Subsequent Biofilm Formation Research Articles

Higher abundance of ammonia-oxidizing bacteria than ammonia-oxidizing archaea in biofilms and the microbial community composition of Kaiping Diaolou of China

We here investigated microbial biofilm communities on the surfaces of Linlu Villa, a villa built on a cultural heritage site known as Kaiping Diaolou and Villages located in southern China, by using next-generation sequencing technology. Then, 16S rRNA gene sequences revealed that the dominant bacterial groups in these biofilms were Cyanobacteria, Proteobacteria, Actinobacteria, Chloroflexi, Acidobacteria, Bacteroidetes, and Deinococcus-Thermus. The site survey revealed that the unique climatic conditions (ambient temperature and humidity), activities in the surroundings (farming and domestic pollution), and the rough surface of Diaolou buildings were the main factors promoting microbial colonization and development, and subsequent biofilm formation. In addition, we conducted inorganic nitrogen detecting on the surrounding environment of the Diaolou buildings and found that the inorganic nitrogen content was very high, with inorganic nitrogen NO3−-N reaching 8947.27 mg/kg; the NH4+-N content can reach 895.88 mg/kg qPCR quantification of AOA-amoA and AOB-amoA genes was performed at four sites and found that the abundance of ammonia-oxidizing bacteria (AOB) was far higher than that of ammonia-oxidizing archaea (AOA), reaching a maximum of 4–5 orders of magnitude, which is different from the current results on other cultural heritage sites. This may be due to the specific geographical location of Kaiping Diaolou and villages in the southern China with severe nitrogen deposition, as well as the surrounding residential areas and agricultural cultivation areas where nitrogen fertilizer is used in nearby agricultural cultivation. This will be worth further investigation, and the results are valuable for the protection for the protection of Kaiping Diaolou and Villages.

Lateral detachment forces of Bacillus niabensis and Alteromonas litorea against antifouling paint additive


 
 
 
 Bacterial adhesion on various marine biotic or abiotic surfaces and subsequent biofilm formation paves the path of biofouling in marine environment. The aim of the present investigation was to determine the lateral detachment forces between coated antifouling paint additive and local isolated marine bacteria; Bacillus niabensis and Alteromonas litorea using atomic force microscopy (AFM). A paint additive was prepared by employing the active compounds, silver ion (Ag+) and surfactant hexadecyltrimethylammonium (HDTMA) embedded in the kaolinite clay structure. An incubated 100 µL bacterial suspension loaded onto the coated antifouling paint additive were scanned using AFM with the scan rate of 40 µm/s and scan size of 10 × 10 µm2. Lateral detachment force was measured from a lower set point value of 0.3V to a maximum set point 10.0V. A weak interaction was observed between the model bacteria and paint additive (Or-Ag-Kao) coated surface with the mean lateral detachment force of 139.4 nN (B. niabensis) and 146.2 nN (A. litorea). Major contact surface area reduction observed on paint additive (Or-Ag-Kao) coated surfaces with 0.275 µm2 for B. niabensis and 0.391 µm2 for A. litorea indicated that paint additive coating successfully minimized bacterial attachment on the surface. The antifouling paint additive shows a reduction in lateral forces and minimized its surface contact, which could further prevent the microfouling formation on marine structures.
 
 
 
 

Unraveling extracellular protein signatures to enhance live attenuated vaccine development through type II secretion system disruption in Vibriomimicus

