T-strain mycoplasma in non-gonococcal urethritis. Pathogen or commensal?

The term "T-strain" was applied by Shepard (1954) to a strain of mycoplasma which, when cultured on solid agar, shows morphological differences from other members of the species (Shepard, 1956). Shepard (1954) recovered T-strain mycoplasmas from urethral scrapings taken from cases of nongonococcal urethritis (NGU) and later found that this organism was present in some 70 per cent. of such cases (Shepard, 1956, 1959). Subsequently he postulated that T-strain mycoplasma was responsible for a specific type of venereal urethritis in which the incubation period was about 4 weeks with a range of 3 to 5 weeks; the symptoms were urethral itching, dysuria, and frequency of micturition, and the discharge was usually mucopurulent in character and scanty to moderate in amount (Shepard, Alexander, Lunceford, and Campbell, 1964). Support for this view was supplied by Ford and his associates. In their initial study these workers recovered T-strain mycoplasmas from 60 per cent. of 45 cases ofNGU (Ford, Rasmussen, and Minkin, 1962). Later they isolated the organism in 79 per cent. of 100 cases of NGU (Ford and Duvernet, 1963). In both studies T-strain mycoplasmas were recovered from the genito-urinary tract of normal men but significantly less frequently than from men suffering from NGU. After a comprehensive study, Csonka, Williams, and Corse (1966) were unable to support the hypothesis that T-strain mycoplasma produced a specific type of urethritis, but they did agree that this organism could be of aetiological significance in NGU. They isolated T-strain mycoplasmas from 70 per cent. of 101 cases of NGU and from 76,9 per cent. of thirteen cases of gonorrhoea in which post-gonococcal urethritis had developed, but from only 28 per cent. of fifty male cases of uncomplicated gonorrhoea, and from 12-5 per cent. of 95 normal males. They found also that T-strain mycoplasmas