Human intestinal spirochetosis--a review

Abstract

Human intestinal spirochetosis (IS) is a condition defined histologically by the presence of spirochetal microorganisms attached to the apical cell membrane of the colorectal epithelium. Intestinal spirochetes comprise a heterogeneous group of bacteria. In humans, Brachyspira aalborgi and Brachyspira pilosicoli predominate. Prevalence rates of IS are low where living standards are high, in contrast to poorly developed areas where IS is common. Homosexuals and HIV-infected individuals are at high risk of being colonized. Clinical significance in individual cases has remained unclear up to now. A review of the literature assumes that invasion of spirochetes beyond the surface epithelium may be associated with gastrointestinal symptoms which respond to antibiotic treatment (metronidazole), whereas individuals lacking this feature may be mostly asymptomatic. Of unknown reason, homosexual and HIV-positive men as well as children are more likely to be symptomatic irrespective of invasion. Rare cases of spirochetemia and multiple organ failure have been reported in critically ill patients with IS.

Keywords: HIV-infection; commensals; human intestinal spirochetosis; intestinal bacterial invasion; microscopic colitis; spirochetemia.

Table 1. Classification of Spirochetes [30]

Figure 1. Exfoliative cytology of the rectal mucosa in human spirochetosis with many spirochetes between rod-like bacteriae. Warthin-Starry silver stain. x600.

Figure 2. Histology of human intestinal spirochetosis. Hematoxylin-Eosin. x350.

Figure 3. Human intestinal spirochetosis in the vermiform appendix. Warthin-Starry silver stain. x350.

Figure 4. Immunohistochemical detection of human intestinal spirochetosis with signs of invasion. Strept-Avidin technique. x680.

Figure 5. Human intestinal spirochetosis in transmission electron microscopy. x3500.