Hiding in Plain Sight: Colonic Spirochetosis in Humans

Abstract

In 1967, Harland and Lee made a startling discovery: in some humans, the colonic epithelium is covered with a "forest" of spirochetes (W. A. Harlan, and F. D. Lee, Br Med J 3:718-719, 1967, https://doi.org/10.1136/bmj.3.5567.718). In this issue of Journal of Bacteriology, Thorell et al. present a systematic analysis of the prevalence and diversity of the spirochetes Brachyspira aalborgi and Brachyspira pilosicoli in the human colon. These and prior studies provide avenues toward resolving important questions: what bacterial and host parameters contribute to this extensive colonization, and what impact does it have on human health?

Keywords: Brachyspira; Brachyspira aalborgi; Brachyspira pilosicoli; gastrointestinal infection; human infection; intestinal colonization.

FIG 1

Human colonic spirochetosis. Spirochetes attach end-on to the colonic epithelium, as demonstrated by electron microscopy. This image is from the landmark 1967 publication by Harland and Lee (3) and is reprinted with permission from the publisher. Arrows indicate microvilli. S, spirochetes; V, reactive vacuole. Bar = 1 μm.