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Chapter 4: Proctitis, Enteritis & Proctocolitis

Sexually transmitted gastrointestinal syndromes are typically caused by syphilis, gonorrhea, herpes simplex virus (HSV), human papillomavirus (HPV or genital warts), and chlamydia (including lymphogranuloma venereum (LGV)). Other infections may be caused by pathogens not typically considered sexually transmitted, such as shigellosis, Campylobacter sp., salmonellosis, hepatitis A and B, amebiasis, and Giardia lamblia (Giardia) (Table 4-1). All of these infectious diseases, as well as the syndromes of enteritis and proctitis, became very common among men who have sex with men (MSM) in the 1970s and early 1980s. Their incidence decreased over the next couple of decades, probably due to increased safer sex practices. However, in the late 1990s, rectal bacterial STDs increased markedly among MSM in many cities in the United States and Europe. Transmission of these pathogens is facilitated by exposure to multiple sexual partners, by specific sexual practices (especially anal intercourse and anilingus), and by the ability of small inocula of these agents to cause infection. A clinical diagnosis of any new anorectal infection should prompt screening for HIV infection, given the high efficiency of HIV transmission through receptive anal sex.


The sexually transmitted organisms most commonly responsible for anorectal and enteric infections in MSM are shown in Table 4-1. In patients with AIDS, opportunistic gastrointestinal infections such as cryptosporidiosis, microsporidiosis, cytomegalovirus (CMV) or Mycobacteria avium intracellulare infections may occur; these infections are not discussed here.

Table 4-1
Sexually Transmissible Causes of Intestinal or Anal Infections
Chlamydia trachomatis (including LGV serovars)
Klebsiella granulomatis (granuloma inguinale)
Haemophilus ducreyi
Neisseria gonorrhoeae
Treponema pallidum (syphilis)
Campylobacter sp.
Salmonella spp.
Shigella spp.
Yersinia spp.
Cryptosporidia sp.
Dientamoeba fragilis
Entamoeba histolytica
Giardia lamblia
Isospora belli sp.
Cytomegalovirus (CMV)
Herpes simplex virus (HSV)
Human papillomavirus (HPV) (genital warts, anal intraepithelial neoplasia)


Figure 4-1
Diagram of the rectum and anal canal, showing normal anal and rectal structures and the types of epithelium lining them

fig 4-1 diagram of  rectum and anal canal


The normal anorectal anatomy is illustrated in Figure 4-1. Symptoms and signs of infection can vary depending on the exact location of the infection. Proctitis, proctocolitis, and enteritis generally have different infectious etiologies, so it is important to be able to distinguish these syndromes. It is also important to realize that some patients with anorectal or enteric infections may be asymptomatic, and some may have polymicrobial infections.

The term "proctitis" refers to inflammation of the rectal mucosa (i.e., the distal 10-12 cm). Classically, symptoms are similar to those associated with urinary tract infection and include increased urinary frequency, urgency and dysuria. Patients may also complain of constipation, tenesmus, rectal discomfort or pain, passage of bloody stools, and a mucopurulent rectal discharge, which is occasionally misinterpreted by the patient as diarrhea. Findings on rectal exam generally reveal exquisite tenderness. Anoscopy, as seen in Image 1, or sigmoidoscopy may reveal the presence of mucous to diffuse inflammation of the mucosa with friability or discrete ulcerations. If the mucosa is abnormal extending to 12 cm above the anus, then proctocolitis is present. A rectal biopsy can provide histologic confirmation of proctitis and may reveal nonspecific inflammation or changes highly suggestive of certain infections such as gonorrhea, LGV, HSV or syphilis.

Enteritis is an inflammatory illness of the duodenum, jejunum, and ileum; thus, sigmoidoscopy will show no abnormalities. Infectious enteritis is usually caused by ingestion of pathogens, either from fecal-oral sexual contact or via non-sexual means; for example, ingestion of contaminated food or water.  The most common cause of enteritis in an otherwise healthy host is Giardia. Symptoms of enteritis usually occur without signs of proctitis or proctocolitis and consist of diarrhea, abdominal pain, bloating, cramps, and nausea. Additional symptoms may include flatulence, urgency, a mucous rectal discharge, and in severe cases, melena. Systemic symptoms such as fever, dehydration, malabsorption syndrome, weight loss, and myalgia may also be present.

