Isolation and identification of bacteria from blood within 12 h using standard laboratory equipment

Sepsis has an incidence of 50 million cases per year and represents a significant cause of morbidity and mortality worldwide. Current diagnostic methods rely on blood drawn directly into blood culture media in hemoculture bottles, followed by culturing, often taking days to yield results and failing to meet urgent clinical needs. We present here a protocol for isolating and identifying bacteria from blood within 12 h after sampling, bypassing prior hemocultures. Starting from blood added into blood culture media, according to standard hospital sampling practice, we isolated up to 85% of bacteria at clinically-relevant concentrations in less than 15 min using an optimized centrifugation protocol. Subsequent overnight culture of the isolated bacteria on chromogenic agar plates enabled species identification of five of the most prevalent sepsis-causing bacteria. The rapidity and simplicity of the protocol may accelerate the diagnostic pipeline for sepsis patients. Moreover, the use of standard laboratory equipment may enable direct translation to clinical praxis and concatenation with downstream assays for antibiotic susceptibility testing.