The Smith family just returned from a weeklong cruise in the Caribbean Sea. It was a wonderful opportunity for the three children to spend time with their grandparents. Much to the satisfaction of Mrs. Smith the trip went without a hitch. The plane was on time. There were no problems with the accommodations. No one got sea sick, and above all...everyone got along just fine.
They returned from their trip on Sunday, and two days later Mrs. Smith had Johnny and Amy in the office. Five-year-old Johnny had an impressive rash on his waist and inner thighs. He did not have a fever. The rash did not itch, and he really had no symptoms at all. The rash appeared like large pimples or insect bites. The lesions were raised and red, with a pus-filled center. He probably had 20-to-30 of these lesions and they all appeared to be at the same stage of development. Mrs. Smith said she first noticed them about a day ago when he was getting ready for bed, and he didn’t seem to have any new ones.
Three-year-old Amy did not have as many lesions as her brother. However, hers were much bigger and were distributed on the chest and flank area. They measured anywhere from 4-to-8 millimeters and were intensely red with an obvious central pustule. Like her brother, she had no fever, and otherwise felt and acted just fine.
Mrs. Smith said, “Here’s the deal. My father, who went on the cruise with us, is in his late seventies and is not in very good health. He is taking a medication that affects the immune system. The doctor told him to avoid being around anybody who is ill. This is chickenpox, isn’t it? If it IS chickenpox I will never forgive myself.” She went on, “I spoke with my mother this morning and she thinks that he has a similar rash. He won’t let her see it. I know he is afraid that it might be chickenpox and he doesn’t want to worry anyone.”
While I was getting the history from Mrs. Smith the children sat on the examining table with only their underpants on. I began talking to them about the trip and how they liked the cruise. When I asked about all the swimming they must have done Amy piped up, “Oh, yes! There were two pools with slides and a really neat Jacuzzi.” I asked if grandfather was able to keep up with them in the pool. Amy said, “Poppa went down the slide!”
Mrs. Smith shook her head and lamented, “He did go down the slide with them. He was a real trooper, but I’ll just die if this is chickenpox. His doctor is gonna kill me. He didn’t think it was a good idea for him to go on this cruise.”
I handed the children their shirts and told them to get dressed. Then I told Mrs. Smith that she had nothing to worry about. It was certain that the children AND their “Poppa” did not have chickenpox. Rather, they had a condition called hot tub folliculitis. This is a skin condition that is caused by Pseudomonas aeruginosa, a bacterium that has an affinity for water. It is commonly acquired from spas, whirlpools and swimming pools where the water is not properly controlled in regard to pH and chemicals. This allows the Pseudomonas to thrive.
There is little doubt that the children and their grandfather became infected while swimming on their trip. The lesions of hot tub folliculitis (HTF) are papules (raised bumps) or pustules (papules with pus in the center) that can be intensely red or violaceous in color. They may itch, and are usually concentrated in areas that are covered by a bathing suit. When they occur, the lesions appear to be at the same stage of development; in other words, they do not come in crops like chickenpox. The lesions of hot tub folliculitis usually will resolve without any treatment in one-to-two weeks, but there may be a residual hyper-pigmented post-inflammatory area where the lesions were. This is not a contagious rash, and children with HTF do not need to be isolated or kept from others.
In rare cases, a patient with HTF may develop fever, swollen glands or malaise. Should this occur, one should consider an oral antibiotic that is affective against P. aeruginosa, such as ciprofloxin.
Since most cases of HTF are benign and self-resolving, most of the literature recommends no treatment...simple watchful waiting. One summer my partner and I were seeing many patients in the office with this diagnosis. We instructed the parents of children with HTF to apply gentamicin ointment to the lesions on the right side of the body and NOT those on the left. Interestingly, the lesions on the right cleared up much faster than did the ones on the left. As a result, we generally do use gentamicin for simple cases of HTF and have had good results. This is what I did for Mrs. Smith’s children...and their “Poppa”.
As P. aeruginosa is a water-loving bug, most cases of HTF are acquired in spas and swimming pools where the conditions are optimal for the bacteria. The best way to prevent HTF is to maintain the water at a pH between 7.2 and 7.4, and the free chlorine concentration at 70.5 mg/L.
Mrs. Smith was thrilled at the news, and quite relieved. “That’s a load off my mind,” she said with a sigh. “I can’t thank you enough. You just made my day!” Then she gathered her things and told the children, “C’mon kids, pick up your toys. Let’s get our pictures developed and take them over to Poppa and Nana’s.”