Bacteriology of anal fistulae

Abstract

Anal fistulae are said to arise from cryptoglandular infection of the anal glands, which lie within the intersphincteric space. The type and virulence of the micro-organism responsible may determine whether an anal fistula develops. The microbiology of chronic anal fistulae has not been reported previously. Twenty-five consecutive anal fistulae were studied prospectively (eight intersphincteric fistulae, 12 trans-sphincteric fistulae, two suprasphincteric fistulae, one extrasphincteric fistula, one superficial fistula, one anovaginal fistula). There were 18 men and seven women, with a median age of 42 (range 22-71) years. Patients with Crohn's disease or acute anorectal suppuration were excluded. In 18 patients, 0.1 ml granulation tissue from the track of the fistula was obtained and processed within 4 h using standard microbiological techniques. Sixty-nine isolates representing at least 17 species were obtained. The predominant organisms were Escherichia coli (22 per cent), Enterococcus spp. (16 per cent) and Bacteroides fragilis (20 per cent). The majority of the growths were obtained only from enrichment. Bacteria from only one patient grew at a dilution of 10(3). Granulation tissue from 25 patients was processed for mycobacterial culture, and Mycobacterium tuberculosis was grown from one patient. No other mycobacterium was isolated. The chronic inflammation in anal fistulae does not seem to be maintained by either excessive numbers of organisms or organisms of an unusual type.

Usefulness of Interferon-Gamma Release Assay for Diagnosis of Tuberculous Fistulae in Ano

“…Anal fistula is the most frequent symptom of anorectal TB (80∼91% of cases) (7)(8)(9) and anal TB is commonly seen in men (4：1 ratio) and …”

Etiology of perianal Crohnʼs disease: Role of genetic, microbiological, and immunological factors

“…42 However, studies assessing microbiological changes in Crohn's fistulae are sparse. One study, in which 13 Crohn's patients with perianal disease had pus aspirated from their fistula tracts and analyzed by standard bacterial culture techniques, reported that Gram-positive organisms, in particular staphylococci, streptococci, and corynebacter, predominated over Gram-negative enteric organisms, 43 in contrast with findings in idiopathic fistula 44,45 where the microbiota found on excised granulation tissue were analyzed and found to be largely of gastrointestinal origin. These trials are limited by differences in the compartments analyzed (exudates versus mucosa) and the use of bacterial culture as opposed to molecular techniques to quantify the microbiota, which are inadequately selective and unable to detect the totality of microbiota within the GI tract.…”

“…Seow-Choen et al 45 studied granulation tissue from the tracks of idiopathic perianal fistulae in 18 patients and processed the samples using standard microbiological techniques. Sixty-nine isolates representing at least 17 species were obtained.…”

S3 guidelines: cryptoglandular anal fistulas

“…Die mikrobiologische Untersuchung weist i. d. R. eine Mischflora auf und ist für die Behandlung der kryptoglandulären Analfisteln nicht relevant [243,382]. Dies wurde auch in einer aktuellen Studie [437] bestätigt.…”