Sexually transmissible infections affecting the gastrointestinal tract: what gastroenterologists and hepatologists need to know

Sexually transmissible gastrointestinal (enteric) infections cause oropharyngitis, hepatitis, enteritis, proctocolitis and anorectal disease, and can mimic neoplastic and inflammatory gastrointestinal disease. Sexually transmissible enteric infections are generally seen in men who have sex with men (MSM) due to sexual behaviours which risk faecal-oral transmission. Oropharyngeal and anorectal sexually transmitted infections (STIs) are transmitted via direct inoculation from oral and anal sexual behaviours. Shigella spp, Campylobacter spp, Salmonella spp, diarrhoeagenic Escherichia coli, Giardia duodenalis and Entamoeba histolytica are recognised sexually transmissible enteric faeco-oral pathogens in MSM. Neisseria gonorrhoeae, Chlamydia trachomatis, herpes simplex virus (HSV), Treponema pallidum subspecies pallidum (Syphilis), mpox and HSV cause sexually transmissible oropharyngeal and anorectal disease. Cryptosporidium, intestinal spirochaetosis, Blastocystis, Strongyloides stercoralis, Enterobius vermicularis and enteric viruses have infrequently been reported as sexually transmissible in MSM. Sexually transmissible enteric infections have increased in MSM over the past 35 years. Gastroenterologists and hepatologists do not generally enquire about sexual behaviours, but identifying sexually transmissible enteric infections is important due to high rates of bacterial antimicrobial resistance, and the additional management includes: bacterial antimicrobial susceptibility testing, testing for STIs/HIV, providing recommendations for sexual abstinence and partner notification; and onward referral to specialist sexual health clinics for sexual health prevention interventions. In this review, we highlight the STIs which can affect the gastrointestinal tract and provide some key management points for gastroenterologists and hepatologists.