Gut Infections Commonly Overlooked in Men Who Have Sex with Men

In recent years, the global health landscape has witnessed a disturbing rise in sexually transmitted enteric infections (STEIs), particularly among men who have sex with men (MSM). These infections, caused by pathogens that primarily colonize the lower digestive tract, are increasingly challenging to manage due to emerging multidrug resistance. A comprehensive literature review published in the journal Clinical Microbiology Reviews sheds light on this evolving public health threat, calling for renewed attention and innovative strategies to stem the tide of these persistent infections.

The senior author of the review, Dr. Ferric C. Fang from the University of Washington School of Medicine, emphasizes that the rapid globalization facilitated by international travel has transformed what was once a contained issue into a worldwide concern. Gastrointestinal “superbugs” are no longer confined to local outbreaks; they now traverse borders with ease, complicating efforts to control their spread. Prominent enteric pathogens such as Shigella, Campylobacter, and pathogenic strains of Escherichia coli have exhibited alarming increases in multidrug resistance, rendering conventional treatment protocols less effective.

Historically, enteric infections were recognized as sexually transmissible among MSM populations as early as the late 1960s and early 1970s, but their significance has expanded dramatically in recent years. The review delineates how behavioral factors—rather than immune status, such as HIV infection—are the primary drivers of the recent surge in STEIs. This pattern underscores the importance of focusing preventive strategies on community education and behavioral interventions alongside clinical management.

One of the principal challenges noted by Dr. Fang and colleagues lies in the under-recognition of sexual transmission as a vector for enteric pathogens. Traditional epidemiological investigations frequently prioritize foodborne exposure, thereby overlooking sexual contact as a critical pathway. Furthermore, standard sexually transmitted infection (STI) control programs tend to concentrate on classical infections like syphilis and gonorrhea, leaving a gap in testing and surveillance for enteric pathogens. This disconnect hampers timely diagnosis and effective responses to outbreaks.

The symptomatic presentation of STEIs is generally uniform across various pathogens, most notably characterized by diarrhea. The diverse microbial landscape includes bacteria (Salmonella, Shigella), viruses (hepatitis A), protozoa (Entamoeba histolytica, Giardia), and parasites (Strongyloides, Microsporidia). While for some pathogens the evidence of sexual transmission remains tentative, the review catalogs a dozen well-recognized STEI agents and highlights others with unclear transmission dynamics, such as Clostridioides difficile and Brachyspira species.

Technological advancements have been a bright spot in this complex scenario. Molecular diagnostics employing sensitive PCR-based assays and genomic sequencing have vastly improved the ability to detect and characterize these pathogens at the strain level. This progress facilitates precision in treatment selection and enhances epidemiological tracing to unravel transmission networks within communities. Early and accurate identification is paramount in addressing the multidrug resistance that increasingly characterizes these enteric infections.

Behavioral shifts in MSM communities exacerbate the ease with which these infections spread. Factors such as increased use of digital platforms for partner acquisition, a decline in condom usage fueled by widespread availability of pre-exposure prophylaxis (PrEP) for HIV and treatments for other STIs, and the phenomenon of chemsex (sexual activity facilitated by recreational drug use) collectively lower barriers to transmission. Oral-anal sexual practices, commonly referred to as “rimming,” are consistently identified as the principal sexual behavior linked to STEI spread.

Despite initial hypotheses, the review clarifies that neither HIV infection status nor the prophylactic intake of antibiotics or antiretroviral drugs significantly alter susceptibility to most enteric pathogens, with the notable exception of some protozoal infections. This insight refocuses preventive efforts on modifying sexual behavior rather than solely on biological susceptibility or HIV-associated immunity modulation.

Public health interventions recommended by the review emphasize education and behavioral modification to interrupt transmission chains. Safe-sex guidelines are extended beyond typical viral STI prevention to include avoidance of sexual activity during and immediately following diarrheal episodes to mitigate spread. In particular, a two-week abstinence period post-diarrhea is advised as a critical window to prevent onward transmission. This calls for improved communication strategies tailored to affected communities.

Demographic analyses reveal that MSM individuals who contract STEIs tend to be younger, urban residents with wide international travel and extensive sexual networks, characteristics that contribute to both exposure risk and dissemination potential. The fluidity of these populations poses a challenge for surveillance and intervention, necessitating flexible, community-engaged public health responses.

Moreover, STEIs do not exist in isolation within MSM populations; transmission may occur between diverse groups including people experiencing homelessness, particularly those engaged in transactional sex, and immunocompromised individuals who suffer disproportionately severe outcomes. This intersectionality highlights a pressing need for inclusive, multisectoral approaches addressing social determinants of health alongside biomedical strategies.

The impending global health ramifications of multidrug-resistant enteric pathogens underline the necessity for coordinated surveillance, timely diagnosis, and expanded research into novel therapeutics. As the review by Dr. Fang and colleagues indicates, these infections represent a re-emerging class of diseases shaped by modern social and behavioral contexts, demanding a robust, multidisciplinary public health response.

This landmark review also marks the first comprehensive synthesis focused specifically on sexually transmitted enteric infections in MSM, with contributions from epidemiologists and clinicians across institutions, including Drs. Kira Newman, Gretchen Snoeyenbos Newman, and Chase A. Cannon. By shining a spotlight on this underappreciated issue, the authors strive to catalyze innovation in prevention, diagnosis, and treatment protocols critical to global health.

In an era marked by increasing antimicrobial resistance and shifting sexual behaviors, the advent of STEIs as a distinct public health challenge necessitates urgent action—melding cutting-edge microbiological insights with targeted community engagement. The path forward must integrate heightened awareness, molecular diagnostics, and culturally competent education to disrupt transmission cycles and safeguard vulnerable populations worldwide.

News Publication Date: 17-Sep-2025

Web References:

• https://journals.asm.org/doi/10.1128/cmr.00075-23
• http://dx.doi.org/10.1128/cmr.007-23