Type II secretion systems (T2SS) are important molecular machines used by bacteria to transport a wide range of proteins across the outer membrane from the periplasm. Vibrio mimicus is an epidemic pathogen threats to both aquatic animals and human health. Our previous study demonstrates that T2SS deletion reduced virulence by 307.26 times in yellow catfish. However, the specific effects of T2SS-mediated extracellular protein secretion in V. mimicus, including its potential role in exotoxin secretion or other mechanisms, require further investigation. Through proteomics and phenotypic analyses, this study observed that the ΔT2SS strain exhibited significant self-aggregation and dynamic deficiency, with a notable negative correlation with subsequent biofilm formation. The proteomics analysis revealed 239 different abundances of extracellular proteins after T2SS deletion, including 19 proteins with higher abundance and 220 proteins with lower and even absent in the ΔT2SS strain. These extracellular proteins are involved in various pathways, such as metabolism, virulence factors expression, and enzymes. Among them, purine, pyruvate, and pyrimidine metabolism, and the Citrate cycle, were the primary pathways affected by T2SS. Our phenotypic analysis is consistent with these findings, suggesting that the decreased virulence of ΔT2SS strains is due to the effect of T2SS on these proteins, which negatively impacts growth, biofilm formation, auto-aggregation, and motility of V. mimicus. These results provide valuable insights for designing deletion targets for attenuated vaccines development against V. mimicus and expand our understanding of the biological functions of T2SS.

Mussel-inspired proteins functionalize catheter with antifouling and antibacterial properties

Bacterial adhesion and subsequent biofilm formation on catheter can cause inevitably infection. The development of multifunctional antibacterial coating is a promising strategy to resist the bacteria adhesion and biofilm formation. Herein, a mussel-inspired chimeric protein MZAgP is prepared and employed to modify a variety of polymeric catheters. The MZAgP is composed of mussel-adhesive peptide, zwitterionic peptide, and silver-binding peptide, which can endow catheters with antifouling, bactericidal and biocompatibility performances. Expectedly, negligible biofilm is observed on the MZAgP coated catheters after incubating with bacteria for 120 h. And ignorable hemolysis and cytotoxicity are obtained on coated catheters. In addition, the modified catheters also display persistent antifouling and bacteriostatic properties throughout 168 h under hydrodynamic conditions. Moreover, the coated catheters can still remain excellent antifouling and antibacterial properties even after 2 months of storage. This multifunctional coating may be promising as antibacterial and antibiofilm biomaterial, and the coated catheters are potential in clinical application.

A study on the microbial biocorrosion behavior of API 5 L X65 carbon steel exposed to seawater

AbstractDespite much progress achieved, corrosion in oil and gas pipelines remains a concern due to industrial failures, and environmental and economic damages. Oil and gas pipeline failures are very common as a result of the natural degradation of carbon steel exposed to the marine environment. It has been reported that the presence of microorganisms in seawater contributes to the intensification of corrosion and subsequent biofilm formation on metal surfaces. Few scientific publications have investigated the effects of seawater containing natural microorganisms on the internal corrosion of pipelines, which is the motivation for this study. The present study aims to report the corrosion behavior of carbon steel American Petroleum Institute (API) 5 L X65 exposed to seawater collected from the Persian Gulf containing microorganisms such as sulfate‐reducing bacteria (SRB), iron‐reducing bacteria (IRB), and acid‐producing bacteria (APB). Microorganisms were detected, segregated, colonized, and finally injected into autoclaved seawater to investigate their effect on the corrosion behavior of carbon steel. Nondestructive electrochemical techniques were performed to study the corrosion behavior and field emission electron microscope images and energy dispersive x‐ray analysis (EDS) were also utilized to characterize the corrosion products. The results confirmed the amounts of oxygen and iron presented of FeO as the main corrosion product in abiotic conditions. Corrosion products and electrochemical properties of steel have been influenced by microbial activity. The variation of the open circuit potentials (OCP) and Electrochemical Impedance Spectroscopy (EIS) demonstrated that SRB and APB could not only significantly harm an alloy, but also could alter its electrochemical behavior from uniform to local damage. The outcomes proved that biofilm formation and bacterial activity can cause serious degradation.

Recent Advances in Dual-Function Superhydrophobic Antibacterial Surfaces.

