Evaluation of preservation methods and solid media suitable for recovery of Ureaplasma urealyticum from transported urine specimens

Abstract

Urine specimens to be tested for Ureaplasma urealyticum (T-strain mycoplasma) must often be transported to a central laboratory for identification. To examine survival of these organisms over 2 days of transport, fresh urine samples were tested for the presence of ureaplasmas and then divided into four groups: (i) fresh, (ii) frozen, (iii) preserved with 1% (wt/vol) boric acid at room temperature, and (iv) preserved with 10% dimethyl sulfoxide and frozen. The samples were cultured on both A7 and New York City solid media, and the estimates of survival were compared to that of fresh urine. Less than 10% survival of Ureaplasma was observed in 11 of 14 specimens stored frozen for 2 days without preservation; six specimens lost all organisms. Specimens containing either dimethyl sulfoxide or boric acid showed higher survival rates, although neither method consistently approached the full recovery of the T-strains found with the fresh urine. Ureaplasmas from fresh specimens grew well on both New York City and A7 media; however, the New York City medium proved superior for those preserved with boric acid and for urine samples containing few ureaplasmas. These results indicate the preservation of samples does increase the yield of U. urealyticum from urine samples delayed in transit.