Sexual behavior shapes male genitourinary microbiome composition.

The origin, composition, and significance of the distal male urethral microbiome are unclear, but vaginal microbiome dysbiosis is linked to new sex partners and several urogynecological syndromes. We characterized 110 urethral specimens from men without urethral symptoms, infections, or inflammation using shotgun metagenomics. Most urethral specimens contain characteristic lactic acid bacteria and Corynebacterium spp. In contrast, several bacteria associated with vaginal dysbiosis were present only in specimens from men who reported vaginal intercourse. Sexual behavior, but not other evaluated behavioral, demographic, or clinical variables, strongly associated with inter-specimen variance in urethral microbiome composition. Thus, the male urethra supports a simple core microbiome that is established independent of sexual exposures but can be re-shaped by vaginal sex. Overall, the results suggest that urogenital microbiology and sexual behavior are inexorably intertwined, and show that the male urethra harbors female urogenital pathobionts.

Diagnosis and Management of Uncomplicated Chlamydia trachomatis Infections in Adolescents and Adults: Summary of Evidence Reviewed for the 2021 Centers for Disease Control and Prevention Sexually Transmitted Infections Treatment Guidelines.

To prepare for the development of the 2021 Centers for Disease Control and Prevention (CDC) sexually transmitted infections treatment guidelines, the CDC convened a committee of expert consultants in June 2019 to discuss recent abstracts and published literature on the epidemiology, diagnosis, and management of sexually transmitted infections.This paper summarizes the key questions, evidence, and recommendations for the diagnosis and management of uncomplicated Chlamydia trachomatis (CT) infections in adolescents and adults that were reviewed and discussed for consideration in developing the guidelines. The evidence reviewed mostly focused on efficacy of doxycycline and azithromycin for urogenital, rectal, and oropharyngeal CT infection, CT risk factors in women, performance of CT nucleic acid amplification tests on self-collected meatal specimens in men, and performance of newer CT point-of-care tests.

Endocervical miRNA Expression Profiles in Women Positive for Chlamydia trachomatis with Clinical Signs and/or Symptoms Are Distinct from Those in Women Positive for Chlamydia trachomatis without Signs and Symptoms.

Chlamydia trachomatis is the leading cause of sexually transmitted infections that may progress to pelvic inflammatory disease and infertility. No effective vaccine exists for Chlamydia, nor are there biomarkers available that readily predict disease progression. In this cross-sectional pilot study, we recruited symptomatic and asymptomatic women with C. trachomatis (CT) infection and asymptomatic, uninfected control women from an urban sexually transmitted disease clinic to determine if there were differences in microRNA (miRNA) expression. Infected women with signs and/or symptoms (CTSS) have distinct miRNA profiles compared to asymptomatic infected women (CTNS). In the CTSS group, miR-142 and -147 showed 2.2- to 6.9-fold increases in expression. In the CTNS group, miR-449c, -6779, -519d, -449a, and -2467 showed 3.9- to 9.0-fold increases in expression. In the CTNS group, cyclins and cell cycle regulation and IL-17 pathways were likely downregulated, while the same signaling pathways were upregulated in the CTSS group. In addition, in the CTSS group, additional inflammatory pathways associated with TNFR1 and IL-8 appear to be upregulated. The miRNA expression patterns differ between CT-infected symptomatic and asymptomatic women, and these differences may warrant further study.

Aetiology and prevalence of mixed-infections and mono-infections in non-gonococcal urethritis in men: a case-control study.

OBJECTIVES: Chlamydia trachomatis (CT) and Mycoplasma genitalium (MG) cause the majority of non-gonococcal urethritis (NGU). The role of Ureaplasma urealyticum (UU) in NGU is unclear. Prior case-control studies that examined the association of UU and NGU may have been confounded by mixed infections and less stringent criteria for controls. The objective of this case-control study was to determine the prevalence and aetiology of mixed infections in men and assess if UU monoinfection is associated with NGU. METHODS: We identified 155 men with NGU and 103 controls. Behavioural and clinical information was obtained and men were tested for Neisseria gonorrhoeae and CT, MG, UU and Trichomonas vaginalis (TV). Men who were five-pathogen negative were classified as idiopathic urethritis (IU). RESULTS: Twelve per cent of NGU cases in which a pathogen was identified had mixed infections, mostly UU coinfections with MG or CT; 27% had IU. In monoinfected NGU cases, 34% had CT, 17% had MG, 11% had UU and 2% had TV. In controls, pathogens were rarely identified, except for UU, which was present in 20%. Comparing cases and controls, NGU was associated with CT and MG monoinfections and mixed infections. UU monoinfection was not associated with NGU and was almost twice as prevalent in controls. Men in both the case and control groups who were younger and who reported no prior NGU diagnosis were more likely to have UU (OR 0.97 per year of age, 95% CI 0.94 to 0.998 and OR 6.3, 95% CI 1.4 to 28.5, respectively). CONCLUSIONS: Mixed infections are common in men with NGU and most of these are UU coinfections with other pathogens that are well-established causes of NGU. UU monoinfections are not associated with NGU and are common in younger men and men who have never previously had NGU. Almost half of NGU cases are idiopathic.

