The pustular skin lesions in Behcet's syndrome are not sterile

Background: The pustular skin lesions of Behcet's syndrome (BS) are clinically and histopathologically similar to ordinary acne, but BS patients get lesions at sites not commonly involved in acne, such as the legs and arms. The microbiology of these lesions has not been studied adequately. Objective: To make a detailed study of the microbiology of BS lesions. Methods: Subjects were patients with BS and acne vulgaris. Material was extracted from pustular lesions and directly plated to aerobic and anaerobic media by sterile swab. Anaerobic bacteria were identified using a commercial kit (API 20A). Aerobic bacteria were defined by standard procedures. Results: 58 BS patients and 37 acne patients were studied. Pustules were cultured from the following sites: BS patients (70 pustules): face (17), back (30), chest (2), arm (4), leg (17); acne patients (37 pustules): face (27), back (6), chest (1), arm (2), leg (1). At least one type of microorganism was grown from each pustule. Staphylococcus aureus (41/70, 58.6%, p = 0.008) and Prevotella spp (17/70, 24.3%, p = 0.002) were significantly more common in pustules from BS patients, and coagulase negative staphylococci (17/37, 45.9%, p = 0.007) in pustules from acne patients. Conclusions: The pustular lesions of BS are not usually sterile. The microbiology of these lesions is different from ordinary acne. It remains to be determined whether the infection is secondary or has any pathogenic implications.