[Comparison of media for the isolation of Ureaplasma urealyticum (author's transl)]

Two liquid media and two agar media were compared for their sensitivity in the isolation of Ureaplasma urealyticum. 22 of the 144 urine specimens examined were positive. The U9-medium with low serum content showed a higher isolation rate and earlier results than a medium with 20% serum (Table 1). However some cultures grew sometimes better in the serum rich medium, suggesting a growth enhancing effect of urine in the U9-cultures. On agar more positive cases were detected with the A6-differential agar which showed urease-activity by brown color (MnO2), and less specimens were positive on A5C-agar without manganese sulfate (19 vs. 16). The number of colonies was only slightly lower on A5C-agar (Fig. 3). The darkbrown colonies on A6 (Fig. 1) were easy to detect and to count. Filtration of the urine specimens through a polycarbonate filter (0.4mum) reduced the number of bacterial contaminations, but resulted also in a lower isolation rate of ureaplasmas (13 of 22). This is probably caused by the tendency of ureaplasmas to attach to other structures e.g. epithelial cells (Fig. 2). For isolation of U. urealyticum from clinical specimens a combination of a liquid medium and a differential agar-medium is recommended.