Differential Methods for Identification of T-Mycoplasmas Based on Demonstration of Urease

tification. Since T-mycoplasmas are the only mycoplasmas so far known to possess this enzyme, demonstration of urease is specific for their identification. The U-9 urease-color-test fluid medium [5] was the first reliable medium of acceptable sensitivity developed in our laboratory for the detection of T-mycoplasmas in clinical material and for the identification of T-mycoplasmas in primary or secondary mycoplasmal cultures. The U-9 medium is extremely useful in estimating numbers of Tmycoplasmas by direct titration in this medium of T-mycoplasmas in urine specimens, urethral exudates, and broth cultures. The U-9 medium is similarly useful in performing quantitative followup cultures of urine from patients with nongonococcal urethritis before, during, and after treatment [6]. Typical reactions in the U-9 medium are shown in figure 1. Development of a red color by the phenol-red indicator is a positive test for urease. The overall agreement (positive and negative) between urease reactions in U-9 medium and findings from primary cultures on standard agar among 686 clinical specimens was 98.1%. The disagreement consisted of 13 falsely-positive urease reactions that were recognized visually as having been caused by other microorganisms. For specimens from the female genitourinary tract, the inclusion of 2.5 Etg of amphotericin B (Fungizone) per ml of U-9 medium is recommended for the suppression of growth of Candida species and of