Clinical diagnostic accuracy of suspected sources of bacteremia and its effect on mortality

Although much has been written about bacteremia, evidence of the clinical diagnostic accuracy of bacteremia sources in the absence of microbiological results and the impact of diagnostic accuracy on mortality is scarce.

This is a retrospective study of bacteremia episodes over a 2-year period at a general hospital in Madrid. Congruence analyses between clinically presumed and definite sources, acquisition, causative organism, empirical treatment and progression to death were performed.

The study included 323 bacteremia episodes. Clinicians' diagnostic accuracy was higher for gastrointestinal (88.8%; 95% CI: 79%-84%), respiratory (93.9%; 95% CI: 79%-99%) and urinary tract sources (83.6%; 95% CI: 75%-89%) and lower for skin and soft tissues (77.2%; 95% CI: 54%-92%) and, notably, intravascular sources (56%; 95% CI: 39%-71%). Overall, a non-significant (3.45%; 95% CI: -0.6%-13.5%, p=0.47) increase in mortality was observed in the incorrectly suspected bacteremia source group. Mortality related to a definitive source was significantly higher when an intravascular origin was not suspected, resulting in a 26% increase in mortality (95% CI: 1%-52%, p=0.03). Differences in mortality related to inaccurate source assumptions were non-significant when the definitive bacteremia sources were gastrointestinal, urinary, respiratory, skin and soft tissues or unknown. Mortality in the group receiving appropriate empirical antimicrobial treatment was 10.6% compared with 19.7% mortality in the group receiving inappropriate empirical antimicrobial treatment (OR 2; 95% CI: 1.01-4.25).

The diagnostic accuracy of bacteremia sources is high in all but intravascular sources. A non-suspected intravascular source and inappropriate empirical treatment are related to a higher mortality.