Adhesion patterns in diffusely adherent Escherichia coli (DAEC) strains isolated from children with and without diarrhea

Introduction. Diffusely adherent E. coli (DAEC) is the sixth recognized group of diarrheagenic E. coli. However, its association with diarrhea remains controversial. Variability in the adherence patterns of clinical strains is unknown. Objectives. To compare the adherence patterns between strains isolated from children with and without diarrhea. Materials and methods. A total of 31 DAEC strains were analyzed, 25 from children with diarrhea and 6 from asymptomatic (control) children, isolated from a cohort study of children under one year of age in the southern districts of Lima. DAEC were identifed by PCR (daaD gene). The pattern and adherence score in HEp-2 cell culture were evaluated, Actin polimerization was determined by fuorescence actin staining (FAS) and motility was evaluated by conventional microbiology methods. Results. Diffuse adherence pattern was found in 88% of diarrhea samples and in the total of control strains. The number of bacteria adhered per cell was signifcantly lower in diarrhea samples (p<0.05). However, actin polymerization was greater in diarrhea samples (60% vs. 17%). Motility test was positive in 60% of the diarrhea samples and in all control samples. Conclusions. Our fndings suggest a difference between adherence patterns, actin polymerization and motility between DAEC strains corresponding to diarrhea and control groups. The signifcance of these results must be confrmed with a bigger number of strains and determining the presence of virulence genes in the strains.