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Methods in Molecular Biology (Clifton,... 2024In vitro biofilm models have allowed researchers to investigate the role biofilms play in the pathogenesis, virulence, and antimicrobial drug susceptibility of a wide...
In vitro biofilm models have allowed researchers to investigate the role biofilms play in the pathogenesis, virulence, and antimicrobial drug susceptibility of a wide range of bacterial pathogens. Rotary cell culture systems create three-dimensional cellular structures, primarily applied to eukaryotic organoids, that better capture characteristics of the cells in vivo. Here, we describe how to apply a low-shear, detergent-free rotary cell culture system to generate biofilms of Mycobacterium bovis BCG. The three-dimensional biofilm model forms mycobacterial cell aggregates in suspension as surface-detached biomass, without severe nutrient starvation or environmental stress, that can be harvested for downstream experiments. Mycobacterium bovis BCG derived from cell clusters display antimicrobial drug tolerance, presence of an extracellular matrix, and evidence of cell wall remodeling, all features of biofilm-associated bacteria that may be relevant to the treatment of tuberculosis.
Topics: Biofilms; Mycobacterium bovis; Cell Culture Techniques; Cell Culture Techniques, Three Dimensional
PubMed: 38949696
DOI: 10.1007/978-1-0716-3981-8_2 -
AMB Express Jun 2024Pseudomonas aeruginosa is a commonly found Gram-negative bacterium in healthcare facilities and is renowned for its ability to form biofilms and its virulence factors...
Pseudomonas aeruginosa is a commonly found Gram-negative bacterium in healthcare facilities and is renowned for its ability to form biofilms and its virulence factors that are controlled by quorum sensing (QS) systems. The increasing prevalence of multidrug-resistant strains of this bacterium poses a significant challenge in the field of medicine. Consequently, the exploration of novel antimicrobial agents has become a top priority. This research aims to optimize chitosan derived from white shrimp (Metapenaeus affinis) using the Response Surface Methodology (RSM) computational approach. The objective is to investigate chitosan's potential as a solution for inhibiting QS activity and biofilm formation in P. aeruginosa ATCC 10,145. Under optimized conditions, chitin was treated with NaOH (1.41 M) for 15.75 h, HCl (7.49% vol) for 2.01 h, and at a deacetylation temperature of 81.15 °C. The resulting chitosan exhibited a degree of deacetylation (DD%) exceeding 93.98%, as confirmed by Fourier-transform infrared (FTIR) spectral analysis, indicating its high purity. The extracted chitosan demonstrated a significant synergistic antibiotic effect against P. aeruginosa when combined with ceftazidime, enhancing its bactericidal activity by up to 15-fold. In addition, sub-MIC (minimum inhibitory concentration) concentrations of extracted chitosan (10 and 100 µg/mL) successfully reduced the production of pyocyanin and rhamnolipid, as well as the swimming motility, protease activity and biofilm formation ability in comparison to the control group (P < 0.05). Moreover, chitosan treatment downregulated the RhlR and LasR genes in P. aeruginosa when compared to the control group (P < 0.05). The optimized chitosan extract shows significant potential as a coating agent for surgical equipment, effectively preventing nosocomial infections caused by P. aeruginosa pathogens.
PubMed: 38949677
DOI: 10.1186/s13568-024-01732-1 -
Critical Reviews in Microbiology Jul 2024is a common pathogen associated with hospital-acquired pneumonia showing increased resistance to carbapenem and colistin antibiotics nowadays. Infections with cause... (Review)
Review
is a common pathogen associated with hospital-acquired pneumonia showing increased resistance to carbapenem and colistin antibiotics nowadays. Infections with cause high patient fatalities due to their capability to evade current antimicrobial therapies, emphasizing the urgency of developing viable therapeutics to treat -associated pneumonia. In this review, we explore current and novel therapeutic options for overcoming therapeutic failure when dealing with -associated pneumonia. Among them, antibiotic combination therapy administering several drugs simultaneously or alternately, is one promising approach for optimizing therapeutic success. However, it has been associated with inconsistent and inconclusive therapeutic outcomes across different studies. Therefore, it is critical to undertake additional clinical trials to ascertain the clinical effectiveness of different antibiotic combinations. We also discuss the prospective roles of novel antimicrobial therapies including antimicrobial peptides, bacteriophage-based therapy, repurposed drugs, naturally-occurring compounds, nanoparticle-based therapy, anti-virulence strategies, immunotherapy, photodynamic and sonodynamic therapy, for utilizing them as additional alternative therapy while tackling -associated pneumonia. Importantly, these innovative therapies further require pharmacokinetic and pharmacodynamic evaluation for safety, stability, immunogenicity, toxicity, and tolerability before they can be clinically approved as an alternative rescue therapy for -associated pulmonary infections.
