BackgroundPseudomonas aeruginosa establishes life-long chronic airway infections in cystic fibrosis (CF) patients. As the disease progresses, P. aeruginosa pathoadaptive variants are distinguished from the initially acquired strain. However, the genetic basis and the biology of host-bacteria interactions leading to a persistent lifestyle of P. aeruginosa are not understood. As a model system to study long term and persistent CF infections, the P. aeruginosa RP73, isolated 16.9 years after the onset of airways colonization from a CF patient, was investigated. Comparisons with strains RP1, isolated at the onset of the colonization, and clonal RP45, isolated 7 years before RP73 were carried out to better characterize genomic evolution of P. aeruginosa in the context of CF pathogenicity.ResultsVirulence assessments in disease animal model, genome sequencing and comparative genomics analysis were performed for clinical RP73, RP45, RP1 and prototype strains. In murine model, RP73 showed lower lethality and a remarkable capability of long-term persistence in chronic airways infection when compared to other strains. Pathological analysis of murine lungs confirmed advanced chronic pulmonary disease, inflammation and mucus secretory cells hyperplasia. Genomic analysis predicted twelve genomic islands in the RP73 genome, some of which distinguished RP73 from other prototype strains and corresponded to regions of genome plasticity. Further, comparative genomic analyses with sequential RP isolates showed signatures of pathoadaptive mutations in virulence factors potentially linked to the development of chronic infections in CF.ConclusionsThe genome plasticity of P. aeruginosa particularly in the RP73 strain strongly indicated that these alterations may form the genetic basis defining host-bacteria interactions leading to a persistent lifestyle in human lungs.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-2276-8) contains supplementary material, which is available to authorized users.
The clinical development of antibiotics with a new mode of action combined with efficient pulmonary drug delivery is a priority against untreatable Pseudomonas aeruginosa lung infections. POL7001 is a macrocycle antibiotic belonging to the novel class of protein epitope mimetic (PEM) molecules with selective and potent activity against P. aeruginosa. We investigated ventilatorassociated pneumonia (VAP) and cystic fibrosis (CF) as indications of the clinical potential of POL7001 to treat P. aeruginosa pulmonary infections. MICs of POL7001 and comparators were measured for reference and clinical P. aeruginosa strains. The therapeutic efficacy of POL7001 given by pulmonary administration was evaluated in murine models of P. aeruginosa acute and chronic pneumonia. POL7001 showed potent in vitro activity against a large panel of P. aeruginosa isolates from CF patients, including multidrug-resistant (MDR) isolates with adaptive phenotypes such as mucoid or hypermutable phenotypes. The efficacy of POL7001 was demonstrated in both wild-type and CF mice. In addition to a reduced bacterial burden in the lung, POL7001-treated mice showed progressive body weight recovery and reduced levels of inflammatory markers, indicating an improvement in general condition. Pharmacokinetic studies indicated that POL7001 reached significant concentrations in the lung after pulmonary administration, with low systemic exposure. These results support the further evaluation of POL7001 as a novel therapeutic agent for the treatment of P. aeruginosa pulmonary infections. Pseudomonas aeruginosa is a difficult-to-treat human pathogen causing a wide range of infections, especially in the respiratory tract. These infections, such as ventilator-associated pneumonia (VAP), are often life-threatening. Cystic fibrosis (CF) is another disease where P. aeruginosa lung infections are associated with worse outcomes (1). The high prevalence of P. aeruginosa infections, in nearly 80% of CF patients Ͼ18 years of age (2), is partially due to the propensity of this species to form biofilms and cause chronic infection.Frequently observed inefficacy of available treatments is due to intrinsic or acquired resistance of P. aeruginosa and/or limited penetration of antibiotics into biofilms (3). However, despite the need for new drugs, only few novel antipseudomonal drugs or modifications of existing molecules are currently in the late stage of preclinical or clinical development (4). A new family of potent protein epitope mimetic (PEM) antibiotics has recently been described. These molecules show selective activity against P. aeruginosa by inhibiting the transport of the lipopolysaccharide to the outer membrane (5). Among these antibiotics, we showed that POL7001 provided protection against lethal P. aeruginosa infection in a mouse septicemia model (5).In this work, to investigate the efficacy of POL7001 in models relevant for VAP or CF, we used murine P. aeruginosa acute and chronic pneumonia, including in CF mice. We report that pulmonary delivery of POL7001 is e...
High incidence, severity and increasing antibiotic resistance characterize Pseudomonas aeruginosa infections, highlighting the need for new therapeutic options. Vaccination strategies to prevent or limit P. aeruginosa infections represent a rational approach to positively impact the clinical outcome of risk patients; nevertheless this bacterium remains a challenging vaccine target. To identify novel vaccine candidates, we started from the genome sequence analysis of the P. aeruginosa reference strain PAO1 exploring the reverse vaccinology approach integrated with additional bioinformatic tools. The bioinformatic approaches resulted in the selection of 52 potential antigens. These vaccine candidates were conserved in P. aeruginosa genomes from different origin and among strains isolated longitudinally from cystic fibrosis patients. To assess the immune-protection of single or antigens combination against P. aeruginosa infection, a vaccination protocol was established in murine model of acute respiratory infection. Combinations of selected candidates, rather than single antigens, effectively controlled P. aeruginosa infection in the in vivo model of murine pneumonia. Five combinations were capable of significantly increase survival rate among challenged mice and all included PA5340, a hypothetical protein exclusively present in P. aeruginosa. PA5340 combined with PA3526-MotY gave the maximum protection. Both proteins were surface exposed by immunofluorescence and triggered a specific immune response. Combination of these two protein antigens could represent a potential vaccine to prevent P. aeruginosa infection.
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