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Salon Footbaths May Promote Infection
What the Study Showed

More than 100 people with severe skin infections contracted the illness from whirlpool footbaths at a nail salon, according to a 2002 study published in the New England Journal of Medicine. The investigators found that the infection, called furunculosis, was caused by contact in the whirlpool with the tenacious bacterium, Mycobacterium fortuitum. The microbes had been introduced through municipal tap water and had then flourished in the baths, a nutrient-rich environment fed by hair and skin debris that collected behind inlet suction screens on the whirlpools.

The infections, which originated deep in the hair follicles, were most common in women who had shaved their legs before receiving pedicures and who received an oil massage of their feet and calves after the footbath. Customers developed severe and recurring boils that often left permanent scars.

How It Was Done

Suspicion of a bacterial outbreak was first raised in September 2000, when a northern California physician reported he had four patients with furunculosis, and that all had received pedicures at a certain nail salon. A team of researchers from local and state health departments, as well as the federal Centers for Disease Control and Prevention, notified local family practitioners and dermatologists of the potential outbreak.

Area doctors were asked to examine patient records over the previous six months and report any cases of lower extremity skin infections which had lasted at least two weeks and failed to respond to routine antibiotics, or which were suspected to be mycobacterial furunculosis for other reasons.

Punch-biopsy specimens of suspicious lesions were sent to the California Microbial Diseases Laboratory to identify the organism involved. The research team also obtained multiple environmental samples from the salon, including massage oils, lotions, bubble soap, tub cleaner, exfoliating scrub, and cuticle oil. The team also cultured behind the 10 footbaths' inlet screens. Tap-water specimens were taken four and eight weeks after the salon was shut down in October 2000.

It turned out that a single strain of M. fortuitum from the tap water was responsible for all the follicular infections found, and the same strain was recovered from all the footbaths (but not from the products used in them, such as bubble soap or detergents, or products used on the customers, such as massage oil). The only additional risk factor for infection was shaving of the legs just prior to the pedicure and leg massage (two-thirds of the affected women had done this). Most likely, tiny openings in the skin from shaving may have helped the infection take hold.

Patients who were treated with oral antibiotics that were active against M. fortuitum eventually were cured of the boils. Those who were treated only for a nonmycobacterial infection did not improve, and many were left with permanent scars.

Why It's Important

The study highlights the risks of salon pedicures. It's important for owners and customers alike to be aware that despite disinfecting regimens, footbaths commonly used in salons may provide good breeding grounds for bacterial organisms that can leave lasting and disfiguring scars. A followup bacteriologic survey of footbaths in other California nail salons also found rapidly growing mycobacteria, similar to the one that caused the first outbreak. And at least one other furunculosis infection was subsequently identified at another salon.

The study authors point out that such rapidly growing and tenacious infections are largely under-recognized and likely to increase in prevalence. Because M. fortuitum and similar organisms can be resistant to a variety of disinfectants, further research is needed to determine optimal cleaning procedures for salon footbaths.

Source: Winthrop K, Abrams M, Yakrus M, et al. An outbreak of mycobacterial furunculosis associated with footbaths at a nail salon. The New England Journal of Medicine 346(18):1366-1371.


Date Published: 10/30/2002
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