title: Probiotic Escherichia coli Nissle 1917 reduces growth, Shiga toxin expression, release and thus cytotoxicity of enterohemorrhagic Escherichia coli.
abstract: Due to increased release or production of Shiga toxin by Enterohemorrhagic Escherichia coli (EHEC) after exposure to antimicrobial agents, the role of antimicrobial agents in EHEC mediated infections remains controversial. Probiotics are therefore rapidly gaining interest as an alternate therapeutic option. The well-known probiotic strain Escherichia coli Nissle 1917 (EcN) was tested in vitro to determine its probiotic effects on growth, Shiga toxin (Stx) gene expression, Stx amount and associated cytotoxicity on the most important EHEC strains of serotype O104:H4 and O157:H7. Following co-culture of EcN:EHEC in broth for 4 and 24 h, the probiotic effects on EHEC growth, toxin gene expression, Stx amount and cytotoxicity were determined using quantitative real time-PCR, Stx-ELISA and Vero cytotoxicity assays. Probiotic EcN strongly reduced EHEC numbers (cfu) of O104:H4 up to (68%) and O157:H7 to (72.2%) (p<0.05) in LB broth medium whereas the non-probiotic E. coli strain MG1655 had no effect on EHEC growth. The level of stx expression was significantly down-regulated, particularly for the stx2a gene. The stx down-regulation in EcN co-culture was not due to reduced numbers of EHEC. A significant inhibition in Stx amounts and cytotoxicity were also observed in sterile supernatants of EcN:EHEC co-cultures. These findings indicate that probiotic EcN displays strong inhibitory effects on growth, Shiga toxin gene expression, amount and cytotoxicity of EHEC strains. Thus, EcN may be considered as a putative therapeutic candidate, in particular against EHEC O104:H4 and O157:H7.
authors.affiliation: Institute of Microbiology and Epizootics, Centre for Infection Medicine, Freie Universität Berlin, Berlin, Germany; Institute of Microbiology, University of Agriculture, Faisalabad, Pakistan.
authors.forename: Mashkoor
authors.initials: M
authors.lastname: Mohsin
authors.affiliation: Institute of Microbiology and Epizootics, Centre for Infection Medicine, Freie Universität Berlin, Berlin, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Guenther
authors.affiliation: Faculty of Natural Sciences, Brandenburg Technical University Cottbus-Senftenberg, Senftenberg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Schierack
authors.affiliation: Institute of Microbiology and Epizootics, Centre for Infection Medicine, Freie Universität Berlin, Berlin, Germany.
authors.forename: Karsten
authors.initials: K
authors.lastname: Tedin
authors.affiliation: Institute of Microbiology and Epizootics, Centre for Infection Medicine, Freie Universität Berlin, Berlin, Germany. Electronic address: lothar.wieler@fu-berlin.de.
authors.forename: Lothar H
authors.initials: LH
authors.lastname: Wieler
mesh_terms: D000818:Animals; D000898:Antibiosis; D002470:Cell Survival / Q000187:drug effects; D002522:Chlorocebus aethiops; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D019936:Probiotics / Q000494:pharmacology*; D060888:Real-Time Polymerase Chain Reaction; D022621:Shiga Toxin / Q000096:biosynthesis* / Q000235:genetics / Q000633:toxicity*; D014709:Vero Cells; D037521:Virulence Factors / Q000096:biosynthesis / Q000235:genetics / Q000633:toxicity
chemical_list: D037521:Virulence Factors; D022621:Shiga Toxin
keywords: Cytotoxicity; EHEC; Gene expression; Nissle 1917; Probiotic; Shiga toxins