The electrophoretic isoenzyme patterns of strains of Entamoeba histolytica isolated in two major cities in Canada
Proctor, E.M.; Wong, Q.; Yang, J.; Keystone, J.S.
American Journal of Tropical Medicine and Hygiene 37(2): 296-301
1987
ISSN/ISBN: 0002-9637 PMID: 2889385 Document Number: 302918
120 isolates of E. histolytica from individuals living in Vancouver, British Columbia (92) and Toronto, Ontario (28) were characterized by electrophoretic patterns of 4 enzymes. 6 known zymodemes (I, II, III, XIV, XVII and XVIII) were identified; a new zymodeme, tentatively designated as XXI, was isolated from a homosexual man in Ontario. In both regions, the non-pathogenic zymodemes I (78) and III (22) were the most common. Positive serology was obtained in 71% of the 9 individuals with pathogenic zymodemes (II in 7 subjects, and XIV in 2 subjects), compared to 8% of individuals with non-pathogenic zymodemes. 43% of subjects with non-pathogenic zymodemes were symptomatic compared to 77.8% of those with pathogenic zymodemes. Clinical symptoms were more frequent in homosexual males (67%) than in heterosexuals infected with non-pathogenic zymodemes (40%). E. histolytica was the only parasite present in 27 cases (in 18 heterosexuals and 9 homosexuals) ; the remainder were infected with 2 or more parasites. The work described, undertaken in Canada, confirms previous, similar observations from various groups around the world. The authors describe and discuss the isoenzyme patterns of 120 cultured isolates of Entamoeba histolytica. Only 9 of those isolates characterized as pathogenic zymodemes, and they "were strongly correlated with clinical symptoms and seropositivity". Of the cultures initiated from homosexual men 34 were shown to be non-pathogenic. A possible new zymodeme is mentioned [but as it was apparently not from a cloned growth it must remain in doubt. As this is the first publication in this area of research from these authors, it is a pity they do not show us pictorial representation of their gel plates, but choose instead to use a diagram.]P.G. Sargeaunt.