A multicenter trial to compare blood culture with polymerase chain reaction in severe human sepsis

To assess the presence of microbial DNA in the blood by polymerase chain reaction (PCR) and its association with disease severity and markers of inflammation in severe sepsis and to compare the performance of PCR with blood culture (BC). Prospective multicentric controlled observational study. Three surgical intensive care units in university centers and large teaching hospitals. One hundred forty-two patients with severe sepsis and 63 surgical controls. Presence of microbial DNA was assessed by multiplex PCR upon enrollment, and each time a BC was obtained. Controls had both approximately 4% positive PCRs and BCs. In severe sepsis, 34.7% of PCRs were positive compared to 16.5% of BCs (P < 0.001). Consistently, 70.3% of BCs had a corresponding PCR result, while only 21.4% of PCR results were confirmed by BC. Compared to patients with negative PCRs at enrollment, those testing positive had higher organ dysfunction scores [SOFA, median (25th-75th percentile) 12 (7-15) vs. 9 (7-11); P = 0.023] and a trend toward higher mortality (PCR negative 25.3%; PCR positive 39.1%; P = 0.115). In septic patients, concordance between BC and PCR is moderate. However, PCR-based pathogen detection correlated with disease severity even if the BC remained negative, suggesting that presence of microbial DNA in the bloodstream is a significant event. The clinical utility to facilitate treatment decisions warrants investigation.