Browsing by Author "Stoodley, Paul"

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Analysis of bacterial spatial patterns at the initial stage of biofilm formation
(1995) Hamilton, Martin A.; Johnson, K. R.; Camper, Anne K.; Stoodley, Paul; Harkin, Gary; Gillis, Richard J.; Shope, Paul A.
Antimicrobials and biofilms
(2002-12) Czechowski, M. H.; Stoodley, Paul
Approaches to biofilm-associated infections: the need for standardized and relevant biofilm methods for clinical applications
(2017-02) Malone, Matthew; Goeres, Darla M.; Gosbell, Iain; Vickery, Karen; Jensen, Slade; Stoodley, Paul
Introduction: The concept of biofilms in human health and disease is now widely accepted as cause of chronic infection. Typically, biofilms show remarkable tolerance to many forms of treatments and the host immune response. This has led to vast increase in research to identify new (and sometimes old) anti-biofilm strategies that demonstrate effectiveness against these tolerant phenotypes. Areas covered: Unfortunately, a standardized methodological approach of biofilm models has not been adopted leading to a large disparity between testing conditions. This has made it almost impossible to compare data across multiple laboratories, leaving large gaps in the evidence. Furthermore, many biofilm models testing anti-biofilm strategies aimed at the medical arena have not considered the matter of relevance to an intended application. This may explain why some in vitro models based on methodological designs that do not consider relevance to an intended application fail when applied in vivo at the clinical level. Expert commentary: This review will explore the issues that need to be considered in developing performance standards for anti-biofilm therapeutics and provide a rationale for the need to standardize models/methods that are clinically relevant. We also provide some rational as to why no standards currently exist.
Bacterial biofilms: a diagnostic and therapeutic challenge
(2003-12) Fux, C. A.; Stoodley, Paul; Hall-Stoodley, Luanne; Costerton, J. William
Bacteria have traditionally been regarded as individual organisms growing in homogeneous planktonic populations. However, bacteria in natural environments usually form communities of surface-adherent organisms embedded in an extracellular matrix, called biofilms. Current antimicrobial strategies often fail to control bacteria in the biofilm mode of growth. Treatment failure is particularly frequent in association with intracorporeal or transcutaneous medical devices and compromised host immunity. The rising prevalence of these risk factors over the last decades has paralleled the increase in biofilm infections. This review discusses the shortcomings of current therapies against biofilms both in theory and with clinical examples. Biofilm characteristics are described with a focus on new diagnostic and therapeutic targets.
Bacterial biofilms: From the environment to infectious disease
(2004-02) Hall-Stoodley, Luanne; Costerton, J. William; Stoodley, Paul
Biofilms—matrix-enclosed microbial accretions that adhere to biological or non-biological surfaces—represent a significant and incompletely understood mode of growth for bacteria. Biofilm formation appears early in the fossil record (3.25 billion years ago) and is common throughout a diverse range of organisms in both the Archaea and Bacteria lineages, including the 'living fossils' in the most deeply dividing branches of the phylogenetic tree. It is evident that biofilm formation is an ancient and integral component of the prokaryotic life cycle, and is a key factor for survival in diverse environments. Recent advances show that biofilms are structurally complex, dynamic systems with attributes of both primordial multicellular organisms and multifaceted ecosystems. Biofilm formation represents a protected mode of growth that allows cells to survive in hostile environments and also disperse to colonize new niches. The implications of these survival and propagative mechanisms in the context of both the natural environment and infectious diseases are discussed in this review. Full test provided (pdf) with permission of: Future Drugs.
