Answer to December 2015 Photo Quiz
Year: 2015
Type: article
Abstract: Answer: Intestinal spirochetosis. The colon biopsy specimen showed intestinal spirochetosis. The endoscopic appearance in intestinal spirochetosis tends to be nonspecific, ranging from normal to polypoid areas or erythema (1). A basophilic fringe of spirochetes can be seen attached to the luminal side of the colonic epithelium. These organisms are known to attach to the mature microvilli of mature colonic and rectal epithelia. The spirochetes appear as an accentuated brush border-like layer coating the microvilli of the superficial epithelium, often referred to as a false brush border. Typically, the diagnosis is made by a pathologist examining the biopsy specimen. A Warthin-Starry silver stain for spirochetes can highlight the organism (see Fig. 1C and D in the photo quiz).
Intestinal spirochetosis in humans is caused predominantly by Brachyspira aalborgi and Brachyspira pilosicoli. This condition is thought to be most prevalent in developing countries (2), among homosexual males (3), and among individuals with human immunodeficiency virus (HIV) infection (3). These organisms are slow-growing fastidious anaerobes and thus are infrequently recovered from stool specimens.
While the pathological significance of intestinal spirochetosis is unclear, this condition has been reported to be associated with chronic diarrheal symptoms, especially in HIV-positive individuals. Evidence suggests that invasion of the organism beyond the epithelium may be associated with symptoms that respond to metronidazole (3). Using CLSI guidelines for susceptibility testing of anaerobes, Brooke et al. tested 123 human isolates of Brachyspira pilosicoli, all of which were susceptible to metronidazole, with an MIC90 of 0.25 μg/ml (4). The introduction of PCR-based assays along with immunohistological methods over the past decade may provide the tools to allow us to study the epidemiology and clinical importance of this organism (5).
(See page 3711 in this issue [doi:10.1128/JCM.00005-14] for photo quiz case presentation.)
Source: Journal of Clinical Microbiology
DOI: 10.1128/jcm.00015-14
Institution: University of California, Irvine
Language: English
Subfield: Small Animals
Field: Veterinary
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2902180343