Transcriptional profiles of pulmonary innate immune responses to isogenic antibiotic-susceptible and multidrug-resistant Pseudomonas aeruginosa.

The virulence of an isogenic pair of Pseudomonas aeruginosa strains was studied under similar experimental conditions in two animal infection models. The time to death was significantly longer for the multidrug resistant (MDR) than the wild-type strain. The transcriptional profiles of 84 innate immune response genes in the lungs of immune competent Balb/C mice were further compared. Significantly weaker expression of genes involved in production of soluble pattern recognition receptor and complement were observed in animals infected with the MDR strain. Altered patterns of innate immune system activation may explain the attenuated virulence in MDR bacteria.