Microbiologic findings and correlations with serum tumor necrosis factor-alpha in patients with severe sepsis and septic shock.

To understand the microbiology of sepsis and its relationship with tumor necrosis factor (TNF)-alpha, 444 septic patients were studied in a phase II clinical trial. In total, 270 (61%) 444 of episodes were microbiologically documented. The most common isolates were Escherichia coli, Staphylococcus aureus, and Streptococcus pneumoniae. In some patients, obligate anaerobes were isolated in pure culture. Data on baseline TNF-alpha (n=409) showed that the geometric mean TNF-alpha concentrations in patients with severe sepsis and in those with late shock were 41 pg/mL (range, 5-3310) and 58 pg/mL (range, 5-1870), respectively. Patients with a positive culture had significantly higher TNF-alpha levels (65.9 vs. 29.2 pg/mL, P=.0001). Patients with a pure gram-negative infection had significantly higher TNF-alpha levels than those with a pure gram-positive or mixed infection, especially in the late shock group (142.6, 64.0, and 52.8 pg/mL, respectively, P=.004). These results provide further support for the concept that patients with sepsis are a heterogeneous group that require more precise definition.