Infective proctitis

Infective proctitis refers to infectious inflammation of the rectum, typically acquired via receptive anal intercourse. It is distinct from proctocolitis (which extends beyond 15 cm) and enteritis. The major causative organisms include Neisseria gonorrhoeae, Chlamydia trachomatis (including lymphogranuloma venereum [LGV] serovars), herpes simplex virus (HSV), and Treponema pallidum (syphilis). Mixed infections are common.

In Australia, infective proctitis is predominantly seen in MSM, including HIV-positive individuals and those on pre-exposure prophylaxis (PrEP). Notification rates for gonorrhoea and chlamydia have risen substantially over the past decade. The Kirby Institute's Annual Surveillance Reports consistently document increasing rectal STI diagnoses in MSM attending sexual health clinics across major Australian cities. LGV, once rare in Australia, has re-emerged since 2004 predominantly in HIV-positive MSM. Syphilis notifications have also surged, with rectal manifestations (proctitis, anal ulcers) becoming increasingly recognised.

Remote and regional areas, including communities with significant Aboriginal and Torres Strait Islander populations, face unique epidemiological challenges with STI-related proctitis, often compounded by limited access to specialist sexual health services.

Causative Organisms

Pathophysiology

Organisms are inoculated directly into the rectal mucosa via receptive anal intercourse. N. gonorrhoeae and C. trachomatis infect columnar epithelium. HSV causes vesicular mucosal ulceration and can establish latency in sacral ganglia. LGV serovars are more invasive, causing granulomatous lymphangitis and tissue destruction, leading to fibrosis and stricture if untreated. T. pallidum causes endarteritis and plasma cell infiltration. Co-infection with HIV alters the clinical presentation and may impair healing.

Symptoms

• Anorectal discharge: Mucopurulent (gonococcal, chlamydial, LGV) or bloody (LGV, HSV, syphilis)
• Tenesmus: Particularly prominent in LGV and HSV proctitis
• Anorectal pain: Often severe in HSV; variable in LGV; may be absent in gonorrhoea/chlamydia
• Bleeding per rectum: LGV, HSV, syphilis, Shigella
• Constipation or change in bowel habit: LGV proctitis may simulate Crohn's disease
• Systemic symptoms: Fever, inguinal lymphadenopathy (LGV); flu-like (secondary syphilis)
• Asymptomatic: Rectal gonorrhoea and non-LGV chlamydia are asymptomatic in the majority

Examination Findings

• Perianal inspection: Vesicles/ulcers (HSV, primary syphilis), warts (HPV co-infection), fissures
• Proctoscopy: Mucosal erythema, friability, mucopus, ulceration; essential for diagnosis
• Inguinal lymphadenopathy: Bilateral buboes in LGV
• Skin/mucous membranes: Rash, condylomata lata (secondary syphilis)

All patients presenting with symptoms of proctitis or at risk for rectal STIs should have a comprehensive screen. Proctoscopy with swab collection from the rectal mucosa is preferred over blind swabs.

• Essential
  Rectal NAAT for N. gonorrhoeae and C. trachomatis

  Nucleic acid amplification test (NAAT) is the gold standard. Available at all Australian pathology laboratories. Rectal swab under proctoscopic visualisation preferred. NAAT for chlamydia includes all serovars but does NOT differentiate LGV — requires LGV-specific typing.
• Essential
  LGV typing (C. trachomatis L1–L3 PCR)

  Request specifically as a reflex test or add-on when C. trachomatis NAAT is positive from a rectal swab AND patient has symptomatic proctitis. Available at major reference laboratories (e.g. Sullivan Nicolaides, Sonic/NSW Health Pathology). May require separate request.
• Essential
  Rectal swab for HSV PCR

  HSV PCR on rectal/perianal swab is significantly more sensitive than culture. Swab from ulcer base or vesicle where present. Available widely across Australian labs. Request HSV typing (HSV-1 vs HSV-2) to guide counselling.
• Essential
  Syphilis serology (RPR + TPPA or EIA)

  Treponemal and non-treponemal tests. RPR titre guides treatment response monitoring. If primary syphilis suspected, darkfield microscopy or PCR of anal ulcer swab may be performed at specialist centres.
• Essential
  HIV serology (4th generation Ag/Ab assay)

