The greater warmth of the facial skin of rosacea sufferers may play a role in triggering the unsightly bumps and pimples that are common signs of this disorder, according to a new study funded by a grant from the National Rosacea Society and reported at the recent annual meeting of the Society for Investigative Dermatology.
In the recently completed study, Dr. Mark Dahl, professor and chairman of dermatology at the Mayo Clinic, Scottsdale, and Dr. Patrick Schlievert, professor of microbiology at the University of Minnesota, found that at higher temperatures bacteria from the facial skin of both rosacea patients and people without rosacea released substantially more potentially toxic substances. The study noted that the surface temperature of facial skin in rosacea patients may be warmer than normal skin due to redness and flushing, and the resulting increase in toxic substances may lead to the bumps and pimples often associated with the disorder.
"Researchers have long wondered whether bacteria may be responsible for the inflammation -- papules and pustules of rosacea -- especially because they can be successfully treated with oral and topical antibiotics that destroy bacteria," Dr. Dahl said.
Drs. Dahl and Schlievert cultured samples of Staphylococcus bacteria from the pustules (pimples) of four untreated rosacea patients and the skin surface of four people without rosacea at both 86 and 99 degrees Fahrenheit. They found that, while the bacteria grew at the same rate in both the lower and higher temperatures, at the higher temperature the samples produced larger amounts of proteins that could potentially cause papules, pustules and inflammation.
In addition, some substances were secreted by the bacteria at the higher temperature that were not produced at the lower one. This included a type of enzyme known as a lipase -- a protein that acts to speed chemical reactions -- that may break down oils on the skin surface, potentially leading to blemishes and inflammation. Moreover, while all samples from rosacea patients produced the lipase, half of the samples from people without rosacea did not.
Dr. Dahl described several possible interpretations of these study results. Common bacteria may have a tendency to generate more of these irritating substances at the higher temperatures encountered on the faces of people with rosacea. Also, they may generate different harmful materials at these higher temperatures. The nature of these materials or the amounts produced could trigger papules and pustules.
Dr. Dahl further noted that other bacteria might also behave differently on the warmer skin of rosacea patients.
"Our findings suggest that temperature may change the toxicity of many types of common bacteria, opening a whole new avenue of research into this widespread but poorly understood disorder," Dr. Dahl said.
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