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Intestinal spirochetosis



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PubMed Search: Intestinal spirochetosis

Giby V. George, M.B.B.S.
Aaron R. Huber, D.O.
Page views in 2022: 6,135
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Cite this page: George GV, Huber AR. Intestinal spirochetosis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/colonspirochetosis.html. Accessed February 7th, 2023.
Definition / general
  • Colonization of the colonic epithelium by the filamentous nontreponemal anaerobic spirochetes, Brachyspira aalborgi or Brachyspira pilosicoli
Essential features
  • Colonization of the colonic epithelium by spirochetes of the Brachyspira species
  • Most commonly asymptomatic but may present with diarrhea or abdominal pain / cramps
  • Diagnosed by histologic examination of colorectal mucosal biopsies that demonstrate a basophilic fringe on the surface epithelium
  • May be confirmed with silver stains (Warthin-Starry, Steiner) or Treponema pallidum immunohistochemistry
  • Typically treated with metronidazole, if symptomatic; otherwise, may be observed
ICD coding
  • ICD-10:
    • A08.8 - other specified intestinal infections
    • A69.9 - spirochetal infection, unspecified
Epidemiology
  • Human intestinal spirochetosis (HIS) was originally recognized in 1967; however, the pathogenicity is still unclear
  • HIS has a global distribution and Brachyspira species have been detected on nearly every continent, with the exception of Antarctica
  • Prevalence rate is highly variable and is not entirely clear from the current literature; however, there appears to be lower prevalence rates (ranging from 0.2% to 3.2%) among healthy people residing in developed countries and higher prevalence rates (ranging from 10.8% to 64.8%) in developing countries
  • In developed nations, the prevalence rates are thought to be highest among men who have sex with men (MSM) and patients with HIV
  • More common in men and patients in the fourth or fifth decades of life
  • Although rare, it may occur in pediatric patients
  • No confirmed seasonality
  • References: Br Med J 1967;3:718, J Gastroenterol Hepatol 2022;37:1222, J Bacteriol 2019;201:e00465, Ann Clin Lab Sci 2020;50:386, Annals Diagn Pathol 2015;19:414, Pediatr Gastroenterol Hepatol Nutr 2019;22:193
Sites
Pathophysiology
Clinical features
  • In most children and adults, human intestinal spirochetosis is asymptomatic and often an incidental histologic finding on endoscopic biopsy material
  • In symptomatic patients, the 2 most common symptoms are diarrhea (often chronic and watery) (51%) and abdominal cramps or pain (46%)
    • Other symptoms may include bloating, weight loss, constipation, nausea, alternating constipation / diarrhea or irritable bowel syndrome-like symptoms and rectal or perirectal bleeding
    • Pediatric patients may develop severe symptoms
  • Brachyspira pilosicoli has a broader host range including swine, birds, humans and nonhuman primates
    • Known cause of diarrhea in pigs and chickens
    • Usually asymptomatic in humans but may cause diarrhea, abdominal pain or perirectal bleeding
    • Critically ill patients may have spirochetemia
  • Brachyspira aalborgi has only been detected in humans, nonhuman primates and opossums
    • Typically, not associated with histologic findings or gastrointestinal symptoms
    • Some believe this is simply a commensal organism
  • Some studies have found an association between human intestinal spirochetosis and juvenile polyps in children
  • References: Ann Clin Lab Sci 2020;50:386, J Gastroenterol Hepatol 2022;37:1222, Pediatr Gastroenterol Hepatol Nutr 2019;22:193, J Bacteriol 2019;201:e00465
Diagnosis
  • Gold standard for diagnosis is histologic examination of an endoscopic colon or rectal biopsy
  • Noninvasive diagnostic methods are not currently routine
  • Reference: J Gastroenterol Hepatol 2022;37:1222
Case reports
Treatment
Gross description
Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Aaron R. Huber, D.O. and @RaulSGonzalezMD on Twitter

Basophilic fringe

Silver stain

Treponema IHC

Intestinal spirochetosis Intestinal spirochetosis Intestinal spirochetosis

Intestinal spirochetosis

Virtual slides

Images hosted on other servers:
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54 year old man with intestinal spirochetosis

Positive stains
  • Organisms may be highlighted by silver stains (Steiner, Warthin-Starry) or immunohistochemical stains for Treponema pallidum, which crossreacts with Brachyspira species
Electron microscopy description
  • Nontreponemal spirochetes are attached perpendicularly to the luminal border of enterocytes
    • The head of the spirochetes anchors between microvilli, while the tail is directed towards the colonic lumen
    • Creates a confluent forest of spirochetes on the surface epithelium, while the microvilli are reduced
  • References: J Gastroenterol Hepatol 2022;37:1222, J Bacteriol 2019;201:e00465
Electron microscopy images

Images hosted on other servers:
Missing Image

Spirochetes attach end on to the colonic epithelium

Sample pathology report
  • Colon, random, biopsy:
    • Intestinal spirochetosis (see comment)
    • Comment: H&E stained sections demonstrate a basophilic fringe on the surface of the colonic epithelium that is highlighted by a Warthin-Starry stain for spirochetes. The findings are compatible with intestinal spirochetosis.
Differential diagnosis
Board review style question #1

A 50 year old man with chronic watery diarrhea had random colon biopsies taken during a colonoscopy, which demonstrated macroscopically normal mucosa throughout the colon. A representative H&E image of his colon biopsies is shown above, as well as a Warthin-Starry stain performed to confirm the morphologic impression. What is the most likely diagnosis?

  1. Enteroadherent Escherichia coli
  2. Intestinal spirochetosis
  3. Normal colonic mucosa
  4. Normal colonic mucosa with prominent glycocalyx
Board review style answer #1
B. Intestinal spirochetosis. The H&E image demonstrates the classic basophilic fringe on the surface epithelium, which is characteristic of intestinal spirochetosis. This is confirmed with the Warthin-Starry stain that highlights the organisms. The findings of intestinal spirochetosis may be subtle and appear like normal colonic mucosa. It is important to evaluate the surface epithelium for the presence of the spirochetes in random colon biopsies performed for diarrhea. Enteroadherent E. coli would be strongly gram negative, if performed.

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Reference: Intestinal spirochetosis
Board review style question #2
Which of the following statements is true regarding human intestinal spirochetosis (HIS)?

  1. All patients diagnosed histologically with human intestinal spirochetosis should be treated with antibiotics
  2. A majority of patients with human intestinal spirochetosis are symptomatic
  3. The most common symptoms in symptomatic patients are diarrhea and abdominal pain / cramps
  4. The most commonly utilized treatment for symptomatic patients is clarithromycin
  5. The pathogenesis, transmission and risk factors for human intestinal spirochetosis are clearly understood and delineated
Board review style answer #2
C. The most common symptoms in symptomatic patients are diarrhea (which is commonly chronic and watery) and abdominal pain / cramps. Most patients with human intestinal spirochetosis diagnosed histologically are asymptomatic and do not require treatment but may be followed or observed. Metronidazole is the most commonly used antibiotic therapy in symptomatic patients. The pathogenesis, transmission and risk factors for human intestinal spirochetosis are still unclear.

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Reference: Intestinal spirochetosis
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