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Abstract & Commentary
Synopsis: An outbreak of a painful, nodular skin eruption of the soles affecting 40 children using a wading pool was caused by Pseudomonas aeruginosa.
Source: Fiorillo L, et al. The pseudomonas hot-foot syndrome. N Engl J Med. 2001;345:335-338.
An unusual outbreak of a distinctive skin eruption occurred among 40 children using a community wading pool. The children developed painful erythematous plantar nodules 10-40 hours after using the pool. The weight bearing areas of the sole were most severely affected. In some children, the nodules were so tender that contact with socks or bedsheets caused severe pain. Several patients had low-grade fever and constitutional symptoms.
Thirty-seven of 40 patients received no antibiotic treatment. All recovered without sequelae within 14 days; 88% recovered within 7 days. Three patients had a relapse within 24 hours of a subsequent visit to the pool. Punch biopsies of plantar nodules showed intense infiltration of neutrophils around blood vessels and adnexal structures. Culture of a dermal abscess yielded Pseudomonas aeruginosa.
The wading pool in question had an abrasive coating on the bottom to reduce slipping. The water was grossly clear but multiple cultures were positive for P aeruginosa. The environmental strains were identical to the clinical isolate by pulsed field gel electrophoresis (PFGE). After extensive disinfection measures, P aeruginosa was eliminated, and no further cases occurred.
Comment by Robert Muder, MD
"Hot tub folliculitis" is a well known entity that occurs after exposure to hot tubs and whirlpool spas contaminated with P aeruginosa.1 The rash tends to occur on the hips, buttocks, axillae, and lateral trunk. Mastitis and otitis externa are occasionally seen. Involvement of the palms and soles is distinctly unusual. Fiorillo and colleagues postulate that the occurrence of plantar lesions among the children they describe may have been facilitated by the abrasive floor of the pool, and by the fact that the plantar skin of children is considerably thinner than that of adults.
The differential diagnosis of nodular lesions on the soles is limited and includes such unusual entities as recurrent idiopathic palmoplantar hidradenitis. The occurrence of mulitple cases in a community makes the diagnosis of such rare disorders unlikely. Early recognition of the distinctive clinical and epidemiologic features of "pseudomonas hot foot syndrome" can allow one to avoid unnecessary diagnostic measures and antibiotic therapy, and lead to elimination of the source of the outbreak.
It should be noted that high-level contamination of pools and hot tubs by P aeruginosa may occur in the absence of obvious clouding of the water or malfunction of filters or chlorinators. Free chlorine levels may be reduced by high temperatures, high pH, or high concentrations of organic material during periods of heavy use. Legionella species can also flourish in the hot tub environment. Outbreaks of nonpneumonic legionellosis, as well as Legionnaires’ disease, have been linked to contaminated whirlpool spas.2,3
1. Gustafson TL, et al. Pseudomonas folliculitis: An outbreak and reveiw. Rev Clin Infect Dis. 1983;5:1-8.
2. Spitalny KC, et al. Pontiac fever associated with a whirlpool spa. Am J Epidemiol. 1984;120:809-817.
3. Jernigan DB, et al. Outbreak of Legionnaires’ disease among cruise ship passengers exposed to a contaminated whirlpool spa. Lancet. 1996;347:494-499.