Specific Organisms and Therapeutic Regimens
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 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 250 mg IM as a single dose together with azithromycin 1 g PO as a single dose or
-
Cefixime 400 mg PO as a single dose together with azithromycin 1 g PO as a single dose
-
Concurrent treatment for chlamydial infection should also be given unless this infection has been excluded by microbiologic testing
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
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)
-
Presumptive treatment should be considered for men who have sex with men (MSM) with proctitis and a positive rectal chlamydia test [9]
T pallidum
Regimens are as follows:
-
Benzathine penicillin G 2.4 million units IM as a single dose (first line)
-
Procaine penicillin 600,000 units IM for 10-14d (second line)
-
Penicillin allergy - Doxycycline 200 mg PO q24h (or 100 mg PO q12h) for 14d or
-
Azithromycin 2 g PO as a single dose
-
HIV infection - Benzathine penicillin G 2.4 million units IM as a single dose for early latent syphilis
HSV
5-Day regimens for first-time infection are as follows:
-
Acyclovir 200 mg PO five times daily or
-
Acyclovir 400 mg PO q8h or
-
Famciclovir 250 mg PO q8h or
-
Valacyclovir 500 mg PO q12h
5-Day to 10-day regimens for HIV-infected patients are as follows:
-
Acyclovir 200-400 mg IV five times daily or
-
Valacyclovir 0.5-1 g IV q12h or
-
Famciclovir 250-500 mg IV q8h
Shigella species
Regimens are as follows [10] :
-
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 [11, 12] :
-
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 (at least 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 [13, 14, 15, 16] :
-
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, [17, 18, 19] discontinue other antimicrobials as soon as possible.
Mild to moderate disease:
-
Metronidazole 500 mg PO q8h for 10-14d or
-
Metronidazole 250 mg PO q6h for 10-14d or
-
Vancomycin 125 mg PO q6h for 10-14d or
-
Fidaxomicin 200mg PO q12h for 10d, especially if there is concern for recurrent disease [20]
Severe disease:
-
Vancomycin 125 mg PO q6h for 10-14d and metronidazole 500 mg IV q8h [20]
-
If there is no clinical improvement, add fidaxomicin 200 mg PO q12h
-
Intracolonic vancomycin by enema therapy, 500 mg in 100 mL of saline q6h
-
Intracolonic vancomycin by ileostomy creation and colonic lavage
Additional therapeutic options:
-
Fecal microbiota transplantation (FMT) [21]
Newer FDA-approved therapeutic options:
-
Monoclonal antibody therapy with bezlotoxumab [21]
Emerging but not yet validated therapeutic options:
-
Cadazolid
-
Surotomycin
-
Tigecycline
-
Ridinilazole [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 [22]
-
With a suspected or confirmed diagnosis, contact precautions should be instituted and strict handwashing implemented [22]
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