Bacterial adhesion and subsequent biofilm formation on the surfaces of synthetic materials imposes a significant burden in various fields, which can lead to infections in patients or reduce the service life of industrial devices. Therefore, there is increasing interest in imbuing surfaces with antibacterial properties. Bioinspired superhydrophobic surfaces with high water contact angles (>150°) exhibit excellent surface repellency against contaminations, thereby preventing initial bacterial adhesion and inhibiting biofilm formation. However, conventional superhydrophobic surfaces typically lack long-term durability and are incapable of achieving persistent efficacy against bacterial adhesion. To overcome these limitations, in recent decades, dual-function superhydrophobic antibacterial surfaces with both bacteria-repelling and bacteria-killing properties have been developed by introducing bactericidal components. These surfaces have demonstrated improved long-term antibacterial performance in addressing the issues associated with surface-attached bacteria. This review summarizes the recent advancements of these dual-function superhydrophobic antibacterial surfaces. First, a brief overview of the fabrication strategies and bacteria-repelling mechanism of superhydrophobic surfaces is provided and then the dual-function superhydrophobic antibacterial surfaces are classified into three types based on the bacteria-killing mechanism: i) mechanotherapy, ii) chemotherapy, and iii) phototherapy. Finally, the limitations and challenges of current research are discussed and future perspectives in this promising area are proposed.

Erg6 Acts as a Downstream Effector of the Transcription Factor Flo8 To Regulate Biofilm Formation in Candida albicans.

The yeast-to-hyphal morphotype transition and subsequent biofilm formation are important virulence factors of Candida albicans and are closely associated with ergosterol biosynthesis. Flo8 is an important transcription factor that determines filamentous growth and biofilm formation in C. albicans. However, the relationship between Flo8 and regulation of the ergosterol biosynthesis pathway remains elusive. Here, we analyzed the sterol composition of a flo8-deficient C. albicans strain by gas chromatography-mass spectrometry and observed the accumulation of the sterol intermediate zymosterol, the substrate of Erg6 (C-24 sterol methyltransferase). Accordingly, the transcription level of ERG6 was reduced in the flo8-deficient strain. Yeast one-hybrid experiments revealed that Flo8 physically interacted with the ERG6 promoter. Ectopic overexpression of ERG6 in the flo8-deficient strain partially restored biofilm formation and in vivo virulence in a Galleria mellonella infection model. These findings suggest that Erg6 is a downstream effector of the transcription factor Flo8 that mediates the cross talk between sterol synthesis and virulence factors in C. albicans. IMPORTANCE Biofilm formation by C. albicans hinders its eradication by immune cells and antifungal drugs. Flo8 is an important morphogenetic transcription factor that regulates the biofilm formation and in vivo virulence of C. albicans. However, little is known about how Flo8 regulates biofilm formation and fungal pathogenicity. Here, we determined that Flo8 directly binds to the promoter of ERG6 to positively regulate its transcriptional expression. Consistently, loss of flo8 results in the accumulation of the substrate of Erg6. Moreover, ectopic overexpression of ERG6 at least partially restores the biofilm formation and virulence of the flo8-deficient strain both in vitro and in vivo. This work provides a new perspective on the metabolic link between transcription factors and morphotypes in C. albicans.

Antimicrobial materials for endotracheal tubes: A review on the last two decades of technological progress.