PubMed: 38949254
DOI: 10.1080/1040841X.2024.2369948 -
Zhonghua Kou Qiang Yi Xue Za Zhi =... Jul 2024To investigate the effects of Porphyromonas gingivalis (Pg) persisters (Ps) on immuno-inflammatory responses in macrophages, and to explore the underlying mechanisms....
To investigate the effects of Porphyromonas gingivalis (Pg) persisters (Ps) on immuno-inflammatory responses in macrophages, and to explore the underlying mechanisms. Pg cells were cultured to the stationary phase (72 h), and subsequently treated by high concentration of metronidazole at 100 mg/L, amoxicillin at 100 mg/L and the combination of them for different time period, named as metronidazole group, amoxicillin group and (metronidazole+amoxicillin) group. Pg cells without management were used as blank control. The survival profile of PgPs cells was measured by colony-forming unit assay. The living state of PgPs was observed by Live/Dead staining. Then, Pg and metronidazole-treated PgPs (M-PgPs) were used to treat macrophages, named as Pg group and M-PgPs group. Transmission electron microscopy (TEM) was used to observe the bacteria in the macrophages. The expression levels of proinflammatory cytokines in macrophages were determined by real-time fluorescence quantitative PCR and enzyme-linked immunosorbent assay. The location of forkhead box 1 (FOXO1) was detected by confocal immunofluorescence microscopy. After inhibiting or enhancing the FOXO1 expressions using inhibitors (Fi) or activators (Fa) respectively, the macrophages were treated with Pg and M-PgPs, divided as Blank group, Pg group, M-PgPs group, Fi group, (Fi+Pg) group, (Fi+M-PgPs) group, Fa group, (Fa+Pg) group and (Fa+M-PgPs) group. Then, the expression pattens of proinflammatory cytokines were assessed. Remarkable number of lived PgPs was observed, both in planktonic culture and Pg biofilms either treated with metronidazole, amoxicillin or both, and those persisters could form new colonies. Pg and M-PgPs were able to enter into the macrophages and the protein expression levels of interleukin (IL)-1β, IL-6, IL-8 and tumor necrosis factor-α (TNF-α) [Pg group: (2 392±188), (162±29), (5 558±661), (789±155) μg/L; M-PgPs group: (2 415±420), (155±3), (5 732±782), (821±176) μg/L)] were significantly upregulated than those in Blank group [(485±140), (21±9), (2 332±87), (77±7) μg/L] (0.01). Moreover, Pg and M-PgPs could facilitate the nuclear translocation and accumulation of FOXO1. In addition, the relative mRNA expression levels of FOXO1, BCL6 and KLF2 were upregulated when compared to Blank group (0.05). Furthermore, the protein expression levels of IL-1β, IL-6, IL-8 and TNF-α in Fi+Pg group [(1 081±168), (70±8), (1 976±544), (420±47) μg/L] were remarkably lower than Pg group [(4 411±137), (179±6), (5 161±929), (934±24) μg/L] (0.05). Similarly, the protein expression levels of IL-1β, IL-6, IL-8 and TNF-α in Fi+M-PgPs group [(1 032±237), (74±10), (1 861±614), (405±32) μg/L] were remarkably lower than M-PgPs group [(4 342±314), (164±17), (4 438±1 374), (957±25) μg/L] (0.05). On the contrary, the protein expression levels of IL-1β, IL-6, IL-8 and TNF-α in Fa+Pg group [(8 198±1 825), (431±28), (8 919±650), (2 186±301) μg/L] and Fa+M-PgPs group [(8 159±2 627), (475±26), (8 995±653), (2 255±387 μg/L) were both significantly higher than Pg group and M-PgPs group, respectively (0.05). PgPs are highly tolerant to metronidazole and amoxicillin. The M-PgPs could enhance the immuno-inflammatory responses in macrophages by upregulating the FOXO1 signaling pathway, while this effect exhibits no significant difference with Pg.
