Effects of Bacteroides asaccharolyticus cells and B. fragilis surface components on serum opsonisation and phagocytosis.

The effect of Bacteroides asaccharolyticus on the opsonisation and phagocytosis of gram-positive and gram-negative bacteria by human polymorphonuclear leukocytes (PMNL) was investigated. Uptake of most isolates of staphylococci, streptococci and clostridia by PMNL after opsonisation with serum treated with B. asaccharolyticus was largely unimpaired. The same treatment of serum before opsonisation of isolates of Pseudomonas, Enterobacter, Klebsiella and Gardnerella resulted in the uptake by PMNL varying with individual isolates; a large reduction occurred with some and none with others. Treatment of serum with B. fragilis lipopolysaccharide before opsonisation of Proteus mirabilis produced a marked reduction in uptake, whereas treatment with B. fragilis capsular polysaccharide had little effect.