Mycoplasma infections of the human urogenital tract with particular reference to non-gonococcal urethritis.

The criteria which need to be fulfilled before regarding a microorganism as a cause of non-gonococcal urethritis (NGU) are considered in relation to Mycoplasma hominis, Ureaplasma urealyticum and M. genitalium. There is no evidence to support an aetiological role for M. hominis, but few appropriate investigations have been undertaken. The criteria have been met, for the most part, in the case of U. urealyticum, but further quantitative studies are required. The role of M. genitalium is unknown, but its biological and morphological features and ability to cause genital disease in animals suggest that it may be pathogenic for man. It is emphasized that the criteria for regarding a microorganism as a cause of NGU should also be used where feasible when investigating the infectious aetiology of other genito-urinary conditions.