Outbreak of warm foot syndrome caused by P.aeruginosa

In March-May 1998, an outbreak of hot foot syndrome, probably caused by P.aeruginosa, was recorded in Canada in 40 children aged 2 to 15 years who used the same pool. This syndrome was characterized by an erythematous rash with nodular elements on the plantar surface of the foot, swelling, burning sensation and severe pain. This symptom developed on average 40 hours after swimming in the pool.

A physical examination revealed red-purple nodes 1 to 2 cm in diameter, not accompanied by regional lymphadenopathy. A few days later, a peeling appeared on the feet.

In one child, Pseudomonas aeruginosa was isolated from a pustule on the foot. The same Pseudomonas aeruginosa strain in high concentration was isolated from the pool water. A skin biopsy of this patient revealed neutrophilic infiltration around the vessels and the sweat glands. A biopsy taken from another patient revealed micro-abscesses in the dermis.

37 patients received symptomatic treatment (analgesics, cold topical compresses, elevated limb position). Three children received cephalexin. All symptoms disappeared within 14 days, although three patients experienced a relapse, which developed within 24 hours after visiting the same pool. A child has developed folliculitis.

Superchlorination of water in the pool has proven ineffective in preventing repeated infections, so the bottom has been cleaned with ammonium and treated with ozone. Since then, no new infections have been reported.

Two cases of subcutaneous nodules which had previously developed on the extremities after taking a hot bath and which could have been caused by Pseudomonas aeruginosa have been previously reported. These two patients recovered in 10 days.