Understanding the acute inflammatory response to Pseudomonas aeruginosa infection: differences between susceptible and multidrug-resistant strains in a mouse peritonitis model
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Updated: Mar 10, 2026
Pseudomonas aeruginosa Induced Lung Injury Model
Published on: October 29, 2014
Silvia Gómez-Zorrilla1, Laura Calatayud2, Carlos Juan3
1Infectious Diseases Service, Hospital Universitari de Bellvitge, Bellvitge Biomedical Research Institute (IDIBELL), University of Barcelona, Feixa Llarga s/n 08907, Hospitalet de Llobregat, Barcelona, Spain.
Abstract:
The increasing emergence of multidrug-resistant (MDR) Pseudomonas aeruginosa strains is associated with the spread of a few international epidemic clones called high-risk clones. The existence of a fitness cost associated with multidrug resistance remains unclear, and little is known about the host inflammatory response in acute P. aeruginosa infections. This study aimed to investigate how the inflammatory response occurs in the most relevant high-risk clones and to compare the process with that recorded in clinical susceptible isolates. Nine P. aeruginosa strains were studied, including the most relevant MDR high-risk clones (ST111, ST175 and ST235) circulating worldwide. The inflammatory response in terms of the release of interleukins in serum was investigated in a mouse peritonitis-sepsis model at three time points (4, 8 and 12 h). TNFα and interleukin-10 (IL-10) levels were significantly higher at all time points in mice inoculated with clinical susceptible strains compared with those inoculated with MDR strains. IL-6 levels were significantly higher in the clinical susceptible strain group at 8 h and 12 h (P = 0.036 and P = 0.007, respectively). Bacterial counts (log CFU/mL) in peritoneal fluid were higher in the clinical susceptible strain group compared with the MDR strain group at 8 h [6.00 (4.30-6.90) vs. 4.46 (3.30-5.34); P = 0.005] and 12 h [7.75 (4.00-7.97) vs. 4.04 (2.58-4.94); P = 0.003]. MDR P. aeruginosa strains elicited a weaker inflammatory response than susceptible strains in an experimental mouse model, suggesting the existence of a fitness cost associated with multidrug resistance.
Insights
Multidrug-resistant (MDR) Pseudomonas aeruginosa strains, including high-risk clones, showed a weaker inflammatory response in mice compared to susceptible strains. This suggests a potential fitness cost associated with MDR in P. aeruginosa infections.
Area of Science:
- Microbiology
- Immunology
- Infectious Diseases
Background:
- Emergence of multidrug-resistant (MDR) Pseudomonas aeruginosa, particularly high-risk clones, poses a significant global health threat.
- The fitness cost of MDR and the host inflammatory response in acute P. aeruginosa infections remain poorly understood.
Purpose of the Study:
- To investigate the inflammatory response to high-risk MDR P. aeruginosa clones.
- To compare the inflammatory response elicited by MDR strains versus clinical susceptible isolates.
Main Methods:
- Utilized a mouse peritonitis-sepsis model with nine P. aeruginosa strains, including MDR high-risk clones (ST111, ST175, ST235).
- Measured serum interleukin (IL) levels (TNFα, IL-10, IL-6) at 4, 8, and 12 hours post-inoculation.
- Quantified bacterial counts (log CFU/mL) in peritoneal fluid at 8 and 12 hours.
Main Results:
- MDR strains induced significantly lower levels of TNFα and IL-10 compared to susceptible strains at all time points.
- IL-6 levels were significantly higher in the susceptible strain group at 8 and 12 hours.
- Bacterial counts were significantly higher in the susceptible strain group at 8 and 12 hours, indicating reduced bacterial clearance.
Conclusions:
- MDR P. aeruginosa strains elicited a weaker host inflammatory response in a mouse model compared to susceptible strains.
- These findings suggest that multidrug resistance may impose a fitness cost on P. aeruginosa.
- Further research is needed to fully elucidate the implications of this reduced inflammatory response and potential fitness cost in clinical settings.
