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Infection and Immunity May 2020The opportunistic pathogen is a leading cause of morbidity and mortality worldwide. To survive in both the environment and the host, must cope with redox stress. In ,...
The opportunistic pathogen is a leading cause of morbidity and mortality worldwide. To survive in both the environment and the host, must cope with redox stress. In , a primary mechanism for protection from redox stress is the antioxidant glutathione (GSH). GSH is a low-molecular-weight thiol-containing tripeptide (l-γ-glutamyl-l-cysteinyl-glycine) that can function as a reversible reducing agent. GSH plays an important role in physiology and is known to modulate several cellular and social processes that are likely important during infection. However, the role of GSH biosynthesis during mammalian infection is not well understood. In this study, we created a mutant defective in GSH biosynthesis to examine how loss of GSH biosynthesis affects virulence. We found that GSH is critical for normal growth and provides protection against hydrogen peroxide, bleach, and ciprofloxacin. We also studied the role of GSH biosynthesis in four mouse infection models, including the surgical wound, abscess, burn wound, and acute pneumonia models. We discovered that the GSH biosynthesis mutant was slightly less virulent in the acute pneumonia infection model but was equally virulent in the three other models. This work provides new and complementary data regarding the role of GSH in during mammalian infection.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Disinfectants; Drug Resistance, Bacterial; Glutathione; Host-Pathogen Interactions; Humans; Microbial Viability; Pneumonia, Bacterial; Pseudomonas Infections; Pseudomonas aeruginosa; Soft Tissue Infections
PubMed: 32284368
DOI: 10.1128/IAI.00116-20 -
Expert Opinion on Drug Discovery Dec 2020Persistent infections caused by the superbug and its resistance to multiple antimicrobial agents are huge threats to patients with cystic fibrosis as well as those... (Review)
Review
INTRODUCTION
Persistent infections caused by the superbug and its resistance to multiple antimicrobial agents are huge threats to patients with cystic fibrosis as well as those with compromised immune systems. Multidrug-resistant has posed a major challenge to conventional antibiotics and therapeutic approaches, which show limited efficacy and cause serious side effects. The public demand for new antibiotics is enormous; yet, drug development pipelines have started to run dry with limited targets available for inventing new antibacterial drugs. Consequently, it is important to uncover potential therapeutic targets.
AREAS COVERED
The authors review the current state of drug development strategies that are promising in terms of the development of novel and potent drugs to treat infection.
EXPERT OPINION
The prevention of infection is increasingly challenging. Furthermore, targeting key virulence regulators has great potential for developing novel anti- drugs. Additional promising strategies include bacteriophage therapy, immunotherapies, and antimicrobial peptides. Additionally, the authors believe that in the coming years, the overall network of molecular regulatory mechanism of virulence will be fully elucidated, which will provide more novel and promising drug targets for treating infections.
Topics: Animals; Anti-Bacterial Agents; Drug Development; Drug Resistance, Multiple, Bacterial; Humans; Immunotherapy; Phage Therapy; Pseudomonas Infections; Pseudomonas aeruginosa; Virulence
PubMed: 32880507
DOI: 10.1080/17460441.2020.1803274 -
Brazilian Journal of Microbiology :... Mar 2021Due to the severity of infections caused by P. aeruginosa and the limitations in treatment, it is necessary to find new therapeutic alternatives. Thus, the use of silver... (Review)
Review
Due to the severity of infections caused by P. aeruginosa and the limitations in treatment, it is necessary to find new therapeutic alternatives. Thus, the use of silver nanoparticles (AgNPs) is a viable alternative because of their potential actions in the combat of microorganisms, showing efficacy against Gram-positive and Gram-negative bacteria, including multidrug-resistant microorganisms (MDR). In this sense, the aim of this work was to conduct a literature review related to the antibacterial and antibiofilm activity of AgNPs against antibiotic-sensitive and multidrug-resistant Pseudomonas aeruginosa strains. The AgNPs are promising for future applications, which may match the clinical need for effective antibiotic therapy. The size of AgNPs is a crucial element to determine the therapeutic activity of nanoparticles, since smaller particles present a larger surface area of contact with the microorganism, affecting their vital functioning. AgNPs adhere to the cytoplasmic membrane and cell wall of microorganisms, causing disruption, penetrating the cell, interacting with cellular structures and biomolecules, and inducing the generation of reactive oxygen species and free radicals. Studies describe the antimicrobial activity of AgNPs at minimum inhibitory concentration (MIC) between 1 and 200 μg/mL against susceptible and MDR P. aeruginosa strains. These studies have also shown antibiofilm activity through disruption of biofilm structure, and oxidative stress, inhibiting biofilm growth at concentrations between 1 and 600 μg/mL of AgNPs. This study evidences the advance of AgNPs as an antibacterial and antibiofilm agent against Pseudomonas aeruginosa strains, demonstrating to be an extremely promising approach to the development of new antimicrobial systems.
