Determinants encoding fimbriae type 1 in fecal Escherichia coli are associated with increased frequency of bacteriocinogeny.

Barbora Štaudová,Juraj Bosák,Eva Slaninková,David Šmajs,Alena Ševčíková,Kristýna Hrazdilová,Martin Vrba,Darina Kohoutová,Lenka Micenková,Jan Bureš,Vladana Woznicová

doi:10.1186/s12866-015-0530-5

Abstract

BackgroundTo screen whether E. coli strains encoding type 1 fimbriae, isolated from fecal microflora, produce bacteriocins more often relative to fimA-negative E. coli strains of similar origin.MethodsPCR assays were used to detect presence of genes encoding 30 bacteriocin determinants (23 colicin- and 7 microcin-encoding genes) and 18 virulence determinants in 579 E. coli strains of human and animal origin isolated from hospitals and animal facilities in the Czech and Slovak Republic. E. coli strains were also classified into phylogroups (A, B1, B2 and D).ResultsfimA-negative E. coli strains (defined as those possessing none of the 18 tested virulence determinants) were compared to fimA-positive E. coli strains (possessing fimA as the only detected virulence determinant). Strains with identified bacteriocin genes were more commonly found among fimA-positive E. coli strains (35.6 %) compared to fimA-negative E. coli strains (21.9 %, p < 0.01) and this was true for both colicin and microcin determinants (p = 0.02 and p < 0.01, respectively). In addition, an increased number of strains encoding colicin E1 were found among fimA-positive E. coli strains (p < 0.01).ConclusionsfimA-positive E. coli strains produced bacteriocins (colicins and microcins) more often compared to fimA-negative strains of similar origin. Since type 1 fimbriae of E. coli have been shown to mediate adhesion to epithelial host cells and help colonize the intestines, bacteriocin synthesis appears to be an additional feature of colonizing E. coli strains.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-015-0530-5) contains supplementary material, which is available to authorized users.

Highlights

To screen whether E. coli strains encoding type 1 fimbriae, isolated from fecal microflora, produce bacteriocins more often relative to fimA-negative E. coli strains of similar origin
Characteristics of E. coli strains Fecal E. coli strains used in this study (n = 579) (Fig. 1) either tested negative for all 18 virulence determinants and were, considered fimA-negative, or the strains were fimA-positive, while still testing negative for all other virulence determinants
Except of 10 isolates, fimApositive isolates were positive for fimH determinants (98.3 % showed both determinants for type 1 fimbriae)

Summary

Introduction

To screen whether E. coli strains encoding type 1 fimbriae, isolated from fecal microflora, produce bacteriocins more often relative to fimA-negative E. coli strains of similar origin. Strains of E. coli differ in a number of important characteristics including genome size [2], gene content and virulence [3]. 80 % of all E. coli strains of fecal origin are able to produce type 1 fimbriae, which are encoded by the chromosomal fim operon [7]. This operon consists of fimAICDFGH genes [8], where fimA encodes the major fimbrial subunit (FimA). E. coli type 1 fimbriae have been shown to mediate adhesion to a number of host cell types (e.g. epithelial and endothelial cells), potentially increasing virulence of fimA-positive E. coli strains [10]

Methods

Results

Discussion

Conclusion