Embrace low culture
About 700 patients with skin infection admitted from the ED were prospectively followed, temperatures recorded, and blood/wound culture results tracked. Only 86/734 (35%) had blood cultures obtained, so the total number of patients was small and confidence intervals wide. As expected, blood culture yields were low 6/86 (7%), even when including IV drug users. Wound culture results were positive in about 30% but grew expected MRSA, MSSA, or group A strep, all sensitive to vancomycin. The IDSA recommends against obtaining routine blood cultures in patients with cellulitis or purulent skin infection, except in cases with, “malignancy, severe systemic features (such as high fever and hypotension), and unusual predisposing factors, such as immersion injury [meaning injury occurring in fresh or saltwater], animal bites, neutropenia, and severe cell-mediated immunodeficiency.”
Blood cultures are low yield in routine patients with skin and soft-tissue infection. Don’t do it unless your patient has one of the above high-risk features. False positive cultures are common and lead to costly follow up for patients. To learn more, see the IDSA link above and this excellent summary on JWatch.
Low yield of blood and wound cultures in patients with skin and soft-tissue infections. Am J Emerg Med. 2017 May 26. pii: S0735-6757(17)30420-5. doi: 10.1016/j.ajem.2017.05.039. [Epub ahead of print]
Peer reviewed by Thomas Davis.