Following-up last week’s publication regarding the efficacy of TMP-SMX monotherapy for skin and soft tissue infections – with specific concern for S. pyogenes resistance – this article takes the opposing approach: cephalexin monotherapy. Cephalexin and other first-generation cephalosporins have been effectively used for their gram-positive coverage in SSTs for quite some time – right up until they fall flat in the MRSA era. They have excellent utility against Group A Strep, but lack any activity against MRSA.
This is a prospective, comparative-effectiveness trial of cephalaxin monotherapy vs. cephalexin + TMP-SMX in the treatment of uncomplicated, non-purulent cellulitis. They enrolled 153 patients, lost 7 to follow-up, and the cure rates were 85% in the dual-therapy group and 82% in the monotherapy group. Baseline differences between groups were generally small and likely clinically insignificant. Oddly, almost a quarter of both groups received IV antibiotics at the initial visit. Regardless, cephalexin monotherapy was non-inferior to cephalexin + TMP-SMX dual-therapy in this small trial.
Of course, as usual, this study excludes all patients with diabetes, immunosuppression, or peripheral vascular disease – which is to say, everyone we realistically see in the Emergency Department. However, for non-purulent cellulitis in the absence of risk factors for MRSA, it is likely reasonable to continue with first-line cephalexin monotherapy. It should also be noted these authors used full weight-based dosing schedules for their patients, with adults >80kg receiving 1000mg of cephalexin and TMP-SMX 160/800 each four times daily.
“Clinical Trial: Comparative Effectiveness of Cephalexin Plus Trimethoprim- Sulfamethoxazole Versus Cephalexin Alone for Treatment of Uncomplicated Cellulitis: A Randomized Controlled Trial”
http://www.ncbi.nlm.nih.gov/pubmed/23457080