title: Screening the enteroaggregative Escherichia coli activity and detection of the aggA, aafA, and astA genes with novel PCR primers for the Escherichia coli isolates from diarrhea cases in Taiwan.
abstract: Enteroaggregative Escherichia coli (EAggEC) are emerging enteropathogens associated with human diarrhea diseases and food poisoning cases. They show distinctive aggregative pattern of adherence to cultured human epithelial cells. However, EAggEC strains are diverse and not all of them have the aggregative adherence fimbria I (AAF/I), AAF/II and heat-stable enterotoxin 1 (EAST1) genes. We attempted to determine the incidence of EAggEC in E. coli isolates from diarrhea patients in Taiwan and to characterize these EAggEC strains. We used three activity assays including HeLa cell adhesion, human blood hemagglutination and bacterial clumping tests and polymerase chain reaction (PCR) primers designed from an aggregative adherence pattern associated plasmid (pCVD432) to screen the EAggEC strains in 403 E. coli isolates including 63 laboratory isolates and 340 clinical isolates obtained from diarrheal disease cases. All these 403 E. coli strains were also assayed with novel PCR primers designed from AAF/I (aggA), AAF/II (aafA) and EAST1 (astA) genes. Results showed that except for the three EAggEC reference strains, only three clinical isolates were identified as EAggEC strains. Including the reference strains, all the E. coli strains with EAggEC activity generated positive PCR results to the aggA gene based primers, but not to the aafA and astA gene targeted primers.
authors.affiliation: Department of Food Science, National Chung-Hsing University, Taichung, Taiwan, Republic of China.
authors.forename: Cheng-Chih
authors.initials: CC
authors.lastname: Tsai
authors.forename: Shu-Yu
authors.initials: SY
authors.lastname: Chen
authors.forename: Hau-Yang
authors.initials: HY
authors.lastname: Tsen
mesh_terms: D018830:Adhesins, Escherichia coli / Q000235:genetics; D001427:Bacterial Toxins / Q000235:genetics; D002448:Cell Adhesion; D017931:DNA Primers; D003967:Diarrhea / Q000175:diagnosis* / Q000453:epidemiology / Q000382:microbiology; D004768:Enterotoxins / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000175:diagnosis* / Q000453:epidemiology; D029968:Escherichia coli Proteins / Q000235:genetics; D036781:Fimbriae Proteins / Q000235:genetics; D005798:Genes, Bacterial; D006367:HeLa Cells; D006384:Hemagglutination; D006801:Humans; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods*; D013624:Taiwan / Q000453:epidemiology
chemical_list: C108511:AafA protein, E coli; D018830:Adhesins, Escherichia coli; C079725:AggA protein, E coli; D001427:Bacterial Toxins; D017931:DNA Primers; D004768:Enterotoxins; D029968:Escherichia coli Proteins; C034151:heat stable toxin (E coli); D036781:Fimbriae Proteins