title: Efficiency of Direct Microscopy of Stool Samples Using an Antigen-Specific Adhesin Test for Entamoeba Histolytica.
abstract: BACKGROUND
  E. histolyticais among the common causes of acute gastroenteritis. The pathogenic speciesE. histolyticaand the nonpathogenic speciesE. disparcannot be morphologically differentiated, although correct identification of these protozoans is important for treatment and public health. In many laboratories, the screening of leukocytes, erythrocytes, amoebic cysts, trophozoites and parasite eggs is performed using Native-Lugol's iodine for pre-diagnosis.
  
  
  OBJECTIVE
  In this study, we aimed to investigate the frequency ofE. histolyticain stool samples collected from 788 patients residing in the Anatolian region of İstanbul who presented with gastrointestinal complaints. We used the information obtained to evaluate the effectiveness of microscopic examinations when used in combination with theE. histolyticaadhesin antigen test.
  
  
  METHODS
  Retrospective cross-sectional study.
  
  
  METHODS
  Preparations of stool samples stained with Native-Lugol's iodine were evaluated using theE. histolyticaadhesin test and examined using standard light microscopy at ×40 magnification. Pearson's Chi-square and Fisher's exact tests were used for statistical analysis. Logistic regression analysis was used for multivariate analysis.
  
  
  RESULTS
  Of 788 samples, 38 (4.8%) were positive forE. histolyticaadhesin antigens. When evaluated together with the presences of erythrocytes, leukocytes, cysts, and trophozoites, respectively, using logistic regression analysis, leukocyte positivity was significantly higher. The odds ratio of leukocyte positivity increased adhesin test-positivity by 2,530-fold (95% CI=1.01-6.330). Adhesin test-positivity was significant (p=0.047).
  
  
  CONCLUSIONS
  In line with these findings, the consistency between the presence of cysts and erythrocytes and adhesin test-positivity was found to be highly significant, but that of higher levels of leukocytes was found to be discordant. It was concluded that leukocytes and trophozoites were easily misjudged using direct microscopy. Although microscopic examination of samples stained with Native-Lugol's iodine is a cheap and simple method, the confusion of trophozoites with leukocytes may direct the clinician toward an incorrect pre-diagnosis. Because trichrome staining is difficult and time consuming, and results may vary depending on the technician, this method is not preferred in most laboratories. Therefore, an enzyme-linked immunosorbent assay method, which is a more advanced method than polymerase chain reaction, should be used to distinguish betweenE. histolyticaandE. disparin order to achieve an accurate diagnosis.
authors.affiliation: Department of Microbiology and Clinical Microbiology, Ümraniye Training and Research Hospital, İstanbul, Turkey.
authors.forename: Arzu
authors.initials: A
authors.lastname: İrvem
authors.affiliation: Clinic of Gastroenterology, Ümraniye Training and Research Hospital, İstanbul, Turkey.
authors.forename: Kamil
authors.initials: K
authors.lastname: Özdil
authors.affiliation: Clinic of Gastroenterology, Ümraniye Training and Research Hospital, İstanbul, Turkey.
authors.forename: Zuhal
authors.initials: Z
authors.lastname: Çalışkan
authors.affiliation: Department of Microbiology and Clinical Microbiology, Ümraniye Training and Research Hospital, İstanbul, Turkey.
authors.forename: Muhterem
authors.initials: M
authors.lastname: Yücel
keywords: Adhesin test; Entamoeba histolytica; Microscopic examination