Proctitis and Proctocolitis Organism-Specific Therapy 

Organism-specific therapeutic regimens for proctitis and proctocolitis are provided below, including those for Neisseria gonorrhoeae, Chlamydiatrachomatis, Treponema pallidum, herpes simplex virus (HSV), Shigella, Salmonella, Entamoeba histolytica, and Clostridioides (Clostridium) difficile. ^{[1, 2, 3, 4, 5, 6, 7, 8]}

Empiric treatment should be directed at the etiology that is most likely on the basis of the history.

• Travel to less developed country - Suspect enteric pathogen
• Recent antibiotics - Suspect C difficile
• Receptive anal intercourse - Suspect Neisseria, Chlamydia, syphilis, or Herpes

N gonorrhoeae

Regimens are as follows:

• Ceftriaxone 500 mg IM as a single dose; for persons >150 kg, 1 g IM as a single dose ^[9] or
• Gentamicin 240 mg IM as a single dose plus azithromycin 2 g PO as a single dose ^[9] or
• Cefixime 800 mg PO as a single dose ^[9]
• Concurrent treatment for chlamydial infection should also be given unless this infection has been excluded by microbiologic testing
• Consider culture and infectious disease consultation if cephalosporin-resistant infection is suspected ^[9]

C trachomatis genotype A-K (non-lymphogranuloma venereum [LGV])

Regimens are as follows:

• Doxycycline 100 mg PO q12h for 7d or
• Azithromycin 1g PO as a single dose or
• Levofloxacin 500 mg PO q24h for 3d ^[9]

C trachomatis genotype LGV

Regimens are as follows:

• Doxycycline 100 mg PO q12h for 21d (first line) 
• Erythromycin base 500 mg q6h for 21d (second line) or
• Azithromycin 1 g PO once weekly for 3wk ^[9]
• Presumptive treatment should be considered for men who have sex with men (MSM) with proctitis and a positive rectal chlamydia test ^[10]

T pallidum

Regimens are as follows:

• Benzathine penicillin G 2.4 million units IM as a single dose (first line)
• Doxycycline 100 mg PO q12h for 14d (penicillin-allergic) ^[9] or
• Azithromycin 2 g PO as a single dose (penicillin-allergic) ^[9]
• HIV infection - Benzathine penicillin G 2.4 million units IM as a single dose for early latent syphilis
• All patients positive for primary or secondary syphilis should also be tested for HIV ^[9]

HSV

For patients with first-time infection, 7- to 10-day regimens are as follows ^[9] :

• Acyclovir 400 mg PO q8h or
• Famciclovir 250 mg PO q8h or
• Valacyclovir 1 g PO q12h or
• Acyclovir 200 mg PO 5 times daily (not recommended, because of frequency of dosing)
• Treatment can be extended if healing is incomplete at 10d

For HIV-infected patients with episodic infection, 5- to 10-day regimens are as follows ^[9] :

• Acyclovir 400 mg PO q8h or
• Valacyclovir 1 g PO q12h or
• Famciclovir 500 mg PO q12h

Shigella species

Regimens are as follows ^[11] :

• Ciprofloxacin 500 mg PO q12h for 3d or
• Levaquin 500 mg/day PO for 3d or
• Trimethoprim-sulfamethoxazole (160 mg/800 mg) 1 DS tablet PO q12h for 5d or
• Ceftriaxone 1-2 g IV q24h for 5d or
• Azithromycin 500 mg/day PO for 3d

Salmonella, severe disease, presence of vascular prosthesis, or immunocompromised

Regimens are as follows ^{[12, 13]} :

• Trimethoprim-sulfamethoxazole (160 mg/800 mg) 1 DS tablet PO q12h or
• Ciprofloxacin 500 mg PO q12h or
• Ceftriaxone 1-2 g IV q24h or
• Cefotaxime 2 g IV q8h
• Duration 3-7d (≥14d for immunocompromised patients)
• Persistent carriers should be treated for 4-6wk
• Sensitivity testing should be carried out because of a high rate of antibiotic resistance among Salmonella strains
• Severe disease in immunocompetent patients is characterized by severe diarrhea, high fever, and need for hospitalization

