title: Fimbrial adhesins produced by atypical enteropathogenic Escherichia coli strains.
abstract: Atypical enteropathogenic Escherichia coli (aEPEC) has emerged as a significant cause of pediatric diarrhea worldwide; however, information regarding its adherence mechanisms to the human gut mucosa is lacking. In this study, we investigated the prevalence of several (fimA, ecpA, csgA, elfA, and hcpA) fimbrial genes in 71 aEPEC strains isolated from children with diarrhea (54 strains) and healthy individuals (17 strains) in Brazil and Australia by PCR. These genes are associated with adhesion and/or biofilm formation of pathogenic and commensal E. coli. Here, the most prevalent fimbrial genes found, in descending order, were hcpA (98.6%), ecpA (86%), fimA (76%), elfA (72%), and csgA (19.7%). Phenotypic expression of pili in aEPEC strains was assessed by several approaches. We were not able to detect the hemorrhagic coli pilus (HCP) or the E. coli laminin-binding fimbriae (ELF) in these strains by using immunofluorescence. Type 1 pili and curli were detected in 59% (by yeast agglutination) and 2.8% (by Congo red binding and immunofluorescence) of the strains, respectively. The E. coli common pilus (ECP) was evidenced in 36.6% of the strains on bacteria adhering to HeLa cells by immunofluorescence, suggesting that ECP could play an important role in cell adherence for some aEPEC strains. This study highlights the complex nature of the adherence mechanisms of aEPEC strains involving the coordinated function of fimbrial (e.g., ECP) and nonfimbrial (e.g., intimin) adhesins and indicates that these strains bear several pilus operons that could potentially be expressed in different niches favoring colonization and survival in and outside the host.
authors.affiliation: Department of Molecular Genetics and Microbiology, Emerging Pathogens Institute, University of Florida, 2055 Mowry Rd., Gainesville, FL 32610, USA.
authors.forename: Rodrigo T
authors.initials: RT
authors.lastname: Hernandes
authors.forename: Irina
authors.initials: I
authors.lastname: Velsko
authors.forename: Suely C F
authors.initials: SC
authors.lastname: Sampaio
authors.forename: Waldir P
authors.initials: WP
authors.lastname: Elias
authors.forename: Roy M
authors.initials: RM
authors.lastname: Robins-Browne
authors.forename: Tânia A T
authors.initials: TA
authors.lastname: Gomes
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Girón
mesh_terms: D018829:Adhesins, Bacterial / Q000096:biosynthesis* / Q000235:genetics; D018830:Adhesins, Escherichia coli / Q000096:biosynthesis* / Q000235:genetics; D001315:Australia; D001422:Bacterial Adhesion; D001938:Brazil; D004269:DNA, Bacterial / Q000235:genetics; D003967:Diarrhea / Q000382:microbiology; D054308:Enteropathogenic Escherichia coli / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism* / Q000472:pathogenicity; D004847:Epithelial Cells / Q000382:microbiology; D004927:Escherichia coli Infections / Q000382:microbiology; D020869:Gene Expression Profiling; D006367:HeLa Cells; D006801:Humans; D016133:Polymerase Chain Reaction
chemical_list: D018829:Adhesins, Bacterial; D018830:Adhesins, Escherichia coli; D004269:DNA, Bacterial