These guidelines for the treatment of persons who have or are at risk for sexually transmitted infections (STIs) were updated by CDC after consultation with professionals knowledgeable in the field of STIs who met in Atlanta, Georgia, June 11-14, 2019. The information in this report updates the 2015 guidelines. These guidelines discuss 1) updated recommendations for treatment of Neisseria gonorrhoeae, Chlamydia trachomatis, and Trichomonas vaginalis; 2) addition of metronidazole to the recommended treatment regimen for pelvic inflammatory disease; 3) alternative treatment options for bacterial vaginosis; 4) management of Mycoplasma genitalium; 5) human papillomavirus vaccine recommendations and counseling messages; 6) expanded risk factors for syphilis testing among pregnant women; 7) one-time testing for hepatitis C infection; 8) evaluation of men who have sex with men after sexual assault; and 9) two-step testing for serologic diagnosis of genital herpes simplex virus. Physicians and other health care providers can use these guidelines to assist in prevention and treatment of STIs. BOX 1. The Five P's approach for health care providers obtaining sexual histories: partners, practices, protection from sexually transmitted infections, past history of sexually transmitted infections, and pregnancy intention Additional information about external condoms is available at https://www.cdc.gov/condomeffectiveness. Internal CondomsCondoms for internal vaginal use, also known as female condoms, are available worldwide (e.g., the FC2 Female Condom, Reddy condom, Cupid female condom, and Woman's condom) (31,32). Use of internal condoms can provide protection from acquisition and transmission of STIs, although data are limited. Internal condoms are more costly compared with external condoms; however, they offer the advantage of being controlled by the receptive partner as an STI and HIV prevention method, and the newer versions might be acceptable to all persons. Although the internal condom also has been used during receptive anal intercourse, efficacy associated with this practice remains unknown (33). Additional information about the internal condom is available at http://www.ashasexualhealth. org/pdfs/Male_and_Female_Condoms.pdf. Cervical DiaphragmsIn observational studies, diaphragm use has been demonstrated to protect against cervical gonorrhea, chlamydia, and trichomoniasis (34). However, a trial examining the effect of a diaphragm plus lubricant on HIV acquisition among women in Africa reported no additional protective effect when compared with the use of male condoms alone. Likewise, no difference by study arm in the rate of acquisition of chlamydia, gonorrhea, or herpes occurred (35,36). Diaphragms should not be relied on as the sole source of protection against HIV and other STIs.

Bacterial vaginosis (BV) is the most common cause of vaginal discharge. It is associated with an increased risk of preterm delivery, pelvic inflammatory disease, and an increased risk of acquisition of sexually transmitted infections including human immunodeficiency virus (HIV). The epidemiology of BV supports sexual transmission. However, its etiology remains unknown. At the center of the debate is whether BV is caused by a primary pathogen or a polymicrobial consortium of microorganisms that are sexually transmitted. We previously published a conceptual model hypothesizing that BV is initiated by sexual transmission of Gardnerella vaginalis. Critics of this model have iterated that G. vaginalis is found in virginal women and in sexually active women with a normal vaginal microbiota. In addition, colonization does not always lead to BV. However, recent advances in BV pathogenesis research have determined the existence of 13 different species within the genus Gardnerella. It may be that healthy women are colonized by nonpathogenic Gardnerella species, whereas virulent strains are involved in BV development. Based on our results from a recent prospective study, in addition to an extensive literature review, we present an updated conceptual model for the pathogenesis of BV that centers on the roles of virulent strains of G. vaginalis, as well as Prevotella bivia and Atopobium vaginae.