Image 4-1. Proctitis due to C. trachomatis
Image 1.
Proctitis due to C. trachomatis

Perianal lesions caused by syphilis [Image 2], HSV [Image 3], granuloma inguinale, chancroid, and HPV generally resemble the corresponding lesions as they appear elsewhere in the genital area (see chapter 9 on Genital Ulcers). Symptomatic infection of the anal canal is commonly very painful and often results in constipation and tenesmus.


In taking the patient's history, inquire about sexual practices, specifically possible exposure to pathogens known to cause proctitis, proctocolitis, and enteritis, either through sex or gastrointestinal exposure, particularly as indicated by travel history. The physical exam should include inspection of the anus and anoscopy (avoiding or minimizing use of bacteriostatic lubricants which might interfere with bacteriological studies) to identify general mucosal abnormalities. Look for friability and exudate, as well as discrete polyps, ulcerations or fissures, which should be cultured and biopsied if appropriate. In general, patients with symptoms and signs of less than 2 weeks duration can be classified into one of the three syndromes (proctitis, proctocolitis, or enteritis) based on their history and examination. Direct studies of any ulcerative lesions detected (for example, PCR or culture for herpes simplex virus or darkfield microscopy for treponemes, if available) should be pursued if possible.

Clinicians should be aware that infection with several pathogens may occur and that overlapping symptoms may make differentiation on clinical grounds even more difficult.

Image 4-2. Perianal chancres (syphilis)
Image 2.
Perianal chancres (syphilis)
Image 4-3. Rectal HSV infection with perianal ulcers Image 3.
Rectal HSV infection w/ perianal ulcer
Image 4-4. Rectal Gram stain showing intracellular Gram negative diplococci
Image 4.
Rectal Gram stain showing intracellular Gram negative diplococci


  1. Gram-stained smear of the rectal mucosa [Image 4] obtained during anoscopy (≥1 PMN /1000X oil immersion field (OIF) considered indicative of proctitis); cultures for gonorrhoeae, chlamydia, and herpes simplex virus. Nucleic acid amplification tests (NAAT) are not currently FDA approved for use on non-genital specimens but many laboratories have established performance specifications (CLIA standards) for rectal NAATs.
  2. If perianal or rectal ulcers are seen, also perform (as possible)
    1. serologic test for syphilis and
    2. darkfield examination, if available
      - specific test for herpes simplex virus (culture, PCR)
  3. If enteritis or proctocolitis are likely, based on fever, bloody diarrhea, or milder diarrheal symptoms persisting l week without diagnosis:
    1. stool culture for Salmonella, Shigella, and Campylobacter, and
    2. stool examination for ova and parasites


Specific clinical characteristics suggesting proctitis, proctocolitis, and enteritis are shown in Table 4-2. Identifying the appropriate syndrome is important, because it limits the number of pathogens that need to be sought. An abnormal anoscopic exam and/or increased leukocytes on a rectal Gram stain (≥1 PMN/1000X OIF) strongly suggest anorectal infection. If no infectious etiology can be found despite appropriate tests, and a trial of antimicrobial therapy has no effect, consideration of HIV-associated opportunistic pathogens should be made in addition to HIV antibody testing. Other diagnoses such as inflammatory bowel disease should also be considered. Additional noninfectious conditions that could be confused with rectal or enteric infection include trauma, foreign bodies, radiation chemically-induced colitis (due to drugs, soap, lubricants, etc.), and neoplasm.

