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Current Biology : CB Feb 2015Mechanosensing of surfaces in bacteria is a process that often uses obstruction of flagellum rotation to trigger behaviors such as adhesion and surface-associated...
Mechanosensing of surfaces in bacteria is a process that often uses obstruction of flagellum rotation to trigger behaviors such as adhesion and surface-associated movement. In a recent publication, the PilY1 protein of Pseudomonas aeruginosa has been implicated as a novel mechanosensor that stimulates virulence in response to surface attachment.
Topics: Bacterial Adhesion; Pseudomonas aeruginosa
PubMed: 25649820
DOI: 10.1016/j.cub.2014.12.026 -
MSphere Aug 2021Antimicrobial susceptibility in Pseudomonas aeruginosa is dependent on a complex combination of host and pathogen-specific factors. Through the profiling of 971 clinical...
Antimicrobial susceptibility in Pseudomonas aeruginosa is dependent on a complex combination of host and pathogen-specific factors. Through the profiling of 971 clinical P. aeruginosa isolates from 590 patients and collection of paired patient metadata, we show that antimicrobial resistance is associated with not only patient-centric factors (e.g., cystic fibrosis and antipseudomonal prescription history) but also microbe-specific phenotypes (e.g., mucoid colony morphology). Additionally, isolates from different sources (e.g., respiratory tract, urinary tract) displayed rates of antimicrobial resistance that were correlated with source-specific antimicrobial prescription strategies. Furthermore, isolates from the same patient often displayed a high degree of heterogeneity, highlighting a key challenge facing personalized treatment of infectious diseases. Our findings support novel relationships between isolate and patient-level data sets, providing a potential guide for future antimicrobial treatment strategies. P. aeruginosa is a leading cause of nosocomial infection and infection in patients with cystic fibrosis. While P. aeruginosa infection and treatment can be complicated by a variety of antimicrobial resistance and virulence mechanisms, pathogen virulence is rarely recorded in a clinical setting. In this study, we discovered novel relationships between antimicrobial resistance, virulence-linked morphologies, and isolate source in a large and variable collection of clinical P. aeruginosa isolates. Our work motivates the clinical surveillance of virulence-linked P. aeruginosa morphologies as well as the tracking of source-specific antimicrobial prescription and resistance patterns.
Topics: Adolescent; Adult; Aged; Anti-Bacterial Agents; Child; Child, Preschool; Cross Infection; Drug Resistance, Multiple, Bacterial; Female; Humans; Infant; Male; Microbial Sensitivity Tests; Middle Aged; Phenotype; Pseudomonas Infections; Pseudomonas aeruginosa; Virulence Factors; Young Adult
PubMed: 34259555
DOI: 10.1128/mSphere.00393-21 -
The Journal of Antimicrobial... Dec 2017The selection and dose of antibiotic therapy for biofilm-related infections are based on traditional pharmacokinetic studies using planktonic bacteria. The objective of...
OBJECTIVES
The selection and dose of antibiotic therapy for biofilm-related infections are based on traditional pharmacokinetic studies using planktonic bacteria. The objective of this study was to characterize the time course and spatial activity of human exposure levels of meropenem and tobramycin against Pseudomonas aeruginosa biofilms grown in an in vitro flow-chamber model.
METHODS
Pharmacokinetic profiles of meropenem and tobramycin used in human therapy were administered to GFP-labelled P. aeruginosa PAO1 grown in flow chambers for 24 or 72 h. Images were acquired using confocal laser scanning microscopy throughout antibiotic treatment. Bacterial biomass was measured using COMSTAT and pharmacokinetic/pharmacodynamic models were fitted using NONMEM7.
RESULTS
Meropenem treatment resulted in more rapid and sustained killing of both the 24 and 72 h PAO1 biofilm compared with tobramycin. Biofilm regrowth after antibiotic treatment occurred fastest with tobramycin. Meropenem preferentially killed subpopulations within the mushroom cap of the biofilms, regardless of biofilm maturity. The spatial killing by tobramycin varied with biofilm maturity. A tobramycin-treated 24 h biofilm resulted in live and dead cells detaching from the biofilm, while treatment of a 72 h biofilm preferentially killed subpopulations on the periphery of the mushroom stalk. Regrowth occurred primarily on the mushroom caps. Combination meropenem and tobramycin therapy resulted in rapid and efficient killing of biofilm cells, with a spatial pattern similar to meropenem alone.