Detection of Rectal Chlamydia trachomatis in Heterosexual Men Who Report Cunnilingus.

BACKGROUND: Rectal infection with Chlamydia trachomatis (CT) is frequent in women who deny receptive anal sex and is thought to arise from autoinoculation of the rectum from vaginal secretions. An alternate hypothesis is that oral sex inoculates and establishes gastrointestinal tract infection. Distinguishing these hypotheses is difficult in women. In men, autoinoculation is unlikely and heterosexual men frequently perform oral sex, but rarely participate in receptive anal exposure behaviors. METHODS: We enrolled high-risk men with and without nongonococcal urethritis who presented to a sexually transmitted infection clinic in Indianapolis, Indiana. Urine and rectal swabs were collected and tested for urogenital and rectal CT, Neisseria gonorrhoeae (NG), and Mycoplasma genitalium (MG). Men completed surveys concerning symptoms, sexual orientation, and detailed recent and lifetime oral and anal sexual behaviors. RESULTS: Rectal CT was detected in 2/84 (2.4%) heterosexual men who reported cunnilingus, but no lifetime receptive anal behaviors. All of the men who denied receptive anal behaviors were negative for rectal NG and MG. In homosexual and bisexual men, rectal CT prevalence was high (9.7%), and rectal NG (4.8%) and MG (4.8%) were also detected. CONCLUSIONS: We detected rectal CT infections in heterosexual men who reported cunnilingus but denied receptive anal behaviors. Oral sex may be a risk factor for rectal CT infection via oral inoculation of the gastrointestinal tract.

Single-Dose Zoliflodacin (ETX0914) for Treatment of Urogenital Gonorrhea.

BACKGROUND: Antibiotic-resistant Neisseria gonorrhoeae has prompted the development of new therapies. Zoliflodacin is a new antibiotic that inhibits DNA biosynthesis. In this multicenter, phase 2 trial, zoliflodacin was evaluated for the treatment of uncomplicated gonorrhea. METHODS: We randomly assigned eligible men and women who had signs or symptoms of uncomplicated urogenital gonorrhea or untreated urogenital gonorrhea or who had had sexual contact in the preceding 14 days with a person who had gonorrhea to receive a single oral dose of zoliflodacin (2 g or 3 g) or a single 500-mg intramuscular dose of ceftriaxone in a ratio of approximately 70:70:40. A test of cure occurred within 6±2 days after treatment, followed by a safety visit 31±2 days after treatment. The primary efficacy outcome measure was the proportion of urogenital microbiologic cure in the microbiologic intention-to-treat (micro-ITT) population. RESULTS: From November 2014 through December 2015, a total of 179 participants (167 men and 12 women) were enrolled. Among the 141 participants in the micro-ITT population who could be evaluated, microbiologic cure at urogenital sites was documented in 55 of 57 (96%) who received 2 g of zoliflodacin, 54 of 56 (96%) who received 3 g of zoliflodacin, and 28 of 28 (100%) who received ceftriaxone. All rectal infections were cured in all 5 participants who received 2 g of zoliflodacin and all 7 who received 3 g, and in all 3 participants in the group that received ceftriaxone. Pharyngeal infections were cured in 4 of 8 participants (50%), 9 of 11 participants (82%), and 4 of 4 participants (100%) in the groups that received 2 g of zoliflodacin, 3 g of zoliflodacin, and ceftriaxone, respectively. A total of 84 adverse events were reported: 24 in the group that received 2 g of zoliflodacin, 37 in the group that received 3 g of zoliflodacin, and 23 in the group that received ceftriaxone. According to investigators, a total of 21 adverse events were thought to be related to zoliflodacin, and most such events were gastrointestinal. CONCLUSIONS: The majority of uncomplicated urogenital and rectal gonococcal infections were successfully treated with oral zoliflodacin, but this agent was less efficacious in the treatment of pharyngeal infections. (Funded by the National Institutes of Health and Entasis Therapeutics; ClinicalTrials.gov number, NCT02257918 .).

