ABSTRACT
There is limited information in the medical setting on antimicrobial susceptibilities and resistance development in ureaplasmas. The study investigated tetracycline and doxycycline resistance in clinical isolates of Ureaplasma parvum and Ureaplasma urealyticum. Culture with species PCR confirmatory techniques were applied to 191 endocervical specimens collected during the period January-March 2006. MIC determinations were performed by microbroth dilution with tetM resistance and int-Tn genes characterised employing PCR and sequencing. Sixty-six Ureaplasma cultures (35 U. parvum; 9 U. urealyticum; 22 U. parvum + U. urealyticum) were obtained. On screening the Ureaplasma cultures; tetM gene regions were demonstrated from both tetracycline-susceptible and -resistant ureaplasmas. Seven isolates [U. parvum (6); U. urealyticum (1)] were resistant to tetracycline with dual doxycycline resistance observed in three strains. Int-Tn gene characterisation of the seven tetracycline-resistant strains revealed three types were present indicating transposons from different origins had integrated into Ureaplasma genomes. TetM sequences of five tetracycline-resistant strains were seen to be highly mosaic in structure. The finding of transposon and/or tetM regions in all Ureaplasma cultures investigated with or without full expression of tetracycline resistance; in conjunction with tetM and int-Tn gene mosaic/diversity; verifies that ureaplasmas undergo extensive genetic exchange of transposon/resistance genes with concomitant genomic remodelling