  All patients with STI-related proctitis should be offered HIV testing. HIV co-infection significantly impacts management and severity.
• Available
  Stool culture / PCR for enteric pathogens

  Consider if diarrhoea prominent or proctocolitis suspected. Shigella, Campylobacter, Salmonella, Entamoeba histolytica panel. Request sensitivity testing given rising antimicrobial resistance in sexually acquired Shigella.
• Available
  Rectal gonorrhoea culture and sensitivity

  Add culture in addition to NAAT when treatment failure is suspected or patient is in a high-prevalence setting for antimicrobial-resistant gonorrhoea. Enables minimum inhibitory concentration (MIC) testing.
• Available
  Hepatitis A, B, C serology

  Hepatitis A and B serology for immunity assessment and vaccination; Hepatitis C antibody/RNA in MSM (especially HIV-positive) given risk of sexual HCV transmission.
• Specialist
  Proctoscopy / flexible sigmoidoscopy

  Direct mucosal visualisation for swab collection and assessment of severity. Sigmoidoscopy indicated if LGV proctitis suspected (assess extent), symptoms persist despite treatment, or IBD needs exclusion. Rectal biopsy may be needed.

Empirical Regimen for Symptomatic Proctitis in MSM

If HSV proctitis suspected (severe pain, ulceration, sacral paraesthesia): add valaciclovir 500 mg BD for 5–10 days (or 1 g BD if immunocompromised). Adjust duration based on clinical response.

Gonococcal Proctitis

Non-LGV Chlamydial Proctitis

Alternative (if doxycycline contraindicated): Azithromycin 1 g orally as a single dose (note: inferior to doxycycline for rectal chlamydia — single dose azithromycin has lower cure rates for rectal compared to urogenital infection).

LGV Proctitis (C. trachomatis L1–L3)

Herpetic Proctitis (HSV)

Syphilitic Proctitis

IV therapy is rarely required for infective proctitis unless the patient has severe HSV proctitis with systemic involvement, is immunocompromised with inability to absorb oral agents, or has confirmed aciclovir-resistant HSV.

• IV aciclovir to oral valaciclovir: Switch when pain is controlled, systemic symptoms have resolved, oral intake is tolerated, and lesions show evidence of healing (typically 3–7 days of IV therapy).
• IV ceftriaxone: Not applicable — ceftriaxone for gonorrhoea is always given as a single IM dose.
• Complete oral doxycycline course: 21-day course for LGV must not be abbreviated; ensure patient understands adherence requirements.

🤰 Pregnancy

STI-related proctitis in pregnancy requires prompt treatment to prevent vertical transmission and obstetric complications.

• Gonorrhoea: Ceftriaxone 500 mg IM single dose is safe in all trimesters. Avoid spectinomycin (limited Australian availability).
• Chlamydia (non-LGV): Azithromycin 1 g orally single dose (doxycycline is contraindicated in pregnancy). For LGV in pregnancy, seek specialist infectious disease/sexual health advice — erythromycin 500 mg QID for 21 days is an alternative but poorly tolerated.
• HSV proctitis: Aciclovir and valaciclovir are safe in pregnancy at standard doses. IV aciclovir for severe primary HSV. Suppressive therapy from 36 weeks if primary HSV acquired in pregnancy.
• Syphilis: Benzathine benzylpenicillin is the only validated treatment in pregnancy. Penicillin-allergic pregnant women require desensitisation — refer to specialist urgently.
• Partner notification and treatment: All sexual partners must be notified and treated to prevent re-infection during pregnancy.

👶 Paediatrics

STI-related proctitis in children (outside the neonatal period) raises mandatory child protection concerns.

• Mandatory reporting: Any STI in a child under 12 years that is consistent with sexual transmission mandates notification to child protection authorities per jurisdictional legislation.
• Neonatal HSV: IV aciclovir 20 mg/kg every 8 hours — urgent paediatric infectious disease consultation required.
• Adolescents: Treat with adult regimens. Doxycycline is safe from age 8 years. Ensure age-appropriate consent processes and confidentiality protections are followed.

🛡️ Immunocompromised (HIV-positive)

HIV-positive patients with infective proctitis may have more severe and atypical disease, increased risk of co-infections, and higher recurrence rates.

