title: Underestimated Amoebic Appendicitis among HIV-1-Infected Individuals in Japan.
abstract: Entamoeba histolytica is not a common causative agent of acute appendicitis. However, amoebic appendicitis can sometimes be severe and life threatening, mainly due to a lack of awareness. Also, its frequency, clinical features, and pathogenesis remain unclear. The study subjects were HIV-1-infected individuals who presented with acute appendicitis and later underwent appendectomy at our hospital between 1996 and 2014. Formalin-fixed paraffin-embedded preserved appendix specimens were reexamined by periodic acid-Schiff (PAS) staining and PCR to identify undiagnosed amoebic appendicitis. Appendectomies were performed in 57 patients with acute appendicitis. The seroprevalence of E. histolytica was 33% (14/43) from the available stored sera. Based on the medical records, only 3 cases were clinically diagnosed as amoebic appendicitis, including 2 diagnosed at the time of appendectomy and 1 case diagnosed by rereview of the appendix after the development of postoperative complications. Retrospective analyses using PAS staining and PCR identified 3 and 3 more cases, respectively. Thus, E. histolytica infection was confirmed in 9 cases (15.8%) in the present study. Apart from a significantly higher leukocyte count in E. histolytica-positive patients than in negative patients (median, 13,760 versus 10,385 cells/μl, respectively, P = 0.02), there were no other differences in the clinical features of the PCR-positive and -negative groups. In conclusion, E. histolytica infection was confirmed in 9 (15.8%) of the appendicitis cases. However, only 3, including one diagnosed after intestinal perforation, were diagnosed before the present analyses. These results strongly suggest there is frequently a failure to detect trophozoites in routine examination, resulting in an underestimation of the incidence of amoebic appendicitis.
authors.affiliation: AIDS Clinical Center, National Center for Global Health and Medicine, Shinjuku, Tokyo, Japan.|Department of Infection Control and Laboratory Diagnostics, Internal Medicine, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.|Department of Parasitology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan.
authors.forename: Taiichiro
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: AIDS Clinical Center, National Center for Global Health and Medicine, Shinjuku, Tokyo, Japan kj_s52@hotmail.com.|Department of Medicine, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Koji
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: Department of Surgery, National Center for Global Health and Medicine, Shinjuku, Tokyo, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yano
authors.affiliation: Pathology Division of Clinical Laboratory, National Center for Global Health and Medicine, Shinjuku, Tokyo, Japan.
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Murata
authors.affiliation: Pathology Division of Clinical Laboratory, National Center for Global Health and Medicine, Shinjuku, Tokyo, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Igari
authors.affiliation: Department of Parasitology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Nakada-Tsukui
authors.affiliation: Department of Parasitology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Yagita
authors.affiliation: Department of Parasitology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan.|Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Tomoyoshi
authors.initials: T
authors.lastname: Nozaki
authors.affiliation: Department of Infection Control and Laboratory Diagnostics, Internal Medicine, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Kaku
authors.affiliation: AIDS Clinical Center, National Center for Global Health and Medicine, Shinjuku, Tokyo, Japan.
authors.forename: Kunihisa
authors.initials: K
authors.lastname: Tsukada
authors.affiliation: AIDS Clinical Center, National Center for Global Health and Medicine, Shinjuku, Tokyo, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Gatanaga
authors.affiliation: AIDS Clinical Center, National Center for Global Health and Medicine, Shinjuku, Tokyo, Japan.
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Kikuchi
authors.affiliation: AIDS Clinical Center, National Center for Global Health and Medicine, Shinjuku, Tokyo, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Oka
mesh_terms: D000328:Adult; D000368:Aged; D000913:Antibodies, Protozoan / Q000097:blood; D001064:Appendicitis / Q000453:epidemiology* / Q000209:etiology*; D001065:Appendix / Q000469:parasitology / Q000473:pathology; D004748:Entamoeba histolytica / Q000302:isolation & purification*; D004749:Entamoebiasis / Q000453:epidemiology*; D005260:Female; D015658:HIV Infections / Q000150:complications*; D006651:Histocytochemistry; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012189:Retrospective Studies; D016036:Seroepidemiologic Studies; D055815:Young Adult
chemical_list: D000913:Antibodies, Protozoan
keywords: Entamoeba histolytica; Japan; PCR; STGA-D locus; appendicitis