Related Experiment Videos
Donor-transmitted pneumonia in experimental lung allografts. Successful prevention with donor antibiotic therapy
R D Dowling1, M Zenati, S A Yousem
1Department of Surgery, University of Pittsburgh, Pa.
Abstract:
Bacterial pneumonia is the most common cause of early morbidity and mortality (less than 2 weeks) after heart-lung transplantation. The majority (76%) of cultures taken from human donor tracheas at the time of explant grew bacteria. The abnormal immune response of the lung allograft and the common finding of bacterial contamination of lung donors led us to hypothesize that clinically silent bacterial contamination of the donor lung progresses to pneumonia in the recipient and that antibiotic treatment of donors will prevent the development of pneumonia in the recipient. Inocula of Streptococcus pneumoniae were instilled into the left middle lobe of normal and donor dogs to identify the number of bacteria that would result in pneumonia in a normal animal and the amount that, when given to a donor, would result in pneumonia in the recipient. Initial studies established that inocula of 10(4) colony-forming units of S. pneumoniae did not result in pneumonia in normal or immunosuppressed animals. When 10(4) colony-forming units or as few as 10(2) were instilled into the left middle lobe of donors 24 hours before explantation and use of the lung for transplantation, severe acute bronchopneumonia developed in all 18 recipients. Treatment of donors with aerosol and intravenous antibiotics, but not with either alone, prevented pneumonia in the recipients. We conclude that bacterial contamination of the donor lung leads to pneumonia in recipients. Intravenous and aerosol antibiotic treatment of donors with bacterial contamination prevents pneumonia in canine lung recipients. Treatment of human donors with this antibiotic regimen may decrease the prevalence of early bacterial pneumonia.
Insights
Bacterial contamination in donor lungs can cause pneumonia in heart-lung transplant recipients. Treating donors with both intravenous and aerosol antibiotics before organ retrieval prevents this serious complication.
Area of Science:
- Transplantation immunology
- Infectious disease
- Pulmonary medicine
Background:
- Bacterial pneumonia is a leading cause of early death after heart-lung transplants.
- Most donor tracheas harbor bacteria, suggesting contamination is common.
- Donor lung contamination may progress to recipient pneumonia due to altered immune responses.
Purpose of the Study:
- To investigate if bacterial contamination of donor lungs leads to pneumonia in recipients.
- To determine if antibiotic treatment of donors can prevent post-transplant pneumonia.
- To establish the bacterial inoculum size causing pneumonia in a canine model.
Main Methods:
- Instilled varying amounts of Streptococcus pneumoniae into donor dog lungs.
- Transplanted lungs into recipients and monitored for pneumonia development.
- Administered aerosol and/or intravenous antibiotics to donor animals before explantation.
Main Results:
- Even small bacterial inoculums (10^2-10^4 CFU) in donor lungs caused severe pneumonia in all recipients.
- Treatment with both aerosol and intravenous antibiotics prevented pneumonia.
- Neither antibiotic route alone was sufficient to prevent pneumonia.
Conclusions:
- Bacterial contamination of donor lungs is a direct cause of pneumonia in lung transplant recipients.
- Combined aerosol and intravenous antibiotic therapy in donors is effective in preventing post-transplant pneumonia.
- This antibiotic strategy may reduce pneumonia rates in human lung transplant recipients.