During 2016–2017, we tested asymptomatic men who have sex with men (MSM) in Melbourne, Australia, for Mycoplasma genitalium and macrolide resistance mutations in urine and anorectal swab specimens by using PCR. We compared M. genitalium detection rates for those asymptomatic men to those for MSM with proctitis and nongonococcal urethritis (NGU) over the same period. Of 1,001 asymptomatic MSM, 95 had M. genitalium; 84.2% were macrolide resistant, and 17% were co-infected with Neisseria gonorrhoeae or Chlamydia trachomatis. Rectal positivity for M. genitalium was 7.0% and urine positivity was 2.7%. M. genitalium was not more commonly detected in the rectums of MSM (n = 355, 5.6%) with symptoms of proctitis over the same period but was more commonly detected in MSM (n = 1,019, 8.1%) with NGU. M. genitalium is common and predominantly macrolide-resistant in asymptomatic MSM. M. genitalium is not associated with proctitis in this population.

Mycoplasma genitalium is a significant pathogen for which first-line treatment is becoming less effective due to increased resistance to macrolides. As conventional culture and antimicrobial susceptibility testing is not feasible for routine detection of this pathogen, molecular markers such as detection of mutations in the 23S rRNA gene have been described to predict resistance. Recently, a novel multiplex quantitative PCR (qPCR) assay, ResistancePlus MG, has been described for the simultaneous detection of Mycoplasma genitalium and macrolide resistance. In the current study, the clinical performance of the assay was evaluated on 1,089 consecutive urine and anogenital swab samples in symptomatic and asymptomatic male and female patients. Overall, 6.0% were positive for M. genitalium, with 63.1% having macrolide resistance-associated mutations. Compared to the laboratory-validated qPCR method targeting the 16S rRNA gene and Sanger sequencing to determine 23S rRNA mutations, the sensitivity and specificity of M. genitalium detection were 98.5% and 100% and for detection of macrolide resistance mutations were 100.0% and 96.2%, respectively. This assay offers a considerable advantage in clinical settings for M. genitalium testing by making the results of macrolide resistance and mutation analyses simultaneously available, which is increasingly important with escalating macrolide resistance.

High levels of macrolide resistance and increasing fluoroquinolone resistance are found in Mycoplasma genitalium in many countries. We evaluated pristinamycin for macrolide-resistant M. genitalium in a sexual health center in Australia. Microbiologic cure was determined by M. genitalium–specific 16S PCR 14–90 days after treatment began. Of 114 persons treated with pristinamycin, infection was cured in 85 (75%). This percentage did not change when pristinamycin was given at daily doses of 2 g or 4 g or at 3 g combined with 200 mg doxycycline. In infections with higher pretreatment bacterial load, treatment was twice as likely to fail for each 1 log10 increase in bacterial load. Gastrointestinal side effects occurred in 7% of patients. Pristinamycin at maximum oral dose, or combined with doxycycline, cured 75% of macrolide-resistant M. genitalium infections. Pristinamycin is well-tolerated and remains an option where fluoroquinolones have failed or cannot be used.

fThe detection of Mycoplasma genitalium was evaluated on 1,080 urine samples by the use of a Panther instrument. Overall sensitivity, specificity, positive predictive values, and negative predictive values were 100%, 99.4%, 93.6%, and 100%, respectively. Detection of M. genitalium by the use of the Panther transcription-mediated amplification assay offers a simple, accurate, and sensitive platform for diagnostic laboratories. Mycoplasma genitalium is a common cause of nongonococcal urethritis (NGU) in men and currently accounts for 10% to 35% of NGU cases globally (1, 2). In women, it has been associated with cervicitis, pelvic inflammatory disease, and infertility (1,(3)(4)(5)(6)(7) and studies have also suggested that it plays an important role in HIV acquisition and transmission (8, 9). The exact rates of M. genitalium prevalence have been reported in a limited number of studies, with prevalences of 0.8% to 2.3% among young women and 1.1% to 6.9% among young men (10)(11)(12)(13)(14).As this organism is highly fastidious and slow growing, culture is not feasible for diagnosis and is performed in only a small number of laboratories worldwide for research purposes. Diagnosis relies on nucleic acid amplification tests (NAAT); however, as there have been limited commercial assays available, most laboratories have utilized in-house NAATs, utilizing quantitative PCR (qPCR) assays with various targets (15-21). For some time, a research-use-only transcription-mediated amplification assay for detection of M. genitalium (MG-TMA) has been available from Hologic (Bedford, MA, USA) for use on either the manual or automated TIGRIS DTS system; however, this has recently been introduced onto the Panther platform utilizing the open-channel software feature, with the manufacturer package insert indicating a sensitivity of 0.01 CFU/ml (equivalent to 0.004 copies per reaction). The assay has received the CE mark for in vitro diagnosis (CE-IVD) in Europe and is becoming accredited through other regulatory bodies for utilization in diagnostic laboratories. In this study, we evaluated the performance of the MG-TMA on the Panther platform for the detection of M. genitalium 16S rRNA by comparison to three assays: an alternative 16S rRNA target assay (Alt-TMA) available on Panther and two previously described PCR assays, one targeting a 78-bp region of the M. genitalium adhesion (MgPa) gene with sensitivity of five copies per reaction (18) and the other targeting a 517-bp region of the 16S rRNA gene with sensitivity of 10 copies per reaction (21). To our knowledge, this is the first clinical evaluation of the Panther assay for detection of M. genitalium.From February to May 2015, consecutive urine samples received for M. genitalium testing were utilized for this evaluation. Ethical approval for this study was granted by the Royal Women's Hospital Research and Ethics Committees. The patient population included 664 men and women attending Melbourne Sexual Health Centre for management of NGU or sexual contacts of infected partners, 309 co...