TetM tetracycline-resistant determinants in Ureaplasma urealyticum

Ureaplasma urealyticum is an organism usually considered susceptible to tetracycline, with a minimal inhibitory concentration of 1 microgram/ml or less. Sixty-three clinical strains of U. urealyticum and serovars 1 through 9 were screened for resistance to tetracycline. Thirteen clinical isolates of U. urealyticum and one serovar (9) were resistant to high levels of tetracycline. They differed from each other on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels and immunoblotting. All 14 strains contained DNA sequences homologous to the streptococcal determinant tetM which suggests the spread of this gene to the genus Ureaplasma.