Virulence determinants in nonsporeforming anaerobic bacteria.

The literature dealing with adherence, host-protective mechanisms and tissues damaging products of nonsporeforming anaerobes is reviewed. The adherence mechanisms are poorly understood. There is evidence for that encapsulation plays a role in the pathogenicity of Bacteroides fragilis and black-pigmented bacteroides. A leukocidin is produced by Fusobacterium necrophorum, and Ig protease, collagenase and a trypsin-like enzyme by some Bacteroides species. Some Bacteroides fragilis strains produce an enterotoxin. The pathogenetic role of endotoxin is unclear.