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We read with interest the article by Kiesslich et al (Gut 2006;55:591) on recent advances in confocal endomicroscopy, eg, in patients with collagenous colitis. Here we demonstrate that confocal endomicroscopy can be a useful tool to detect intestinal spirochaetosis in vivo.
Intestinal spirochaetosis is characterised by the presence of spirochaetes attached to the apical cell membrane of the colonic epithelium. The prevalence in Western countries is reported as 1.1–5%. However, the prevalence is much higher among people of developing countries (11.4–64.3%) as well as homosexuals and people infected with HIV (20.6–62.5%) (reviewed by Korner and Gebbers1).
Patients with intestinal spirochaetosis can be asymptomatic or symptomatic, presenting with clinical symptoms such as chronic watery diarrhoea, rectal bleeding or abdominal pain. It is not yet clear whether spirochaetes are commensal or responsible for these symptoms.
Because of the unclear clinical relevance of intestinal spirochaetosis, investigations for this bacterium are usually not included in routine diagnostic procedures. If the bacterial load is high, intestinal spirochaetosis can be detected on colonic biopsies stained with haematoxylin & eosin (H&E) as a layer of basophilic organisms adherent to the surface of the intestinal epithelium. In many cases, however, a silver stain like Warthin–Starry has to be applied to detect intestinal spirochaetosis. It is easier to perform an immunostain using an antibody against Treponema pallidum (rabbit polyclonal to Treponema pallidum; Abcam, Cambridge, UK, ab20923, dilution 1:500) which has been reported to cross-react with Brachyspira spp. found in intestinal spirochaetosis, like B aalborgi and B pilosicoli.2 Nevertheless, intestinal spirochaetosis will remain unobserved in many cases.3 Consequently, in vivo visualisation of intestinal spirochaetosis may be of practical interest.
The confocal laser endomicroscope (EC-3870CIFK; Pentax, Tokyo, Japan) is a newly introduced endoscope that combines standard video endoscopy with confocal microscopic imaging of the upper mucosal layer of living tissue during ongoing endoscopy. Images are produced by an argon ion laser generating an excitation wavelength of 488 nm. Intravenously injected fluorescein sodium (10%; Alcon Pharma, Freiburg/Breisgau, Germany) was used as the contrast agent. Acriflavine hydrochloride (0.05%; Sigma Aldrich, Munich, Germany) is applied topically and highlights the superficial cell borders and their nuclei. Confocal images are generated every 7 μm from 0 to 250 μm in mucosal depth with a lateral resolution of 0.7 μm.4
A 50-year-old man with chronic HIV infection (CDC stage B2; first diagnosed in 1992) who displayed no detectable viral load (<40 copies/ml, Cobas Taqman; Roche, Mannheim, Germany) under highly active antiretroviral therapy with zidovudine, lamivudine and nevirapine since 2000, presented with bloating and recurring episodes of watery diarrhoea (up to five stools per day) ongoing for 2 months. Apart from diarrhoea there were no other constitutional symptoms, such as fever or weight loss. Laboratory testing did not reveal any signs of systemic inflammation, the CD4 cell count was 577 cells/μl. Several stool samples showed negative results for enteropathogenic bacteria, Giardia lamblia and other enteric protozoa, helminths and Clostridium difficile toxins A and B.
Colonoscopy was performed using the confocal laser endoscope. Video endoscopically, the colonic mucosa appeared normal. Endomicroscopically, after administrating 5 ml fluorescein (10%) intravenously and 25 ml acriflavine (0.05%) topically, however, bright ring-like bands appeared on the epithelial layer inside the lumina of the colonic crypts (fig 1D,E). Within the upper parts of the lamina propria no abnormalities were seen. Biopsy specimens were fixed in 4% formalin and embedded in paraffin. Sections (3 μm) were stained with H&E. Histopathological examination revealed a dense spirochaetal colonisation of the epithelial layer (fig 1A). The diagnosis was confirmed by immunostaining (insert in fig 1A) and Warthin–Starry silver staining (fig 1B).
The immunohistochemical test for cytomegalovirus on the colonic biopsies was negative. The patient received antibiotic treatment with metronidazole (400 mg three times daily) for 10 days.5 The watery diarrhoea disappeared. After a period of 4 months a follow-up sigmoidoscopy was performed. No spirochaetal colonisation of the intestinal epithelium was found in endomicroscopy and conventional histology indicating successful antibiotic treatment of intestinal spirochaetosis (fig 1C,F). In conclusion, endomicroscopy allows in vivo detection of spirochaetes attached to the intestinal epithelium, displaying a typical pattern with bright ring-like bands inside the lumina of the crypts. The diagnostic management of immunocompromised patients, eg, patients infected with HIV and with persistent diarrhoea should consider intestinal spirochaetosis as a potential cause and, if possible, initiate additional endomicroscopy.
Footnotes
Competing interests: None declared.
Patient consent: Obtained.