Topics: Anti-Bacterial Agents; Biofilms; Drug Resistance, Multiple, Bacterial; Humans; Metal Nanoparticles; Microbial Sensitivity Tests; Pseudomonas aeruginosa; Silver
PubMed: 33231865
DOI: 10.1007/s42770-020-00406-x -
The Israel Medical Association Journal... May 2020Although indwelling catheters are increasingly used in modern medicine, they can be a source of microbial contamination and hard-to-treat biofilms, which jeopardize...
BACKGROUND
Although indwelling catheters are increasingly used in modern medicine, they can be a source of microbial contamination and hard-to-treat biofilms, which jeopardize patient lives. At times 70% ethanol is used as a catheter-lock solution due to its bactericidal properties. However, high concentrations of ethanol can result in adverse effects and in malfunction of the catheters.
OBJECTIVES
To determine whether low concentrations of ethanol can prevent and treat biofilms of Pseudomonas aeruginosa.
METHODS
Ethanol was tested at a concentration range of 0.625-80% against laboratory and clinical isolates of P. aeruginosa for various time periods (2-48 hours). The following parameters were evaluated following ethanol exposure: prevention of biofilm formation, reduction of biofilm metabolic activity, and inhibition of biofilm regrowth.
RESULTS
Exposing P. aeruginosa to twofold ethanol gradients demonstrated a significant biofilm inhibition at concentrations as low as 2.5%. Treating pre-formed biofilms of P. aeruginosa with 20% ethanol for 4 hours caused a sharp decay in the metabolic activity of both the laboratory and clinical P. aeruginosa isolates. In addition, treating mature biofilms with 20% ethanol prevented the regrowth of bacteria encased within it.
CONCLUSIONS
Low ethanol concentrations (2.5%) can prevent in vitro biofilm formation of P. aeruginosa. Treatment of previously formed biofilms can be achieved using 20% ethanol, thereby keeping the catheters intact and avoiding complications that can result from high ethanol concentrations.
Topics: Anti-Infective Agents, Local; Biofilms; Catheter-Related Infections; Ethanol; Humans; Microbial Sensitivity Tests; Pseudomonas Infections; Pseudomonas aeruginosa
PubMed: 32378822
DOI: No ID Found -
International Journal of Molecular... Nov 2021is an opportunistic pathogen that synthesizes and secretes a wide range of virulence factors. poses a potential threat to human health worldwide due to its omnipresent... (Review)
Review
is an opportunistic pathogen that synthesizes and secretes a wide range of virulence factors. poses a potential threat to human health worldwide due to its omnipresent nature, robust host accumulation, high virulence, and significant resistance to multiple antibiotics. The pathogenicity of , which is associated with acute and chronic infections, is linked with multiple virulence factors and associated secretion systems, such as the ability to form and utilize a biofilm, pili, flagella, alginate, pyocyanin, proteases, and toxins. Two-component systems (TCSs) of perform an essential role in controlling virulence factors in response to internal and external stimuli. Therefore, understanding the mechanism of TCSs to perceive and respond to signals from the environment and control the production of virulence factors during infection is essential to understanding the diseases caused by infection and further develop new antibiotics to treat this pathogen. This review discusses the important virulence factors of and the understanding of their regulation through TCSs by focusing on biofilm, motility, pyocyanin, and cytotoxins.
Topics: Biofilms; Gene Expression Regulation, Bacterial; Persistent Infection; Pseudomonas Infections; Pseudomonas aeruginosa; Pyocyanine; Virulence Factors
PubMed: 34830033
DOI: 10.3390/ijms222212152 -
Microbial Genomics Mar 2021The Liverpool epidemic strain (LES) is an important transmissible clonal lineage of that chronically infects the lungs of people with cystic fibrosis (CF). Previous...
The Liverpool epidemic strain (LES) is an important transmissible clonal lineage of that chronically infects the lungs of people with cystic fibrosis (CF). Previous studies have focused on the genomics of the LES in a limited number of isolates, mostly from one CF centre in the UK, and from studies highlighting identification of the LES in Canada. Here we significantly extend the current LES genome database by genome sequencing 91 isolates from multiple CF centres across the UK, and we describe the comparative genomics of this large collection of LES isolates from the UK and Canada. Phylogenetic analysis revealed that the 145 LES genomes analysed formed a distinct clonal lineage when compared with the wider population. Notably, the isolates formed two clades: one associated with isolates from Canada, and the other associated with UK isolates. Further analysis of the UK LES isolates revealed clustering by clinic geography. Where isolates clustered closely together, the association was often supported by clinical data linking isolates or patients. When compared with the earliest known isolate, LESB58 (from 1988), many UK LES isolates shared common loss-of-function mutations, such as in genes and . Other loss-of-function mutations identified in previous studies as common adaptations during CF chronic lung infections were also identified in multiple LES isolates. Analysis of the LES accessory genome (including genomic islands and prophages) revealed variations in the carriage of large genomic regions, with some evidence for shared genomic island/prophage complement according to clinic location. Our study reveals divergence and adaptation during the spread of the LES, within the UK and between continents.