E histolytica

Regimens are as follows ^{[14, 15, 16, 17]} :

• Metronidazole 500-750 mg PO q8h for 5-10d or
• Tinidazole 2 g PO q24h for 2-3d, followed by an intraluminal agent for 5-10d (paromomycin, diloxanide furoate, cloquinol)

C difficile

In addition to initiating therapy as below, ^{[18, 19, 20]} discontinue other antimicrobials as soon as possible.

Mild-to-moderate disease:

• Vancomycin 125 mg PO q6h for 10d ^[21] or
• Fidaxomicin 200 mg PO q12h for 10d, especially if there is concern for recurrent disease ^[22]
• Bezlotoxumab 10 mg/kg infusion as adjunct for high-risk patients ^[21]

Severe disease:

• Vancomycin 500 mg PO q6h for 10-14d and metronidazole 500 mg IV q8h ^{[22, 21]}
• If there is no clinical improvement, add fidaxomicin 200 mg PO q12h
• Bezlotoxumab 10 mg/kg infusion as adjunct for high-risk patients ^[21]
• Intracolonic vancomycin by enema therapy, 500 mg in 100 mL of saline q6h
• Intracolonic vancomycin by ileostomy creation and colonic lavage
• Consider intracolonic therapy if ileus is present ^[21]

Additional therapeutic options:

• Fecal microbiota transplantation (FMT) ^[23]

Additional adjunctive agents:

• Rifaximin ^[21]
• Nitazoxanide ^[21]
• Tigecycline ^[21]

Diagnostic testing

Diagnostic testing is as follows:

• Patients with acute proctitis will need anoscopy
• A Gram-stained smear of any anorectal exudate should be examined for polymorphonuclear leukocytes (PMNs)
• Patient-collected nucleic acid amplification testing (NAAT) is a preferred diagnostic test for suspected anorectal gonorrhea or chlamydial infection
• Dark-field examinations and tests to detect T pallidum directly from lesion exudate or tissue are the definitive methods for diagnosing early syphilis
• HSV diagnosis can be obtained from viral culture, polymerase chain reaction (PCR) assay, or direct fluorescent antibody (DFA) of vesicle discharge or serologic testing
• Diagnosis of enteric pathogens such as Shigella, Salmonella, Campylobacter, and Yersinia is confirmed by stool culture on selective media
• Stool microscopy can suggest intestinal amebiasis, but it is not specific for E histolytica; antigen testing, serologic examination, and PCR are all useful for specific detection of E histolytica infection
• Diagnosis of C difficile is established via a positive laboratory stool test for C difficile toxins; send stool initially for glutamate dehydrogenase (GDH) antigen test and for toxin antibody test for antibody to toxin A and B; if results are indeterminate, send stool for C difficile PCR
• Clinical criteria for C difficile infection (CDI) - Three or more unformed stools within 24 hours (in the absence of other causes) and a positive stool test or demonstration of pseudomembranous colitis ^[24]
• With a suspected or confirmed diagnosis, contact precautions should be instituted and strict handwashing implemented ^[24]

Special considerations

Special considerations include the following:

• Supportive treatment is the standard treatment for immunocompetent, healthy individuals with Salmonella, Yersinia, or Campylobacter; normally, these diseases are self-limited
• Severe cases of proctitis/proctocolitis refractory to medical treatment may call for surgical intervention (subtotal colectomy, total proctocolectomy, loop ileostomy creation, colonical lavage)
• Complications of C difficile colitis include hypotension, toxic megacolon, bowel perforation, renal failure, and sepsis
• Partner notification and simultaneous treatment are integral to the treatment of sexually transmitted causes of proctitis and proctocolitis