Examination of human semen infected with Ureaplasma urealyticum by fluorescence microscopy.

Semen specimens from men complaining of involuntary infertility were cultured for Ureaplasma urealyticum and large-colony mycoplasmas. Samples positive for ureaplasmas (but negative for large-colony mycoplasmas) were washed and stained with a DNA-binding fluorochrome (Hoechst No. 33258) and examined by fluorescence microscopy. DNA-containing particles of a size consistent with ureaplasmas were found adherent to the heads and tails of spermatozoa as well as to exfoliated urethral epithelial cells when present. The number of spermatozoa with adherent particles varied widely in different clinical samples, ranging from less than 1% to 20%. In a preliminary study of the possible use of this technique as an aid in diagnosing genital ureaplasma infection, we were able to correctly identify 13 of 15 positive samples prior to culture.