Characterization of enteroaggregative Escherichia coli isolates

Forty enteraggregative Escherichia coli (EAggEC) previously characterized b y their ability to adhere to HEp-2 cells or/and their hybridization with th e 1-kb EAggEC DNA probe were investigated for the presence of adherence fac tors and heat-stable enterotoxin (EAST1)-encoding genes. Only 45% of the is olates harbored the EAST1-encoding genes as detected by polymerase chain re action. None of them hybridized with an AAF/II-encoding gene specific DNA p robe and 35% (14/40) were positive in a PCR assay using primers specific fo r aggC, an accessory gene of the AAF/I-encoding operon. Cloning and sequenc e analysis of the aggA variant from one isolate, EAggEC 457, revealed 68.9% identity between its deduced amino acid sequence and those of the aggA pro duct from the AAF/I-producing reference strain, E. coli 17.2. No major prot ein subunit was detected at the surface of EAggEC 457 compared to the bacte rial surface extract of E. coli 17.2. (C) 1999 Federation of European Micro biological Societies. Published by Elsevier Science B.V. All rights reserve d.