Comparison of media for isolation of Ureaplasma urealyticum and genital Mycoplasma species.

A total of 484 frozen patient specimens originally positive for Ureaplasma urealyticum or Mycoplasma spp. or both were recultured, and the results were compared on the following media: Shepard's A7 agar, modified phenol red-urea, SP-4-urea, modified phenol red-arginine, and SP-4-arginine broths. Of 351 specimens positive for U. urealyticum, 30 (8.5%) were detected only in one or more of the broth media, whereas 117 (33%) were positive only on A7 agar. Separate use of the SP-4-urea broth or modified phenol red-urea broth isolated all but 1 and 2, respectively, of the negative A7 agar cultures. Of the 76 specimens positive for large colony Mycoplasma spp., 58 (76.3%) were not grown on the primary plating (A7) agar. Of 73 broth isolates, 73 (100%) grew in SP-4-arginine broth, and 64 (87.7%) grew in modified phenol red-arginine broth. Modified SP-4 broth appears to be a useful supplement to the A7 plating medium commonly used in the diagnostic laboratory for the isolation of U. urealyticum and Mycoplasma spp.