201312-09

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LETTER TO THE EDITOR

Perianal Fistula Caused by Intestinal Invasive Amebiasis in a Male Patient

with AIDS

Perianal fistula (PF) is an unpleasant condition. The differential diagnosis of anal dermatoses includes inflammatory diseases (e.g., Crohn’s disease), sexually transmitted illnesses (e.g., amebi-asis), nonsexual infectious diseases, and malignant diseases.1 Clini-cians should check for abscess, mass, vesicles/bullae, pustule/ulcer/ sinus tract, or erythema during physical examination to understand the pathophysiology.1Amebiasis is a parasitic infection caused by the protozoan Entamoeba histolytica, which principally affects the colon and the liver. Although most infected patients remain asymp-tomatic, infection is relatively serious in immunocompromised pa-tients, including human immunodeficiency virus (HIV)-positive patients.2 We report the case of an HIV-infected patient with PF caused by intestinal invasive amebiasis (IA) and its favorable outcome by therapy with antimicrobial reagents and surgery.

A 34-year-old HIV-infected Japanese male with a history of same-sex activity presented with a 4-month history of anal pain and bloody stool. He had a low CD4 cell count (20 cells/mm3) and had not received antiretroviral therapy. On anal examination, PF (Figure 1, ar-rows) was found, and feces were excreted through thefistula, which acted like a pseudoanus. The patient had no cutaneous lesions, including in the perianal area (Figure 1). The orifice of the fistula at the rectal site was observed with an endoscope and exhibited pro-nounced ulceration. Erythrophagocytic trophozoites of Entamoeba were identified in fresh feces. Stool cultures to identify bacterial spe-cies (e.g., enterohemorrhagic Escherichia coli or a dysentery bacillus) or acid-fast bacillus (e.g., Mycobacterium tuberculosis or M. avium complex) were shown to be negative. He had positive serum anti-bodies (200-fold) against E. histolytica, which were measured by a fluorescent antibody test as described previously.2_{Amebic dysentery}

was treated with metronidazole, followed by a luminal amebicide. The definitive diagnosis was based on three findings: (1) presence of amebic trophozoites showing characteristic hemophagocytosis, which is specific for E. histolytica infection; (2) positive serum anti-bodies against E. histolytica, and (3) a positive clinical response to metronidazole. A highly active antiretroviral regimen (sanilvudine/ lamivudine/nelfinavir) was also introduced. A colostomy was per-formed to reduce stool entry into thefistula and promote healing. His postoperative course was uneventful. At 1-year follow-up, the fis-tula had disappeared, and the colostomy was closed.

A homosexual AIDS patient with acute fulminant amebic colitis leading to the development of a perianal ulcer has also been re-ported in Japan.3Onset of acute fulminant amebic colitis is often fatal, with a high mortality rate because of serious complications such as colonic perforation and necrotizing colitis.4,5Areas with high incidences of amebic infection include India, Africa, Mexico, and parts of Central and South America. In countries with low

incidence (Taiwan, South Korea, and Australia), IA is uncommon, but reports indicate that amebiasis is an emerging infection, partic-ularly among homosexual men. The prevalence of amebic colitis in Japan was increased in 2009 (0.88%) relative to 2003 (0.16%).6Male sex, age<50 years, a history of syphilis, and HIV infection were in-dependent risk factors for IA. Contact with commercial sex workers was a new risk factor among HIV-negative patients. Homosexual intercourse appears to be a risk factor among HIV-positive patients. Clinicians should consider the contribution of IA when a patient with these risk factors complains of anal pain and bloody stool and exhibits PF.

Figure 1 Feces were excreted through perianal ﬁstula, which acted like a pseudoanus (arrows), and the true anus can be observed below. The patient had no cutaneous lesions, including in the perianal area.

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Journal of Experimental and Clinical Medicine

j o u r n a l h o m e p a g e : h t t p : / / w w w . j e c m - o n l i n e .c o m

J Exp Clin Med 2013;5(6):237e238

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References

1. Mansour M, Weston LA. Perianal infections: a primer for nonsurgeons. Curr Gas-troenterol Rep 2010;12:270e9.

2. Mitarai S, Nagai H, Satoh K, Hebisawa A, Shishido H. Amebiasis in Japanese ho-mosexual men with human immunodeﬁciency virus infection. Intern Med 2001;40:671e5.

3. Torigoe T, Nakayama Y, Yamaguchi K. Development of perianal ulcer as a result of acute fulminant amoebic colitis. World J Gastroenterol 2012;18:4794e7. 4. Hanaoka N, Higuchi K, Tanabe S, Sasaki T, Ishido K, Ae T, Koizumi W, et al.

Fulmi-nant amoebic colitis during chemotherapy for advanced gastric cancer. World J Gastroenterol 2009;15:3445e7.

5. Gupta SS, Singh O, Shukla S, Raj MK. Acute fulminant necrotizing amoebic colitis: a rare and fatal complication of amoebiasis: a case report. Cases J 2009;2:6557, http://dx.doi.org/10.4076/1757-1626-2-6557.

6. Nagata N, Shimbo T, Akiyama J, Nakashima R, Nishimura S, Yada T, Watanabe K, et al. Risk factors for intestinal invasive amebiasis in Japan, 2003e2009. Emerg Infect Dis 2012;18:717e24.

Takashi Takahashi*

Laboratory of Infectious Diseases, Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan Aikichi Iwamoto Division of Infectious Diseases, Advanced Clinical Research Center, Institute of Medical Science, University of Tokyo, Tokyo, Japan *_{Corresponding author.} E-mail: T. Takahashi <taka2si@lisci.kitasato-u.ac.jp>. Sep 5, 2013 Letter to the Editor 238