CONCLUSIONS
Simulated human concentrations of meropenem and tobramycin in young and mature PAO1 biofilms exhibited differences in temporal and spatial patterns of killing and antibiotic tolerance development.
Topics: Anti-Bacterial Agents; Biofilms; Biomass; Drug Tolerance; Green Fluorescent Proteins; Meropenem; Microbial Sensitivity Tests; Microbial Viability; Microscopy, Confocal; Pseudomonas aeruginosa; Spatio-Temporal Analysis; Staining and Labeling; Thienamycins; Tobramycin
PubMed: 28961810
DOI: 10.1093/jac/dkx288 -
Journal of Applied Microbiology Feb 2019The aim of this study was to investigate the natural variation in the antibiotic sensitivity, biofilm formation and virulence among Pseudomonas aeruginosa isolated from...
AIM
The aim of this study was to investigate the natural variation in the antibiotic sensitivity, biofilm formation and virulence among Pseudomonas aeruginosa isolated from the catheter-associated urinary tract infection (CAUTI) from a single centre.
METHODS AND RESULTS
Pseudomonas aeruginosa strains were isolated from the patients with CAUTI after obtaining informed consent. These isolates were identified by routine biochemical methods and 16S rRNA gene sequencing. Antibiotic sensitivity and virulence factors were measured using standard protocols. Crystal violet staining, scanning electron microscopy and confocal laser scanning microscopy were used for the biofilm studies. The extent of infectivity of the strains to induce cell lysis was studied in vitro using the Human Embryonic Kidney cells (HEK 293T). Association between virulence factors, biofilm formation and antibiotic resistance among the strains was analysed statistically. Among the 1266 patients admitted during the 2016-2017 period, 98 cases of CAUTI were reported and 18·36% (n = 18) was due to P. aeruginosa infection. Antibiogram showed that 94·4% of isolates were resistant to multiple antibiotics and 73·7% were carbapenem-resistant. All the isolates formed biofilm on different material surfaces with varying intensity (OD ≥0·20-1·11). The biofilm intensity on silicone-latex material was significantly higher compared to the polystyrene surface (P > 0·05). All the strains were highly virulent and able to cause cell killing of HEK 293T cells with a rate ranging from 69·35 to 100% and showed very low sensitivity to healthy human serum.
CONCLUSIONS
Antibiotic sensitivity and association between the virulence factors and biofilm formation in the P. aeruginosa clinical strains showed complex natural diversity.
SIGNIFICANCE AND IMPACT OF THE STUDY
This study demonstrates the natural diversity and adaptation in virulence factors, biofilm formation and host-pathogen interaction among catheter-associated P. aeruginosa strains. The findings from the study urge for developing individualized drug strategy for targeting these multidrug-resistant pathogens.
Topics: Adaptation, Physiological; Biodiversity; Biofilms; Drug Resistance, Multiple, Bacterial; HEK293 Cells; Humans; Middle Aged; Pseudomonas Infections; Pseudomonas aeruginosa; Silicones; Urinary Catheters; Urinary Tract Infections; Virulence Factors
PubMed: 30372578
DOI: 10.1111/jam.14143 -
Nature Communications Dec 2016The oxygenation of unsaturated fatty acids by dioxygenases occurs in all kingdoms of life and produces physiologically important lipids called oxylipins. The biological...
The oxygenation of unsaturated fatty acids by dioxygenases occurs in all kingdoms of life and produces physiologically important lipids called oxylipins. The biological roles of oxylipins have been extensively studied in animals, plants, algae and fungi, but remain largely unidentified in prokaryotes. The bacterium Pseudomonas aeruginosa displays a diol synthase activity that transforms several monounsaturated fatty acids into mono- and di-hydroxylated derivatives. Here we show that oxylipins derived from this activity inhibit flagellum-driven motility and upregulate type IV pilus-dependent twitching motility of P. aeruginosa. Consequently, these oxylipins promote bacterial organization in microcolonies, increasing the ability of P. aeruginosa to form biofilms in vitro and in vivo (in Drosophila flies). We also demonstrate that oxylipins produced by P. aeruginosa promote virulence in Drosophila flies and lettuce. Our study thus uncovers a role for prokaryotic oxylipins in the physiology and pathogenicity of bacteria.
