Phenotypic complexity in Mobiluncus.

A total of 74 Mobiluncus strains were collected from various laboratories and examined morphologically, biochemically and serologically. Repeated Gram-staining showed a greater variety of cell morphology than hitherto reported with some strains changing their appearance between long and short. All strains except two were motile. Sixty-five of 74 strains were designated M. curtisii and M. mulieris in contrast to atypical strains. In spite of this several of them reacted aberrantly in one or more tests. Biochemical tests and antigenic characterization by monoclonal antimobiluncus antibodies placed most but not all strains in their species groups. One atypical strain had the cellmorphology and biochemical profile of a M. mulieris but reacted only with anticurtisii antibodies. One M. mulieris had the cellmorphology and biochemical profile of a M. curtisii but reacted with an antimulieris antibody. We conclude that there is a greater variance in Mobiluncus' phenotypic appearance than has so far been appreciated.