April 12, 2011

Acne Antibiotic Use Not Linked To Bacterial Resistance

A new study suggests that people who use certain prescribed antibiotics for treatment of acne are unlikely to develop bacteria resistance to those drugs, even when they use the antibiotics for months at a time.

Researchers are surprised by the findings given what is known about bacteria's ability to adapt to common antibiotics and become immune to their effects. And it's interesting because the bacteria the researchers studied -- Staphylococcus aureus -- is the root cause of MRSA.

MRSA is an infection resistant to multiple antibiotics and is extremely difficult treat and more dangerous than other non-resistant infections, the researchers note in the journal: Archives of Dermatology.

"A lot of the work that we've done over the years has often shown problems with long-term antibiotic use," Dr. David Margolis, a co-author of the study from the University of Pennsylvania School of Medicine in Philadelphia, told Reuters Health.

Tetracycline, one of the most common antibiotics for acne treatment, has been around for a long time and "it's interesting to notice that Staphylococcus aureus hasn't become overtly resistant to it," said Margolis.

He and his colleagues took nose and throat swabs from 83 acne patients to search for signs of staph bacteria. Nearly half of the patients in the study had been treated with antibiotics, some for up to a year.

A total of 36 of the 83 patients in the study were colonized with S. aureus. Two of the 36 patients had MRSA; 20 had S. aureus solely in their throats; nine had S. aureus solely in their noses; and seven had S. aureus in both their noses and throats, the authors reported.

"Long-term use of antibiotics decreased the prevalence of S. aureus colonization by nearly 70 percent," the authors report. "A decreased rate of colonization was noted with the use of both oral and topical antibiotics."

Patients who took antibiotics to treat their acne were less likely to have the bacteria -- perhaps because the drugs were killing nose and throat bacteria in addition to the bacteria that causes acne, said Margolis.

The researchers noted that only about 10 percent of all staph bacteria sampled were resistant to tetracycline antibiotics. Using the antibiotics to treat acne didn't increase the chance that a patient would have staph bacteria that tested positive for tetracycline resistance.

While patients most often use antibiotics only for a week or so to fight off an infection, acne patients may be on antibiotics for months or even years, Margolis said.

This causes concern due to the fact that these patients may be more likely to harbor bacteria that are resistant to tetracycline. It could become a major problem if the normally harmless staph bacteria becomes a more serious infection or if those patients spread the resistant bacteria to others.

But this research adds to data suggesting that the odds of acne patients getting a serious, drug-resistant infection are low, noted Dr. Guy Webster, a dermatologist at Jefferson Medical College in Philadelphia.

"A lot of the public panic about treating acne with antibiotics is unwarranted, at least as far as Staph aureus and resistance goes," Webster told Reuters Health.

Webster, who did not participate in the current study, said it "affirms what we kind of already know." Dermatologists have long used tetracyclines in acne patients and yet they are still some of the few drugs that treat MRSA successfully, he added.

Webster said tetracycline resistance is still a possibility in acne patients who use antibiotics long-term. And there are other negative effects of tetracycline treatment -- including the likelihood of yeast infections in women using the drugs.

The new study results contradict the current belief about long-term use of antibiotics.

"Specifically, in our study, the prolonged use of antibiotics from the tetracycline class that are commonly used to treat acne lowered the prevalence of colonization by S. aureus and did not increase resistance to the tetracycline antibiotics," the authors explained.

"Future research should be conducted with respect to other organisms and antibiotics," Margolis added.

But for now, when doctors are considering treatment for acne, the risks of these antibiotics seem to be smaller than the benefits, said Webster.

Staphylococcus aureus is found both in hospitals and the community. "While S. aureus colonizes the skin, it can also be responsible for localized skin infections and life-threatening systemic infections," the authors wrote. "At one time, it was sensitive to many antibiotics and antimicrobial agents. However, because of its ability to adapt to these therapies and become resistant, clinical scenarios now exist in which few therapeutic options remain to treat this organism. Therefore, methicillin-resistant S. aureus (MRSA) has become commonplace."

The report of the new study was published online Monday and will appear in the August print edition of Archives of Dermatology.


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