title: Inhibition of growth of Shiga toxin-producing Escherichia coli by nonpathogenic Escherichia coli.
abstract: During routine quality control testing of diagnostic methods for Shiga toxin-producing Escherichia coli (STEC) using stool samples spiked with STEC, it was observed that the Shiga toxin could not be detected in 32 out of 82 samples tested. Strains of E. coli isolated from such stool samples were shown to be responsible for this inhibition. One particular isolate, named E. coli 1307, was intensively studied because of its highly effective inhibitory effect; this strain significantly reduced growth and Shiga toxin levels in coculture of several STEC strains regardless of serovar or Shiga toxin type. The probiotic E. coli Nissle 1917 inhibited growth and reduced Shiga toxin levels in STEC cultures to an extent similar to E. coli 1307, but commensal E. coli strains and several other known probiotic bacteria (enterococci, Bacillus sp., Lactobacillus acidophilus) showed no, or only small, inhibitory effects. Escherichia coli 1307 lacks obvious fitness factors, such as aerobactin, yersiniabactin, microcins and a polysaccharide capsule, that are considered to promote the growth of pathogenic bacteria. We therefore propose strain E. coli 1307 as a candidate probiotic for use in the prevention and treatment of infections caused by STEC.
authors.affiliation: Robert Koch Institut, Wernigerode Branch, Wernigerode, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Reissbrodt
authors.forename: Walter P
authors.initials: WP
authors.lastname: Hammes
authors.forename: Fabio
authors.initials: F
authors.lastname: dal Bello
authors.forename: Rita
authors.initials: R
authors.lastname: Prager
authors.forename: Angelika
authors.initials: A
authors.lastname: Fruth
authors.forename: Klaus
authors.initials: K
authors.lastname: Hantke
authors.forename: Alexander
authors.initials: A
authors.lastname: Rakin
authors.forename: Marjanca
authors.initials: M
authors.lastname: Starcic-Erjavec
authors.forename: Peter H
authors.initials: PH
authors.lastname: Williams
mesh_terms: D000898:Antibiosis; D018920:Coculture Techniques; D003470:Culture Media; D004926:Escherichia coli / Q000145:classification / Q000254:growth & development* / Q000302:isolation & purification; D019453:Escherichia coli O157 / Q000254:growth & development / Q000378:metabolism; D005243:Feces / Q000382:microbiology; D006801:Humans; D019936:Probiotics; D012703:Serotyping; D022621:Shiga Toxin / Q000378:metabolism*; D054323:Shiga-Toxigenic Escherichia coli / Q000254:growth & development* / Q000378:metabolism
chemical_list: D003470:Culture Media; D022621:Shiga Toxin