Curved rods related to Mobiluncus--phenotypes as defined by monoclonal antibodies

51 strains, including clinical isolates, type and reference strains of Mobiluncus, were studied as to phenotype and reactivity with a set of monoclonal antibodies to defined Mobiluncus antigens. Numerical analysis of phenotypic data and the reactivity with monoclonal antibodies showed that the bacteria are clustered to form the two main species, M. mulieris and M. curtisii, although some atypical variants occur. In indirect immunofluorescence assay, the unique antigens were fully exposed on the cell surface and could therefore be used as markers for specific microscopic identification of Mobiluncus in mixed vaginal samples from women attending an STD clinic. The monoclonal antibodies identified M. mulieris and M. curtisii, showing a high correlation with the detection of motile curved rods in wet smears and curved rods in Gram-stained preparations. 70% of the samples harbouring Mobiluncus as seen by direct identification with monoclonal antibodies were culture-positive when an elaborate dilution technique for culture was used.