2 and 45.2%

respectively). These rates are comparable or better than values for other probes for aggregative or diffusely adherent E. coli. However the false positives identified by the daaC probe were not randomly distributed across E. coli categories. The daaC probe recognized 18.8% (9 out of 48) of aggregative adherent strains but only 1.1% of non-adherent strains (Table 3, p < 0.0001; Fishers exact test). Table 3 Adherence patterns of 509 isolates collected prospectively from 130 travellers with diarrhoea and their hybridization to the daaC probe. Adherence pattern Number of isolates showing NVP-HSP990 in vivo pattern (n = 509) Number (%) of isolates hybridizing to the daaC probe AA 48 9 (18.8) DA 52 28 (53.8) AA/DA 49 22 (44.9) Other adherence patterns (non AA or DA) 179 1 (0.6) Non-adherent 181 2 (1.1) AA = aggregative adherence; DA = diffuse adherence; AA/DA = elements of both aggregative and diffuse adherence To verify that the hybridizing aggregative adherent strains were true

and typical EAEC, that is strains carrying a partially conserved AZD9291 Selleckchem NCT-501 plasmid referred to as pAA, we screened them for EAEC virulence loci. Only one of the nine aggregative adherent daaC-positive strains hybridized with the CVD432 probe [6], but seven of the nine strains hybridized with at least one other EAEC probe (the pAA-borne aggC for aggregative Clomifene adherence fimbrial usher [18] or aap for dispersin [19] or the chromosomal gene pic

for mucinase, which is also present in Shigella [20]). Only one daaC-positive strain showing aggregative adherence did not hybridize with one of the four EAEC probes we employed. Importantly, all but one of nine aafA-positive EAEC strains identified among the 509 E. coli isolates hybridized with the daaC probe. Four of the nine daaC-positive EAEC strains were from the same individual and probably clonal. The other five were from five separate patients, who were recent returnees from four different countries. Overall, evidence from two independently derived strain sets suggests that the daaC probe recognizes a specific subset of EAEC, that is strains that possess aafA. The daaC cross-hybridizing locus in EAEC is aafC The daaC probe is excised from plasmid pSLM862 with PstI prior to use (7). We used vector-priming M13 oligonucleotides to sequence the pSLM862 insert, which we have deposited in the Genbank database (Accession Number EU010379). A BLAST search of the Genbank nucleotide database revealed that the daaC probe was 97% identical to draC/afaC/dafaC genes from other, diffuse-adherence associated operons in the Genebank database (Accession numbers AF325672.1, X76688.1 and AF329316.1). A BLAST search of the recently completed genome of cross-hybridizing EAEC strain 042 at http://​www.​sanger.​ac.