• HSV proctitis: Higher dose or longer duration valaciclovir (1 g BD instead of 500 mg BD) for primary episodes; IV aciclovir if severe. Suppressive therapy strongly recommended (valaciclovir 500 mg daily).
• Aciclovir-resistant HSV: Occurs with CD4 <50 cells/μL and repeated aciclovir exposure. Use IV foscarnet 40 mg/kg every 8–12 hours — specialist referral mandatory.
• LGV: May have more severe tissue destruction; ensure full 21-day doxycycline course and close follow-up.
• CMV proctitis: Consider cytomegalovirus as a cause in severely immunocompromised patients (CD4 <50); treat with IV ganciclovir or oral valganciclovir.
• ART optimisation: Review antiretroviral therapy and ensure virological suppression. Interactions between doxycycline and some ARTs are generally not clinically significant.

🫘 Renal Impairment

Dose adjustments are required for antiviral agents in renal impairment; antibacterials used for proctitis generally require minimal adjustment.

• Valaciclovir (eGFR 30–49): 500 mg BD for treatment; 500 mg daily for suppression.
• Valaciclovir (eGFR 10–29): 500 mg once daily for treatment and suppression.
• Valaciclovir (eGFR <10 / dialysis): 500 mg after each haemodialysis session; specialist advice recommended.
• IV aciclovir: Mandatory dose reduction in renal impairment; monitor creatinine and ensure adequate hydration to prevent crystalluria and nephrotoxicity.
• Doxycycline and ceftriaxone: No dose adjustment required in renal impairment. Doxycycline is preferred over tetracycline as it does not accumulate in renal failure.

👴 Elderly Patients

STI-related proctitis in older adults is often under-recognised and under-tested; a non-judgemental approach to sexual history is essential.

• Renal function: Age-related decline in eGFR increases risk of antiviral toxicity — always check renal function before prescribing aciclovir/valaciclovir.
• Drug interactions: Review polypharmacy; doxycycline absorption may be affected by antacids and calcium supplements.
• Dexterity/adherence: Simplified regimens and blister packaging may assist with adherence to 21-day doxycycline courses.

• Avoid azithromycin for rectal chlamydia: Single-dose azithromycin has inferior cure rates for rectal (versus urogenital) chlamydial infection. Use doxycycline 100 mg BD for 7 days as first-line.
• Gonorrhoea culture for resistance monitoring: Request culture in addition to NAAT in patients attending for test of cure, to support national surveillance of antimicrobial resistance in N. gonorrhoeae.
• Shigella resistance: Sexually acquired Shigella flexneri in MSM shows increasing resistance to azithromycin and ciprofloxacin in Australia. Request sensitivity testing and consult infectious disease specialist for multidrug-resistant strains.
• LGV course completion: Reinforce 21-day doxycycline adherence — incomplete treatment risks relapse, stricture formation, and ongoing transmission.
• Avoidance of dual therapy for gonorrhoea: Updated Australian guidelines (2024) recommend single-agent ceftriaxone without azithromycin for uncomplicated gonorrhoea in regions where co-existing chlamydia has been excluded by NAAT.
• Allergy documentation: Review penicillin allergy labels carefully before prescribing ceftriaxone. Most reported penicillin allergies are not true IgE-mediated reactions and cross-reactivity with cephalosporins is low.

Follow-Up Schedule

Prevention Strategies

• Condom use: Consistent condom use with new or casual partners reduces transmission of gonorrhoea, chlamydia, LGV, and syphilis. Condoms provide partial protection against HSV.
• Vaccination: Hepatitis A and B vaccination for all susceptible MSM. HPV vaccination (Gardasil 9) up to age 26 years on NIP; consider off-NIP in older adults. Mpox vaccination (JYNNEOS) in eligible MSM.
• Doxycycline PEP (Doxy-PEP): Post-exposure doxycycline 200 mg within 72 hours of condomless sex reduces acquisition of gonorrhoea, chlamydia, and syphilis in MSM and transgender women. Currently available in specialist sexual health settings in Australia pending further guideline incorporation.
• Regular screening: Asymptomatic rectal STI screening at 3-monthly intervals for sexually active MSM is the most effective strategy for early detection and treatment.

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