Bacterial colonization of surfaces in flowing systems: methods and analysis
(1994) Camper, Anne K.; Hamilton, Martin A.; Johnson, K. R.; Stoodley, Paul; Harkin, Gary; Daly, Don Simone
The biofilm life cycle: expanding the conceptual model of biofilm formation
(Springer Science and Business Media LLC, 2022-10) Sauer, Karin; Stoodley, Paul; Goeres, Darla M.; Hall-Stoodley, Luanne; Burmølle, Mette; Stewart, Philip S.; Bjarnsholt, Thomas
Bacterial biofilms are often defined as communities of surface-attached bacteria and are typically depicted with a classic mushroom-shaped structure characteristic of Pseudomonas aeruginosa. However, it has become evident that this is not how all biofilms develop, especially in vivo, in clinical and industrial settings, and in the environment, where biofilms often are observed as non-surface-attached aggregates. In this Review, we describe the origin of the current five-step biofilm development model and why it fails to capture many aspects of bacterial biofilm physiology. We aim to present a simplistic developmental model for biofilm formation that is flexible enough to include all the diverse scenarios and microenvironments where biofilms are formed. With this new expanded, inclusive model, we hereby introduce a common platform for developing an understanding of biofilms and anti-biofilm strategies that can be tailored to the microenvironment under investigation.
Biofilm material properties as related to shear-induced deformation and detachment phenomena
(2002-12) Stoodley, Paul; Cargo, R.; Rupp, Cory J.; Wilson, Suzanne; Klapper, Isaac
Biofilms of various Pseudomonas aeruginosa strains were grown in glass flow cells under laminar and turbulent flows. By relating the physical deformation of biofilms to variations in fluid shear, we found that the biofilms were viscoelastic fluids which behaved like elastic solids over periods of a few seconds but like linear viscous fluids over longer times. These data can be explained using concepts of associated polymeric systems, suggesting that the extracellular polymeric slime matrix determines the cohesive strength. Biofilms grown under high shear tended to form filamentous streamers while those grown under low shear formed an isotropic pattern of mound-shaped microcolonies. In some cases, sustained creep and necking in response to elevated shear resulted in a time-dependent fracture failure of the "tail" of the streamer from the attached upstream "head." In addition to structural differences, our data suggest that biofilms grown under higher shear were more strongly attached and were cohesively stronger than those grown under lower shears.
Biofilm removal from silicone tubing: an assessment of the efficacy of dialysis machine decontamination procedures using an in vitro model
(2003-01) Marion-Ferey, Karine; Pasmore, M.; Stoodley, Paul; Wilson, Suzanne; Husson, Gilles; Costerton, J. William
The aim of this study was to assess the efficacy of 21 decontamination procedures, for the removal of a multispecies biofilm. Experiments were performed on five-day-old biofilms grown inside silicone tubing, using a reactor system that mimics a dialysis machine. The treatments were tested on 5 cm tubing samples. Effects of treatment were measured using direct microscopy following staining. Bacterial viability and endotoxin removal were determined using conventional microbiological methods following biofilm detachment by scraping. The 21 procedures were classified into four groups based on the amount of biofilm removed. The most effective treatment was an acid pre-treatment, followed by use of a concentrated bleach solution. Acid pre-treatment removes calcium and magnesium carbonate crystals that are always found in dialysis biofilms. Treatments performed at high temperature did not increase the efficacy of biofilm removal. Most treatments caused at least a 105-fold reduction in bacterial viability with a few resulting in complete kill. Autoclaved and bleach-treated samples gave the best results for viability reduction, with both treatments providing an equally effective and complete kill. In addition, autoclaving led to a significant decrease in endotoxin level (removal of 99.99%).
Biofilm structure and influence on biofouling under laminar and turbulent flows
(1999) Stoodley, Paul; Boyle, John D.; Cunningham, Alfred B.; Dodds, I.; Lappin-Scott, H. M.; Lewandowski, Zbigniew
Biofilm structure, behavior, and hydrodynamics
(2004) Purevdorj, B.; Stoodley, Paul
Hexavalent uranium [U(VI)] was immobilized using biofilms of the sulfate-reducing bacterium (SRB) Desulfovibrio desulfuricans G20. The biofilms were grown in flat-plate continuous-flow reactors using lactate as the electron donor and sulfate as the electron acceptor. U(VI)was continuously fed into the reactor for 32 weeks at a concentration of 126 microM. During this time, the soluble U(VI) was removed (between 88 and 96% of feed) from solution and immobilized in the biofilms. The dynamics of U immobilization in the sulfate-reducing biofilms were quantified by estimating: (1) microbial activity in the SRB biofilm, defined as the hydrogen sulfide (H2S) production rate and estimated from the H2S concentration profiles measured using microelectrodes across the biofilms; (2) concentration of dissolved U in the solution; and (3) the mass of U precipitated in the biofilm. Results suggest that U was immobilized in the biofilms as a result of two processes: (1) enzymatically and (2) chemically, by reacting with microbially generated H2S. Visual inspection showed that the dissolved sulfide species reacted with U(VI) to produce a black precipitate. Synchrotron-based U L3-edge X-ray absorption near edge structure (XANES) spectroscopy analysis of U precipitated abiotically by sodium sulfide indicated that U(VI) had been reduced to U(IV). Selected-area electron diffraction pattern and crystallographic analysis of transmission electron microscope lattice-fringe images confirmed the structure of precipitated U as being that of uraninite.
