Biofilm formation in wounds and implants can have numerous negative effects on a patient's health, including delayed healing and implant removal. Current treatments for biofilms do not completely ...eradicate microbial colonies or prevent their formation, implying the need for further investigation. Recent research into treatments for wound and implant biofilm infections focus on nanotechnology-based mechanisms for drug delivery, combined therapies, and implant modifications. Ultrasound debridement and hydrogels, and new developments in implant modifications possess great potential for application in wound and implant treatments respectively. The aim of this review is to summarize recent developments in biofilm treatments and to understand the direction of current research.
Various methods have been reported to quantify total biofilm or different components of biofilm; however, these methods are often confusedly used, leading to discrepancies and misleading results. In ...this study, different methods for quantification of biofilm, including those for total biomass, total amount of bacterial cells, viable cell number, and amount of extracellular polymeric substances, were systematically compared in microtiter plates. To evaluate which method is suitable for assessment of biofilm removal and for bacterial killing, biofilm samples were treated with various cleaners possessing removing and/or killing capacities. It was found that most of the methods tested in this study in general exhibited high reproducibility and repeatability. Crystal Violet staining was a simple but reliable method for total biomass quantification. Total bacteria cell numbers could be reliably quantified by the fluorescent DNA-binding dye Acridine Orange. Viable cells could be quantified by either an ATP-based assay or a proliferation assay. Both of these viability methods showed a broad detection range and led to precise measurement. For quantification of proteins in the biofilm, staining with fluorescein isothiocyanate was most suitable. Furthermore, it was revealed that a combination of different methods is required to determine if a cleaner kills or removes biofilm.
Bacteria primarily exist in robust, surface-associated communities known as biofilms, ubiquitous in both natural and anthropogenic environments. Mature biofilms resist a wide range of antimicrobial ...treatments and pose persistent pathogenic threats. Treatment of adherent biofilm is difficult, costly, and, in medical systems such as catheters or implants, frequently impossible. At the same time, strategies for biofilm prevention based on surface chemistry treatments or surface microstructure have been found to only transiently affect initial attachment. Here we report that Slippery Liquid-Infused Porous Surfaces (SLIPS) prevent 99.6% of Pseudomonas aeruginosa biofilm attachment over a 7-d period, as well as Staphylococcus aureus (97.2%) and Escherichia coli (96%), under both static and physiologically realistic flow conditions. In contrast, both polytetrafluoroethylene and a range of nanostructured superhydrophobic surfaces accumulate biofilm within hours. SLIPS show approximately 35 times the reduction of attached biofilm versus best case scenario, state-of-the-art PEGylated surface, and over a far longer timeframe. We screen for and exclude as a factor cytotoxicity of the SLIPS liquid, a fluorinated oil immobilized on a structured substrate. The inability of biofilm to firmly attach to the surface and its effective removal under mild flow conditions (about 1 cm/s) are a result of the unique, nonadhesive, “slippery” character of the smooth liquid interface, which does not degrade over the experimental timeframe. We show that SLIPS-based antibiofilm surfaces are stable in submerged, extreme pH, salinity, and UV environments. They are low-cost, passive, simple to manufacture, and can be formed on arbitrary surfaces. We anticipate that our findings will enable a broad range of antibiofilm solutions in the clinical, industrial, and consumer spaces.
Bacterial biofilms occur in many natural and industrial environments. Besides bacteria, biofilms comprise over 70 wt% water. Water in biofilms occurs as bound- or free-water. Bound-water is adsorbed ...to bacterial surfaces or biofilm (matrix) structures and possesses different Infra-red and Nuclear-Magnetic-Resonance signatures than free-water. Bound-water is different from intra-cellularly confined-water or water confined within biofilm structures and bacteria are actively involved in building water-filled structures by bacterial swimmers, dispersion or lytic self-sacrifice. Water-filled structures can be transient due to blocking, resulting from bacterial growth, compression or additional matrix formation and are generally referred to as "channels and pores." Channels and pores can be distinguished based on mechanism of formation, function and dimension. Channels allow transport of nutrients, waste-products, signalling molecules and antibiotics through a biofilm provided the cargo does not adsorb to channel walls and channels have a large length/width ratio. Pores serve a storage function for nutrients and dilute waste-products or antimicrobials and thus should have a length/width ratio close to unity. The understanding provided here on the role of water in biofilms, can be employed to artificially engineer by-pass channels or additional pores in industrial and environmental biofilms to increase production yields or enhance antimicrobial penetration in infectious biofilms.
Most biofilms in nature are formed by multiple microbial species, and such mixed-species biofilms represent the actual lifestyles of microbes, including bacteria, fungi, viruses (phages), and/or ...protozoa. Microorganisms cooperate and compete in mixed-species biofilms. Mixed-species biofilm formation and environmental resistance are major threats to water supply, food industry, and human health. The methods commonly used for microbial eradication, such as antibiotic or disinfectant treatments, are often ineffective for mixed-species biofilm consortia due to their physical matrix barrier and physiological interactions. For the last decade, an increasing number of investigations have been devoted to the usage of cold atmospheric plasma (CAP), which is produced by dielectric barrier discharges or plasma jets to prevent or eliminate microbial biofilms. Here, we summarized the production of CAP, the inactivation of microorganisms upon CAP treatment, and the microbial factors affecting the efficacy of CAP procedure. The applications of CAP as antibiotic alternative strategies for fighting mixed-species biofilms were also addressed.
