Antibiotic Treatment for Bacterial Proctitis
For bacterial proctitis, initiate empiric treatment with ceftriaxone 250-500 mg IM as a single dose PLUS doxycycline 100 mg orally twice daily for 7 days to cover the most common sexually transmitted pathogens: Neisseria gonorrhoeae and Chlamydia trachomatis. 1
Pathogen-Specific Coverage
The empiric regimen must address the primary causative organisms:
- Gonorrhea and Chlamydia: These are the most common sexually transmitted anorectal pathogens causing infectious proctitis 1
- Lymphogranuloma venereum (LGV): Caused by specific C. trachomatis serovars (L1-L3), increasingly found in HIV-negative men who have sex with men 1
- Syphilis: Treponema pallidum can cause proctitis mimicking malignancy or inflammatory bowel disease 2
- Herpes simplex virus: Requires antiviral rather than antibiotic therapy 1
Recommended Treatment Algorithm
First-Line Empiric Therapy
- Ceftriaxone 250-500 mg IM as a single dose 3
- PLUS Doxycycline 100 mg orally twice daily for 7 days 3, 1
This combination provides broad coverage against gonorrhea and chlamydia, which are the predominant bacterial causes 1.
Alternative Regimens
If the patient cannot tolerate doxycycline:
- Erythromycin 500 mg orally four times daily for 10-14 days as a substitute 3
- Azithromycin 1 g orally as a single dose for atypical pathogen coverage 4
When to Suspect LGV
If symptoms are severe (marked anorectal pain, tenesmus, bloody discharge) or if initial therapy fails:
- Extend doxycycline to 21 days (100 mg orally twice daily) for presumptive LGV treatment 1
- LGV requires longer treatment duration than uncomplicated chlamydial proctitis 1
Syphilitic Proctitis
If Treponema pallidum serology is positive:
- Benzathine penicillin G 2.4 million units IM (may require three doses depending on stage) 2
- Syphilitic proctitis can present as a rectal mass mimicking cancer 2
Critical Diagnostic Considerations
Essential History Elements
- Sexual history: Specifically ask about receptive anal intercourse, as this is the primary risk factor 1
- Partner history: Multiple partners or partners with known STIs increase risk 1
- HIV status: HIV-positive patients may have more severe presentations 1
- Symptom pattern: Anorectal pain, tenesmus, bleeding, mucous discharge, and constipation suggest proctitis 5, 1
Required Laboratory Testing
Before initiating treatment, obtain:
- Rectal swabs for N. gonorrhoeae and C. trachomatis nucleic acid amplification testing (NAAT) 1
- Syphilis serology (T. pallidum testing) 2, 1
- HIV testing (co-infection screening) 1
- Herpes simplex virus testing if vesicular lesions present 1
Endoscopic Findings
Rectosigmoidoscopy typically shows:
- Inflammatory changes in the distal 10-15 cm of rectum 5
- Ulcerations, friability, or mass-like lesions that may mimic inflammatory bowel disease or malignancy 2
- Biopsy to exclude malignancy and inflammatory bowel disease 5, 2
Common Pitfalls to Avoid
Do Not Delay Treatment
- Initiate empiric antibiotics immediately after obtaining specimens, without waiting for culture results 1, 6
- The majority of rectal chlamydia and gonococcal infections are asymptomatic and require screening in at-risk populations 1
Do Not Confuse with Inflammatory Bowel Disease
- Always screen for STIs in patients with proctitis symptoms, especially with risk factors for sexual transmission 5, 6
- Infectious proctitis lacks the classical histologic features of ulcerative colitis 5
Do Not Use Fluoroquinolones Empirically for Gonorrhea
- Avoid ciprofloxacin or other fluoroquinolones as first-line treatment due to widespread gonococcal resistance 6
- Cephalosporins (ceftriaxone) remain the treatment of choice 3
Do Not Forget Partner Treatment
- All sexual partners within the preceding 60 days should be evaluated and treated presumptively 1
- This prevents reinfection and ongoing transmission 1
Follow-Up and Monitoring
- Reassess at 72 hours: If no clinical improvement, consider hospitalization or alternative diagnoses 3
- Test of cure: Repeat NAAT testing 3-4 weeks after treatment completion for chlamydia and gonorrhea 1
- Repeat endoscopy: If symptoms persist, perform follow-up rectosigmoidoscopy to assess resolution 2
- Screen for other STIs: Test for co-infections including HIV, hepatitis B, and hepatitis C 1
Special Populations
Men Who Have Sex with Men (MSM)
- Higher prevalence of infectious proctitis, particularly LGV 1
- Routine screening recommended even in asymptomatic individuals with receptive anal intercourse 1
Women with Anal Intercourse
- Also at risk for sexually transmitted proctitis, though less studied than MSM 1
- Apply the same diagnostic and treatment approach 1