Biofilms as complex differentiated communities
(2002-10) Stoodley, Paul; Sauer, K.; Davies, David Gwilym; Costerton, J. William
Prokaryotic biofilms that predominate in a diverse range of ecosystems are often composed of highly structured multispecies communities. Within these communities metabolic activities are integrated, and developmental sequences, not unlike those of multicellular organisms, can be detected. These structural applications and interrelationships are made possible by the expression of sets of genes that result in phenotypes that differ profoundly from those of planktonically grown cells of the same species. Molecular and microscopic evidence suggests the existence of a succession of de facto biofilm phenotypes. We submit that complex cell-cell interactions within prokaryotic communities are an ancient characteristic, the development of which was facilitated by the localization of cells at surfaces. In addition to spatial localization, surfaces may have provided the protective niche in which attached cells could create a localized homeostatic environment. In a holistic sense both biofilm and planktonic phenotypes may be viewed as integrated components of prokaryote life.
Biofilms, biomaterials and device-related infections
(2004) Costerton, J. William; Stoodley, Paul; Shirtliff, Mark E.; Pasmore, M.; Cook, Guy S.
Can laboratory reference strains mirror 'real-world' pathogenesis?
(2005-02) Fux, C. A.; Shirtliff, Mark E.; Stoodley, Paul; Costerton, J. William
The extraordinary plasticity of bacterial genomes raises concerns about the adequacy of laboratory-adapted reference strains for the study of 'real world' pathogenesis. Some laboratory strains have been sub-cultured for decades since their first isolation and might have lost important pathophysiological characteristics. Evidence is presented that bacteria rapidly adapt to in vitro conditions. Genomic differences between laboratory reference strains and corresponding low-passage clinical isolates are reviewed. It appears that no bacterial strain can truly represent its species. For DNA microarray and proteomic studies, this limitation might be overcome by the summation of individual genomes to produce a species-specific virtual supragenome.
Chemical effects of biofilm colonization on 304 stainless steel
(1996-05) Pendyala, Jyostna; Avci, Recep; Geesey, Gill G.; Stoodley, Paul; Hamilton, Martin A.; Harkin, Gary
Changes in the surface concentrations of the main alloying elements of an as‐received 304 stainless steel, exposed to a mixed culture of biofilm‐forming bacteria under flowing conditions, were observed using Auger electron spectroscopy. In the oxide film close to the bulk stainless steel, there was an enrichment in the relative concentration of Cr with a corresponding decrease in the relative Fe concentration as compared to a control coupon exposed only to sterile media. There were no changes observed in the relative Ni concentration.
