Causes of Proctitis
Sexually Transmitted Infections (Primary Causes)
The most common causes of proctitis are sexually transmitted infections, specifically Neisseria gonorrhoeae, Chlamydia trachomatis (including lymphogranuloma venereum serovars), Treponema pallidum, and herpes simplex virus, which occur predominantly in persons who engage in receptive anal intercourse. 1, 2
Key Sexually Transmitted Pathogens
- Gonorrhea and Chlamydia are the most frequently identified bacterial causes, with C. trachomatis including LGV serovars capable of causing particularly severe proctitis 1, 2, 3
- Herpes simplex virus can cause severe proctitis, especially in HIV-infected individuals where disease severity is markedly increased 1, 2, 3
- Syphilis (T. pallidum) should be considered in all cases of acute proctitis with receptive anal intercourse history 1
- Lymphogranuloma venereum (LGV) specifically presents with bloody discharge, perianal ulcers, or mucosal ulcers and requires extended 3-week treatment rather than standard 7-day therapy 1, 4, 3
Transmission Mechanism
- These infections are acquired through receptive anal intercourse, though condom use does not guarantee complete protection as infections often spread without penile penetration 4, 5
- Digital contact and toys can also transmit infectious proctitis 5
Enteric Pathogens (Proctocolitis)
When inflammation extends beyond the distal 10-12 cm of rectum, consider enteric pathogens that cause proctocolitis:
- Campylobacter species and Shigella species are common causes, particularly in men who have sex with men, and can be transmitted via oral-anal contact 1, 2
- Entamoeba histolytica causes proctocolitis in individuals engaging in oral-anal contact 1, 2
- Giardia lamblia is most frequently implicated in enteritis among otherwise healthy persons with oral-anal sexual practices 1
Opportunistic Infections (Immunosuppressed Patients)
In HIV-infected or immunosuppressed patients, additional pathogens must be considered:
- Cytomegalovirus (CMV) can cause severe proctitis in immunosuppressed patients and is a critical consideration in HIV-positive individuals 1, 2
- Mycobacterium avium-intracellulare, Cryptosporidium, Microsporidium, and Isospora can cause enteritis in HIV-infected individuals 1, 2
Emerging Pathogens
- Mycoplasma genitalium should be considered in patients with symptomatic proctitis after exclusion of N. gonorrhoeae, C. trachomatis, syphilis, and herpes 5
- LGV proctitis is increasingly found in HIV-negative MSM, not just HIV-positive populations as previously thought 5
Non-Infectious Causes to Consider
- Traumatic proctitis should be considered in sexually active patients, particularly those using toys or engaging in fisting 5
- Inflammatory bowel disease (ulcerative colitis, Crohn's disease) remains an important differential diagnosis, though infectious causes are increasingly common and can mimic IBD endoscopically and symptomatically 6, 7, 8
Critical Clinical Pitfall
The incidence of infectious proctitis is rising, especially among men who have sex with men, and these infections frequently mimic inflammatory bowel disease both clinically and endoscopically. 6, 7, 9 A detailed sexual history specifically asking about receptive anal intercourse and oral-anal contact is essential to avoid misdiagnosis as IBD and unnecessary immunosuppressive therapy 4, 8. The majority of rectal chlamydia and gonococcal infections are asymptomatic and can only be detected by laboratory testing, making routine screening crucial in at-risk populations 5.