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For children with skin and soft tissue infections, clindamycin is the antibiotic of choice for empiric treatment, researchers found.

In a retrospective cohort study, the drug (sold under various brand names) led to fewer treatment failures and recurrences than either trimethoprim-sulfamethoxazole (Bactrim, Septra) or any beta-lactam, according to Derek Williams, MD, of Vanderbilt University School of Medicine in Nashville, and colleagues.

The difference persisted whether or not the lesions were drained, but the effect was stronger among children whose lesions were drained, Williams and colleagues reported online in Pediatrics.

Methicillin-resistant Staphylococcus aureus (MRSA), whose prevalence is increasing, is a frequent cause of skin and soft tissue infections in children, the researchers noted, and the best antimicrobial management strategy for such infections in the MRSA era is not clear.

To help shed light on the issue, Williams and colleagues constructed a retrospective cohort consisting of children enrolled in TennCare, Tennessee's Medicaid program, and who had an incident skin or soft tissue infection between Jan. 1, 2004, and Dec. 31, 2007.

The study population included those who were prescribed one of the three drugs, but not two or more. As well, children whose lesions were drained but who were not given an antibiotic were excluded.

All told, the cohort consisted of 47,501 children, including 7,459 treated with clindamycin, 10,623 given trimethoprim-sulfamethoxazole, and 29,419 who received a beta-lactam.

The man outcome measures were treatment failures and recurrences -- defined as renewed infection within 14 days or within 15 through 365 days, respectively, after the incident infection, Williams and colleagues reported.

Among the 6,407 children who had a drainage procedure, they found:

• 107 clindamycin patients had treatment failure, compared with 246 taking trimethoprim-sulfamethoxazole and 215 getting a beta-lactam.
• With clindamycin as the reference, the adjusted hazard ratios for treatment failure were 1.92 with trimethoprim-sulfamethoxazole and 2.23 with a beta-lactam. The 95% confidence intervals were 1.49 to 2.47 and 1.71 to 2.90, respectively.
• Recurrence occurred in 280 clindamycin patients, 359 on trimethoprim-sulfamethoxazole, and 355 taking a beta-lactam.
• Also with clindamycin as the reference, the adjusted hazard ratios for recurrence were 1.26 with trimethoprim-sulfamethoxazole and 1.42 with a beta-lactam. The 95% confidence intervals were 1.06 to 1.49 and 1.19 to 1.69, respectively.

Among the 41,094 children without a drainage procedure, the pattern was similar. Specifically:

• There were 2,435 treatment failures and 5,436 cases of recurrence.
• The adjusted hazard ratios for treatment failure, compared with clindamycin, were 1.67 for trimethoprim-sulfamethoxazole and 1.22 for beta-lactams, with respective 95% confidence intervals of 1.44 to 1.95 and 1.06 to 1.41.
• And the adjusted hazard ratios for recurrence were 1.30 for trimethoprim-sulfamethoxazole and 1.08 for beta-lactams, with respective 95% confidence intervals of 1.18 to 1.44 and 0.99 to 1.18.

Clindamycin was superior, the researchers concluded, with the effect greatest among children with purulent infections who had a drainage procedure.

They cautioned that the study results might be affected by residual confounding and possible errors in classification of antibiotic exposure and outcomes. As well, they noted, the study lacks microbiologic data, which might give insight into the mechanisms of treatment failure and recurrence.

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