Identification of novel persistence genes in Pseudomonas aeruginosa in the combat against emerging antimicrobial resistance.

Journal Articleinfo:eu-repo/semantics/publishe

Pseudomonas aeruginosa fosfomycin resistance mechanisms affect non-inherited fluoroquinolone tolerance.

Pseudomonas aeruginosa is an opportunistic pathogen that poses a threat in clinical settings due to its intrinsic and acquired resistance to a wide spectrum of antibiotics. Additionally, the presence of a subpopulation of cells surviving high concentrations of antibiotics, called persisters, makes it virtually impossible to eradicate a chronic infection. The mechanism underlying persistence is still unclear, partly due to the fact that it is a non-inherited phenotype. Based on our findings from a previously performed screening effort for P. aeruginosa persistence genes, we hypothesize that crosstalk can occur between two clinically relevant mechanisms: the persistence phenomenon and antibiotic resistance. This was tested by determining the persistence phenotype of P. aeruginosa strains that are resistant to the antibiotic fosfomycin due to either of two unrelated fosfomycin resistance mechanisms. Overexpression of fosA (PA1129) confers fosfomycin resistance by enzymic modification of the antibiotic, and in addition causes a decrease in the number of persister cells surviving ofloxacin treatment. Both phenotypes require the enzymic function of FosA, as mutation of the Arg119 residue abolishes fosfomycin resistance as well as low persistence. The role for fosfomycin resistance mechanisms in persistence is corroborated by demonstrating a similar phenotype in a strain with a mutation in glpT (PA5235), which encodes a glycerol-3-phosphate transporter essential for fosfomycin uptake. These results indicate that fosfomycin resistance, conferred by glpT mutation or by overexpression of fosA, results in a decrease in the number of persister cells after treatment with ofloxacin and additionally stress that further research into the interplay between fosfomycin resistance and persistence is warranted.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Role of persister cells in chronic infections: clinical relevance and perspectives on anti-persister therapies.

Certain infectious diseases caused by pathogenic bacteria are typically chronic in nature. Potentially deadly examples include tuberculosis, caused by Mycobacterium tuberculosis, cystic fibrosis-associated lung infections, primarily caused by Pseudomonas aeruginosa, and candidiasis, caused by the fungal pathogen Candida albicans. A hallmark of this type of illness is the recalcitrance to treatment with antibiotics, even in the face of laboratory tests showing the causative agents to be sensitive to drugs. Recent studies have attributed this treatment failure to the presence of a small, transiently multidrug-tolerant subpopulation of cells, so-called persister cells. Here, we review our current understanding of the role that persisters play in the treatment and outcome of chronic infections. In a second part, we offer a perspective on the development of anti-persister therapies based on genes and mechanisms that have been implicated in persistence over the last decade.Journal ArticleResearch Support, Non-U.S. Gov'tReviewinfo:eu-repo/semantics/publishe

Novel persistence genes in Pseudomonas aeruginosa identified by high-throughput screening.

Persister cells are phenotypic variants that are extremely tolerant to high concentrations of antibiotics. They constitute a fraction of stationary phase cultures and biofilm populations of numerous bacterial species, such as the opportunistic pathogen Pseudomonas aeruginosa. Even though persisters are believed to be an important cause of incomplete elimination of infectious populations by antibiotics, their nature remains obscure. Most studies on persistence have focused on the model organism Escherichia coli and only a limited number of persistence genes have been identified to date. We performed the first large-scale screening of a P. aeruginosa PA14 mutant library to identify novel genes involved in persistence. A total of 5000 mutants were screened in a high-throughput manner and nine new persistence mutants were identified. Four mutants (with insertions in dinG, spuC, PA14_17880 and PA14_66140) exhibited a low persister phenotype and five mutants (in algR, pilH, ycgM, pheA and PA14_13680) displayed high persistence. These genes may serve as new candidate drug targets in the combat against P. aeruginosa infections.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Cell surface properties determine persistence of Pseudomonas aeruginosa.

Journal Articleinfo:eu-repo/semantics/publishe

A putative de-N-acetylase of the PIG-L superfamily affects fluoroquinolone tolerance in Pseudomonas aeruginosa

A major cause of treatment failure of infections caused by Pseudomonas aeruginosa is the presence of antibiotic-insensitive persister cells. The mechanism of persister formation in P.aeruginosa is largely unknown, and so far, only few genetic determinants have been linked to P.aeruginosa persistence. Based on a previous high-throughput screening, we here present dnpA (de-N-acetylase involved in persistence; gene locus PA14_66140/PA5002) as a new gene involved in noninherited fluoroquinolone tolerance in P.aeruginosa. Fluoroquinolone tolerance of a dnpA mutant is strongly reduced both in planktonic culture and in a biofilm model, whereas overexpression of dnpA in the wild-type strain increases the persister fraction. In addition, the susceptibility of the dnpA mutant to different classes of antibiotics is not affected. dnpA is part of the conserved LPS core oligosaccharide biosynthesis gene cluster. Based on primary sequence analysis, we predict that DnpA is a de-N-acetylase, acting on an unidentified substrate. Site-directed mutagenesis suggests that this enzymatic activity is essential for DnpA-mediated persistence. A transcriptome analysis indicates that DnpA primarily affects the expression of genes involved in surface-associated processes. We discuss the implications of these findings for future antipersister therapies targeted at chronic P.aeruginosa infections