Comparative evaluation of media for isolation of ureaplasma urealyticum and genital mycoplasma species.

Two media systems were compared for isolation of Ureaplasma urealyticum and genital Mycoplasma sp. System 1 (S-1) consisted of arginine agar and an arginine biphasic medium for isolation of Mycoplasma sp. and urea agar and urea broth for isolation of U. urealyticum. System 2 (S-2) utilized Boston broth, which is a urea-containing broth, and A7 agar, both of which support the growth of both species. Urine samples, some freshly collected and some known-positive frozen samples, were used as inocula for the two media systems. With S-1, U. urealyticum was recovered in 68% of U. urealyticum-positive cultures: 58% were detected in urea broth, and 60% were identified on urea agar. When the S-2 system was used for culture of the same samples. U. urealyticum was recovered in 98% of the cultures, with 94% detected in Boston broth and 92% identified on A7 agar. Mycoplasma sp. was recovered in S-1 and S-2 in 97 and 100% of Mycoplasma sp.-positive cultures, respectively. The S-1 arginine broth gave positive results for 89% of the cultures, and the arginine agar was positive for 97% of the cultures. The S-2 Boston broth and A7 agar gave positive results for 92 and 97% of the cultures, respectively. For the isolation of U. urealyticum, colony counts were higher, growth was seen sooner, and colonies were larger when the S-2 media system was used. Overall, the cost per test of the S-2 system was less both in technologist time and in reagent costs.