Gepotidacin for the Treatment of Uncomplicated Urogenital Gonorrhea: A Phase 2, Randomized, Dose-Ranging, Single-Oral Dose Evaluation.

Background: In this phase 2 study, we evaluated the efficacy and safety of oral gepotidacin, a novel triazaacenaphthylene bacterial type II topoisomerase inhibitor, for the treatment of uncomplicated urogenital gonorrhea. Methods: Adult participants with suspected urogenital gonorrhea were enrolled and completed baseline (day 1) and test-of-cure (days 4-8) visits. Pretreatment and posttreatment urogenital swabs were collected for Neisseria gonorrhoeae (NG) culture and susceptibility testing. Pharyngeal and rectal swab specimens were collected if there were known exposures. Participants were stratified by gender and randomized 1:1 to receive a 1500-mg or 3000-mg single oral dose of gepotidacin. Results: The microbiologically evaluable population consisted of 69 participants, with NG isolated from 69 (100%) urogenital, 2 (3%) pharyngeal, and 3 (4%) rectal specimens. Microbiological eradication of NG was achieved by 97%, 95%, and 96% of participants (lower 1-sided exact 95% confidence interval bound, 85.1%, 84.7%, and 89.1%, respectively) for the 1500-mg, 3000-mg, and combined dose groups, respectively. Microbiological cure was achieved in 66/69 (96%) urogenital infections. All 3 failures were NG isolates that demonstrated the highest observed gepotidacin minimum inhibitory concentration of 1 µg/mL and a common gene mutation. At the pharyngeal and rectal sites, 1/2 and 3/3 NG isolates, respectively, demonstrated microbiological cure. There were no treatment-limiting adverse events for either dose. Conclusions: This study demonstrated that single, oral doses of gepotidacin were ≥95% effective for bacterial eradication of NG in adult participants with uncomplicated urogenital gonorrhea. Clinical Trials Registration: NCT02294682.

Neisseria meningitidis ST11 Complex Isolates Associated with Nongonococcal Urethritis, Indiana, USA, 2015-2016.

At a clinic in Indianapolis, Indiana, USA, we observed an increase in Neisseria gonorrhoeae-negative men with suspected gonococcal urethritis who had urethral cultures positive for N. meningitidis. We describe genomes of 2 of these N. meningitidis sequence type 11 complex urethritis isolates. Clinical evidence suggests these isolates may represent an emerging urethrotropic clade.

Genotype-Specific Concordance of Chlamydia trachomatis Genital Infection Within Heterosexual Partnerships.

BACKGROUND: Sexual transmission rates of Chlamydia trachomatis (Ct) cannot be measured directly; however, the study of concordance of Ct infection in sexual partnerships (dyads) can help to illuminate factors influencing Ct transmission. METHODS: Heterosexual men and women with Ct infection and their sex partners were enrolled and partner-specific coital and behavioral data collected for the prior 30 days. Microbiological data included Ct culture, and nucleic acid amplification testing (NAAT), quantitative Ct polymerase chain reaction, and ompA genotyping. We measured Ct concordance in dyads and factors (correlates) associated with concordance. RESULTS: One hundred twenty-one women and 125 men formed 128 dyads. Overall, 72.9% of male partners of NAAT-positive women and 68.6% of female partners of NAAT-positive men were Ct-infected. Concordance was more common in dyads with culture-positive members (78.6% of male partners, 77% of female partners). Partners of women and men who were NAAT-positive only had lower concordance (33.3%, 46.4%, respectively). Women in concordant dyads had significantly higher median endocervical quantitative Ct polymerase chain reaction values (3,032) compared with CT-infected women in discordant dyads (1013 inclusion forming units DNA equivalents per mL; P < 0.01). Among 54 Ct-concordant dyads with ompA genotype data for both members, 96.2% had identical genotypes. CONCLUSIONS: Higher organism load appears associated with concordance among women. Same-genotype chlamydial concordance was high in sexual partnerships. No behavioral factors were sufficiently discriminating to guide partner services activities. Findings may help model coitus-specific transmission probabilities.

Novel Chlamydia trachomatis strains in heterosexual sex partners, Indianapolis, Indiana, USA.