PubMed: 38949135
DOI: 10.3760/cma.j.cn112144-20231114-00248 -
BioRxiv : the Preprint Server For... Jun 2024Bacteria find suitable locations for colonization by sensing and responding to surfaces. Complex signaling repertoires control surface colonization, and surface contact...
UNLABELLED
Bacteria find suitable locations for colonization by sensing and responding to surfaces. Complex signaling repertoires control surface colonization, and surface contact sensing by the flagellum plays a central role in activating colonization programs. adheres to surfaces using a polysaccharide adhesin called the holdfast. In , disruption of the flagellum through interactions with a surface or mutation of flagellar genes increases holdfast production. Our group previously identified several genes involved in flagellar surface sensing. One of these, called , codes for a protein with homology to the flagellar C-ring protein FliN. We show here that a fluorescently tagged FssF protein localizes to the flagellated pole of the cell and requires all components of the flagellar C-ring for proper localization, supporting the model that FssF associates with the C-ring. Deleting results in a severe motility defect that we show is due to a disruption of chemotaxis. Epistasis experiments demonstrate that promotes adhesion through a stator-dependent pathway when late-stage flagellar mutants are disrupted. Separately, we find that disruption of chemotaxis through deletion of or other chemotaxis genes results in a hyperadhesion phenotype. Key genes in the surface sensing network ( , , and ) contribute to both Δ dependent and Δ dependent hyperadhesion, but these genes affect adhesion differently in the two hyperadhesive backgrounds. Our results support a model in which the stator subunits of the flagella incorporate both mechanical and chemical signals to regulate adhesion.
IMPORTANCE
Biofilms pose a threat in clinical and industrial settings. Surface sensing is an early step in biofilm formation. Studying surface sensing can help develop strategies for combating harmful biofilms. Here, we use the freshwater bacterium to study surface sensing. We characterize a previously unstudied gene, , and find that it localizes to the cell pole in the presence of three proteins that make up a component of the flagellum called the C-ring. Additionally, we find that is required for chemotaxis but dispensable for swimming motility. Lastly, our results show that mutating and other genes required for chemotaxis causes a hyperadhesive phenotype. We propose that surface sensing requires chemotaxis for a robust response to a surface.
PubMed: 38948737
DOI: 10.1101/2024.06.20.599946 -
Biofilm Jun 2024platforms capable of mimicking the hydrodynamic conditions prevailing in natural aquatic environments have been previously validated and used to predict the fouling...
platforms capable of mimicking the hydrodynamic conditions prevailing in natural aquatic environments have been previously validated and used to predict the fouling behavior on different surfaces. Computational Fluid Dynamics (CFD) has been used to predict the shear forces occurring in these platforms. In general, these predictions are made for the initial stages of biofilm formation, where the amount of biofilm does not affect the flow behavior, enabling the estimation of the shear forces that initial adhering organisms have to withstand. In this work, we go a step further in understanding the flow behavior when a mature biofilm is present in such platforms to better understand the shear rate distribution affecting marine biofilms. Using 3D images obtained by Optical Coherence Tomography, a mesh was produced and used in CFD simulations. Biofilms of two different marine cyanobacteria were developed in agitated microtiter plates incubated at two different shaking frequencies for 7 weeks. The biofilm-flow interactions were characterized in terms of the velocity field and shear rate distribution. Results show that global hydrodynamics imposed by the different shaking frequencies affect biofilm architecture and also that this architecture affects local hydrodynamics, causing a large heterogeneity in the shear rate field. Biofilm cells located in the streamers of the biofilm are subjected to much higher shear values than those located on the bottom of the streamers and this dispersion in shear rate values increases at lower bulk fluid velocities. This heterogeneity in the shear force field may be a contributing factor for the heterogeneous behavior in metabolic activity, growth status, gene expression pattern, and antibiotic resistance often associated with nutrient availability within the biofilm.
