Differences in the growth requirements of some strains of Ureaplasma urealyticum of human origin.

The growth requirements of Ureaplasma urealyticum strains T-McA, T-Pi, T-27, and T-207 were studied. All strains grew in T-broth containing horse serum. Only strain T-McA grew in broth containing serum fraction A, a finding that confirmed that ureaplasmas are not homogeneous and suggested that they can be divided into two species on the basis of their requirement for horse serum. The growth factors required by T-McA are arginine, cystine, methionine, and unidentified metabolites in serum fraction A and trypticase soy broth. The vitamins in Eagle's minimal essential medium are not essential metabolites for T-McA but enhanced its growth. Therefore, we recommend that these vitamins be incorporated in ureaplasma media and that the effect of supplementing media with arginine, cystine, and methionine for the primary isolation of ureaplasmas be ascertained.