in HIV infection.Proctitis is inflammation of the rectal mucosa; proctocolitis is inflammation extending >15 cm into the sigmoid colon.
Related to penetrative anorectal intercourse and analingus. Rarely found in ♀, most arise in MSM. Proctitis increases transmission of HIV.
Symptoms depend on site. HSV and syphilis infect anal verge and perianal area, and may be painful. Chlamydia and gonorrhoea infect rectum and thus may be less painful (85% can be asymptomatic).
• Rectal inflammation: Neisseria gonorrhoeae, Chlamydia trachomatis genotypes (D-K and LGV genotypes), Treponema pallidum, HSV, syphilis, possibly Mycoplasma genitalium (limited evidence).
• feeling of rectal fullness or incomplete defaecation, leading to urge to defecate (most common)
• feeling of incomplete defaecation (sometimes).
• Shigella spp., Campylobacter spp., Salmonella spp., Entamoeba histolytica, Cryptosporidium spp., CMV
• feeling of incomplete defaecation.
• inflammation of the small intestine: Giardia duodenalis, Cryptosporidium spp.
• large-volume watery diarrhoea
• Anal irritation: Enterobius vermicularis
• Anal itching, especially at night
• Distal proctitis (i.e. distal 12–15 cm of the rectum):
• loss of normal vascular pattern (although may not be evident in distal 10 cm of normal rectum)
• inflammatory mass (sometimes, e.g. with syphilis and LGV).
• Proctocolitis: as for distal proctitis, but changes beyond rectosigmoid junction.
• Enteritis: normal rectal mucosa unless concurrent infection with organisms causing proctitis.
• Acute anorectal symptoms related to peno-anal intercourse or the insertion of a fist, forearm, or foreign body. May lead to:
• fissures, ulcers, tears, and rectal perforation
• Chronic symptoms (non-specific proctitis): possibly related to recurrent trauma associated with rectal coitus and associated with an 8-fold in HIV infection.
• Neisseria gonorrhoeae (
Chapter 8, ‘Clinical features’, pp. 140–142).
• Chlamydia trachomatis ( Chapter 9, ‘Clinical features’, pp. 152–153).
• Treponema pallidum ( Chapter 7, ‘Clinical features of acquired syphilis’, pp. 120–122).
• HSV ( Chapter 22, ‘Clinical features’, pp. 280–281).
• Tropical STIs: chancroid, LGV (current epidemics and endemic outbreaks in MSM in Western Europe and America), and granuloma inguinale ( Chapter 18, ‘Tropical genital and sexually acquired infections’, pp. 245–253).
• HIV infection ( Chapter 42, ‘Enteric disease’, pp. 495–500, and ‘Anal disease’, pp. 501–502).
• Mycoplasma genitalium (limited evidence for causative association; Chapter 10, Box 10.1, p. 166).
If altered bowel habits, take stool samples for culture and microscopy for ova, cysts, and parasites. Proctoscopy, swabs for C. trachomatis (including LGV), N. gonorrhoeae, +/– M. genitalium. Syphilis serology, HIV serology.
Consider empiric treatment of proctitis for N. gonorrhoeae and C. trachomatis.
• Usual spread: hand to mouth, fomites, water, and food. Outbreaks reported in MSM.
• Incubation period 2–7 days: apyrexial; frequent loose stools usually resolving in a week. Occasionally, chronic proctocolitis develops. Reactive arthritis may complicate. Prepubertal ♀ may develop vaginitis, especially with S. flexneri.
• Treated conservatively with bed rest, fluid replacement, and anti-motility drugs if necessary. Unless severe or patient has AIDS, antibiotics should be avoided to 
risk of resistance, normally self-limiting. If required, drug choice informed by local antimicrobial resistance pattern.
• Usual spread: food or water contaminated with faecal material, but clusters reported amongst MSM, considered to have been spread sexually. Non-typhi serotypes have not been recognized as sexually transmitted, despite their importance as a cause of bloodstream infection in those with HIV infection.
• Patient may be systemically unwell with fever.
• Diagnosed by stool culture and/or blood culture.