Topics: A549 Cells; Animals; Biofilms; Drosophila; Humans; Lactuca; Microbial Interactions; Oxylipins; Pseudomonas aeruginosa; Virulence
PubMed: 27929111
DOI: 10.1038/ncomms13823 -
NPJ Biofilms and Microbiomes 2019tends to be among the dominant species in multi-species bacterial consortia in diverse environments. To understand physiology and interactions with co-existing...
tends to be among the dominant species in multi-species bacterial consortia in diverse environments. To understand physiology and interactions with co-existing bacterial species in different conditions, we established physiologically reproducible 18 species communities, and found that dominated in mixed-species biofilm communities but not in planktonic communities. H1 type VI secretion system was highly induced in mixed-species biofilm consortia, compared with its monospecies biofilm, which was further demonstrated to play a key role in 's enhanced fitness over other bacterial species. In addition, the type IV pili and Psl exopolysaccharide were required for to compete with other bacterial species in the biofilm community. Our study showed that the physiology of is strongly affected by interspecies interactions, and both biofilm determinants and type VI secretion system contribute to higher 's fitness over other species in complex biofilm communities.
Topics: Biofilms; Gene Expression Profiling; Gene Expression Regulation, Bacterial; Microbial Interactions; Microbiota; Population Dynamics; Pseudomonas aeruginosa
PubMed: 30675369
DOI: 10.1038/s41522-018-0076-z -
Journal of Applied Microbiology Apr 2016To establish the ability of the rhamnolipids biosurfactants from Pseudomonas aeruginosa, in the presence and absence of caprylic acid and ascorbic acid, to disrupt...
AIMS
To establish the ability of the rhamnolipids biosurfactants from Pseudomonas aeruginosa, in the presence and absence of caprylic acid and ascorbic acid, to disrupt bacterial biofilms, compared with the anionic alkyl sulphate surfactant Sodium dodecyl sulphate (SDS).
METHODS AND RESULTS
Pseudomonas aeruginosa ATCC 15442 biofilms were disrupted by rhamnolipids at concentrations between 0·5 and 0·4 g l(-1) and with SDS at 0·8 g l(-1) . The combination of rhamnolipids 0·4 g l(-1) and caprylic acid at 0·1 g l(-1) showed a remarkable effect on biofilm disruption and cell killing. After 30 min of treatment most of the biofilm was disrupted and cell viability was significantly reduced. Neither caprylic acid nor ascorbic acid has any effect on biofilm disruption at 0·1 g l(-1) . SDS is an effective antimicrobial agent; however, in the presence of caprylic acid its effect was neutralized.
CONCLUSIONS
The results show that rhamnolipids at low concentration in the presence of caprylic acid are promising molecules for inhibition/disruption of biofilms formed by Ps. aeruginosa ATCC 15442.
SIGNIFICANCE AND IMPACT OF THE STUDY
The disruption of biofilms has major significance in many industrial and domestic cleaning applications and in medical situations.
Topics: Biofilms; Glycolipids; Pseudomonas aeruginosa; Sodium Dodecyl Sulfate; Surface-Active Agents
PubMed: 26742560
DOI: 10.1111/jam.13049 -
Scientific Reports Mar 2021Pseudomonas aeruginosa uses quorum sensing (QS) to modulate the expression of several virulence factors that enable it to establish severe infections. The QS system in...
