freundii strain to assess the capacity of DAEC strains to form biofilms alone or with other bacteria, as well as to investigate the occurrence of synergistic effects as seen for EAEC strains. Furthermore, we analyzed characteristics potentially associated with virulence or related to biofilm formation, such as Afa/Dr adhesins, SAT toxin, TTSS, F pili, curli, cellulose and stimulus of IL-8 secretion by epithelial cells. The aim of this work is to study the overall profile of DAEC strains isolated from children and adults, both from cases

of diarrhea and controls, thereby performing a systematic study of DAEC. Results Prevalence of DAEC strains A total of 1,253 E. coli isolates recovered from stool samples of 127 cases of diarrhea in children and 127 asymptomatic controls were examined for the presence of genes belonging to the conserved region of the afa operons (afaB-C), which encode the Afa/Dr PF-3084014 family of adhesins. Since EPEC strains occasionally have these adhesins, the presence of eae gene, typical of this category, was also investigated. One hundred and eighteen afaB-C positive isolates tested negative for eae. In adhesion tests, most strains (95/118 – 80.5%) showed diffuse adherence. Nine strains (7.7%) were non-adherent and one strain (0.8%) adhered in an unclassified pattern. These strains were excluded from the study. Despite the fact that other thirteen

strains (11%) caused cell detachment, learn more diffusely adhering bacteria could be detected in remaining cells, and these strains were included in the sample. Thus, one hundred and eight strains, including 50 from cases of diarrhea and 58 from controls, were considered as DAEC possessing Afa/Dr genes (Table 1). Table 1 DAEC Glutathione peroxidase strains possessing Afa/Dr genes detected among patients and controls Group Children Adults Total   Diarrhea Control Diarrhea Control   Number of subjects enrolled 127 127 143 119 516 Number of subjects harboring DAEC 21 (16.5%) 25 (19.6%) 27* (18.9%) 5* (4.2%) 78 (15.7%) Number of DAEC strains isolated in each group 50 58 27 15 150 *(P < 0.01). The prevalence

of DAEC possessing Afa/Dr genes in cases of diarrhea in children and their controls was similar (Table 1). DAEC strains were detected in 21 of the 127 cases of diarrhea in children (16.5%), and in 25 of 127 asymptomatic controls (19.6%). Association with diarrhea was not found even when the children were stratified by age (comparing children check details younger or older than six months, as well as 12 months). Furthermore, DAEC strains possessing Afa/Dr genes were recovered from 27 out of 143 (18.8%) cases of diarrhea in adults, and from five out of 119 (4.2%) healthy subjects (Table 1). All strains showed diffuse adherence in adhesion tests. Consequently, DAEC strains were found in higher prevalence in cases of diarrhea in adults (P < 0.01). Twenty seven DAEC strains were obtained from adults with diarrhea and fifteen from asymptomatic adults (Table 1).