Objective Although Chlamydia trachomatis (CT) and Mycoplasma genitalium (MG) are major causes of non-gonococcal urethritis (NGU), up to 50% of cases are of unknown aetiology. We sought to identify urethral exposures at last sexual episode associated with NGU and non-CT/non-MG NGU to identify anatomical sites from which aetiologically relevant micro-organisms may be acquired.
Methods We enrolled STD clinic patients with and without NGU assigned male sex at birth and age ≥16 into a cross-sectional study. NGU was urethral symptoms or visible discharge plus ≥5 polymorphonuclear leucocytes without Neisseria gonorrhoeae. Urine was tested for CT and MG (Aptima). We used logistic regression to estimate the association between urethral exposures at last sex and NGU separately among cisgender men and transgender women who have sex with men (MSM/TGWSM) and cisgender men who have sex with women (MSW).
Results Between 8 August 2014 and 1 November 2017, we enrolled 432 patients, including 183 MSM/TGWSM (118 NGU+, 65 NGU−) and 249 MSW (126 NGU+, 123 NGU−). The mean age was 34; 59% were white. CT and MG were detected in 72 (30%) and 49 (20%) NGU+ participants, respectively. Compared with MSM/TGWSM reporting only non-urethral exposures at last sex, those reporting insertive anal intercourse (IAI) only (adjusted OR (AOR)=4.46, 95% CI 1.09 to 18.19) and IAI with insertive oral sex (IOS) (AOR=7.88, 95% CI 2.67 to 23.26) had higher odds of NGU. MSM/TGWSM reporting IOS only had no significant increased odds (AOR=1.67, 95% CI 0.58 to 4.85). Compared with MSW whose only urethral exposure at last sex was vaginal sex (VS), MSW reporting IOS and VS had similar odds of NGU (OR=0.84, 95% CI 0.50 to 1.41). The results were similar for non-CT/non-MG NGU.
Conclusions Among MSM/TGWSM, IAI may lead to transmission of yet-unidentified rectal micro-organisms that cause non-CT/non-MG NGU, in addition to transmission of known pathogens. Sites of urethral exposure appear less important for understanding NGU risk among MSW due to minimal variation in behaviour.
- sexual behavior
- chlamydia trachomatis
- mycoplasma genitalium
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Handling editor Professor Jackie A Cassell
Presented at This work was presented in part at the 2016 US Centers for Disease Control and Prevention STD Prevention Conference, Atlanta, Georgia, 20–23 September 2016.
Contributors Authors contributed to the manuscript (MS) in the following manner. MS concept: LCC, LEM. Data collection: LCC, JLM, SML, TSR, SSR, GLL. Data analysis and interpretation: LCC, JPH, MRG, CMK, DNF, LEM. Drafting of the MS: LCC. Critical revision of the MS: LCC, JLM, SML, TSR, SSR, GLL, JPH, MRG, CMK, DNF, LEM.
Funding This study was funded by http://dx.doi.org/10.13039/100000060 the National Institute of Allergy and Infectious Diseases (Grant Number: 1 R01 AI110666-011 U19 AI113173-01), and http://dx.doi.org/10.13039/100006108 the National Center for Advancing Translational Sciences (Grant Number: TL1 TR002318UL1 TR002319).
Competing interests CMK and LEM have received donations of test kits and reagents from Hologic. All other authors declare that they have no conflict of interest.
Patient consent Not required.
Ethics approval This study was approved by the University of Washington Human Subjects Division, IRB Committee J (STUDY00002016).
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement This study is nested within a larger project. Data will be made available to other investigators after the completion of the project and publication of additional key results.
Author note This work was performed while TSR was at UW; she is currently in the Public Health Associate Program of the Centers for Disease Control and Prevention at the Office for State, Tribal, Local, and Territorial Support in Shoreline, Washington.
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