Biofilm-like structures and pathogenicity ofEscherichia hermanniiYS-11, a clinical isolate from a persistent apical periodontitis lesion

Abstract

Escherichia hermannii, formerly classified as enteric group 11 of Escherichia coli, is considered to be nonpathogenic. In this report, we described some of the pathogenic properties of a viscous material-producing E. hermannii strain YS-11, which was clinically isolated from a persistent apical periodontitis lesion. YS-11 possessed cell surface-associated meshwork-like structures that are found in some biofilm-forming bacteria and its viscous materials contained mannose-rich exopolysaccharides. To further examine the biological effect of the extracellular viscous materials and the meshwork structures, we constructed a number of mutants using transposon mutagenesis. Strain 455, which has a transposon inserted into wzt, a gene that encodes an ATP-binding cassette transporter, lacked the expression of the cell surface-associated meshwork structures and the ability to produce extracellular materials. Complementation of the disrupted wzt in strain 455 with an intact wzt resulted in the restoration of these phenotypes. We also compared these strains in terms of their ability to induce abscess formation in mice as an indication of their pathogenicity. Strains with meshwork-like structures induced greater abscesses than those induced by strains that lacked such structures. These results suggest that the ability to produce mannose-rich exopolysaccharides and to form meshwork-like structures on E. hermannii might contribute to its pathogenicity.

Complete Genome Sequence of Rothia mucilaginosa DY-18: A Clinical Isolate with Dense Meshwork-Like Structures from a Persistent Apical Periodontitis Lesion

“…If allowed to progress, apical periodontitis can cause the destruction of supporting connective tissues and bones, ultimately resulting in tooth loss. The ability to produce extracellular matrix and to form biofilms is recently considered to be crucial for microorganisms that are present in a root canal to resist the intraroot canal procedures of disinfection, to occupy apical foramina of teeth, and to cause persistent chronic inflammatory lesions [9,[12][13][14]. For future studies to genetically clarify the mechanism of matrix production, we have determined a complete genome sequence of DY-18 with a combined strategy of pyrosequencing and paired-end sequencing.…”

Comparison of the virulence of exopolysaccharide-producing Prevotella intermedia to exopolysaccharide non-producing periodontopathic organisms

“…Complementation of this gene to the transposant restored and dramatically augmented the formation of meshwork structures. Our studies using an abscess model in mice indicated that this EPS phenotype might be involved in the pathogenicity of this organism [36]. Likewise, as described above, EPS productivity could be associated with P. intermedia and P. nigrescens pathogenicity [7,8].…”

“…[33] reported that Aggregatibacter actinomycetemcomitans has a gene cluster which is homologous to E. coli pgaABCD and encodes the production of poly-ß-1,6-GlcNAc (PGA) [34]. Rothia mucilaginosa DY-18 [35] and Escherichia hermannii YS-11 [36] isolated from persistent apical periodontitis lesions produced EPS and exhibited cell surface meshwork structures. The meshwork structures of E. hermannii YS-11 disappeared when wzt , one of the ABC-transporter genes, was disrupted by transposon random insertion mutagenesis.…”

PICC-associated infection with Escherichia hermannii: A case report and review of the literature

“…The species was felt to be non-pathogenic except in immunocompromised hosts. Yamanaka et al in 2009 demonstrated strains that were able to produce mannose-rich exo-polysaccharides and mesh-like structures, similar to some biofilm forming bacteria, suggesting a mechanism of pathogenicity of E. hermannii that lends itself well to development of CRBSIs [4]. …”