title: Differential identification of Entamoeba spp. based on the analysis of 18S rRNA.
abstract: Entamoeba histolytica is known to cause intestinal and extra-intestinal disease while the other Entamoeba species are not considered to be pathogenic. However, all Entamoeba spp. should be reported when identified in clinical samples. Entamoeba polecki, Entamoeba coli, and Entamoeba hartmanii can be differentiated morphologically from E. histolytica, but some of their diagnostic morphologic features overlap. E. histolytica, Entamoeba dispar, and Entamoeba moshkovskii are morphologically identical but can be differentiated using molecular tools. We developed a polymerase chain reaction (PCR) procedure followed by DNA sequencing of specific regions of 18S rRNA gene to differentiate the Entamoeba spp. commonly found in human stools. This approach was used to analyze 45 samples from cases evaluated for the presence of Entamoeba spp. by microscopy and a real-time PCR method capable of differential detection of E. histolytica and E. dispar. Our results demonstrated an agreement of approximately 98% (45/44) between the real-time PCR for E. histolytica and E. dispar and the 18S rRNA analysis described here. Five previously negative samples by microscopy revealed the presence of E. dispar, E. hartmanii, or E. coli DNA. In addition, we were able to detect E. hartmanii in a stool sample that had been previously reported as negative for Entamoeba spp. by microscopy. Further microscopic evaluation of this sample revealed the presence of E. hartmanii cysts, which went undetected during the first microscopic evaluation. This PCR followed by DNA sequencing will be useful to refine the diagnostic detection of Entamoeba spp. in stool and other clinical specimens.
authors.affiliation: Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Helena Lúcia Carneiro
authors.initials: HL
authors.lastname: Santos
authors.forename: Rebecca
authors.initials: R
authors.lastname: Bandea
authors.forename: Luci Ana Fernandes
authors.initials: LA
authors.lastname: Martins
authors.forename: Heloisa Werneck
authors.initials: HW
authors.lastname: de Macedo
authors.forename: Regina Helena Saramago
authors.initials: RH
authors.lastname: Peralta
authors.forename: Jose Mauro
authors.initials: JM
authors.lastname: Peralta
authors.forename: Mackevin I
authors.initials: MI
authors.lastname: Ndubuisi
authors.forename: Alexandre J
authors.initials: AJ
authors.lastname: da Silva
mesh_terms: D000818:Animals; D017931:DNA Primers / Q000235:genetics; D016054:DNA, Protozoan / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics*; D004747:Entamoeba / Q000145:classification* / Q000166:cytology / Q000235:genetics* / Q000302:isolation & purification; D005243:Feces / Q000469:parasitology; D006801:Humans; D010274:Parasitology / Q000379:methods*; D016133:Polymerase Chain Reaction / Q000379:methods*; D012337:RNA, Ribosomal, 18S / Q000235:genetics*; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA
chemical_list: D017931:DNA Primers; D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D012337:RNA, Ribosomal, 18S