Scholarly Work - Center for Biofilm Engineering
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/9335
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Item 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, ThomasBacterial 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.Item The importance of understanding the infectious microenvironment(Elsevier BV, 2022-03) Bjarnsholt, Thomas; Whiteley, Marvin; Rumbaugh, Kendra P.; Stewart, Philip S.; Jensen, Peter Ø.; Frimodt-Møller, NielsStandard doses of antibiotics do not efficiently treat chronic infections of the soft tissue and bone. In this Personal View, we advocate for improving treatment of these infections by taking the infectious microenvironment into account. The infectious microenvironment can cause sensitive bacteria to lose their susceptibility to antibiotics that are effective in standard laboratory susceptibility testing. We propose that bacteria behave substantially different in standard laboratory conditions than they do in actual infections. The infectious microenvironment could impose changes in growth and metabolic activity that result in increased protection against antibiotics. Therefore, we advocate that improved antibiotic treatment of chronic infection is achievable when antibiotics are recommended on the basis of susceptibility testing in relevant in vitro conditions that resemble actual infectious microenvironments. We recommend establishing knowledge of the relevant conditions of the chemical and physical composition of the infectious microenvironment. Recent advances in RNA sequencing, metabolomics, and microscopy have made it possible for the characterisation of the microenvironment of infections and to validate the clinical relevance of in vitro conditions to actual infections.Item The origin of extracellular DNA in bacterial biofilm infections in vivo(Oxford University Press, 2020-03) Alhede, Maria; Alhede, Morten; Qvortrup, Klaus; Kragh, Kasper Nørskov; Jensen, Peter Østrup; Stewart, Philip Shook; Bjarnsholt, ThomasExtracellular DNA (eDNA) plays an important role in both the aggregation of bacteria and in the interaction of the resulting biofilms with polymorphonuclear leukocytes (PMNs) during an inflammatory response. Here, transmission electron and confocal scanning laser microscopy were used to examine the interaction between biofilms of Pseudomonas aeruginosa and PMNs in a murine implant model and in lung tissue from chronically infected cystic fibrosis patients. PNA FISH, DNA staining, labeling of PMN DNA with a thymidine analogue and immunohistochemistry were applied to localize bacteria, eDNA, PMN-derived eDNA, PMN-derived histone H3 (H3), neutrophil elastase (NE) and citrullinated H3 (citH3). Host-derived eDNA was observed surrounding bacterial biofilms but not within the biofilms. H3 localized to the lining of biofilms while NE was found throughout biofilms. CitH3, a marker for neutrophil extracellular traps (NETs) was detected only sporadically indicating that most host-derived eDNA in vivo was not a result of NETosis. Together these observations show that, in these in vivo biofilm infections with P. aeruginosa, the majority of eDNA is found external to the biofilm and derives from the host.Item The zone model: A conceptual model for understanding the microenvironment of chronic wound infection(Wiley, 2020-06) Kirketerp‐Møller, Klaus; Stewart, Philip S.; Bjarnsholt, ThomasIn 2008, two articles in Wound Repair and Regeneration changed the clinical perspective on chronic wounds. They stated that chronic wounds that do not heal contain bacterial biofilms and that these biofilms may be one of the reasons for the nonhealing properties of the wounds. However, we still do not understand the exact role biofilms play in the halted healing process, and we are not able to successfully treat them. The reason for this could be that in vivo biofilms differ substantially from in vitro biofilms, and that most of the knowledge about biofilms originates from in vitro research. In this article, we introduce the zone model as a concept for understanding bacterial behavior and the impact of the microenvironment on both the host and the bacteria. Until now, identification of bacteria, gene expression, and postscript regulation have been looking at a bulk of bacteria and averaging the behavior of all the bacteria. As the zone model dictates that every single bacterium reacts to its own microenvironment, the model may facilitate the planning of future research with improved clinical relevance. The zone model integrates physiology and biology from single cells, microbial aggregates, local host response, surrounding tissue, and the systemic context of the whole host. Understanding the mechanisms behind the actions and reactions by a single bacterium when interacting with other neighboring bacteria cells, other microorganisms, and the host will help us overcome the detrimental effects of bacteria in chronic wounds. Furthermore, we propose use of the terminology “bacterial phenotype” when describing the actions and reactions of bacteria, and the term “biofilms” to describe the morphology of the bacterial community.Item Minimum information guideline for spectrophotometric and fluorometric methods to assess biofilm formation in microplates(Elsevier BV, 2020) Allkja, Jontana; Bjarnsholt, Thomas; Coenye, Tom; Cos, Paul; Fallarero, Adyary; Harrison, Joe