Chlamydia trachomatis causes a high number of sexually transmitted infections worldwide, but reproducible and precise strain typing to link partners is lacking. We evaluated multilocus sequence typing (MLST) for this purpose by detecting sequence types (STs) concordant for the ompA genotype, a single-locus typing standard. We tested samples collected during April 2000-October 2003 from members of established heterosexual partnerships (dyads) in the Indianapolis, Indiana, USA, area who self-reported being coital partners within the previous 30 days. C. trachomatis DNA from 28 dyads was tested by MLST; sequences were aligned and analyzed for ST and phylogenetic relationships. MLST detected 9 C. trachomatis STs, 4 unique to Indianapolis; STs were identical within each dyad. Thirteen unique strains were identified; 9 (32%) dyads harbored novel recombinant strains that phylogenetically clustered with strains comprising the recombinants. The high rate of novel C. trachomatis recombinants identified supports the use of MLST for transmission and strain diversity studies among at-risk populations.

Randomized, double-blind, multicenter safety and efficacy study of rifalazil compared with azithromycin for treatment of uncomplicated genital Chlamydia trachomatis infection in women.

A randomized, double-blind study comparing single-dose chlamydia therapies of oral rifalazil (25 mg) and azithromycin (1 g) was conducted in 82 women with uncomplicated genital Chlamydia trachomatis infection. The microbiologic cure rate of C. trachomatis with rifalazil (n = 33) was 84.8% at the visit on day 22 to 26 (test-of-cure visit), versus 92.1% with azithromycin (n = 38), and the number of treatment failures in each group was 5 and 3, respectively. The difference in cure rate was -7.3%, with a lower limit of the 95% confidence interval (95% CI) of -22.5, and thus, noninferiority was not established at the prespecified margin (lower limit of CI of -15%). The overall treatment-emergent adverse event (TEAE) and treatment-related TEAE rates were lower in the rifalazil group (68% and 55%) than in the azithromycin group (71% and 62%), respectively. Subjects classified as treatment failures at day 22 to 26 had a lower mean plasma concentration of rifalazil at the visit on day 8 to 12 than those classified as treatment cures, but this difference was not significant; however, the levels were similar for both groups at the visit on day 22 to 26. A single 25-mg dose of rifalazil was well tolerated and eradicated C. trachomatis in most of these women with uncomplicated genital C. trachomatis infection. (The study was registered at clinicaltrials.gov under registration no. NCT01631201).

Duration of polymerase chain reaction-detectable DNA after treatment of Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis infections in women.

BACKGROUND: To avoid positive results attributable to residual DNA, the Centers for Disease Control and Prevention recommends avoiding repeat testing with nucleic-acid based tests within 3 weeks after treatment of chlamydial (Chlamydia trachomatis [CT]) or gonococcal (Neisseria gonorrhoeae [GC]) infection. We retrospectively analyzed the duration of detectable DNA from a longitudinal cohort of adolescent women after diagnosis and treatment of infection with CT, GC, or Trichomonas vaginalis (TV). METHODS: Vaginal swabs were obtained weekly from young women for up to 12 weeks (observation period) after treatment of CT, GC and TV infections. Swabs were tested using a commercially available first generation nucleic acid amplification test (NAAT) for CT and GC, and a laboratory developed NAAT for TV. Kaplan-Meier statistics were used to estimate median time to the first negative DNA-based polymerase chain reaction (PCR) result. RESULTS: Observation periods were available for analysis for 195, 82 and 102 treatments for CT, GC, and TV infection, respectively. Median time to a first negative PCR result for CT, GC, and TV was 9 (range 0-84), 6 (0-76), and 7 (0-84) days, and by day 21, 89%, 95%, and 85% were negative, respectively. CONCLUSIONS: Data from this retrospective analysis indicate that greater than 85% of these young women did not have detectable CT, GC, or TV DNA by day 21 post-treatment. This data may be useful to clinicians for patient management and post-treatment testing purposes.

Safety and efficacy of WC2031 versus vibramycin for the treatment of uncomplicated urogenital Chlamydia trachomatis infection: a randomized, double-blind, double-dummy, active-controlled, multicenter trial.

