Indian Journal of Pathology and Microbiology

: 2018  |  Volume : 61  |  Issue : 1  |  Page : 151--152

Intestinal spirochetosis: The hue is the cue

Purnima Malhotra, Minakshi Bhardwaj 
 Department of Pathology, PGIMER, Dr. Ram Manohar Lohia Hospital, New Delhi, India

Correspondence Address:
Purnima Malhotra
Department of Pathology, PGIMER, Dr. Ram Manohar Lohia Hospital, New Delhi

How to cite this article:
Malhotra P, Bhardwaj M. Intestinal spirochetosis: The hue is the cue.Indian J Pathol Microbiol 2018;61:151-152

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Malhotra P, Bhardwaj M. Intestinal spirochetosis: The hue is the cue. Indian J Pathol Microbiol [serial online] 2018 [cited 2021 Jul 31 ];61:151-152
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Human intestinal spirochetosis (IS) is a condition defined histologically by the presence of spirochetal microorganisms attached to the apical cell membrane of colorectal epithelium. Prevalence rates vary from 1.1% to 5% in developed countries with higher rates reported in rural regions of developing countries.[1] However, majority of the cases are reported in homosexuals or immunocompromised individuals. We report a case of IS in an immunocompetent heterosexual male.

A 30-year-old male presented to the gastroenterology outpatient clinic with complaints of fever and pain in the right lower quadrant for 2 months. There was a history of watery diarrhea off and on. There was no history of melena, passage of mucus, or weight loss. Stool R/M and culture results were noncontributory. Colonoscopy showed two small subcentimetric nodules in the cecum. Rest of the colon was unremarkable. There was no evidence of ulceration, friability, erythema, or loss of vascular pattern.

Biopsy showed maintained crypt architecture with moderate mononuclear inflammatory infiltrate in lamina propria. A prominent violaceous hue was noted on the luminal aspect of the surface epithelial cells producing a false brush border [Figure 1]. This was produced by a hematoxyphilic layer of spirochetes covering the luminal aspect of mucosa. The spirochete density was higher in the mouths of the crypts than on the surface. Periodic acid-Schiff (PAS) and silver stains highlighted the filamentous spiral-shaped bacilli embedded on the epithelial cell surface producing a fuzzy border [Figure 2] and [Figure 3]. There was a focal flattening of surface epithelium and mild increase in intraepithelial lymphocytes. There was no evidence of cryptitis/crypt abscess formation. Lamina propria showed moderate mononuclear inflammatory infiltrate composed of lymphocytes, plasma cells, and eosinophils. No neutrophilic infiltrate was noted. A diagnosis of colonic spirochetosis was rendered. Patient was treated with a course of metronidazole 500 mg qid for 10 days. There was complete resolution of symptoms.{Figure 1}{Figure 2}{Figure 3}

Harland and Lee coined the term IS in 1967.[2]

Human IS is colonization of the colon/cecum by nonpathogenic spirochetes. It is commonly seen in homosexuals, HIV-infected individuals, and people living in poor sanitation conditions. Few cases are reported in immunocompetent patients.[3] The most common species causing IS are Brachyspira aalborgi and Brachyspira pilosicoli.[4] These are anaerobic spirochetes of the Brachyspiraceae family.

Majority of the cases are asymptomatic. Some present with self-limited or chronic watery diarrhea and vague abdominal pain. Uncommon presentations include nausea, malaise, rectal bleeding, weight loss, and failure to thrive in children.[5] Rare cases of spirochetemia with multiple organ failures have been reported.[1] Homosexuals and HIV-infected individuals are more likely to be symptomatic. Our patient was symptomatic and presented with fever, abdominal pain, and intermittent diarrhea. He was heterosexual and immunocompetent.

Endoscopic findings are variable and nonspecific ranging from normal to erythematous and rarely polypoid mucosa. Small subcentimetric nodules were detected in the present case on colonoscopy.

Microscopic appearance is diagnostic showing colonization of colonic mucosa by rows of spiral organisms embedded in the epithelial cell border. This produces a violaceous hue on hematoxylin and eosin sections. PAS and silver stains confirm and highlight the same. These also help in differentiating spirochetes from a thickened glycocalyx, patchy accentuation of mucin, and rarely coliforms embedded in surface mucosa. The organism may be limited to one or two of a series of biopsies and is sometimes limited to the mouths of crypts. Morphologic abnormalities of the mucosa itself are usually not seen. Some cases may show a mild or focal increase in inflammatory cells with some cryptitis. Rare cases have shown features of lymphocytic colitis or focal active colitis.

The morphology of a thickened glycocalyx may mimic spirochetosis, especially when hematoxylin stain is strong or on use of certain hematoxylin types like Harris's which highlight mucus. However, mucus staining is patchy whereas spirochetes are more uniformly distributed with special predilection for the mouth of crypts. Silver stain will highlight the organisms and clinch the diagnosis. Heavy infestation of coliforms, when embedded in surface mucus layer, may rarely mimic spirochetosis. These may even be highlighted on silver stain. However, culture and serology results help in distinction.

Treatment with metronidazole has been shown to eliminate the spirochetes.[6] Our patient showed a prompt and complete response to a 10-day course of metronidazole (500 mg qid). Awareness of this entity and routine screening of surface epithelium of all large bowel biopsies for these organisms facilitates specific diagnosis and cure for patients of IS presenting with nonspecific colitis-like symptoms.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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