[Gram-negative bacteria folliculitis].

Gram-negative folliculitis was first described in 1968 and had since given rise to numerous publications. To our knowledge, no case has yet been published in France, although we observed 6 of them in 12 months. Between March, 1985 and March, 1986, samples of pus for bacteriological examination were obtained from all our patients with acnea vulgaris resistant to the standard treatment (i.e. oral tetracycline combined with topical applications of tretinoin or benzoyl peroxide), thus enabling us to detect patients who had a Gram-negative bacillus (GNB) in at least one pustule. Inflammatory and painful episodes were noted in every case. Tetracyclines, initially effective, gradually lost their activity. The lesions were always limited to the face and consisted of: either superficial small pustules located in the naso-labial line and on the upper lip and chin, associated with inflammatory papulopustular lesions of the cheeks and perioral region; or deeply sited and painful nodules of the cheeks. Various GNBs of the lactose-fermenting Gram-negative rod group were isolated from the superficial lesions, and a Proteus mirabilis strain from the deep lesions. The GNB was never found in all samples but only in 1 to 3 pustules. Four patients were treated with antibiotics proved to be active in vitro against the responsible organisms, and their lesions disappeared within a fortnight. Two patients were given isotretinoin in doses of 1 mg/kg/day with a satisfactory result after 2 and 3 months respectively. The prevalence of Gram-negative folliculitis is probably underestimated. The clinical picture is stereotyped. GNBs are found in some pustules but rarely in all.(ABSTRACT TRUNCATED AT 250 WORDS)