• Should be treated with antibiotics, depending on antimicrobial sensitivity.
• Usual spread: contaminated water, food, and milk. In MSM sporadic case reports and higher rates in those with proctocolitis (compared with asymptomatic controls).
• Incubation period up to 10 days: sudden diarrhoea with abdominal pain, malaise, pyrexia, muscle, and joint pains. Usually resolves in 10 days. Reactive arthritis rarely.
• Diagnosed by stool culture and serology.
• No treatment unless severe; antibiotics guided by sensitivity pattern.
It has been suggested that H. pylori may be transmitted by the ingestion of infected vomit and regurgitated food during sexual contact, although there is no firm evidence.
Only in severely immunocompromised patients in the context of HIV infection with CD4 counts <100/mm3.
• Usual spread: oral–faecal (in poor social conditions), by water or animal contact. Symptomatic disease more commonly associated with HIV infection, where outbreaks occur. Sporadic cases in immunocompetent MSM, associated with multiple contacts (especially at sex-on-premises venues) and anal sex.
• Offensive watery diarrhoea with abdominal pain, low-grade pyrexia, anorexia, and vomiting, which spontaneously resolves in 1–3 weeks.
• detecting oocysts in faecal samples
• jejunal, colonic, rectal biopsies showing various stages of the organism within enterocytes
• cryptosporidial antigen detection using enzyme immuno-assay or direct immunofluorescence tests
• PCR for cryptosporidium is developed.
• Treatment: no specific treatment, but anti-motility drugs as required. Where severe and intractable, particularly in HIV, nitazoxanide or paromomycin may be used.
• Usual spread: water or food contaminated with faecal material. Sexual transmission recognized, especially in MSM.
• Incubation period 1–14 days: sudden onset of foul-smelling diarrhoea, abdominal pain, and distension. Stools float due to steatorrhoea with malabsorption contributing to weight loss. Symptoms resolve in 2–6 weeks and by 3 months in most.
• microscopy of fluid stool samples for trophozoites and cysts, or solid samples for cysts—repeated examinations (at least 3) are often required
• jejunal biopsy if clinical suspicion and negative stools
• antigen detection tests (available and more sensitive than single-specimen microscopy, but at least two samples should be submitted).
• Treatment: oral metronidazole 2 g daily for 3 days, or 400 mg tid for 5 days or tinidazole 2 g orally as a single dose.
• Usual spread: from faecally contaminated water and food (infecting about 10% of the world’s population). The non-pathogenic strain, reclassified as Entamoeba dispar, is commonly found in faeces of MSM.
• >90% are asymptomatic. Symptoms include bloody diarrhoea, abdominal discomfort, weight loss, and fever with colitis in >20%. Invasive disease includes hepatic abscess and granulating ulceration around the anus and genitalia, but is rare in MSM.
• detecting trophozoites on diarrhoeal stool samples, rectal exudate, or scrapings from rectal ulcers by microscopy as E. histolytica if trophozoites contain red blood cells
• detecting cysts in diarrhoeal or formed stools by microscopy, differentiating between E. histolytica and the non-pathogenic E. dispar by PCR
• serology (for invasive disease).
• oral metronidazole 800mg 3 times a day or tinidazole 2g daily, both for 5-8 days (for trophozoites)
• simultaneous oral diloxanide furoate 500 mg tid for 10 days (to eliminate all bowel infection)
• hepatic abscesses may require aspiration if large or close to liver capsule.
• Usual spread: by food or fomites contaminated by ova (especially in children). Associated with analingus in MSM.
• Rarely causes vaginal infection in prepubertal girls. Cause pruritus ani (or vulvo-vaginitis in young girls).
• Diagnosed by seeing the adult worm in the anal canal or detecting ova from the peri-anal skin by microscopy using material collected on transparent adhesive tape.
• Treatment: oral mebendazole single 100 mg dose, or oral piperazine single 4 g dose repeated in 14 days. Neither treatment is advised in pregnancy.
Reports of detection in faeces of MSM STI clinic attenders (rarely sexually transmitted).