An investigation of the relationship between clinical features of amoebiasis and Entamoeba histolytica genotypes

Aim: To determine the presence of Entamoeba histolytica/E. dispar and E. moshkovskii in stool samples, tRNA-based short tandem repeat gene polymorphism in E. histolytica isolates, and the relationship between amoeba load and clinical outcome in studies. Materials and methods: This study involved 840 stools samples of individuals having diarrhea/dysentery and individuals who were asymptomatic by using microscopy, culture, E. histolytica antigen ELISA, and conventional/real-time PCR methods. Results: Of the 840 samples analyzed, 4.3% (36/840), 2.6% (22/840), and 7.4% (62/840) of the stool samples were determined to be positive by E. histolytica antigen ELISA, and real-time PCR for E. histolytica and E. dispar, respectively. Thirty-five of the 62 (56.4%) samples positive for E. dispar and 20 of the 22 (91.0%) samples positive for E. histolytica were from dysenteric individuals as revealed by real-time PCR. Although there was no statistically significant difference in patients with diarrhea, a correlation might be seen between amoeba load and clinical outcome in those infected with E. histolytica, since amoeba load was usually determined 10^3 copies/mL or higher in patients with diarrhea. In this study, 3 different genotypes were defined in 16 isolates by using 6 loci (A-L, N-K2, D-A, R-R, S-D, and S^TGA-Q). Conclusion: Our results demonstrated that real-time PCR is a useful, reliable, and sensitive method for the determination of E. histolytica in stools and for differentiation from E. dispar. It is suggested that parasite load might affect clinical outcome.