Adherence Patterns of Verotoxigenic Escherichia coli (VTEC) Non-O157 Strains Isolated from Faecal Samples in Iran

The adherence property of 70 verotoxigenicE. coli (VTEC) strains, not belonging to O157: H7 serotype (non-O157) was checked on HeLa cells adherence assay. These strains were isolated from patients with diarrhea and healthy individuals. The results obtained in this study revealed that localised adherence (LA) was manifested by 3 strains of which two belonged to serogroups O111, O127 and the third one was non-enteropathogenicE. coli. The LA pattern was not found among strains isolated from healthy persons (P<0.001). Diffuse adherence (DA) was exhibited by six strains equally distributed among both groups and none of them belonged to enteropathogenic strains. However, aggregative adherence (AA) was manifested by 9 strains and was the most frequent among VTEC strains isolated from diarrheal cases (P<0.001) and was comprised of non-enteropathogenicE. coli strains. Non-specific adherence (NSA) was observed in 17 strains. Overall, the results obtained revealed that AA and LA adherence were significantly (P<0.001) associated with strains isolated from patients.