Purpose of Review-The etiology of BV, the most common cause of vaginal discharge in women, remains controversial. We recently published an updated conceptual model on BV pathogenesis, focusing on the roles of G. vaginalis and Prevotella bivia as early colonizers and Atopobium vaginae and other BVAB as secondary colonizers in this infection. In this paper, we extend the description of our model to include a discussion on the role of host-vaginal microbiota interactions in BV pathogenesis.Recent Findings-Although G. vaginalis and P. bivia are highly abundant in women with BV, neither induce a robust inflammatory response from vaginal epithelial cells. These early colonizers may be evading the immune system while establishing the BV biofilm. Secondary colonizers, including A. vaginae, Sneathia spp., and potentially other BVAB are more potent stimulators of the host immune response to BV and likely contribute to its signs and symptoms as well as its adverse outcomes.Summary-Elucidating the etiology of BV has important implications for diagnosis and treatment. Our current BV pathogenesis model provides a framework for key elements that should be considered when designing and testing novel BV diagnostics and therapeutics.

Despite reportedly high rates of human immunodeficiency virus (HIV) and other sexually transmitted infections (STIs) among transgender people, laboratory-proven prevalence of these infections in this population has not been systematically reviewed. We performed a systematic review and meta-analysis of the medical literature involving laboratory-proven HIV and STI diagnoses among transgender people. Methods: A systematic review of the English literature regarding laboratory-proven HIV and/or STI testing in transgender populations within the last 50 years was performed. Preliminary meta-analyses assessing the prevalence of HIV and STIs among both transgender men and transgender women were performed. Given the heterogeneity of included studies, these analyses were difficult to interpret and not included in our results. Results: Our literature review identified 25 studies, representing 11 countries. All of these studies included transgender women, with 9 (36%) including data on transgender men. HIV was the most commonly studied STI, with prevalence ranging from 0% to 49.6% in transgender women and 0% to 8.3% in transgender men. For syphilis, gonorrhea, and chlamydia, respectively, prevalence ranged from 1.4% to 50.4%, 2.1% to 19.1%, and 2.7% to 24.7% in transgender women and from 0% to 4.2%, 0% to 10.5%, and 1.2% to 11.1% in transgender men. Site-specific testing practices for gonorrhea and chlamydia were variable. No studies reported prevalence data on trichomoniasis. Conclusion: The literature describing STIs and transgender people primarily focuses on transgender women and HIV. Data involving HIV and STIs among transgender men are lacking. These findings highlight opportunities for the future study of epidemiology of HIV/STIs in transgender men and the relevance of STIs in transgender people.

Background: Trichomonias is the most common non-viral STI among women worldwide and is associated with serious reproductive morbidity, poor birth outcomes and amplified HIV transmission. Single-dose metronidazole therapy has been the treatment of choice for over three decades. There is mounting evidence, however, of high rates of repeat positives following single-dose metronidazole, and among HIVinfected women, bacterial vaginosis (BV) was found to alter treatment efficacy. The purpose of this study was to examine the effectiveness of single-dose metronidazole compared to 7 day-dose metronidazole for the treatment of trichomoniasis among HIV-uninfected, non-pregnant women and to determine if this effect was modified by BV. Methods: This was a randomized, parallel, multi-site, open-label trial of single-dose (2 g one-time) versus 7 day-dose (500 mg twice daily) for the treatment of trichomoniasis. The primary outcome was T. vaginalis infection by arm, per nucleic acid amplification test or culture, four weeks post-completion of treatment, in intentto-treat analyses. This analysis was also stratified by BV status. Findings: Of 623 women randomized, those in the 7 day-dose arm were less likely to be T. vaginalis positive at test-of-cure compared to those in the single-dose arm [34/312 (10.9%) vs. 58/311 (18.6%), p=0·001] [R.R. 0.55 (95% C.I. 0.34–0.70)]. Risk was similar by BV status (p=0·17). Self-reported adherence in both arms was > 95%. Side effects were similar by arm. Interpretation: In this sample of HIV-uninfected, non-pregnant women with trichomoniasis, compared to single-dose, 7 day-dose metronidazole treatment resulted in 45% fewer treatment failures. The 7 day-dose metronidazole should be the preferred treatment for trichomoniasis among women.