Pseudomonas aeruginosa uses quorum sensing (QS) to modulate the expression of several virulence factors that enable it to establish severe infections. The QS system in P. aeruginosa is complex, intricate and is dominated by two main N-acyl-homoserine lactone circuits, LasRI and RhlRI. These two QS systems work in a hierarchical fashion with LasRI at the top, directly regulating RhlRI. Together these QS circuits regulate several virulence associated genes, metabolites, and enzymes in P. aeruginosa. Paradoxically, LasR mutants are frequently isolated from chronic P. aeruginosa infections, typically among cystic fibrosis (CF) patients. This suggests P. aeruginosa can undergo significant evolutionary pathoadaptation to persist in long term chronic infections. In contrast, mutations in the RhlRI system are less common. Here, we have isolated a clinical strain of P. aeruginosa from a CF patient that has deleted the transcriptional regulator RhlR entirely. Whole genome sequencing shows the rhlR locus is deleted in PA80 alongside a few non-synonymous mutations in virulence factors including protease lasA and rhamnolipid rhlA, rhlB, rhlC. Importantly we did not observe any mutations in the LasRI QS system. PA80 does not appear to have an accumulation of mutations typically associated with several hallmark pathoadaptive genes (i.e., mexT, mucA, algR, rpoN, exsS, ampR). Whole genome comparisons show that P. aeruginosa strain PA80 is closely related to the hypervirulent Liverpool epidemic strain (LES) LESB58. PA80 also contains several genomic islands (GI's) encoding virulence and/or resistance determinants homologous to LESB58. To further understand the effect of these mutations in PA80 QS regulatory and virulence associated genes, we compared transcriptional expression of genes and phenotypic effects with isogenic mutants in the genetic reference strain PAO1. In PAO1, we show that deletion of rhlR has a much more significant impact on the expression of a wide range of virulence associated factors rather than deletion of lasR. In PA80, no QS regulatory genes were expressed, which we attribute to the inactivation of the RhlRI QS system by deletion of rhlR and mutation of rhlI. This study demonstrates that inactivation of the LasRI system does not impact RhlRI regulated virulence factors. PA80 has bypassed the common pathoadaptive mutations observed in LasR by targeting the RhlRI system. This suggests that RhlRI is a significant target for the long-term persistence of P. aeruginosa in chronic CF patients. This raises important questions in targeting QS systems for therapeutic interventions.
Topics: Bacterial Proteins; Cystic Fibrosis; Gene Expression Regulation, Bacterial; Genetic Variation; Genomics; Humans; Mutation; Phylogeny; Pseudomonas aeruginosa; Quorum Sensing; Virulence Factors
PubMed: 33707533
DOI: 10.1038/s41598-021-85100-0 -
Current Opinion in Microbiology Apr 2016The first step in the development of a bacterial biofilm is contact with the surface on which the microbe will form this community. We review recent progress on 'surface... (Review)
Review
The first step in the development of a bacterial biofilm is contact with the surface on which the microbe will form this community. We review recent progress on 'surface sensing', and engage the question of 'how does a microbe know it is on a surface?'
Topics: Biofilms; Nucleotides, Cyclic; Pseudomonas aeruginosa; Quorum Sensing
PubMed: 26968016
DOI: 10.1016/j.mib.2016.02.004 -
Microbial Cell Factories Mar 2021Rhamnolipids have recently attracted considerable attentions because of their excellent biosurfactant performance and potential applications in agriculture, environment,... (Review)
Review
Rhamnolipids have recently attracted considerable attentions because of their excellent biosurfactant performance and potential applications in agriculture, environment, biomedicine, etc., but severe foaming causes the high cost of production, restraining their commercial production and applications. To reduce or eliminate the foaming, numerous explorations have been focused on foaming factors and fermentation strategies, but a systematic summary and discussion are still lacking. Additionally, although these studies have not broken through the bottleneck of foaming, they are conducive to understanding the foaming mechanism and developing more effective rhamnolipids production strategies. Therefore, this review focuses on the effects of fermentation components and control conditions on foaming behavior and fermentation strategies responded to the severe foaming in rhamnolipids fermentation and systematically summarizes 6 impact factors and 9 fermentation strategies. Furthermore, the potentialities of 9 fermentation strategies for large-scale production are discussed and some further strategies are suggested. We hope this review can further facilitate the understanding of foaming factors and fermentation strategies as well as conducive to developing the more effective large-scale production strategies to accelerate the commercial production process of rhamnolipids.
Topics: Fermentation; Glycolipids; Industrial Microbiology; Pseudomonas aeruginosa; Surface-Active Agents
PubMed: 33781264
DOI: 10.1186/s12934-021-01516-3