Biology subjects

Gloag, E. S.

Publications and source records attributed to Gloag, E. S..

5 recordsLinked to original sources

bioRxiv2023

Cross-Species Protection to Innate Immunity Mediated by A Bacterial Pigment

Bacterial infections are often polymicrobial. Pseudomonas aeruginosa and Staphylococcus aureus cause chronic co-infections, which are more problematic than mono-species infections. We found that the production of S. aureus membrane-bound pigment staphyloxanthin (STX), was induced by the P. aeruginosa exoproduct, 2-heptyl-4-hydroxyquinoline N-oxide (HQNO). The induction phenotype was conserved in P. aeruginosa and S. aureus clinical isolates examined. When subjected to hydrogen peroxide or human neutrophils, P. aeruginosa survival was significantly higher when mixed with wild-type (WT) S. aureus, compared to a mutant deficient in STX production or P. aeruginosa alone. In a murine wound model, co-infection with WT S. aureus, but not the STX-deficient mutant, enhanced P. aeruginosa burden and disease compared to mono-infection. In conclusion, we discovered a novel role for P. aeruginosa HQNO mediating polymicrobial interactions with S. aureus by inducing STX production, which consequently promotes resistance of both pathogens to innate immune effectors. These results further our understanding of how different bacterial species cooperatively cause co-infections.

microbiology↗

bioRxiv2021

Arginine induced Streptococcus gordonii biofilm detachment using a novel rotating-disc rheometry method

Oral diseases are one of the most common pathologies affecting human health. These diseases are typically associated with dental plaque-biofilms, through either build-up of the biofilm or dysbiosis of the microbial community. Arginine can disrupt dental plaque-biofilms, and maintain plaque homeostasis, making it an ideal therapeutic to combat the development of oral disease. Despite our understanding of the actions of arginine towards dental plaque-biofilms, it is still unclear how or if arginine effects the mechanical integrity of the dental plaque-biofilm. Here we adapted a rotating-disc rheometry assay, which is routinely used in marine microbial ecology, to study how arginine treatment of Streptococcus gordonii biofilms influences biofilm detachment from surfaces. We demonstrate that the assay is highly sensitive at quantifying the presence of biofilm and the detachment or rearrangement of the biofilm structure as a function of shear stress. We demonstrate that arginine treatment leads to earlier detachment of the biofilm, indicating that arginine treatment weakens the biofilm, making it more suspectable to removal by shear stresses. Our results add to the understanding that arginine targets biofilms by multifaceted mechanisms, both metabolic and physical, further promoting the potential of arginine as an active compound in dentifrices to maintain oral health.

microbiology↗

bioRxiv2021

Rampant prophage movement among transient competitors drives rapid adaptation during infection

Interactions between bacteria, their close competitors, and viral parasites are common in infections but understanding of these eco-evolutionary dynamics is limited. Most examples of adaptations caused by phage lysogeny are through the acquisition of new genes. However, integrated prophages can also insert into functional genes and impart a fitness benefit by disrupting their expression, a process called active lysogeny. Here, we show that active lysogeny can fuel rapid, parallel adaptations in establishing a chronic infection. These recombination events repeatedly disrupted genes encoding global regulators, leading to increased cyclic-di-GMP levels and elevated biofilm production. The implications of prophage-mediated adaptation are broad, as even transient members of microbial communities can alter the course of evolution and generate persistent phenotypes associated with poor clinical outcomes. One Sentence SummaryBacteriophage act as genetic regulators that are key to establishing chronic infections and are rapidly shared among co-infecting strains.

microbiology↗

bioRxiv2020

Mycobacterium abscessus biofilms have viscoelastic properties which may contribute to their recalcitrance in chronic pulmonary infections.

Mycobacterium abscessus is emerging as a cause of recalcitrant chronic pulmonary infections, particularly in people with cystic fibrosis (CF). Biofilm formation has been implicated in the pathology of this organism, however the role of biofilm formation in infection is unclear. Two colony-variants of M. abscessus are routinely isolated from CF samples, smooth (MaSm) and rough (MaRg). These two variants display distinct colony morphologies due to the presence (MaSm) or absence (MaRg) of cell wall glycopeptidolipids (GPLs). We hypothesized that MaSm and MaRg variant biofilms might have different biophysical and mechanical properties, including stiffness, viscosity and elasticity. To test this hypothesis, we performed uniaxial mechanical indentation, and shear rheometry on MaSm and MaRg colony-biofilms. We identified that MaRg biofilms were significantly stiffer than MaSm under a normal force, while MaSm biofilms were more pliant compared to MaRg, under both normal and shear forces. Furthermore, using theoretical indices of mucociliary and cough clearence, we identified that M. abscessus biofilms may be more resistant to mechanical forms of clearance from the lung, compared to other common pulmonary pathogens, such as P. aeruginosa. Thus, the mechanical properties of M. abscessus biofilms may contribute to the persistent nature of pulmonary infections caused by this organism.

microbiology↗

bioRxiv2018

The Pseudomonas aeruginosa Wsp pathway undergoes positive evolutionary selection during chronic infection

Author Contributions Author Contributions Introductory paragraph Results Discussion Materials and Methods References ESG and CWM performed the experimental work. JSH performed the colony PCR. SBC infected and sampled the porcine burn wounds. DS generated the sequence library. MW and GRL quantified the strain frequency in the wounds. ESG, CWM, MW, VSC, and DJW conceptualized the project and wrote the manuscript.\n\nIntroductory paragraph Author Contributions Introductory paragraph Results Discussion Materials and Methods References Pathogens experience pressure in an infection to adapt, with selection favoring mutants that persist. Pseudomonas aeruginosa commonly ad ...

microbiology↗