BACKGROUND: Recent studies have raised concern about efficacy of azithromycin for Chlamydia trachomatis infection. Research investigating new antibiotic regimens for chlamydia has been sparse, especially regimens that may reduce adherence difficulties with the recommended twice-daily doxycycline regimen. METHODS: We conducted a randomized, double-blind, double-dummy, active-controlled, multicenter trial with the objective of evaluating the safety and efficacy of WC2031 (doxycycline hyclate delayed-release 200-mg tablet) orally once daily for 7 days versus Vibramycin (doxycycline hyclate capsule) 100 mg orally twice daily for 7 days for treatment of uncomplicated urogenital chlamydia. Men and nonpregnant women aged 19-45 years with a urogenital chlamydial diagnosis or a sexual partner with chlamydia were eligible. The primary outcome was microbial cure by nucleic acid amplification testing at day 28. Noninferiority of WC2031 was inferred if the lower limit of the 95% confidence interval (CI) of the difference in cure rates was >-10%. RESULTS: A total of 495 subjects were randomized. The modified intent-to-treat (mITT) population with evaluable efficacy consisted of 323 subjects. Baseline patient characteristics did not differ between the mITT groups. Microbial cure rates for WC2031 were 95.5% (95% CI, 92.3-98.8) versus 95.2% (95% CI, 92.0-98.4) for Vibramycin (95% CI for the difference in cure rates, -4.3% to 4.9%). Types of adverse events were comparable. Nausea and vomiting occurred less frequently with WC2031 than with Vibramycin (13% vs 21% and 8% vs 12%, respectively). CONCLUSIONS: WC2031 was noninferior to Vibramycin for uncomplicated urogenital chlamydia treatment, better tolerated, and demonstrated comparable safety. WC2031 could improve treatment adherence over twice-daily Vibramycin. CLINICAL TRIALS REGISTRATION: NCT01113931.

Protective immunity to Chlamydia trachomatis genital infection: evidence from human studies.

Background. Some screening and treatment programs implemented to control Chlamydia trachomatis genital infections and their complications have shown initial reductions in infection prevalence, followed by increases to preprogram levels or higher. One hypothesis is that treatment shortens duration of infection, attenuates development of protective immunity, and thereby, increases risk of reinfection. Methods. A literature review was undertaken to assess evidence supporting the concept of protective immunity,its characteristics, and its laboratory correlates in human chlamydial infection. The discussion is organized around key questions formulated in preparation for the Chlamydia Immunology and Control Expert Advisory Meeting held by the Centers for Disease Control and Prevention in April 2008. Results. Definitive human studies are not available, but cross-sectional studies show that chlamydia prevalence,organism load, and concordance rates in couples decrease with age, and organism load is lower in those with repeat infections, supporting the concept of protective immunity. The protection appears partial and can be overcome after reexposure, similar to what has been found in rodent models of genital infection. No data are available to define the duration of infection required to confer a degree of immunity or the time course of immunity after resolution of untreated infection. In longitudinal studies involving African sex workers, a group presumed to have frequent and ongoing exposure to chlamydial infection, interferon-g production by peripheral blood mononuclear cells in response to chlamydial heat-shock protein 60 was associated with low risk of incident infection.In cross-sectional studies, relevant T helper 1-type responses were found in infected persons, paralleling the studies in animal models. Conclusions. The data support the concept that some degree of protective immunity against reinfection develops after human genital infection, although it appears, at best, to be partial. It is likely that factors besides population levels of immunity contribute to trends in prevalence observed in screening and treatment programs.Future studies of protective immunity in humans will require longitudinal follow-up of individuals and populations,frequent biological and behavioral sampling, and special cohorts to help control for exposure.

Repeated Chlamydia trachomatis genital infections in adolescent women.

BACKGROUND: Repeated Chlamydia trachomatis infections are common among young sexually active women. The relative frequency of reinfection and antibiotic treatment failure is undefined. METHODS: Adolescent women enrolled in a longitudinal cohort had behavioral and sexually transmitted infection assessments performed every 3 months, including amplification tests for C. trachomatis, ompA genotyping, and interviews and diary entries to document sex partner-specific coitus and event-specific condom use. Repeated infections were classified as reinfection or treatment failure by use of an algorithm. All infections for which treatment outcomes were known were used to estimate the effectiveness of antibiotic use. RESULTS: We observed 478 episodes of infection among 210 study participants; 176 women remained uninfected. The incidence rate was 34 episodes/100 woman-years. Of the women who were infected, 121 experienced 1 repeated infections, forming 268 episode pairs; 183 pairs had complete data available and were classified using the algorithm. Of the repeated infections, 84.2% were definite, probable, or possible reinfections; 13.7% were probable or possible treatment failures; and 2.2% persisted without documented treatment. For 318 evaluable infections, we estimated 92.2% effectiveness of antibiotic use. CONCLUSIONS: Most repeated chlamydial infections in this high-incidence cohort were reinfections, but repeated infections resulting from treatment failures occurred as well. Our results have implications for male screening and partner notification programs and suggest the need for improved antibiotic therapies.

