Serum Complement Levels in Bacteremia Due to Gram-Negative Organisms

Mean (± S.D.) levels of C3 did not differ significantly between 75 control patients (141.4 ± 22 mg per 100 ml) and 68 patients with bacteremia due to gram-negative organisms(132 ± 50 mg per 100 ml). In the 41 patients with uncomplicated bacteremia the mean C3 levels (151 ± 51 mg per 100 ml) did not differ from values in controls; however, a significant reduction in C3 levels was observed in 26 patients with shock (105 ± 31 mg per 100 ml) and the 19 patients who died (98 ± 38 mg per 100 ml) of bacteremia (p less than 0.001). The frequency of occurrence of shock or fatal outcome tended to parallel the degree of lowering of C3 levels in serum specimens obtained shortly after the onset of bacteremia.