Antibiotics Before Blood Cultures Decrease Sensitivity

For patients with severe sepsis or septic shock, early administration of antibiotics improves outcomes. At the same time, guidelines recommend deferring antibiotics until blood cultures are obtained, so that cultures can confirm the diagnosis and guide future antimicrobial selection. These authors used an elegant study design to determine the precise impact of antibiotics on blood culture sensitivity.

In seven different emergency departments, they enrolled 330 patients with severe manifestations of sepsis (systolic blood pressure <90 mm Hg or lactate >4 mmol/L), in whom blood cultures were obtained before antibiotics were given. They then collected a second set of blood cultures 30 to 240 minutes after the first antibiotic was administered. …