Experimental Pseudomonas aeruginosa pneumonia: evaluation of the associated inflammatory response

An abnormal inflammatory response (IR) in pneumonia is associated with poor outcomes and high mortality. Animal models could help to better understand the relationship between the pulmonary infection and the associated IR. The aims of the present study were to validate an experimental model of pneumonia induced by the inoculation of Pseudomonas aeruginosa in ventilated piglets and to study the associated IR over a long period of time (96 h). Five Lagerwhite–Landrace piglets were ventilated for 4 days. After intubation, a solution containing 75 mL of P. aeruginosa (106 colony-forming units·mL−1) was bronchoscopically inoculated. Physiological and laboratory parameters were monitored throughout the study. Pro-inflammatory cytokines were measured in serum and in bronchoalveolar lavage (BAL). Histopathology of the lungs and cultures from blood, BAL and lungs were performed. All the animals developed histopathological evidence of pneumonia. Microbiological studies of both BAL and lung confirmed the presence of P. aeruginosa in all the samples. Throughout the study, an increase in interleukin-6 was observed in serum and in BAL. In conclusion, the experimental model of pneumonia induced by the inoculation of high concentrations of Pseudomonas aeruginosa in ventilated piglets is feasible and could be appropriate for the evaluation of different aspects of the associated inflammatory response.