Time from first intercourse to first sexually transmitted infection diagnosis among adolescent women.

OBJECTIVE: To determine the time between first intercourse and first sexually transmitted infection (STI) with Chlamydia trachomatis, Neisseria gonorrhoeae, or Trichomonas vaginalis and time between repeated infections. DESIGN: Observational study. SETTING: Three adolescent medicine clinics. PARTICIPANTS: A cohort of 386 urban young women aged 14 to 17 years at enrollment. MAIN OUTCOME MEASURES: Age at first intercourse; organism-specific interval between first intercourse and first STI diagnosis; interval between repeated infections; and age at first STI test prior to study participation. RESULTS: Participants had first intercourse at a young age (first, second, and third quartiles were 13, 14, and 15 years of age, respectively). By age 15 years, 25% of the women acquired their first STI, most often C trachomatis. Median interval between first intercourse and first STI diagnosis was 2 years. Within 1 year of first intercourse, 25% had their first C trachomatis infection. Repeated infections were common; within 3.6, 6, and 4.8 months, 25% of the women with prior C trachomatis, N gonorrhoeae, and T vaginalis infection were reinfected with the respective organisms. Considerable delay in STI testing was found for those who began sex at a younger age. The median interval between first sex and first test were 4.9, 3.5, 2.1, 1.8, and 1.2 years for those who had first sex at ages 10, 11, 12, 13, and 14 years, respectively. CONCLUSIONS: Timely screening and treatment are important for prevention of STI sequelae. For urban adolescent women, STI screening (especially for C trachomatis) should begin within a year after first intercourse and infected individuals should be retested every 3 to 4 months.

Depressive symptoms and sexual risk behavior in young, chlamydia-infected, heterosexual dyads.

PURPOSE: To examine associations between depressive symptoms and dyad-level sexual risk behavior in young heterosexual dyads with sexually transmitted infection (STI). METHODS: Chlamydia-positive 14-24-year-old, heterosexually active outpatients and their opposite-sex partners completed an assessment that included demographics, past and recent STI risk behaviors, and the Beck Depression Inventory (BDI). Participants in the top 25% of BDI scores within gender were categorized as depressed. Variables were created to identify dyads in which the female or male partner was depressed, as well as a measure of concordance of depression between partners. Dyad-level STI risk variables were created from the STI risk characteristics reported by each dyad member, and associations between these and the depression variables were analyzed. RESULTS: The 130 dyads were comprised of young men and women at high STI risk. One-third of dyads had at least one depressed partner. Dyads in which the female partner was depressed had greater partner age difference, greater total number of lifetime partners, and one or more partners reporting substance use within 2 hours before sex, compared with dyads in which the female partner was not depressed. Dyads in which the male partner was depressed were more likely than the nondepressed-male dyads to report substance use before sex. All dyads in which both partners were depressed reported substance use before sex. CONCLUSIONS: In young, chlamydia-infected, heterosexual dyads, depressive symptoms, especially in women, is related to increased dyad-level STI risk, including greater partner age difference, more partners, and substance use before sex.

Mycoplasma genitalium among adolescent women and their partners.

PURPOSE: Mycoplasma genitalium is a possible sexually transmitted pathogen and its study among the adolescent age group has been limited. In this longitudinal study, the epidemiology, natural history, and associated clinical findings of M. genitalium among adolescents in a primary care setting were explored. METHODS: A sample of 383 young women (14-17 years of age) and 117 male partners provided sexual behavior data and urogenital samples for polymerase chain reaction testing to detect M. genitalium, Chlamydia trachomatis, and other sexually transmitted infections. Women were tested quarterly for up to 27 months and, during every other quarter, tested weekly. The presence of any signs or symptoms of infection among the female subjects was also documented. RESULTS: Cumulatively, 13.6% (52/383) of women tested positive for M. genitalium. All women with M. genitalium, except one, were sexually experienced. M. genitalium was associated with number of sexual partners (p < .001) and C. trachomatis infection (p < .03). M. genitalium was more likely among male partners of M. genitalium-positive women (p < .02); 31.3% of untreated M. genitalium cases had infection lasting over 8 weeks. M. genitalium was not associated with the presence of clinical signs or symptoms of infection. CONCLUSIONS: Findings support sexual transmissibility of M. genitalium and add to understanding of M. genitalium natural history and clinical findings.