The impact of wound infections on our healthcare system is enormous. Infections of the dermis, including burns, surgical-site infections and non-healing diabetic foot ulcers affect over a million people, cause thousands of amputations and deaths and cost billions of dollars in direct medical costs in the United States annually. The microbial populations of these infections are typically polymicrobial, biofilm- associated, and display increased tolerance to antimicrobials, but despite the prevalence and severity of wound infections, microbial interactions in this environment have been significantly understudied. We hypothesize that the wound environment promotes co-infection with Pseudomonas aeruginosa and Staphylococcus aureus, resulting in chronic wound infections that are extremely tolerant to antimicrobials. Our goals are to 1) characterize P. aeruginosa and S. aureus interspecies interactions in an in vitro wound environment;2) determine how components of the wound environment inhibit P. aeruginosa's ability to kill S. aureus and thus promote stable coinfections; and 3) investigate what consequences P. aeruginosa/S. aureus coinfection has on wound resolution in vivo. To complete these goals we will use an innovative in vitro wound model to study the population dynamics of P. aeruginosa/S. aureus coinfection in response to environmental stimuli, and a mouse chronic wound model to test whether coinfection results in wounds that more difficult to treat or slower to heal. The results of this project will provide important new information about how the interspecies relationship of these two extremely important and prevalent wound pathogens influences wound infections.

Public Health Relevance

The impact of wound infections on our healthcare system is enormous. But despite the prevalence and severity of wound infections, microbial interactions in this environment have been significantly understudied. Pseudomonas aeruginosa (PA) and Staphylococcus aureus (SA) are the two most common causes of chronic wound infections, and both are infamous for their resistance to antimicrobials. While wounds are frequently co-infected with PA and SA there is very little known about their interspecies relationship. The ultimate goals of this project are to understand how the wound environment promotes PA/SA co-infection and determine whether wound infections are more serious or difficult to treat when both of these species of bacteria are present.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Academic Research Enhancement Awards (AREA) (R15)
Project #
1R15AI105763-01A1
Application #
8617679
Study Section
Special Emphasis Panel (ZRG1-IDM-S (81))
Program Officer
Huntley, Clayton C
Project Start
2014-04-01
Project End
2017-03-31
Budget Start
2014-04-01
Budget End
2017-03-31
Support Year
1
Fiscal Year
2014
Total Cost
$448,435
Indirect Cost
$148,826
Name
Texas Tech University
Department
Surgery
Type
Schools of Medicine
DUNS #
609980727
City
Lubbock
State
TX
Country
United States
Zip Code
79430
DeLeon, Stephanie; Clinton, Allie; Fowler, Haley et al. (2014) Synergistic interactions of Pseudomonas aeruginosa and Staphylococcus aureus in an in vitro wound model. Infect Immun 82:4718-28