Fourteen serotypes of ureaplasma urealyticum (T-mycoplasmas) demonstrated by the complement-dependent mycoplasmacidal test.

Previously, we found that strains of Ureaplasma urealyticum could be divided into 11 serotypes using the mycoplasmacidal (MC) method for serotyping. Subsequent study has shown that two pairs of these strains were sufficiently closely related to cause us to revise the typing scheme into nine distinct serotypes. Other investigators, using different methods to detect serotypic diversity, have found eight serotypes. We have now compared our nine strains with the eight prototype strains developed by Ford and Black, and we have used reciprocal MC titers of antisera for the comparison. Three pairs of strains from our group and the group prepared by Ford and Black were found to be serologically closely related or identical, leaving six serotypes in our series and five in the other series that were serologically unique. Thus 14 serotypes of U. urealyticum have been identified in these studies, and a 15th strain that is apparently serologically distinct from the others, has recently been described in Vancouver.