Topics: Adaptation, Physiological; Canada; Cystic Fibrosis; Epidemics; Genome, Bacterial; Humans; Lung; Opportunistic Infections; Phylogeny; Pseudomonas Infections; Pseudomonas aeruginosa; United Kingdom
PubMed: 33720817
DOI: 10.1099/mgen.0.000511 -
BMC Microbiology Jan 2022Pseudomonas aeruginosa is an opportunistic pathogen that causes a wide range of acute and chronic infections and is frequently associated with healthcare-associated...
BACKGROUND
Pseudomonas aeruginosa is an opportunistic pathogen that causes a wide range of acute and chronic infections and is frequently associated with healthcare-associated infections. Because of its ability to rapidly acquire resistance to antibiotics, P. aeruginosa infections are difficult to treat. Alternative strategies, such as a vaccine, are needed to prevent infections. We collected a total of 413 P. aeruginosa isolates from the blood and cerebrospinal fluid of patients from 10 countries located on 4 continents during 2005-2017 and characterized these isolates to inform vaccine development efforts. We determined the diversity and distribution of O antigen and flagellin types and antibiotic susceptibility of the invasive P. aeruginosa. We used an antibody-based agglutination assay and PCR for O antigen typing and PCR for flagellin typing. We determined antibiotic susceptibility using the Kirby-Bauer disk diffusion method.
RESULTS
Of the 413 isolates, 314 (95%) were typed by an antibody-based agglutination assay or PCR (n = 99). Among the 20 serotypes of P. aeruginosa, the most common serotypes were O1, O2, O3, O4, O5, O6, O8, O9, O10 and O11; a vaccine that targets these 10 serotypes would confer protection against more than 80% of invasive P. aeruginosa infections. The most common flagellin type among 386 isolates was FlaB (41%). Resistance to aztreonam (56%) was most common, followed by levofloxacin (42%). We also found that 22% of strains were non-susceptible to meropenem and piperacillin-tazobactam. Ninety-nine (27%) of our collected isolates were resistant to multiple antibiotics. Isolates with FlaA2 flagellin were more commonly multidrug resistant (p = 0.04).
CONCLUSIONS
Vaccines targeting common O antigens and two flagellin antigens, FlaB and FlaA2, would offer an excellent strategy to prevent P. aeruginosa invasive infections.
Topics: Anti-Bacterial Agents; Drug Resistance, Bacterial; Flagellin; Humans; Microbial Sensitivity Tests; O Antigens; Pseudomonas Infections; Pseudomonas aeruginosa; Serogroup; Serotyping
PubMed: 34991476
DOI: 10.1186/s12866-021-02427-4 -
Communications Biology Feb 2023Pseudomonas aeruginosa is one of the leading causes of hospital-acquired infections. To decipher the metabolic mechanisms associated with virulence and antibiotic...
Pseudomonas aeruginosa is one of the leading causes of hospital-acquired infections. To decipher the metabolic mechanisms associated with virulence and antibiotic resistance, we have developed an updated genome-scale model (GEM) of P. aeruginosa. The model (iSD1509) is an extensively curated, three-compartment, and mass-and-charge balanced BiGG model containing 1509 genes, the largest gene content for any P. aeruginosa GEM to date. It is the most accurate with prediction accuracies as high as 92.4% (gene essentiality) and 93.5% (substrate utilization). In iSD1509, we newly added a recently discovered pathway for ubiquinone-9 biosynthesis which is required for anaerobic growth. We used a modified iSD1509 to demonstrate the role of virulence factor (phenazines) in the pathogen survival within biofilm/oxygen-limited condition. Further, the model can mechanistically explain the overproduction of a drug susceptibility biomarker in the P. aeruginosa mutants. Finally, we use iSD1509 to demonstrate the drug potentiation by metabolite supplementation, and elucidate the mechanisms behind the phenotype, which agree with experimental results.
