extensive BP or receive more TCS than the others. In two of three patients with NF, an immunosuppressant drug (methotrexate or mycophenolate mofetil) had been recently initiated (inferior to one month). The offending organism was Staphylococcus aureus in seven cases (methicillin-resistant in three cases) and Streptococcus A in five cases (three NF, one lymphangitis and one impetiginisation). The outcome was fatal in the three cases of NF but was favourable with local and/or systemic antibiotic therapy in the remaining cases.

In this study, we noted cutaneous superinfection in nine of 30 (30%) patients receiving topical corticosteroids for bullous pemphigoid, among which were three cases of fatal NF due to streptococcus A (10%). The infectious risks associated with TCS must not be neglected, particularly since treated patients are old and fragile, and frequently have multiple well-known risk factors for NF (e.g. extensive lesions, diabetes, etc.). In the event of signs of cutaneous superinfection, especially in cases of diabetes and prolonged TCS treatment, bacteriological analysis should be conducted. Adequate treatment should be initiated without delay, especially in cases of beta-haemolytic streptococcal infection.