PubMed: 38948680
DOI: 10.1016/j.bioflm.2024.100204 -
Asian Journal of Pharmaceutical Sciences Jun 2024The intrinsic resistance of MRSA coupled with biofilm antibiotic tolerance challenges the antibiotic treatment of MRSA biofilm infections. Phytochemical-based...
The intrinsic resistance of MRSA coupled with biofilm antibiotic tolerance challenges the antibiotic treatment of MRSA biofilm infections. Phytochemical-based nanoplatform is a promising emerging approach for treatment of biofilm infection. However, their therapeutic efficacy was restricted by the low drug loading capacity and lack of selectivity. Herein, we constructed a surface charge adaptive phytochemical-based nanoparticle with high isoliquiritigenin (ISL) loading content for effective treatment of MRSA biofilm. A dimeric ISL prodrug (ISL-G2) bearing a lipase responsive ester bond was synthesized, and then encapsulated into the amphiphilic quaternized oligochitosan. The obtained ISL-G2 loaded NPs possessed positively charged surface, which allowed cis-aconityl-d-tyrosine (CA-Tyr) binding via electrostatic interaction to obtain ISL-G2@TMDCOS-Tyr NPs. The NPs maintained their negatively charged surface, thus prolonging the blood circulation time. In response to low pH in the biofilms, the fast removal of CA-Tyr led to a shift in their surface charge from negative to positive, which enhanced the accumulation and penetration of NPs in the biofilms. Sequentially, the pH-triggered release of d-tyrosine dispersed the biofilm and lipase-triggered released of ISL effectively kill biofilm MRSA. An study was performed on a MRSA biofilm infected wound model. This phytochemical-based system led to ∼2 log CFU (>99 %) reduction of biofilm MRSA as compared to untreated wound ( < 0.001) with negligible biotoxicity in mice. This phytochemical dimer nanoplatform shows great potential for long-term treatment of resistant bacterial infections.
PubMed: 38948398
DOI: 10.1016/j.ajps.2024.100923 -
Biotechnology Reports (Amsterdam,... Jun 2024The environmental and economic impact of an oil spill can be significant. Biotechnologies applied during a marine oil spill involve bioaugmentation with immobilised or...
The environmental and economic impact of an oil spill can be significant. Biotechnologies applied during a marine oil spill involve bioaugmentation with immobilised or encapsulated indigenous hydrocarbonoclastic species selected under laboratory conditions to improve degradation rates. The environmental factors that act as stressors and impact the effectiveness of hydrocarbon removal are one of the challenges associated with these applications. Understanding how native microbes react to environmental stresses is necessary for effective bioaugmentation. Herein, isolated from a marine oil spill mooring system showed hydrocarbonoclastic activity on Maya crude oil in a short time by means of total petroleum hydrocarbons (TPH) at 144 h: up to 98.79 % and 97.77 % removal. The assessment of biofilms at different temperature (30 °C and 50 °C), pH (5, 6, 7, 8, 9), salinity (30, 50, 60, 70, 80 g/L), and crude oil concentration (1, 5, 15, 25, 35 %) showed different response to the stressors depending on the strain. According to response surface analysis, the main effect was temperature > salinity > hydrocarbon concentration. The hydrocarbonoclastic biofilm architecture was characterised using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Subtle but significant differences were observed: pili in by SEM and the topographical differences measured by AFM Power Spectral Density (PSD) analysis, roughness was higher in than in In all three domains of life, the Universal Stress Protein (Usp) is crucial for stress adaptation. Herein, the A gene expression was analysed in biofilm under environmental stressors. The A expression increased up to 2.5-fold in biofilms at 30 °C, and 1.3-fold at 50 °C. The highest A expression was recorded in M. biofilms at 50 °C with 2.5 and 3-fold with salinities of 50, 60, and 80 g/L at hydrocarbon concentrations of 15, 25, and 35 %. biofilms showed greater resilience than biofilms when exposed to harsh environmental stressors. biofilms were thicker than biofilms. Both biofilm responses to environmental stressors through A gene expression were consistent with the behaviours observed in the response surface analyses. The gene is a suitable biomarker for assessing environmental stressors of potential microorganisms for bioremediation of marine oil spills and for biosensing the ecophysiological status of native microbiota in a marine petroleum environment.
