Use of Polymerase Chain Reaction, Cell Adhesion, Hemagglutination and Bacterial Clump Formation Tests in Detection of Enteroaggregative Escherichia coli Strains

Abstract

Enteroaggregative Escherichia coli (EAggEC) is one of the pathogenic E. coli strains which may cause diarrhoea. In vitro studies have shown that EAggEC strains could establish a "stacked-brick" like adherence pattern on the surface of tissue culture cells and such a pattern is termed as aggregative adherence (AA). The purpose of this study is to compare the methods of polymerase chain reaction (PCR), HeLa cell adhesion, hemagglutination, and bacteria clumping tests for the specific detection of EAggEC suspected strains. This study isolated 340 E. coli strains from clinical samples of diarrhea cases which were firstly screened with the PCR method for the presence of suspected EaggEC strains. Strains of negative PCR results were also confirmed with HeLa cell adhesion and bacteria clumping tests for the EAggEC activity. Results showed that of these 340 clinical isolates, only three are EAggEC strains. Thus, EAggEC strains accounted for 0.88% in total strains. Also, for the above described methods, the in vitro HeLa cells adhesion test gave the clearest results followed by the bacteria clumping test. The hemagglutination tests might generate ambiguous results.