Infectious Proctitis

Infectious proctitis is inflammation of the rectal mucosa (distal 15 cm) caused by sexually transmitted or enteric pathogens.

• Sexually transmitted causes: Neisseria gonorrhoeae, Chlamydia trachomatis (serovars D to K, and L1 to L3 causing lymphogranuloma venereum), Treponema pallidum, herpes simplex virus, Mycoplasma genitalium, cytomegalovirus in advanced HIV, and mpox.
• Enteric causes: Shigella, Campylobacter, Entamoeba histolytica, Salmonella, Clostridioides difficile, Giardia.
• Risk groups: men who have sex with men, people with HIV, receptive anal intercourse, multiple partners, sex workers.

Anorectal pain, tenesmus, rectal discharge (mucopurulent or bloody), urgency, constipation or diarrhoea, bleeding.

• Gonorrhoea and chlamydia are often asymptomatic.
• Lymphogranuloma venereum: severe proctitis with inguinal buboes, fever, and later strictures and fistulae.
• Herpes: severe anorectal pain, vesicles and ulcers, sacral radiculopathy, urinary retention.
• Syphilis: painless or painful ulcer (chancre), condylomata lata.
• Differential diagnosis: Crohn disease, ulcerative proctitis, radiation proctopathy, ischaemic proctitis, anorectal malignancy, trauma, solitary rectal ulcer, anal fissure and abscess.
• Complications: abscess, fistula, rectal stricture, systemic spread, chronic proctitis, HIV acquisition, sexual transmission to partners, and infertility from coinfection.

Proctoscopy or flexible sigmoidoscopy shows erythema, friability, mucopus, ulcers, bleeding.

• Nucleic acid amplification tests from rectal swab for gonorrhoea, chlamydia (with LGV genotyping if positive), and Mycoplasma genitalium; herpes simplex PCR of lesion swab; syphilis serology (treponemal and non-treponemal); HIV, hepatitis B and C tests.
• Stool culture and PCR panel, ova and parasites, Clostridioides difficile toxin; biopsy if persistent and non-diagnostic (including cytomegalovirus immunohistochemistry).
• Microscopy: Gram stain of rectal swab for gonococci (intracellular diplococci).

Supportive: abstain from sex until treatment completed and partners treated, analgesia (paracetamol 1 g every 6 hours, lidocaine 2 percent gel topically), sitz baths, fluids.

Pharmacological (empirical therapy for symptomatic proctitis, adjusted when tests return):

• Ceftriaxone 1 g IM single dose plus doxycycline 100 mg twice daily for 7 days (for 21 days if lymphogranuloma venereum is suspected or confirmed).
• Alternative for chlamydia: azithromycin 1 g single dose (less effective rectally).
• Syphilis (early): benzathine penicillin G 2.4 million units IM single dose; allergic patients doxycycline 100 mg twice daily for 14 days. Late or unknown duration: benzathine penicillin G 2.4 million units IM weekly for 3 weeks.
• Herpes simplex: aciclovir 400 mg three times daily for 7 to 10 days (or valaciclovir 1 g twice daily for 7 to 10 days); suppression with aciclovir 400 mg twice daily for frequent recurrences.
• Cytomegalovirus proctitis in HIV: valganciclovir 900 mg twice daily for 21 days with antiretroviral therapy.
• Shigella: ciprofloxacin 500 mg twice daily for 3 days or azithromycin 500 mg daily for 3 days; Entamoeba: metronidazole 800 mg three times daily for 5 days then paromomycin 25 to 35 mg/kg/day in 3 divided doses for 7 days.
• Mycoplasma genitalium: doxycycline 100 mg twice daily for 7 days then moxifloxacin 400 mg daily for 7 days.

Special groups: HIV (start antiretroviral therapy, test annually for sexually transmitted infections), pregnancy (azithromycin and ceftriaxone, avoid doxycycline and fluoroquinolones), children (consider sexual abuse; refer).

Prevention: condoms, vaccination against hepatitis A and B and HPV, doxycycline post-exposure prophylaxis in selected high risk groups.

Red flags: severe pain with fever, rectal bleeding, abscess, stricture, systemic symptoms, persistent symptoms after treatment.

Follow-up: test of cure at 3 to 4 weeks for gonorrhoea and chlamydia; rescreen at 3 months; repeat syphilis serology at 3, 6 and 12 months; partner notification and treatment.