A new medium for the presumptive identification of gram-positive uropathogens.

A significant percentage of urinary tract infections are caused by gram-positive microorganisms. The rapid identification of these uropathogens is important in determining the appropriate treatment of such infections. A selective medium containing colistin sulfate and nalidixic acid (Columbia CNA Agar) was modified by the addition of esculin, ferric ammonium citrate, mannitol and phenol red. The new medium (Esculin-Mannitol Agar) was extensively evaluated as a primary plating medium for urine specimens. Isolates were presumptively identified solely by colonial morphology and reaction of the medium. Presumptive identification of the isolates was confirmed by conventional tests. The accuracy of the presumptive identification indicated that Esculin-Mannitol Agar was useful in the primary plating of urine specimens when employed together with an appropriate medium for the recovery of gram-negative organisms.