Intestinal colonization with Enterococcus faecium does not influence pulmonary defense against Pseudomonas aeruginosa in mice.
BACKGROUND
Enterococci, and especially multiresistant Enterococcus faecium, are increasingly found colonizing hospitalized patients. This increased prevalence of colonization is not only associated with an increased prevalence of infections caused by enterococci, but also by infections with other nosocomial pathogens. In this study we investigated the causality of this observed relationship, by determining the influence of intestinal colonization with E. faecium on pulmonary defense against Pseudomonas aeruginosa.


RESULTS
Three groups of mice were tested; 2 groups of mice were pre-treated with vancomycin, of which one group was subsequently treated by oral gavage of vancomycin-resistant E. faecium (VRE). The third group did not receive any pre-treatment. P. aeruginosa pneumonia was induced in all mice. Vancomycin treatment resulted in intestinal gram-negative bacterial overgrowth and VRE treatment resulted in colonization throughout the intestines. All 3 groups of mice were able to clear P. aeruginosa from the lungs and circulation, with comparable lung cytokine responses and lung damage. Mice treated with vancomycin without VRE colonization displayed modestly increased plasma levels of TNF-alpha and IL-10.


CONCLUSIONS
Overgrowth of E. faecium and/or gram-negative bacteria does not impact importantly on pulmonary defense against P. aeruginosa pneumonia.
Leendertse
Masja
M
Center for Infection and Immunity Amsterdam, Academic Medical Center, Amsterdam, The Netherlands. m.leendertse@amc.uva.nl
Willems
Rob J L
RJ
Giebelen
Ida A J
IA
Roelofs
Joris J T H
JJ
Top
Janetta
J
Bonten
Marc J M
MJ
van der Poll
Tom
T
D000818:Animals; D016984:Enterococcus faecium / Q000254:growth & development / Q000502:physiology*; D005260:Female; D007422:Intestines / Q000382:microbiology*; D008168:Lung / Q000382:microbiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018410:Pneumonia, Bacterial / Q000276:immunology; D011550:Pseudomonas aeruginosa / Q000472:pathogenicity*