Clinical significance of seeding dispersal in biofilms: A response
(2005-11) Stoodley, Paul; Purevdorj, B.; Costerton, J. William
We welcome the dialogue concerning the potential clinical significance of seeding dispersal (Purevdorj-Gage et al., 2005) in the life cycle of mucoid Pseudomonas aeruginosa biofilms. We had based our hypothesis that the seeding dispersal phenomenon may be more relevant for non-mucoid, environmental strains on (1) the propensity of diseases associated with reduced mucociliary clearance in the lung, such as cystic fibrosis (CF) or chronic obstructive pulmonary disease (COPD), to select for mucoid P. aeruginosa phenotypes, and (2) that conversion to mucoidy is usually associated with a concomitant down-regulation of flagella production and loss of swimming motility (see Garrett et al., 1999). However, as Kirov et al. discuss above, there may be greater diversity in mucoid CF isolates than generally acknowledged, and the perceived dichotomy between mucoidy and swimming phenotypes should be a topic for debate. More recently it has been shown that expression of flagellum genes in response to oxygen limitation precedes loss of mucoidy and is reversible during this state of transition (Wyckoff et al., 2002). Further, in an ongoing screen of mucoid CF isolates it was found that 6 out of 20 were motile (D.J. Wozniak, personal communication). However, it was suspected that growth medium may also play a role in the outcome of the motility assay and exact proportions may vary depending on culture conditions. The growth-condition-dependent transient switching between mucoid and swimming phenotypes is problematic when relating a particular biofilm behaviour with phenotype and stresses the importance of attempting to characterize the phenotypic state at various time points during biofilm development. Broadly though, the finding of Dr Wozniak is in agreement with that of Kirov et al. We agree that to fully assess the role of seeding dispersal (and other yet unidentified behavioural developmental phenotypes) in the context of lung infections, biofilm studies should include greater diversity in strains, growth conditions and be conducted over longer time scales. The interesting observation that seeding motility occurred in a mucoid CF isolate clearly demonstrates that the phenomenon may have clinical relevance.
Commonality of elastic relaxation times in biofilms
(2004-08) Shaw, T.; Winston, Matthew T.; Rupp, Cory J.; Klapper, Isaac; Stoodley, Paul
Biofilms, sticky conglomerations of microorganisms and extracellular polymers, are among the Earth's most common life forms. One component for their survival is an ability to withstand external mechanical stress. Measurements indicate that biofilm elastic relaxation times are approximately the same (about 18 min) over a wide sample of biofilms though other material properties vary significantly. A possible survival significance of this time scale is that it is the shortest period over which a biofilm can mount a phenotypic response to transient mechanical stress.
Community structure and co-operation in biofilms
(2000) Stoodley, Paul; Hall-Stoodley, Luanne; Boyle, John D.; Jørgensen, Frieda; Lappin-Scott, H. M.
Consensus guidelines for the identification and treatment of biofilms in chronic nonhealing wounds
(2017-09) Schultz, Gregory; Bjarnsholt, Thomas; James, Garth A.; Leaper, David; McBain, Andrew J.; Malone, Matthew; Stoodley, Paul; Swanson, Terry; Tachi, Masahiro; Wolcott, Randall D.
Background: Despite a growing consensus that biofilms contribute to a delay in the healing of chronic wounds, conflicting evidence pertaining to their identification and management can lead to uncertainty regarding treatment. This, in part, has been driven by reliance on in vitro data or animal models, which may not directly correlate to clinical evidence on the importance of biofilms. Limited data presented in human studies have further contributed to the uncertainty. Guidelines for care of chronic wounds with a focus on biofilms are needed to help aid the identification and management of biofilms, providing a clinical focus to support clinicians in improving patient care through evidence-based medicine. Methods: A Global Wound Biofilm Expert Panel, comprising 10 clinicians and researchers with expertise in laboratory and clinical aspects of biofilms, was identified and convened. A modified Delphi process, based on published scientific data and expert opinion, was used to develop consensus statements that could help identify and treat biofilms as part of the management of chronic nonhealing wounds. Using an electronic survey, panel members rated their agreement with statements about biofilm identification and treatment, and the management of chronic nonhealing wounds. Final consensus statements were agreed on in a face-to-face meeting. Results: Participants reached consensus on 61 statements in the following topic areas: understanding biofilms and the problems they cause clinicians; current diagnostic options; clinical indicators of biofilms; future options for diagnostic tests; treatment strategies; mechanical debridement; topical antiseptics; screening antibiofilm agents; and levels of evidence when choosing antibiofilm treatments. Conclusion: This consensus document attempts to clarify misunderstandings about the role of biofilms in clinical practice, and provides a basis for clinicians to recognize biofilms in chronic nonhealing wounds and manage patients optimally. A new paradigm for wound care, based on a stepped-down treatment approach, was derived from the consensus statements.
Consensus model of biofilm structure
(1997) Stoodley, Paul; Boyle, John D.; Dodds, I.; Lappin-Scott, H. M.