A novel model of pneumonia from intraperitoneal injection of bacteria.
BACKGROUND
Pneumonia remains a major clinical problem in the surgical patient. Experimental modeling by intratracheal injection of bacteria is not consistently reproducible. In an attempt to produce peritonitis by Klebsiella, we found evidence of pneumonia on autopsy and further developed this approach as a new experimental model.


METHODS
Male Swiss Webster mice were given intraperitoneal (IP) injections of Klebsiella pneumoniae serotype 2 in different doses and this was compared with similar doses given intravenously (IV). A dose dependent survival curve was generated. Subsequently, 10(3) colony forming units (CFU) of bacteria were used in further experiments. Blood, peritoneal fluid and lung tissue were collected at time points up to 72 hours after injection and were cultured for levels of bacteria. Lung weights and myeloperoxidase levels were also measured.


RESULTS
Intraperitoneal administration of Klebsiella was uniformly lethal with as few as 10(2) bacteria. Lung weight increased after IP Klebsiella, and all animals became bacteremic within 24 hours correlating with high bacterial levels in the lung. Conversely, most animals (72%) survived IV injection of bacteria, and were able to clear bacteria from the blood and lung.


CONCLUSIONS
We found that this model produced no clinically apparent peritonitis after 48 hours, but uniformly resulted in histopathologic changes of pneumonia by 24 hours. Survival time was related to initial dose of Klebsiella and there was a linear correlation between bacterial levels in the blood and lung. This model is reproducible, simple to perform, and the severity is easy to manipulate.
Veterans Affairs Medical Center, and Department of Surgery, University of Louisville, 2nd Floor ACB, Louisville, KY 40292, USA. glen.franklin@louisville.edu
Glen A
GA
Franklin
Melanie J
MJ
Scott
Manoj
M
Patel
J Jason
JJ
Hoth
James C
JC
Peyton
William G
WG
Cheadle
D000818:Animals; D003114:Colony-Forming Units Assay; D007274:Injections, Intraperitoneal; D007710:Klebsiella Infections / Q000209:etiology* / Q000473:pathology; D007711:Klebsiella pneumoniae; D008168:Lung / Q000473:pathology; D008297:Male; D051379:Mice; D009195:Peroxidase / Q000032:analysis; D018410:Pneumonia, Bacterial / Q000209:etiology* / Q000473:pathology
D009195:Peroxidase