Research Summary: The Intestinal Microbiota Plays a Role in Salmonella-Induced Colitis Independent of Pathogen Colonization


The intestinal microbiota is composed of hundreds of species of bacteria, fungi
and protozoa and is critical for numerous biological processes, such as nutrient
acquisition, vitamin production, and colonization resistance against bacterial
pathogens. We studied the role of the intestinal microbiota on host resistance
to Salmonella enterica serovar Typhimurium-induced colitis.
Using multiple antibiotic treatments in 129S1/SvImJ mice, we showed that
disruption of the intestinal microbiota alters host susceptibility to infection.
Although all antibiotic treatments caused similar increases in pathogen
colonization, the development of enterocolitis was seen only when streptomycin
or vancomycin was used; no significant pathology was observed with the use of
metronidazole. Interestingly, metronidazole-treated and infected C57BL/6 mice
developed severe pathology. We hypothesized that the intestinal microbiota
confers resistance to infectious colitis without affecting the ability of
S. Typhimurium to colonize the intestine. Indeed, different
antibiotic treatments caused distinct shifts in the intestinal microbiota prior
to infection. Through fluorescence in situ hybridization,
terminal restriction fragment length polymorphism, and real-time PCR, we showed
that there is a strong correlation between the intestinal microbiota composition
before infection and susceptibility to Salmonella-induced
colitis. Members of the Bacteroidetes phylum were present at significantly
higher levels in mice resistant to colitis. Further analysis revealed that
Porphyromonadaceae levels were also increased in these mice. Conversely, there
was a positive correlation between the abundance of
Lactobacillus sp. and predisposition to colitis. Our data
suggests that different members of the microbiota might be associated with
S. Typhimurium colonization and colitis. Dissecting the
mechanisms involved in resistance to infection and inflammation will be critical
for the development of therapeutic and preventative measures against enteric


Publisher: Public Library of Science

Date Published: 25-May-2011

Author(s): Ferreira R., Gill N., Willing B., Antunes L., Russell S., Croxen M., Finlay B.


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