Escherichia coli strains colonising the gastrointestinal tract protect germfree mice againstSalmonella typhimuriuminfection (original) (raw)
Gastrointestinal infection
Escherichia coli strains colonising the gastrointestinal tract protect germfree mice against_Salmonella typhimurium_infection
- S Hudault,
- J Guignot,
- A L Servin
- Institut National de la Santé et de la Recherche Médicale, Unité 510, Faculté de Pharmacie Paris XI, 92296 Châtenay-Malabry, France
- S Hudault. sylvie.hudault{at}cep.u-psud.fr
Abstract
BACKGROUND Escherichia coli is part of the normal gastrointestinal microflora which exerts a barrier effect against enteropathogens. Several_E coli_ strains develop a protective effect against other Enterobacteriaceae.
AIMS Two_E coli_ strains, EM0, a human faecal strain, and JM105 K-12 were tested for their ability to prevent in vivo and in vitro infection by Salmonella typhimurium C5.
METHODS Inhibition of C5 cell invasion by E coli was investigated in vitro using Caco-2/TC7 cells. The protective effect of_E coli_ was examined in vivo in germfree or conventional C3H/He/Oujco mice orally infected by the lethal strain C5.
RESULTS EMO expresses haemolysin and cytotoxic necrotising factor in vitro. In vitro, the two strains did not prevent the growth of C5 by secreted microcins or modified cell invasion of C5. In vivo, establishment of EM0 or JM105 in the gut of germfree mice resulted in a significant increase in the number of surviving mice: 11/12 and 9/12, respectively, at 58 days after infection (2×106/mouse) versus 0/12 in control germfree group at 13 days after infection. Colonisation level and translocation rate of C5 were significantly reduced during the three days after infection. In contrast, no reduction in faecal C5 excretion was observed in C5 infected conventional mice (1×108/mouse) receiving the EM0 or JM105 cultures daily.
CONCLUSIONS Establishment of E coli strains, which do not display antimicrobial activity, protects germfree mice against infection and delays the establishment of C5 in the gut. Possible mechanisms of defence are discussed.
Escherichia coli
gastrointestinal infection
Salmonella
germfree mice
bacterial antagonism
Abbreviations used in this paper
LB broth
Luria-Bertoni broth
hlyA
α-haemolysin
cdt
cytolethal distending toxin
PBS
phosphate buffered saline
TSA
tryptic soy agar
SS agar, Shigella and Salmonella agar
PCR, polymerase chain reaction
LDH
lactate dehydrogenase
CNF
cytotoxic necrotising factor
MLN
mesenteric lymph nodes
IL
interleukin
TNF-α
tumour necrosis factor α
Statistics from Altmetric.com
Request Permissions
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.