Global transcriptomic analysis during murine pneumonia infection unravels new virulence factors in Acinetobacter baumannii.

Background Infections caused by multidrug-resistant pathogens such as Acinetobacter baumannii constitute a major health problem worldwide. In this study we present a global in vivo transcriptomic analysis of A. baumannii isolated from the lungs of mice with pneumonia infection. Material/methods Mice were infected with A. baumannii ATCC 17978 and AbH12O-A2 strains and the total bacterial RNA was analyzed by RNA-seq. Lists of differentially expressed genes were obtained and 14 of them were selected for gene deletion and further analysis. Results Transcriptomic analysis revealed a specific gene expression profile in A. baumannii during the lung infection with up-regulation of genes involved in iron acquisition and host invasion. Mutant strains lacking the feoA, mtnN, yfgC, basB, hisF, oatA and bfnL showed a significant loss of virulence in murine pneumonia. A decrease in biofilm formation, adherence to human epithelial cells and growth rate was observed in some mutants. Conclusions This study provides an insight into the A. baumannii gene expression profile during the murine pneumonia infection. Data revealed that 7 in vivo up-regulated genes were involved in virulence, and could be considered new therapeutic targets.