Wrong antibiotic used for resistant skin infections

For many pediatricians, trimethoprim-sulfamethoxazole (TMP-SMX; Bactrim) may be the oral antibiotic of choice when a patient presents with a community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) skin infection, but another drug-clindamycin-may actually work better, according to a new study.

“These data are very revealing as to what is happening out in the trenches-that Bactrim is not as effective as clindamycin in either treating the initial infection (of skin boils) or preventing repeat infections over the next year,” said one of the study investigators, C Buddy Creech, MD, MPH, assistant professor of pediatric infectious diseases at Vanderbilt University Medical Center in Nashville.

For the retrospective study, researchers examined public health insurance records for about 50,000 Tennessee children to compare outcomes of 3 drugs: beta-lactams, Bactrim, or clindamycin. Although the research looked at a range of skin infections, there was a special interest in boils because a previous Vanderbilt study indicated that 70% to 80% of boils are caused by CA-MRSA.

Children who had the standard drainage procedures and then were prescribed either Bactrim or a penicillin-based drug had more than twice the rate of treatment failure or recurrence compared with children who received clindamycin. Yet, prescriptions for Bactrim increased dramatically in Tennessee from 2004 to 2007, from 4% to almost 40%. Researchers suggested that Bactrim was the drug of choice over clindamycin because it is less expensive and tastes better.

“When MRSA became the predominant skin bug, we all went scrambling for an oral antibiotic that would work. Bactrim looked like it worked in the lab, but it has not been put to the test in clinical trials with these skin infections in people,” Creech said.

Researchers said that the study is only a first step in changing the standard of care, but lead investigator Derek J. Williams, MD, MPH, noted, “This study is strongly suggestive and has good evidence behind it that physicians should stop and think twice. Bactrim may not be the best choice for skin boils.”

The study indicated that penicillin still worked well for nonboil-type skin infections such as impetigo.

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