Bacteremia: host-specific lung clearance and pulmonary failure.

Area of Science:

• Comparative Pathology
• Infectious Disease Research
• Pulmonary Medicine

Background:

• Bloodstream infections can lead to severe organ damage.
• Understanding host responses to bacterial dissemination is crucial for treating sepsis.
• Pseudomonas aeruginosa is a common opportunistic pathogen.

Purpose of the Study:

• To compare the pulmonary effects, lung clearance, and tissue retention of Pseudomonas aeruginosa in dogs and pigs.
• To investigate host-dependent mechanisms in bacteremia-induced pulmonary failure.

Main Methods:

• Continuous intravenous infusion of Pseudomonas aeruginosa in dogs and pigs over 6 hours.
• Monitoring of pulmonary artery pressures, arterial blood gases, and fluid balance.
• Assessment of bacterial tissue retention in various organs.

Main Results:

• Pigs developed pulmonary artery hypertension, hypoxemia, pulmonary edema, and atelectasis, mimicking human ARDS.
• Dogs showed no significant changes in pulmonary artery pressure, no edema, and improved oxygenation.
• Pigs retained the most bacteria in the lungs, while dogs showed minimal lung retention, with higher retention in the liver and spleen.

Conclusions:

• Lung clearance of blood-borne Pseudomonas aeruginosa is highly host-dependent.
• Pigs exhibit a greater susceptibility to bacteremia-induced pulmonary failure compared to dogs.
• These findings highlight significant interspecies differences in response to bacterial sepsis.