Ventilator-associated pneumonia (VAP) is an unresolved problem in nosocomial settings, remaining consistently associated with a lack of treatment, high mortality, and prolonged hospital stay. The endotracheal tube (ETT) is the major culprit for VAP development owing to its early surface microbial colonization and biofilm formation by multiple pathogens, both critical events for VAP pathogenesis and relapses. To combat this matter, gradual research on antimicrobial ETT surface coating/modification approaches has been made. This review provides an overview of the relevance and implications of the ETT bioburden for VAP pathogenesis and how technological research on antimicrobial materials for ETTs has evolved. Firstly, certain main VAP attributes (definition/categorization; outcomes; economic impact) were outlined, highlighting the issues in defining/diagnosing VAP that often difficult VAP early- and late-onset differentiation, and that generate misinterpretations in VAP surveillance and discrepant outcomes. The central role of the ETT microbial colonization and subsequent biofilm formation as fundamental contributors to VAP pathogenesis was then underscored, in parallel with the uncovering of the polymicrobial ecosystem of VAP-related infections. Secondly, the latest technological developments (reported since 2002) on materials able to endow the ETT surface with active antimicrobial and/or passive antifouling properties were annotated, being further subject to critical scrutiny concerning their potentialities and/or constraints in reducing ETT bioburden and the risk of VAP while retaining/improving the safety of use. Taking those gaps/challenges into consideration, we discussed potential avenues that may assist upcoming advances in the field to tackle VAP rampant rates and improve patient care. STATEMENT OF SIGNIFICANCE: The use of the endotracheal tube (ETT) in patients requiring mechanical ventilation is associated with the development of ventilator-associated pneumonia (VAP). Its rapid surface colonization and biofilm formation are critical events for VAP pathogenesis and relapses. This review provides a comprehensive overview on the relevance/implications of the ETT biofilm in VAP, and on how research on antimicrobial ETT surface coating/modification technology has evolved over the last two decades. Despite significant technological advances, the limited number of gathered reports (46), highlights difficulty in overcoming certain hurdles associated with VAP (e.g., persistent colonization/biofilm formation; mechanical ventilation duration; hospital length of stay; VAP occurrence), which makes this an evolving, complex, and challenging matter. Challenges and opportunities in the field are discussed.

Precise Localization and Simultaneous Bacterial Eradication of Biofilms Based on Nanocontainers with Successive Responsive Property toward pH and ATP.

The bacterial colonization of surfaces and subsequent biofilm formation are a great threat in medical therapy and clinical diagnosis. The complex internal structure and composition sets an enormous obstacle for the localization and removal of biofilms. In this study, we proposed a novel biofilm-targeted nanocontainer with successive responsive property toward pH and ATP for precise localization and simultaneous bacterial eradication, with an acidic and adenosine triphosphate (ATP)-rich microenvironment within biofilms, formed due to the accumulation of fatty acids and ATP in the three-dimensional enclosed structure, integrated as two successive indicators to improve the precision of biofilm identification and removal. The biofilm-targeted nanocontainer was composed of a ATP-responsive zeolitic imidazolate framework-90 (ZIF-90) core loaded with Rho 6G and doxorubicin hydrochloride (DOX) encapsulated in the pH-responsive amorphous calcium carbonate/poly(acrylic acid) (ACC/PAA) shell. In the presence of biofilms, the ACC/PAA shell and ZIF-90 core were successively degraded by the accumulated H+ and ATP within biofilms, resulting in the release of fluorescence indicators and antimicrobial agents. On the other hand, to meet the application requirements of different biofilm scenarios, the pH response ability of the nanocontainers could be adjusted by changing the metallic ions (Ni2+, Zn2+, and Cu2+) doped into the structure of the ACC/PAA shell. Owing to excellent water dispersion of the pH/ATP double-responsive ZIF-90@Zn-ACC/PAA nanocontainer, precise localization and simultaneous bacterial eradication was successfully realized via a simple spray process. The successive pH/ATP two-step unlocking processes endowed the nanocontainers high precision for localization and simultaneous eradication of biofilms, which made the proposed nanocontainers high promising in food safety and medical treatment.

