Pathogenicity of ureaplasmas for animals and man.

Since their original isolation from the genital tract of man, ureaplasmas, previously termed T-strain mycoplasmas, have been isolated from a variety of animal species. Under experimental conditions they have been shown to cause mastitis in cattle, goats and mice, and observations made on naturally-occurring bovine pneumonia, as well as the results of experimental inoculation, suggest that ureaplasmas are responsible for a portion of bovine cuffing pneumonia. Ureaplasmas have been isolated from the genital tract of a wide variety of animals and have the potential for causing disease in this anatomical area, as the results of experimental intra-urethral inoculation of goats, for example, indicate. However, there are no data, as yet, to incriminate ureaplasmas as a cause of naturally-occurring genital tract disease nor as a cause of infertility, the latter being an area in which the results of studies are often conflicting and difficult to interpret. In man, the rôle of ureaplasmas in genito-urinary disease has been a bone of contention for many years. Experimentally, ureaplasmas produce bladder calculi in rats but so far there is no evidence that they do so in man. Further, there are no convincing data to support the notion that infertile couples possessing ureaplasmas should be treated with tetracyclines. There is an undoubted association between spontaneous abortion and low birth-weight on the one hand and the presence of ureaplasmas in the mother, abortus or infant on the other. However, evidence that the organisms cause abortion is lacking and whether they are directly responsible for low birth-weight is unknown. The association between chorioamnionitis and ureaplasma isolation is provocative enough to stimulate further work. In the case of non-gonococcal urethritis, the weight of evidence suggests that ureaplasmas cause the disease in some men. This is based on quantitative isolation, volunteer inoculation, as well as treatment studies including the use of antibiotics, such as rifampicin, which differentiate between chlamydiae and ureaplasmas.