A pig model of acute Staphylococcus aureus induced pyemia.
BACKGROUND
Sepsis caused by Staphylococcus aureus constitutes an important cause of morbidity and mortality in humans, and the incidence of this disease-entity is increasing. In this paper we describe the initial microbial dynamics and lesions in pigs experimentally infected with S. aureus, with the aim of mimicking human sepsis and pyemia.


METHODS
The study was conducted in anaesthetized and intravenously inoculated pigs, and was based on bacteriological examination of blood and testing of blood for IL-6 and C-reactive protein. Following killing of the animals and necropsy bacteriological and histological examinations of different organs were performed 4, 5 or 6 h after inoculation.


RESULTS
Clearance of bacteria from the blood was completed within the first 2 h in some of the pigs and the highest bacterial load was recorded in the lungs as compared to the spleen, liver and bones. This probably was a consequence of both the intravenous route of inoculation and the presence of pulmonary intravascular macrophages. Inoculation of bacteria induced formation of acute microabscesses in the lungs, spleen and liver, but not in the kidneys or bones. No generalized inflammatory response was recorded, i.e. IL-6 was not detected in the blood and C-reactive protein did not increase, probably because of the short time course of the study.


CONCLUSIONS
This study demonstrates the successful induction of acute pyemia (microabscesses), and forms a basis for future experiments that should include inoculation with strains of S. aureus isolated from man and an extension of the timeframe aiming at inducing sepsis, severe sepsis and septic shock.
Nielsen
Ole L
OL
Department of Veterinary Disease Biology, University of Copenhagen, Frederiksberg C, Denmark. ole@life.ku.dk
Iburg
Tine
T
Aalbaek
Bent
B
Leifsson
Páll S
PS
Agerholm
Jørgen S
JS
Heegaard
Peter
P
Boye
Mette
M
Simon
Sofie
S
Jensen
Kristine B
KB
Christensen
Sophie
S
Melsen
Karin
K
Bak
Anne K
AK
Backman
Elín R
ER
Jørgensen
Mia H
MH
Groegler
Désirée K
DK
Jensen
Asger L
AL
Kjelgaard-Hansen
Mads
M
Jensen
Henrik E
HE