Criteria for culture-negative sepsis:
(1) negative blood cultures
(2) systemic inflammatory response (with hemodynamic instability, organ dysfunction, altered mental status)
(3) exclusion of alternative diagnoses
Alternative methods may be able to detect a bacterial pathogen:
(1) multiple blood cultures
(2) PCR (if a specific pathogen suspected)
(3) prolonged incubation
Differential diagnosis:
(1) blood cultures collected after the starting of antibiotics
(2) specimen for blood cultures insufficient
(3) SIRS due to a noninfectious cause
(4) SIRS due to non-bacterial infection (fungal, virus, parasitic)
(5) laboratory error
(6) limited blood culturing (inadequate number to detect)
(7) bacteria with special nutritional requirements
