By Dr. Chinta SidharthanReviewed by Benedette Cuffari, M.Sc.Apr 10 2024

In a recent study published in PLOS ONE, researchers examine the interplay between Neisseria gonorrhoeae, Chlamydia trachomatis, Torquetenovirus, high-risk human papillomavirus (HPV), and the anorectal microbiome in cases of sexually transmitted rectal infections in men who have sex with men (MSM).

Study: Chlamydia trachomatis and Neisseria gonorrhoeae rectal infections: Interplay between rectal microbiome, HPV infection and Torquetenovirus. Image Credit: New Africa / Shutterstock.com

MSM and STIs

MSM have a high prevalence of sexually transmitted infections (STIs) in the rectal region, with N. gonorrhoeae and C. trachomatis the most common pathogens responsible for these infections. These infections are typically asymptomatic, thus resulting in higher transmission rates and patients often serving as reservoirs for the pathogens.

Untreated N. gonorrhoeae and C. trachomatis infections can also lead to severe sequelae and complications, such as an increased risk of acquiring human immunodeficiency virus (HIV). MSM who are HIV positive are also more vulnerable to high-risk HPV infections, which contribute significantly to anal neoplasia.

Characterizing microbial communities in the mucosa of the anorectal region, which is the origin and proliferation site of gonococcal or chlamydial and HPV infections, is essential in understanding the pathogenesis of sexually transmitted rectal infections and developing effective prevention strategies and therapies.

About the study

In the present study, researchers examine the interplay between N. gonorrhoeae, C. trachomatis, Torquetenovirus, high-risk HPV, and the anorectal microbiome in MSM based on the presence and absence of N. gonorrhoeae and C. trachomatis infections. For each individual, the positivity of each type of high-risk HPV was assessed using 16S ribosomal ribonucleic acid (rRNA) sequencing to determine the bacterial community composition, whereas real-time polymerase-chain-reaction (RT-PCR) assay was used to measure Torquetenovirus titers.

Previously, the researchers of this study reported that in individuals with sexually transmitted rectal infections, the anorectal microbiome exhibited a reduced abundance of Escherichia and an increased abundance of anaerobic bacteria such as Peptostreptococcus, Peptoniphilus, and Parvimonas. HIV infections further impacted the bacterial composition, with alterations in the abundance of genera such as Corynebacterium, Lactobacillus, Gardnerella, and Sutterella.

Previous studies also showed that MSM with suppressed viral loads of HIV and concurrent HPV-16 infection had an abundance of bacteria from the phylum Fusobacteria. However, there remains a lack of data on the association between the microbiome of the anorectal region and Torquetenovirus, which primarily replicates in T lymphocytes. Although this single-stranded deoxyribonucleic acid (DNA) virus is an endogenous non-pathogenic virus, the viral titers of Torquetenovirus are an indicator of immune function.

Herein, study participants were over 18 years of age, had not undergone any antimicrobial treatments one month before enrollment, and did not have infectious gastroenteritis or inflammatory bowel diseases. Anorectal swabs were used to determine the presence of N. gonorrhoeae, C. trachomatis, Torquetenovirus, and HPV and analyze the anorectal microbiome. The Aptima HPV assay was also used to determine the types of high-risk HPV.

Study findings

The incidence of high-risk HPV rectal infections was 61% among MSM. Among HIV-positive MSM with concurrent N. gonorrhoeae or C. trachomatis infections, the incidence rates were higher at 70.2% and 84%, respectively. The prevalence of Torquetenovirus was also higher among MSM with N. gonorrhoeae and C. trachomatis infections than in uninfected subjects.

The anorectal microbiome evaluation showed that the abundance of Escherichia was lower among individuals infected with either N. gonorrhoeae, C. trachomatis, or both. Furthermore, a significantly higher abundance of Bacteroides was associated with the presence of Torquetenovirus.

The types of high-risk HPV positively correlated with Corynebacterium and Escherichia, while Oscillospira, Prevotella, Sutterella, and the phylum Firmicutes were negatively associated with high-risk HPV types. Although the presence of Torquetenovirus alone did not significantly impact the rectal microbiome, the presence of both Torquetenovirus and N. gonorrhoeae or C. trachomatis infections was associated with changes in the beta-diversity of the anorectal microbiome.

Conclusions

High-risk HPV infections were more prevalent among MSM; however, concurrent HIV and N. gonorrhoeae or C. trachomatis infections increased incidence rates. Furthermore, the presence of Torquetenovirus, N. gonorrhea, and C. trachomatis infections had a significant impact on the abundance of various bacteria in the anorectal microbiome.

The study findings highlight the need to test for the concurrent presence of various STIs to form effective prevention and treatment strategies.