Prevotella amnii sp. nov., isolated from human amniotic fluid.

Two Gram-negative, anaerobic, non-spore-forming, rod-shaped organisms were isolated from human amniotic fluid. Based on morphological and biochemical criteria, the strains were tentatively identified as Bacteroidaceae but they did not appear to correspond to any recognized species of this family. Comparative 16S rRNA gene sequencing studies showed the strains were highly related to each other and confirmed their placement in the genus Prevotella, but sequence divergence values of >4% with reference Prevotella species demonstrated that the organisms from human clinical sources represent a novel species. Phylogenetic analysis revealed the novel organism to be most closely related to Prevotella bivia, an organism frequently associated with pelvic inflammatory diseases. The major long-chain cellular fatty acids of the novel species consist of iso-C(14:0), anteiso-C(15:0), iso-C(15:0), C(16:0), iso-C(16:0) and iso-3-OH-C(17:0). Based on biochemical criteria and phylogenetic considerations, it is proposed that the unknown isolates from human amniotic fluid be assigned to a new species of the genus Prevotella, as Prevotella amnii sp. nov. The type strain of Prevotella amnii is CCUG 53648(T) (=JCM 14753(T)).