Acne meds, resistant staph not linked

Philadelphia - Long-term use of tetracycline agents in treating acne does not lead to high rates of resistant Staphylococcus aureus and may actually reduce the risk of colonization with staph bacteria, MedPage Today reports.

In a small, cross-sectional study of 83 patients, most using antibiotics for acne, researchers from the University of Pennsylvania School of Medicine found that while 43 percent were colonized with Staphylococcus aureus, less than 10 percent of their bacterial isolates were resistant to tetracycline, the most commonly used antibiotic to treat acne.

Overall, the study found long-term use for acne of any oral or topical antibiotic agent was associated with a nearly 70 percent decreased prevalence of S. aureus colonization in those patients.

The study’s results, published online in Archives of Dermatology, are in direct opposition to the common belief that the mostly young and healthy patients who used antibiotics for prolonged periods for their acne would become resistant to the drugs and would have increased S. aureus colonization.

The study’s 83 patients - mean age, 24 - all had been diagnosed with acne and were being treated at the University of Pennsylvania dermatology clinic. Among the cohort, 34 percent were using topical agents at enrollment, 28 percent were using oral agents and 11 percent had received antibiotics for reasons other than acne during the previous month. All participants had throat and nasal swabs to determine the presence of S. aureus. The swabs were then evaluated for methicillin resistance. It was determined that 43 percent of the patients were colonized with S. aureus and 6 percent with methicillin-resistant S. aureus (MRSA).

Those currently using oral preparations, however, were significantly less likely to be colonized compared with those not on oral antibiotics. Those using topical preparations were also less likely to be colonized by S. aureus.

Investigators noted that contrary to what might have been expected, at no time was the rate of colonization with S. aureus greater in acne patients who were receiving antibiotics than among those who were not.

“Tetracycline antibiotics are more active against S. aureus and MRSA, and resistance is poorly acquired,” the authors wrote, noting that they also found no evidence of high levels of resistance to other antibiotics tested.

The authors recommended prospective studies to look at the colonization status of S. aureus immediately after antibiotics are initiated on a weekly basis to see if there is a point at which S. aureus colonization increases with longer usage time.