ABSTRACT
Background: Entamoeba histolytica and Entamoeba dispar are morphologically identical. However, the former is highly pathogenic and the latter is not. Aim: To differentiate Entamoeba histolytica from Entamoeba dispar through ELISA and PCR techniques in Colombian isolates from feces. Material and Methods: Descriptive study of Colombian fecal samples from 53 males and 47 women, that were positive for the complex E. histolytica/E. dispar on light microscopy. Positive samples were cultured on Robinson medium to isolate trophozoites. The presence of specific Gal/ GalNAc-lectin was determined by ELISA and polymerase chain reaction in genomic DNA, using the combination of three nucleotides that recognize a variable region of 16S small subunit ribosomal RNA, generating a 166 base pair (bp) product for E. histolytica and 752 pb product for E. dispar. Results: After verification, only eight of the 100 samples were positive for the complex E. histolytica/E. dispar and were cultivated. Isolates were obtained in six cultures, one corresponded to E. histolytica and six to E. dispar. Conclusions: The presence of E. histolytica/E. dispar complex was largely overestimated with light microscopy. In the few samples where isolates were obtained, the technique described differentiated between both strains.
Subject(s)
Female , Humans , Male , Entamoeba/metabolism , Entamoebiasis/parasitology , Colombia , DNA, Protozoan/genetics , Entamoeba histolytica/genetics , Entamoeba histolytica/isolation & purification , Entamoeba/genetics , Entamoeba/isolation & purification , Entamoebiasis/diagnosis , Enzyme-Linked Immunosorbent Assay , Feces/parasitology , Lectins , Polymerase Chain Reaction/methods , Protozoan Proteins , /genetics , Sensitivity and SpecificityABSTRACT
Background. It has been described that the walls of the amebic cyst from Entamoeba invadens are composed mainly of chitin, a polysaccharide of amino-sugars. It is also know that the synthesis of this polysaccharide is closely related to the degradation of the intracellular glycogen in this organisms. Nevertheless, it is not know whether the intracellular glycogen is really the source of the glucose requirements for the synthesis of the cell wall. Methods. To determine the relationship between the wall cyst synthesis and glycogen degradation, it was considered to develop an in vitro culture cell system to label this polysaccharide with radioactive glucose. In this study, a system of 14C-glucose incorporation in axenic cultures of E. invaden was developed. The experiments in the study were carried out to recognize if an increase occurred in the 14C-glucose incorportation into ameba when the amount of the radioctivity used was increased, or whether this incorporation is a dependent metabolic stage. Results. The results showed that the amount of glucose incorportation reached similar values of 4.5 x 10-12 mmol per cell in both cases. A differente slope in the glucose kinetic incorporation between the cultures previously subjected to glucose depletion and the standard cultures was observed. Conclusions. This axenic method of radioactive glucose incorporation in Entamoeba invadens could facilitate the analysis on a greater scale of the metabolism of this nutrient