Warp knitted spacer microfiber biomass carrier for wastewater treatment

The development of novel biomass carriers is an option for increasing the efficiency of processes at wastewater treatment plants (WWTPs). Biomass carriers support the adhesion of specific bacteria and the subsequent biofilm formation. As part of this work, a new type of microfibrous biomass carrier with a unique sandwich structure was developed. Technologically, the structure of the biomass carrier is based on warp knitted spacer fabric created on a double-needle bar machine. Commercially available microfiber materials were used to achieve a large specific surface area (SSA) and internal porosity of the carrier to ensure high microorganism capture. A yarn combination was chosen to reach a final carrier density slightly lower than water to float in an aqueous environment. As the first, was developed and described a three-dimensional warp knitted microfiber biomass carrier. Next, were evaluated the properties of this carrier for post nitrification on WWTPs and compared with commercially available biomass carriers. Testing biofilm (using respirometry, real-time polymerase chain reaction, and next-generation sequencing) growing on the developed carrier in a post-nitrification laboratory reactor showed excellent adhesion, stability, and abundance of microorganisms. A high rate (more than 95%) of ammonia nitrogen removal was achieved in post-nitrification, and molecular genetics methods confirmed the high concentration of nitrifying bacteria in the biofilm. The developed three-dimensional microfiber biomass carriers have proven their functionality and can be considered an advance in biofilm processes.

Additive manufacturing of a cementless hip stem demonstrator with local drug delivery functionality

Periprosthetic joint infection from implant surface colonization by pathogenic bacteria and subsequent biofilm formation remains a serious complication following total hip arthroplasty. Local delivery of antimicrobial drugs is an effective approach to prevent and treat such infection. This paper presents a prototype development process chain for a cementless hip stem from which an antimicrobial drug can be delivered directly to the implant surface. A systematic approach was followed in which the external surface of the hip stem represents an area requiring antibacterial coverage. Individual features were tested first to determine the zone of inhibition, represented by the two-dimensional area surrounding the drug release source where the pathogen cannot survive. This zone, determined for the antibiotic vancomycin against strains of the pathogen Staphylococcus aureus to be 15 mm in diameter, was simplified geometrically to circles of uniform radius which should cover the necessary implant surface. A freeform internal channel layout was then designed with source points for drug delivery at the centre of each of these circles. The final cementless stem design was manufactured with laser powder bed fusion from Ti6Al4V ELI. Internal features were free from any blockages and ∼3 mL of 15 mg/mL aqueous vancomycin could be loaded into the demonstrator stem without obstruction. Antimicrobial efficacy of the demonstrator was qualitatively evaluated in a custom experimental setup against Staphylococcus aureus Xen 31 incubated for 24 hours with a commercial hip stem as negative control. Qualitative evaluation of the inoculum revealed that surface colonization was prevented, indicating that the effective released vancomycin concentration exceeded the minimum inhibitory concentration of ∼5 µg/mL. The results contribute evidence to the applicability of laser powder bed fusion for implants with local drug delivery functionality. Further development of the concept could increase the efficacy and resource efficiency of periprosthetic joint infection prophylaxis and treatment.

The effect of Er:YAG laser treatment on biofilm formation on titanium and zirconia disc surfaces.

Lasers represent a promising method for implant decontamination, but evidence on implant surface changes and subsequent biofilm formation is limited. This study aimed to assess the effect of erbium-doped yttrium aluminum garnet (Er:YAG) laser treatment on zirconia and titanium discs, and the differences in biofilm formation as a result of surface alterations. A two-stage (in vitro and in vivo) experiment utilizing Er:YAG laser on titanium and zirconia discs was performed. In vitro, surface alterations, roughness, and elemental-material weight differences following laser treatment were assessed using scanning electron microscopy and atomic force microscopy. In vivo, four participants wore custom-made intra-oral stents, embedded with laser-treated and untreated titanium and zirconia discs overnight. Biofilm-coated discs were stained using nucleic acid fluorescence dye and visualized using multiphoton confocal laser scanning microscopy. Biofilm 3D structure, biomass, thickness, and live-to-dead bacteria ratio were assessed. Both titanium and zirconia discs treated with Er:YAG laser resulted in visual surface alterations, but showed no significant change in average surface roughness (titanium P=0.53, zirconia P=0.34) or elemental-material-weight (titanium, P=0.98), (zirconia, P=0.96). No significant differences in biofilm biomass, average thickness, and live-to-dead bacteria ratio of laser-treated titanium and zirconia discs were identified compared to untreated groups (titanium P>0.05, zirconia P>0.05). Generally, zirconia discs presented with a lower live-to-dead bacteria ratio compared to titanium discs, regardless of laser treatment. Er:YAG laser treatment of titanium and zirconia implant surfaces does not significantly affect surface roughness, elemental material weight, or early biofilm formation in the oral cavity.

