Bacterial Enteric Pathogen Detection Common Among Men Who Have Sex With Men

Bacterial enteric pathogens in MSM were common among those who received an STI diagnosis within the past year and was associated with high-risk sexual behaviors.

Nearly 10% of men who have sex with men (MSM) were found to be positive for bacterial enteric pathogens, according to results of a study published in the Journal of Infection.

Researchers conducted a cross-sectional study to determine the prevalence and risk factors associated with bacterial enteric pathogen detection among MSM. This study was conducted between 2017 and 2018 at the United Kingdom’s (UK) largest sexual health and HIV clinic. Residual rectal swab specimens from boys and men (N=2116) aged 16 years and older were collected and evaluated for bacterial enteric pathogens. A subset of swabs was assessed for azithromycin resistance conferred by the macrolide 2′-phosphotransferase I (mphA) gene.

Among patients included in the analysis, most (98.5%) were older than 19 years, 77.8% were White, 47.2% were born in the UK, 96.2% self-identified as gay, and 22.9% had a bacterial sexually transmitted infection (STI) at baseline. In addition, 95.2% of the patients reported anorectal sexual intercourse, 52.4% reported condomless sex within the past 6 months, 23.6% reported 10 or more sexual partners in the past 3 months, 37.0% reported HIV pre-exposure prophylaxis (PrEP) use, and 17.6% had HIV infection.

The overall prevalence of detected bacterial enteric pathogens was 9.8% (n=207), but gastrointestinal symptoms consistent with pathogen detection were reported by only 1.7% of the patients. Stratified by bacteria, the prevalence was 4.9% for enteroaggregative Escherichia coli, 1.7% for Campylobacter species and enteropathogenic E coli, 1.2% for Shiga toxin-producing E coli, and 0.8% for Shigella species.

[T]he association between BEP detection and STI-risk behaviours strengthens the evidence that transmission of these pathogens is an important public health concern for MSM.

Multivariable Poisson regression with robust error variances was used to assess for associations between bacterial enteric pathogen detection and clinical, sociodemographic, and behavioral risk factors. Pathogen detection was associated with HIV-negativity with PrEP use (adjusted prevalence ratio [aPR], 2.06; 95% CI, 1.48-2.86) and HIV-positivity (aPR, 1.85; 95% CI, 1.25-2.75) compared with HIV-negativity without PrEP use (P <.001).

Detection was also associated with bacterial STI diagnosis at baseline (aPR, 1.45; 95% CI, 1.09-1.91; P =.01) and within the past year (aPR, 1.41; 95% CI, 1.08-1.84; P =.01). Of note, linear testing showed positive associations between increasing numbers of overall (P =.003) or new (P <.001) sexual partners in the past 3 months and bacterial enteric pathogen detection.

A subset of 207 pathogen-positive and 99 pathogen-negative rectal swab specimens were tested for mphA. Overall, mphA was detected in 99 (32.5%) specimens. Of these specimens, the rate of mphA detection was higher in those that were positive vs negative for bacterial enteric pathogens (41.3% vs 14.1%; P <.001). Similar results were observed between patients who tested positive vs negative for a bacterial STI within the past year, with mphA detected in 41.3% vs 24.7% of these patients (P =.002).

Limitations of this study include potential bias due to its reliance on routinely-collected data.

“[T]he association between BEP [bacterial enteric pathogen] detection and STI-risk behaviours strengthens the evidence that transmission of these pathogens is an important public health concern for MSM,” the researchers concluded.

References:

Mitchell HD, Whitlock G, Zdravkov J, et al. Prevalence and risk factors of bacterial enteric pathogens in men who have sex with men: a cross-sectional study at the UK’s largest sexual health service. J Infect. Published online November 4, 2022. doi:10.1016/j.jinf.2022.10.033