Escherichiacoli DERIVED FROM DIFFERENT SOURCES SHARE ANTIGENIC CHARACTERISTICS WITH Shigellaboydii 18AND VIRULENCE FACTORS WITH ENTEROTOXIGENIC E. coli

Genotypic studies have shown that enteroinvasive Escherichia coli (EIEC) and Shigella form a single pathotype sharing a common composition of carbohydrates in the lipopolysaccharide (LPS).In this study 23 E. coli strains isolated from different sources, were characterized. Serotyping was performed with 187 O and 53 H E. coli and 46Shigella sera samples. PCR assays to lacY, lacZ, uidA,cyd, ipaH, wzx,wzy,ltA,stp, cfaI,sc3 and phylogenetic groups were performed. A serum against the E. coli 44037 strain was obtained. Serotyping of 23 strains only showed reaction against S. boydii 18 and 44037antisera and were positive for lacY, lacZ, uidA and cyd, but negative for ipaH. The same gene analysis ofS. boydii 18 strain showed positive reaction for ipaH, uid andcyd but negative for lacZ and lacY. Both E. coli and S. boydii 18 strains amplified wzx and wzy genes. The genes ltA,stp, cfaI and sc3 were detected in 14 (61%), 6 (26%), 21 (91%) and 13 (57%) of E. coli strains. The phylogenetic analysis included the E. coli strains in: clade I (35%), and A (22%), B1 (22%), B2 (13%) and D (4 %) groups. The 23 E. coli strains isolated from children with diarrhea and dairy cattle reacted against S. boydii 18 but that amplified ETEC genes, constitute a new serogroup (44037) with the serotypes 44037:NM, H2 and H16 in children and 44037:H3, H9 and H48 from dairy cattle.