Table 4-2
Characteristic Features of Infections of the Bowel
Proctitis Rectum Any combination of rectal discharge (including mucous or exudate on stools), rectal pain, tenesmus, or anal pruritus; constipation is common in severe cases. On examination, external anal erythema or lesions may be seen; anoscopy may show any combination of mucosal edema, erythema, bleeding, ulceration, or inflammatory exudate. If a sigmoidoscopy is done, abnormalities are limited to distal 10-12 cm. N. gonorrhoeae, HSV-2, chlamydia (including LGV), syphilis.
Proctocolitis Rectum and colon Symptoms of proctitis, plus diarrhea and/or abdominal cramps; examination as for proctitis, but involvement extends proximally to >12 cm; abdominal palpation may show left lower quadrant tenderness. C. jejuni, Shigella, chlamydia (including LGV), E. histolytica
Enteritis Jejunum, duodenum, and ileum Diarrhea, sometimes bloody; abdominal pain, cramps, nausea, bloating, or fever may also occur; anoscopy normal. Abdominal palpation may show diffuse or localized tenderness. G. lamblia, Shigella, Salmonella, Campylobacter, Yersinia

Figure 4 -2 Algorithm for evaluation and management of proctitis


For a more detailed discussion of these regimens and other treatment considerations, please refer to the CDC 2010 STD Treatment Guidelines at

Gonorrhea, Herpes Simplex Virus, and Syphilis

See Chapter 2 and Chapter 6 for gonorrhea and Chapter 9 for HSV and syphilis management.

Acute Proctitis

If an anorectal exudate is detected on examination or if PMNs are detected on a Gram-stained smear of anal secretions, provide the following therapy while awaiting additional laboratory testing:

Ceftriaxone 250 mg IM in a single dose


Doxycycline 100 mg orally twice a day for 7 days

For patients who present with painful perianal ulcers or ulcers detected on anoscopy, presumptive therapy should include a regimen for both genital herpes and LGV. Appropriate diagnostic testing for LGV should be obtained if possible; if LGV is suspected but specific diagnostic testing is not available, the patient should receive doxycycline therapy at 100 mg orally twice daily for 3 weeks. Specifically, practitioners should consider presumptive therapy for LGV proctitis/proctocolitis with 3 weeks of doxycycline among MSM with clinical evidence for proctitis (including the presence of >10 white-blood cells upon high-power field of an anal specimen) or those with HIV infection.

Targeted Treatment

Chlamydial infection (LGV strains)

Doxycycline 100 mg bid for 3 weeks

Chlamydial infection (non-LGV strains)

Doxycycline 100 mg bid for 7 to 10 days

Herpes proctitis or proctocolitis

Any of the following:

Acyclovir 400 mg orally three times a day for 7-10 days

Acyclovir 200 mg orally five times a day for 7-10 days

Famciclovir 250 mg orally three times a day for 7-10 days

Valacyclovir 1.0 g orally twice a day for 7-10 days.


Metronidazole 500 mg tid for 7 days


Either no treatment (if asymptomatic cyst passer)


Metronidazole 750 mg tid for 10 days often followed by paromomycin 25-30 mg/kg per day TID for 7 days for intraluminal cyst eradication


Ciprofloxacin 500 mg bid for 7 days

Campylobacter enteritis

Erythromycin 500 mg bid x 5 days


Follow-up should be based on specific etiology and severity of clinical symptoms. In the setting of ongoing or recurrent symptoms, clinicians should consider that reinfection can be difficult to distinguish from treatment failure. Many clinicians do not realize that LGV proctitis requires 3 weeks of therapy instead of the one week used for non-LGV chlamydial infections; inadequately treated LGV proctitis should thus be considered in men whose proctitis fails to respond to a single week of doxycycline.


Sex partners of individuals diagnosed with sexually transmitted enteric infections should be evaluated for those diseases diagnosed in the index patient. See appropriate chapters in this book on syphilis, gonorrhea, chlamydial infection, herpes, and HPV.

Confirmed cases of syphilis, gonorrhea, or other reportable diseases should be reported to the state or local health departments.

CDC. Update to CDC's sexually transmitted diseases treatment guidelines, 2010: oral cephalosporins no longer a recommended treatment for gonococcal infections. MMWR 2012:61(31); 590-594

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