Keller Funnel Efficacy in "No Touch" Breast Augmentation and Reconstruction: A Systematic Review.

A systematic review of PubMed, Embase, the Cochrane database, and Google Scholar was performed between 2005 and 2021. All clinical-based, retrospective and prospective studies utilizing the Keller funnel method for breast implant insertion were selected. Six studies were identified for evaluation: five were retrospective cohorts and one was a prospective trial. No randomized controlled trials were found. Outcomes reported included lower rates of capsular contracture (RR, 0.42; P = 0.0006; 95% CI, 0.25-0.69), shorter incision lengths (35.5 ± 2.1 mm), less insertion time (mean = 6 seconds), and decreased complications, and one paper reported ultimately greater patient satisfaction with outcomes (BREAST-Q Score: 92%). This review suggests that the Keller funnel is a useful method for no-touch breast augmentation and reconstruction surgery. The Keller funnel reduces subsequent capsular contracture rate, surgical time, and incision length and allows for easier insertion. However, our findings support recommendation of a prospective randomized controlled clinical trial with larger population size and follow-up intervals.

Dietary sugars modulate bacterial-fungal interactions in saliva and inter-kingdom biofilm formation on apatitic surface.

Bacteria and fungi can interact to form inter-kingdom biofilms in the oral cavity. Streptococcus mutans and Candida albicans are frequently detected in saliva and in dental biofilms associated with early childhood caries (tooth-decay), a prevalent oral disease induced by dietary sugars. However, how different sugars influence this bacterial-fungal interaction remains unclear. Here, we investigate whether specific sugars affect the inter-kingdom interaction in saliva and subsequent biofilm formation on tooth-mimetic surfaces. The microbes were incubated in saliva containing common dietary sugars (glucose and fructose, sucrose, starch, and combinations) and analyzed via fluorescence imaging and quantitative computational analyses. The bacterial and fungal cells in saliva were then transferred to hydroxyapatite discs (tooth mimic) to allow microbial binding and biofilm development. We found diverse bacterial-fungal aggregates which varied in size, structure, and spatial organization depending on the type of sugars. Sucrose and starch+sucrose induced the formation of large mixed-species aggregates characterized by bacterial clusters co-bound with fungal cells, whereas mostly single-cells were found in the absence of sugar or in the presence of glucose and fructose. Notably, both colonization and further growth on the apatitic surface were dependent on sugar-mediated aggregation, leading to biofilms with distinctive spatial organizations and 3D architectures. Starch+sucrose and sucrose-mediated aggregates developed into large and highly acidogenic biofilms with complex network of bacterial and fungal cells (yeast and hyphae) surrounded by an intricate matrix of extracellular glucans. In contrast, biofilms originated from glucose and fructose-mediated consortia (or without sugar) were sparsely distributed on the surface without structural integration, growing predominantly as individual species with reduced acidogenicity. These findings reveal the impact of dietary sugars on inter-kingdom interactions in saliva and how they mediate biofilm formation with distinctive structural organization and varying acidogenicity implicated with human tooth-decay.

Real-time monitoring of the dynamics and interactions of bacteria and the early-stage formation of biofilms

