Diarrhea-associated biofilm formed by enteroaggregative Escherichia coli and aggregative Citrobacter freundii: a consortium mediated by putative F pili

BMC Microbiology

Research Article

Ana CG Araújo¹  Ana CMM Gomes¹  Thiago N Silva²  Loreny G Giugliano²  Alex L Pereira² 

[1] Embrapa Recursos Genéticos e Biotecnologia (Cenargen), Brasília, DF, Brazil;Laboratório de Microbiologia, Departamento de Biologia Celular, Universidade de Brasília, Brasília, DF, Brazil;

关键词: HeLa Cell;    Bacterial Adhesion;    oxyR;    Persistent Diarrhea;    Abiotic Surface;   

DOI  :  10.1186/1471-2180-10-57

 received in 2009-09-13, accepted in 2010-02-23,  发布年份 2010

来源: Springer

【 摘 要 】

BackgroundEnteroaggregative Escherichia coli (EAEC) are enteropathogenic strains identified by the aggregative adhesion (AA) pattern that share the capability to form biofilms. Citrobacter freundii is classically considered as an indigenous intestinal species that is sporadically associated with diarrhea.ResultsDuring an epidemiologic study focusing on infantile diarrhea, aggregative C. freundii (EACF) and EAEC strains were concomitantly recovered from a severe case of mucous diarrhea. Thereby, the occurrence of synergic events involving these strains was investigated. Coinfection of HeLa cells with EACF and EAEC strains showed an 8-fold increase in the overall bacterial adhesion compared with single infections (P < 0.001). The synergic effect was mediated by physical interactions among the bacteria and primed in the absence of chemical signaling and without the participation of host cells. Thus, significant increases (2.7-fold on average) in bacterial adhesion were also observed during the formation of mixed biofilms on abiotic surfaces. Bacterial settling assays showed that EAEC strains harboring F-pili genes (traA) were capable of forming bacterial aggregates only in the presence of EACF. Scanning electronic microscopy analyses revealed that bacterial aggregates as well as enhanced biofilms formed by EACF and traA-positive EAEC were mediated by non-bundle forming, flexible pili. Moreover, mixed biofilms formed by EACF and traA-positive EAEC strains were significantly reduced using nonlethal concentration of zinc, a specific inhibitor of F pili. In addition, EAEC strains isolated from diarrheic children frequently produced single biofilms sensitive to zinc.ConclusionsPutative F pili expressed by EAEC strains boosted mixed biofilm formation when in the presence of aggregative C. freundii.

【 授权许可】

Unknown   
© Pereira et al; licensee BioMed Central Ltd. 2010. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.