Comparison of Transcription-Mediated Amplification and PCR Assay Results for Various Genital Specimen Types for Detection of Mycoplasma genitalium

Abstract

Mycoplasma genitalium is now recognized as a possible cause of several idiopathic sexually transmitted disease (STD) syndromes. However, due to the difficulty of culture of this fastidious bacterium, nucleic acid amplification tests (NAATs) are necessary for its detection in patient specimens. In the current study we compared a newly developed research-only transcription-mediated amplification (TMA) assay (Gen-Probe Incorporated) to our in-house DNA-based PCR assay for detection of M. genitalium. The relative performance characteristics of these two NAATs were assessed with genital specimens from 284 women and 352 men reporting to an STD clinic in Seattle, WA. Among the women, M. genitalium was detected by the TMA and PCR assays in 36 (13%) and 39 (14%) vaginal swab specimens, respectively ( ‫؍‬ 0.923); 26 (9%) and 23 (8%) cervical swab specimens, respectively ( ‫؍‬ 0.843); and 25 (9%) and 28 (10%) urine specimens, respectively ( ‫؍‬ 0.687). Among the M. genitalium-positive women, the relative sensitivities of detection for the TMA and PCR assays were 84% and 91%, respectively, for vaginal swab specimens; 60% and 53%, respectively, for cervical swab specimens; and 58% and 65%, respectively, for urine specimens. By using an infected patient (a woman positive at any site by TMA assay and at any site by PCR) as a proxy for a "gold standard," the specificities of detection were >99.5% for both the TMA and the PCR assays. Among the men, M. genitalium was detected in 24 urine specimens (6.8%) by the TMA assay, 26 (7.4%) urine specimens by PCR assay, and 32 urine specimens (9%) by either test ( ‫؍‬ 0.791). We conclude that the M. genitalium TMA and PCR assays are highly specific and that vaginal swab specimens are the most sensitive specimen type for the detection of M. genitalium in women.Mycoplasma genitalium was first isolated from urethral exudates from two men with urethritis in 1981 (38), yet the isolation and culture of this fastidious organism are extremely difficult and time-consuming. Although culture techniques for M. genitalium have improved in the last two decades (20), efficient isolation and cultivation of this organism remain elusive (2,20), and thus, identification of infected individuals has relied on the use of PCR tests (16,36). The application of M. genitalium-specific PCR tests has allowed studies that assess reproductive tract disease in men and women, including urethritis, cervicitis, endometritis, and pelvic inflammatory disease (7,14,16,19,25,27,36,37), suggesting a disease spectrum similar to those caused by Chlamydia trachomatis and Neisseria gonorrhoeae. Detection of DNA from this organism by PCR in fallopian tube tissue from a woman with salpingitis (8) and the association of M. genitalium with tubal factor infertility by serologic tests (6) suggest an even broader range of disease associations and sequelae for this emerging pathogen. These results are particularly disconcerting, considering that M. genitalium has been detected in 1% of young adults in the U.S. general population, a preval...

Utility of Urine, Vaginal, Cervical, and Rectal Specimens for Detection of Mycoplasma genitalium in Women

“…Thus, we are able to determine only a relative sensitivity within the context of our own assay rather than absolute sensitivity and specificity. However, our results are very similar to those of Wroblewski et al, who determined relative sensitivities of vaginal, endocervical, and urine specimens not only by their laboratory's PCR assay but also by the Gen-Probe research-only transcription-mediated amplification assay (13). The implications of these findings are several.…”

“…Our study is the first to compare the utility of urine, cervical, vaginal, and rectal specimens for the detection of M. genitalium by NAATs in women, although one published study has compared vaginal, cervical, and urine specimens (13) and another has compared cervical and urine specimens for M. genitalium detection (6).…”

Clinical Laboratory Assessment of Mycoplasma genitalium Transcription-Mediated Amplification Using Primary Female Urogenital Specimens

“…In the realm of laboratory diagnosis, initial studies of target capture-based transcription-mediated amplification (TMA) in females reported 87.8% (14) We recently demonstrated the utility of TMA-based M. genitalium detection in male specimens originating from both STI and community outpatient clinics (16). In contrast, previous studies of M. genitalium TMA in females have largely focused on high-risk demographics (14,15,(17)(18)(19). Assessment of M. genitalium detection rates in a communitywide setting would be beneficial.…”

Mycoplasma genitalium Infection Prevalence in Patients with Human Immunodeficiency Virus

“…Currently, examination by PCR is the method of choice for the detection of M. genitalium and the most published target genes are major adhesin MgPa genes or 16S rRNA gene. 1,9,16 The most sensitive clinical samples for testing M. genitalium in females when PCR is used, according to the study performed by Wroblewski et al, 17 is from the vaginal swab (91%) compared to the cervical smear (53%) and urine (65%). However, the vaginal smear examination has not been approved by the Food and Drug Administration.…”