In this systematic review and meta-analysis, no single aspect of the physical examination, imaging, or LRINEC score had high enough sensitivity to exclude necrotizing soft tissue infections. Contrast CT performed the best, but it was only 94.3% sensitive at best. If you have a high clinical suspicion, early surgical consultation is necessary for definitive diagnosis and management.
We can't draw firm conclusions from this paper, since it was not designed or powered to detect differences in subgroups with skin abscesses. But it was notable that patients who received TMP/SMX did better than those who received placebo across all subgroups, including those with larger abscesses; especially those with fever, history of MRSA, or MRSA positive culture.