Bacteroidaceae in Thromboembolic Disease: Effects of Cell Wall Components on Blood Coagulation In Vivo and In Vitro

Abstract

The effects of Bacteroides sp., Fusobacterium mortiferum, Bacteroides fragilis , and Sphaerophorus necrophorus on various parameters of blood coagulation in vivo and in vitro were determined and compared to the coagulation effects of Escherichia coli and Salmonella minnesota , wild type and R595. Intravenous injection of washed cells, culture filtrate, lipopolysaccharide, or lipid A of the anaerobic gram-negative microorganisms into mice resulted in acceleration of coagulation. Lipopolysaccharide and lipid A of the anaerobic microorganisms had no apparent effect on circulating platelets in mice or rabbits and did not cause aggregation of human platelets in vitro. Washed cells, lipopolysaccharide, and lipid A of Bacteroides sp. and F. mortiferum also significantly accelerated the clotting time of recalcified platelet poor normal human plasma and C6-deficient rabbit plasma. Lipid A, but not lipopolysaccharide, of E. coli and washed cells of S. minnesota R595 accelerated coagulation by a similar mechanism. These results indicated that Bacteroides sp. and F. mortiferum can accelerate blood coagulation in vivo and in vitro by a mechanism which does not involve platelets or terminal components of complement.