Administering antimicrobial agents before obtaining blood cultures could potentially decrease time to treatment and improve outcomes, but it is unclear how this strategy affects diagnostic sensitivity” Cheng et al (2019).
Background: Administering antimicrobial agents before obtaining blood cultures could potentially decrease time to treatment and improve outcomes, but it is unclear how this strategy affects diagnostic sensitivity.
Objective: To determine the sensitivity of blood cultures obtained shortly after initiation of antimicrobial therapy in patients with severe manifestations of sepsis.
Design: Patient-level, single-group, diagnostic study. (ClinicalTrials.gov: NCT01867905)
Setting: 7 emergency departments in North America.
Participants: Adults with severe manifestations of sepsis, including systolic blood pressure less than 90 mm Hg or a serum lactate level of 4 mmol/L or more.
Intervention: Blood cultures were obtained before and within 120 minutes after initiation of antimicrobial treatment.
Measurements: Sensitivity of blood cultures obtained after initiation of antimicrobial therapy.
Results: Of 3164 participants screened, 325 were included in the study (mean age, 65.6 years; 62.8% men) and had repeated blood cultures drawn after initiation of antimicrobial therapy (median time, 70 minutes ). Preantimicrobial blood cultures were positive for 1 or more microbial pathogens in 102 of 325 (31.4%) patients. Postantimicrobial blood cultures were positive for 1 or more microbial pathogens in 63 of 325 (19.4%) patients. The absolute difference in the proportion of positive blood cultures between pre- and postantimicrobial testing was 12.0% (95% CI, 5.4% to 18.6%; P < 0.001). Sensitivity of postantimicrobial culture was 52.9% (CI, 42.8% to 62.9%). When the results of other microbiological cultures were included, microbial pathogens were found in 69 of 102 (67.6% ) patients. Limitation: Only a proportion of screened patients were recruited. Conclusion: Among patients with severe manifestations of sepsis, initiation of empirical antimicrobial therapy significantly reduces the sensitivity of blood cultures drawn shortly after treatment initiation. Primary Funding Source: Vancouver Coastal Health, St. Paul's Hospital Foundation Emergency Department Support Fund, the Fonds de recherche Santé–Québec, and the Maricopa Medical Foundation.
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Cheng, M.P., Stenstrom, R., Paquette, K., Stabler, S.N., Akhter, M., Davidson, A.C., Gavric, M., Lawandi, A., Jinah, R., Saeed, Z., Demir, K., Huang, K., Mahpour, A., Shamatutu, C., Caya, C., Troquet, J-M., Clark, G., Yansouni, C.P. and Sweet, D. (2019) Blood Culture Results Before and After Antimicrobial Administration in Patients With Severe Manifestations of Sepsis: A Diagnostic Study. Annals of Internal Medicine. 171(8), p.547-554. DOI: 10.7326/M19-1696.