Question and Methods: Multi-center diagnostic study that investigated the sensitivity of post-antimicrobial blood cultures compared to pre-antimicrobial blood cultures in severe sepsis.
Findings: The absolute difference in pre-antimicrobial (102/325 (31.4%)) compared to post-antimicrobial blood cultures (63/325 (19.4%)) was 12.0% (5.4%-18.6%;P < 0.001) yielding a sensitivity of 52.9% (42.8%-62.9%).
Limitations: Recruitment while investigators were on-site with an average of 1 enrollment per site per month. Low number of culture positives.
Interpretation: This practical study quantifies the decreased sensitivity of post-antimicrobial blood cultures with time and lays the groundwork for future research investigating impact on patient-centered outcomes.