PubMed: 38948351
DOI: 10.1016/j.btre.2024.e00834 -
Infection and Drug Resistance 2024Contact lenses (CL) have become an immensely popular means of vision correction, offering comfort to millions worldwide. However, the persistent issue of biofilm... (Review)
Review
Contact lenses (CL) have become an immensely popular means of vision correction, offering comfort to millions worldwide. However, the persistent issue of biofilm formation on lenses raises significant problems, leading to various ocular complications and discomfort. The aim of this review is to develop safer and more effective strategies for preventing and managing microbial biofilms on CL, improving the eye health and comfort of wearers. Taking these into consideration, the present study investigates the intricate mechanisms of biofilm formation, by exploring the interplay between microbial adhesion, the production of extracellular polymeric substances, and the properties of the lens material itself. Moreover, it emphasizes the diverse range of microorganisms involved, encompassing bacteria, fungi, and other opportunistic pathogens, elucidating their implications within lenses and other medical device-related infections and inflammatory responses. Going beyond the challenges posed by biofilms on CL, this work explores the advancements in biofilm detection techniques and their clinical relevance. It discusses diagnostic tools like confocal microscopy, genetic assays, and emerging technologies, assessing their capacity to identify and quantify biofilm-related infections. Finally, the paper delves into contemporary strategies and innovative approaches for managing and preventing biofilms development on CL. In Conclusion, this review provides insights for eye care practitioners, lens manufacturers, and microbiology researchers. It highlights the intricate interactions between biofilms and CL, serving as a foundation for the development of effective preventive measures and innovative solutions to enhance CL safety, comfort, and overall ocular health. Research into microbial biofilms on CL is continuously evolving, with several future directions being explored to address challenges and improve eye health outcomes as far as CL wearers are concerned.
PubMed: 38947374
DOI: 10.2147/IDR.S463779 -
Frontiers in Cellular and Infection... 2024Convergence of (KP) pathotypes has been increasingly reported in recent years. These pathogens combine features of both multidrug-resistant and hypervirulent KP....
BACKGROUND
Convergence of (KP) pathotypes has been increasingly reported in recent years. These pathogens combine features of both multidrug-resistant and hypervirulent KP. However, clinically used indicators for hypervirulent KP identification, such as hypermucoviscosity, appear to be differentially expressed in convergent KP, potential outbreak clones are difficult to identify. We aimed to fill such knowledge gaps by investigating the temperature dependence of hypermucoviscosity and virulence in a convergent KP strain isolated during a clonal outbreak and belonging to the high-risk sequence type (ST)307.
METHODS
Hypermucoviscosity, biofilm formation, and mortality rates in larvae were examined at different temperatures (room temperature, 28°C, 37°C, 40°C and 42°C) and with various phenotypic experiments including electron microscopy. The underlying mechanisms of the phenotypic changes were explored via qPCR analysis to evaluate plasmid copy numbers, and transcriptomics.
RESULTS
Our results show a temperature-dependent switch above 37°C towards a hypermucoviscous phenotype, consistent with increased biofilm formation and mortality, possibly reflecting a bacterial response to fever-like conditions. Furthermore, we observed an increase in plasmid copy number for a hybrid plasmid harboring carbapenemase and genes. However, transcriptomic analysis revealed no changes in expression at higher temperatures, suggesting alternative regulatory pathways.
CONCLUSION
This study not only elucidates the impact of elevated temperatures on hypermucoviscosity and virulence in convergent KP but also sheds light on previously unrecognized aspects of its adaptive behavior, underscoring its resilience to changing environments.
Topics: Klebsiella pneumoniae; Biofilms; Virulence; Animals; Klebsiella Infections; Temperature; Larva; Plasmids; Moths; Humans; Virulence Factors; Bacterial Proteins; Lepidoptera; Viscosity; Phenotype; Gene Expression Profiling
PubMed: 38947124
DOI: 10.3389/fcimb.2024.1411286