J.; Lopes, Susana P.; Oliver, Antonio; Pereira, Maria Olivia; Ramage, Gordon; Shirtliff, Mark E.; Stoodley, Paul; Webb, Jeremy S.; Zaat, Sebastian A.J.; Goeres, Darla M.; Azevedo, Nuno FilipeThe lack of reproducibility of published studies is one of the major issues facing the scientific community, and the field of biofilm microbiology has been no exception. One effective strategy against this multifaceted problem is the use of minimum information guidelines. This strategy provides a guide for authors and reviewers on the necessary information that a manuscript should include for the experiments in a study to be clearly interpreted and independently reproduced. As a result of several discussions between international groups working in the area of biofilms, we present a guideline for the spectrophotometric and fluorometric assessment of biofilm formation in microplates. This guideline has been divided into 5 main sections, each presenting a comprehensive set of recommendations. The intention of the minimum information guideline is to improve the quality of scientific communication that will augment interlaboratory reproducibility in biofilm microplate assays.Item Delayed neutrophil recruitment allows nascent Staphylococcus aureus biofilm formation and immune evasion(Elsevier BV, 2021-08) Pettygrove, Brian A.; Kratofil, Rachel M.; Alhede, Maria; Jensen, Peter O.; Newton, MIchelle; Qvortup, Klaus; Pallister, Kyler B.; Bjarnsholt, Thomas; Kubes, Paul; Voyich, Jovanka M.; Stewart, Philip S.Biofilms that form on implanted medical devices cause recalcitrant infections. The early events enabling contaminating bacteria to evade immune clearance, before a mature biofilm is established, are poorly understood. Live imaging in vitro demonstrated that Staphylococcus aureus sparsely inoculated on an abiotic surface can go undiscovered by human neutrophils, grow, and form aggregates. Small (~50 μm2) aggregates of attached bacteria resisted killing by human neutrophils, resulting in neutrophil lysis and bacterial persistence. In vivo, neutrophil recruitment to a peritoneal implant was spatially heterogenous, with some bacterial aggregates remaining undiscovered by neutrophils after 24 hours. Intravital imaging in mouse skin revealed that attached S. aureus aggregates grew and remained undiscovered by neutrophils for up to three hours. These results suggest a model in which delayed recruitment of neutrophils to an abiotic implant presents a critical window in which bacteria establish a nascent biofilm and acquire tolerance to neutrophil killing.Item Minimum information guideline for spectrophotometric and fluorometric methods to assess biofilm formation in microplates(2020-12) Allkja, Jontana; Bjarnsholt, Thomas; Coenye, Tom; Cos, Paul; Fallarero, Adyary; Harrison, Joe J.; Lopes, Susana P.; Oliver, Antonio; Pereira, Maria Olivia; Ramage, Gordon; Shirtliff, Mark E.; Stoodley, Paul; Webb, Jeremy S.; Zaat, Sebastian A. J.; Goeres, Darla M.; Azevedo, Nuno FilipeThe lack of reproducibility of published studies is one of the major issues facing the scientific community, and the field of biofilm microbiology has been no exception. One effective strategy against this multifaceted problem is the use of minimum information guidelines. This strategy provides a guide for authors and reviewers on the necessary information that a manuscript should include for the experiments in a study to be clearly interpreted and independently reproduced. As a result of several discussions between international groups working in the area of biofilms, we present a guideline for the spectrophotometric and fluorometric assessment of biofilm formation in microplates. This guideline has been divided into 5 main sections, each presenting a comprehensive set of recommendations. The intention of the minimum information guideline is to improve the quality of scientific communication that will augment interlaboratory reproducibility in biofilm microplate assays.Item Should standardized susceptibility testing for microbial biofilms be introduced in clinical practice?(2018-06) Coenye, T.; Goeres, Darla M.; Van Bambeke, F.; Bjarnsholt, ThomasItem 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.Item The prevalence of biofilms in chronic wounds: a systematic review and meta-analysis of published data(2017-01) Malone, Matthew; Bjarnsholt, Thomas; McBain, Andrew J.; James, Garth A.; Stoodley, Paul; Leaper, David; Tachi, Masahiro; Schultz, Gregory; Swanson, Terry; Wolcott, Randall D.The presence of biofilms in chronic non-healing wounds, has been identified through in vitro model and in vivo animal data. However, human chronic wound studies are under-represented and generally report low sample sizes. For this reason we sought to ascertain the prevalence of biofilms in human chronic wounds by undertaking a systematic review and meta-analysis. Our initial search identified 554 studies from the literature databases (Cochrane Library, Embase, Medline). After removal of duplicates, and those not meeting the requirements of inclusion, nine studies involving 185 chronic wounds met the inclusion criteria. Prevalence of biofilms in chronic wounds was 78.2 % (confidence interval [CI 61.6-89, p<0.002]). The results of our meta-analysis support our clinical assumptions that biofilms are ubiquitous in human chronic non-healing wounds.