Summertime skin rash

Abstract

The diagnosis is Pseudomonas aeruginosa folliculitis, confermed by the cutaneous swab. Pseudomonas aeruginosa is a Gram-negative rod, which is ubiquitous and can cause a wide range of symptoms; pseudomonas dermatitis, such as otitis externa outbreaks, is commonly associated with swimming pool and hot tub use. Pseudomonas folliculitis typically develops 8–48 h after bathing in non-chlorinated and contaminated swimming pools or hot tubs, due to bacterial colonisation of hair follicles. The rash consists of papulo-pustular elements or nodules, on an erythematous base, involving mainly the bathing suit area. In this specific case, the swimming pool was filled with seawater and crowded with children, providing an excellent environment to the pseudomonas replication. Dermoscopy can facilitate the diagnosis, identifying the vellus hairs at the center of each lesion, otherwise not clinically visible, thus displaying the folliculocentric nature of the rash and ruling out insect bites and nodular scabies. Pseudomonas folliculitis, as staphylococcal folliculitis, can generally resolve spontaneously after 7–10 days with good skin hygiene. In case of extensive disease, topical or oral antibiotic treatment are needed, and ciprofloxacin represents the first-line agent. A folliculitis non-responsive to common anti-staphylococcal treatments and a history of swimming pool bathing should raise the suspicion of Pseudomonas folliculitis. A consent to publication has been signed by child parents; the form is held by the treating institution.