Bacterial biofilms are complex colonies of bacteria adhered to a static surface and/or one to another. Bacterial biofilms exhibit high resistance to antimicrobial agents and can cause life-threatening nosocomial infections. Despite the effort of the scientific community investigating the formation and growth of bacterial biofilms, the preliminary interaction of bacteria with a surface and the subsequent early-stage formation of biofilms is still unclear. In this study, we present real-time, label-free monitoring of the interaction of Escherichia coli and Pseudomonas aeruginosa bacteria with untreated glass control surfaces and surfaces treated with benzalkonium chloride, a chemical compound known for its antimicrobial properties. The proof of principle investigation has been performed in a standard inverted optical microscope exploiting the optical phenomenon of caustics as a tool for monitoring bacterial diffusion and early adhesion and associated viability. The enhanced resolving power of the optical set-up allowed the monitoring and characterization of the dynamics of the bacteria, which provided evidence for the relationship between bacterial adhesion dynamics and viability, as well as the ability to form a biofilm. Viable bacteria adhered to the surface exhibited noticeable sliding or rotary dynamics while bacteria killed by surface contact remained static once adhered to the surface. This difference in dynamics allowed the early detection of biofilm formation and offers the potential to quantify the efficiency of antimicrobial surfaces and coatings.

Hydroquinones Including Tetrachlorohydroquinone Inhibit Candida albicans Biofilm Formation by Repressing Hyphae-Related Genes.

ABSTRACTCandida albicans is an opportunistic pathogenic fungus responsible for candidiasis. The pathogen readily forms antifungal agent-resistant biofilms on implanted medical devices or human tissue. Morphologic transition from yeast to filamentous cells and subsequent biofilm formation is a key virulence factor and a prerequisite for biofilm development by C. albicans. We investigated the antibiofilm and antifungal activities of 18 hydroquinones against fluconazole-resistant C. albicans. Tetrachlorohydroquinone (TCHQ) at subinhibitory concentrations (2 to 10 μg/mL) significantly inhibited C. albicans biofilm formation with an MIC of 50 μg/mL, whereas the backbone hydroquinone did not (MIC > 400 μg/mL), and it markedly inhibited cell aggregation and hyphal formation. Transcriptomic analyses showed that TCHQ downregulated the expressions of several hyphae-forming and biofilm-related genes (ALS3, ECE1, HWP1, RBT5, and UME6) but upregulated hyphae- and biofilm-inhibitory genes (IFD6 and YWP1). Furthermore, it prevented C. albicans biofilm development on porcine skin and at concentrations of 20 to 50 μg/mL was nontoxic to the nematode Caenorhabditis elegans and did not adversely affect Brassica rapa seed germination and growth. This study indicates that hydroquinones, particularly TCHQ, diminish the virulence, biofilm formation, and animal tissue adhesion of C. albicans, which suggests hydroquinones should be considered potential candidate antifungal agents against drug-resistant C. albicans strains.IMPORTANCE Persistence in chronic infections by Candida albicans is due to its ability of biofilm formation that endures conventional antifungals and host immune systems. Hence, the inhibition of biofilm formation and virulence characteristics is another mean of addressing infections. This study is a distinctive one since 18 hydroquinone analogues were screened and TCHQ efficiently inhibited the biofilm formation by C. albicans with significantly changed expressional profile of hyphae-forming and biofilm-related genes. The antibiofilm efficacy was confirmed using a porcine skin model and chemical toxicity was investigated using plant seed germination and nematode models. Our findings reveal that TCHQ can efficiently control the C. albicans biofilms and virulence characteristics.

The denture microbiome in health and disease: an exploration of a unique community.

The United Nations suggests the global population of denture wearers (an artificial device that acts as a replacement for teeth) is likely to rise significantly by the year 2050. Dentures become colonized by microbial biofilms, the composition of which is influenced by complex factors such as patient’s age and health, and the nature of the denture material. Since colonization (and subsequent biofilm formation) by some micro‐organisms can significantly impact the health of the denture wearer, the study of denture microbiology has long been of interest to researchers. The specific local and systemic health risks of denture plaque are different from those of dental plaque, particularly with respect to the presence of the opportunist pathogen Candida albicans and various other nonoral opportunists. Here, we reflect on advancements in our understanding of the relationship between micro‐organisms, dentures, and the host, and highlight how our growing knowledge of the microbiome, biofilms, and novel antimicrobial technologies may better inform diagnosis, treatment, and prevention of denture‐associated infections, thereby enhancing the quality and longevity of denture wearers.