Topics: Virulence; Pseudomonas aeruginosa; Drug Synergism; Virulence Factors; Biofilms
PubMed: 36765199
DOI: 10.1038/s42003-023-04540-8 -
Journal of Bacteriology Jul 2022The oxylipin-dependent quorum-sensing system (ODS) of Pseudomonas aeruginosa relies on the production and sensing of two extracellular oxylipins,...
The oxylipin-dependent quorum-sensing system (ODS) of Pseudomonas aeruginosa relies on the production and sensing of two extracellular oxylipins, 10-hydroxy-(8)-octadecenoic acid (10-HOME) and 7,10-dihydroxy-(8)-octadecenoic acid (7,10-DiHOME). Here, we implemented a genetic screen of P. aeruginosa strain PAO1 aimed to identify genes required for 10-HOME and 7,10-DiHOME production. Among the 14 genes identified, four encoded previously known components of the ODS and 10 encoded parts of the Xcp type II secretion system (T2SS). We subsequently created a clean deletion mutant, which encodes the necessary outer membrane component of Xcp, and found it recapitulated the impaired functionality of the T2SS transposon mutants. Further studies showed that the Δ mutant was unable to secrete the oxylipin synthase enzymes across the outer membrane. Specifically, immunoblotting for OdsA, which is responsible for the generation of 10-HOME from oleic acid, detected the enzyme in supernatants from wild-type PAO1 but not Δ cultures. Likewise, chromatography of supernatants found that 10-HOME was not in supernatants collected from the Δ mutant. Accordingly, diol synthase activity was increased in the periplasm of Δ mutant consistent with a stoppage in its transport. Importantly, after exposure of the Δ mutant to exogenous 10-HOME and 7,10-DiHOME, the ODS effector genes become active; thus, the sensing component of the ODS does not involve the T2SS. Finally, we observed that Xcp contributed to robust and biofilm formation in oleic acid availability- and ODS-dependent manner. Thus, T2SS-mediated transport of the oxylipin synthase enzymes to outside the bacterial cell is required for ODS functionality. We previously showed that the ODS of P. aeruginosa produces and responds to oxylipins derived from host oleic acid by enhancing biofilm formation and virulence. Here, we developed a genetic screen strategy to explore the molecular basis for oxylipins synthesis and detection. Unexpectedly, we found that the ODS autoinducer synthases cross the outer membrane using the Xcp type 2 secretion system (T2SS) of P. aeruginosa, and so the biosynthesis of oxylipins occurs extracellularly. T2SS promoted biofilm formation in the presence of oleic acid as a result of ODS activation. Our results identify two new T2SS secreted proteins in P. aeruginosa and reveal a new way by which this important opportunistic pathogen interacts with the host environment.
Topics: Bacterial Proteins; Oleic Acid; Oxylipins; Pseudomonas aeruginosa; Type II Secretion Systems
PubMed: 35658521
DOI: 10.1128/jb.00114-22 -
Journal of Bacteriology Oct 2021Pseudomonas aeruginosa strains PA14 and PAO1 are among the two best-characterized model organisms used to study the mechanisms of biofilm formation while also...
Pseudomonas aeruginosa strains PA14 and PAO1 are among the two best-characterized model organisms used to study the mechanisms of biofilm formation while also representing two distinct lineages of P. aeruginosa. Previous work has shown that PA14 and PAO1 use different strategies for surface colonization; they also have different extracellular matrix composition and different propensities to disperse from biofilms back into the planktonic phase surrounding them. We expand on this work here by exploring the consequences of these different biofilm production strategies during direct competition. Using differentially labeled strains and microfluidic culture methods, we show that PAO1 can outcompete PA14 in direct competition during early colonization and subsequent biofilm growth, that they can do so in constant and perturbed environments, and that this advantage is specific to biofilm growth and requires production of the Psl polysaccharide. In contrast, P. aeruginosa PA14 is better able to invade preformed biofilms and is more inclined to remain surface-associated under starvation conditions. These data together suggest that while P. aeruginosa PAO1 and PA14 are both able to effectively colonize surfaces, they do so in different ways that are advantageous under different environmental settings. Recent studies indicate that P. aeruginosa PAO1 and PA14 use distinct strategies to initiate biofilm formation. We investigated whether their respective colonization and matrix secretion strategies impact their ability to compete under different biofilm-forming regimes. Our work shows that these different strategies do indeed impact how these strains fair in direct competition: PAO1 dominates during colonization of a naive surface, while PA14 is more effective in colonizing a preformed biofilm. These data suggest that even for very similar microbes there can be distinct strategies to successfully colonize and persist on surfaces during the biofilm life cycle.
Topics: Biofilms; Cell Death; Lab-On-A-Chip Devices; Pseudomonas aeruginosa; Surface Properties
PubMed: 34516283
DOI: 10.1128/JB.00265-21