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Updated: Aug 30, 2026
A Non-invasive and Technically Non-intensive Method for Induction and Phenotyping of Experimental Bacterial Pneumonia in Mice
Published on: September 28, 2016
A novel model of pneumonia from intraperitoneal injection of bacteria
Glen A Franklin1, Melanie J Scott, Manoj Patel
1Veterans Affairs Medical Center, and Department of Surgery, University of Louisville, 2nd Floor ACB, Louisville, KY 40292, USA. glen.franklin@louisville.edu
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.
Insights
Intraperitoneal Klebsiella pneumoniae injection in mice uniformly causes pneumonia, unlike intravenous administration. This reproducible model allows for manipulation of severity, aiding pneumonia research in surgical patients.
Area of Science:
- Microbiology
- Immunology
- Surgical Pathology
Background:
- Pneumonia is a significant complication in surgical patients.
- Current experimental models for pneumonia lack reproducibility.
- An attempt to model peritonitis led to the discovery of a novel pneumonia model.
Purpose of the Study:
- To develop and validate a reproducible experimental model for studying pneumonia.
- To investigate the effects of Klebsiella pneumoniae administration via different routes.
Main Methods:
- Male Swiss Webster mice received intraperitoneal (IP) or intravenous (IV) injections of Klebsiella pneumoniae.
- Bacterial doses were varied, and survival curves were generated.
- Blood, peritoneal fluid, and lung tissue were analyzed for bacterial load, lung weight, and myeloperoxidase levels.
Main Results:
- IP Klebsiella pneumoniae was uniformly lethal, causing pneumonia and bacteremia within 24 hours.
- IV administration resulted in higher survival rates, with successful bacterial clearance.
- A dose-dependent relationship was observed, with increased lung weight and bacterial levels in the lungs after IP injection.
Conclusions:
- The IP Klebsiella pneumoniae model reliably induces pneumonia, not peritonitis, in mice.
- This model is reproducible, simple, and allows for adjustable severity.
- Findings correlate bacterial load with disease progression, offering a valuable tool for pneumonia research.