Electrochemical Control of Biofilm Formation and Approaches to Biofilm Removal

This review deals with microbial adhesion to metal-based surfaces and the subsequent biofilm formation, showing that both processes are a serious problem in the food industry, where pathogenic microorganisms released from the biofilm structure may pollute food and related material during their production. Biofilm exhibits an increased resistance toward sanitizers and disinfectants, which complicates the removal or inactivation of microorganisms in these products. In the existing traditional techniques and modern approaches for clean-in-place, electrochemical biofilm control offers promising technology, where surface properties or the reactions taking place on the surface are controlled to delay or prevent cell attachment or to remove microbial cells from the surface. In this overview, biofilm characterization, the classification of bacteria-forming biofilms, the influence of environmental conditions for bacterial attachment to material surfaces, and the evaluation of the role of biofilm morphology are described in detail. Health aspects, biofilm control methods in the food industry, and conventional approaches to biofilm removal are included as well, in order to consider the possibilities and limitations of various electrochemical approaches to biofilm control with respect to potential applications in the food industry.

Antimicrobial peptide in polymethylmethacrylate bone cement as a prophylaxis of infectious complications in orthopedics-an experiment in a murine model.

Polymethylmethacrylate (PMMA) bone cement mixed with antibiotics is used in orthopedic surgery to cope with implant-related infections which are typically associated with the formation of bacterial biofilms. Taking into account the growing bacterial resistance to current antibiotics, we examined here the efficacy of a selected antimicrobial peptide (AMP) mixed into the bone cement to inhibit bacterial adhesion and the consequent biofilm formation on its surface. In particular, we followed the formation of bacterial biofilms of methicillin-resistant Staphylococcus aureus (MRSA) on implants made from PMMA bone cement loaded with AMP composed of 12 amino acid residues. This was evaluated by CFU counting of bacteria released by sonication from the biofilms formed on their surfaces after these implants were retrieved from the infected murine femoral canals. The AMP loaded in these model implants prevented adhesion of MRSA and the subsequent formation of MRSA biofilm on the surfaces of more than 80% of these implants, whereas biofilms did form on control implants made from the plain cement. The results of our experiments performed in the murine femoral canal indicate the potential for this murine osteomyelitis model to mimic actual operations in orthopedics.

Influence of the Available Surface Area and Cell Elasticity on Bacterial Adhesion Forces on Highly Ordered Silicon Nanopillars.

Initial bacterial adhesion to solid surfaces is influenced by a multitude of different factors, e.g., roughness and stiffness, topography on the micro- and nanolevel, as well as chemical composition and wettability. Understanding the specific influences and possible interactive effects of all of these factors individually could lead to guidance on bacterial adhesion and prevention of unfavorable consequences like medically relevant biofilm formation. On this way, the aim of the present study was to identify the specific influence of the available surface area on the adhesion of clinically relevant bacterial strains with different membrane properties: Gram-positive Staphylococcus aureus and Gram-negative Aggregatibacter actinomycetemcomitans. As model surfaces, silicon nanopillar specimens with different spacings were fabricated using electron beam lithography and cryo-based reactive ion etching techniques. Characterization by scanning electron microscopy and contact angle measurement revealed almost defect-free highly ordered nanotopographies only varying in the available surface area. Bacterial adhesion forces to these specimens were quantified by means of single-cell force spectroscopy exploiting an atomic force microscope connected to a microfluidic setup (FluidFM). The nanotopographical features reduced bacterial adhesion strength by reducing the available surface area. In addition, the strain-specific interaction in detail depended on the bacterial cell’s elasticity and deformability as well. Analyzed by confocal laser scanning microscopy, the obtained results on bacterial adhesion forces could be linked to the subsequent biofilm formation on the different topographies. By combining two cutting-edge technologies, it could be demonstrated that the overall bacterial adhesion strength is influenced by both the simple physical interaction with the underlying nanotopography and its available surface area as well as the deformability of the cell.