The Infectious Disease Society of America updated their recommendations last year with very reasonable guidelines. Simple, uncomplicated cellulitis requires nothing more than penicillin or a first-generation cephalosporin. This recognizes the overwhelming preponderance of susceptible organisms implicated in such infections. Now, in the era of increasingly endemic methicillin-resistant S. aureus, the current prevailing worry is the rate of treatment failure for such inexpensive and old-fashioned first-line agents.
So, why are these authors testing clindamycin versus trimethoprim/sulfamethoxazole? Not only that, in addition to uncomplicated cellulitis, these authors are also testing these agents following abscess drainage – yet another uncertain indication for antibiotics.
But, so, yes – with 524 patients in the phase of the trial enrolling those with uncomplicated cellulitis, mixed abscess and cellulitis, and abscesses greater than 5 cm, the comparison was a wash. Clindamycin and TMP/SMX had small differences favoring the former, but not large enough to reach statistical significance. Each antibiotic has its own specific constellation of adverse effects and interactions, and with treatment failures at roughly 1 in 5 in the ITT population for each, other considerations are probably more important than any efficacy difference between the two.
Of the 296 patients for which cultures were obtained, 167 (31.9% of the total cohort) grew MRSA. Oddly, the methods state non-suppurative lesions were not cultured, and they report only 47% of patients had purulent drainage. Yet, cultures were obtained in 56%. What sort of culture swab was performed on simple cellulitis?
And, of course, as with every trial, every possible comorbidity was excluded. Someday, we’ll have the wherewithal to compare failure rates in our typical Emergency Department patient – the diabetic, obese, and renally insufficient!
The other arm of the trial, a “limited abscess” group comparing I&D plus antibiotics versus I&D plus placebo will be published separately.
“Clindamycin versus Trimethoprim–Sulfamethoxazole for Uncomplicated Skin Infections”
http://www.nejm.org/doi/full/10.1056/NEJMoa1403789