Advances in biotechnology to treat and cure human disease have markedly improved human health and the development of modern societies. However, substantial challenges remain to overcome innate ...biological factors that thwart the activity and efficacy of pharmaceutical therapeutics. Until recently, the importance of extracellular DNA (eDNA) in biofilms was overlooked. New data reveal its extensive role in biofilm formation, adhesion, and structural integrity. Different approaches to target eDNA as anti‐biofilm therapies have been proposed, but eDNA and the corresponding biofilm barriers are still difficult to disrupt. Therefore, more creative approaches to eradicate biofilms are needed. The production of eDNA often originates with the genetic material of bacterial cells through cell lysis. However, genomic DNA and eDNA are not necessarily structurally or compositionally identical. Variations are noteworthy because they dictate important interactions within the biofilm. Interactions between eDNA and biofilm components may as well be exploited as alternative anti‐biofilm strategies. In this review, we discuss recent developments in eDNA research, emphasizing potential ways to disrupt biofilms. This review also highlights proteins, exopolysaccharides, and other molecules interacting with eDNA that can serve as anti‐biofilm therapeutic targets. Overall, the array of diverse interactions with eDNA is important in biofilm structure, architecture, and stability.
Biofilms can be disrupted and dispersed by targeting eDNA.
Biofilms, particularly those formed by multiple bacterial species, pose significant economic and environmental challenges, especially in the context of medical implants. Addressing the urgent need ...for effective treatment strategies that do not exacerbate drug resistance, we developed a novel nanoformulation, Ce6&PMb@BPN, based on black phosphorus nanosheets (BPN) for targeted treatment of mixed-species biofilms formed by Acinetobacter baumannii (A. baumannii) and methicillin-resistant Staphylococcus aureus (MRSA).The formulation leverages polymyxin B (PMb) for bacterial targeting and chlorin e6 (Ce6) for photodynamic action. Upon near-infrared (NIR) irradiation, Ce6&PMb@BPN efficiently eliminates biofilms by combining chemotherapy, photodynamic therapy (PDT) and photothermal therapy (PTT), reducing biofilm biomass significantly within 30 min. In vivo studies on mice infected with mixed-species biofilm-coated catheters demonstrated the formulation's potent antibacterial and biofilm ablation effects. Moreover, comprehensive biosafety evaluations confirmed the excellent biocompatibility of Ce6&PMb@BPN. Taken together, this intelligently designed nanoformulation holds potential for effectively treating biofilm-associated infections, addressing the urgent need for strategies to combat antibiotic-resistant biofilms, particularly mixed-species biofilm, in medical settings.
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•Lipopeptide type biosurfactant was isolated from Bacillus tequilensis strain SDS21.•Biosurfactant exhibited bactericidal and biofilm dislodging activity.•Biosurfactant removed ...biofilm from glass, stainless steel and polystyrene surface.•Exposure to extreme pH and temperature has no influence on biosurfactant activity.•Biosurfactant retained its bactericidal and anti-biofilm activity in hard water.
Antiseptics and disinfectants are widely applied for eliminating microorganisms. However, microorganisms dwelling in the biofilm are less susceptible and in some cases resistant to biocide treatment. The present study describes isolation and characterization of lipopeptide biosurfactant exhibiting disinfectant-like activity. Biosurfactant was produced by an endo-rhizospheric bacterium Bacillus tequilensis strain SDS21. Biosurfactant reduced the surface tension of water from 72 to 30 mN/m with CMC of 40 mg/l. The Liquid Chromatography–Mass Spectrometry analysis of biosurfactant suggested it to be a mixture of C14, C15, C16 and C17 surfactin homologues. The lipopeptide biosurfactant exhibited bactericidal activity against planktonic cells and biofilm residing sessile cells. The biosurfactant treatment eradicated more than 99% of bacterial biofilm present on polystyrene, glass and stainless steel surface. The biosurfactant retained its bactericidal and biofilm eradicating activities even after exposure to extreme conditions like high temperate and extreme pH. Unlike some of the commonly used disinfectant, biosurfactant retained its bactericidal and biofilm removing activity even in the hard water containing Mg2+ and Ca2+ ions. Thus, suggesting that biosurfactant produced by strain SDS21 can be used as a disinfectant or in disinfectant-like formulations effective against both planktonic and biofilm residing bacteria.
The presence of organic micropollutants (OMPs) in natural water bodies has become an emerging concern due to their fast dissemination into natural water sources, high persistence, ubiquitous nature, ...and detrimental impact on the environment and human health. This study evaluated the Membrane Aerated Biofilm Reactor (MABR) efficiency in the removal of 13 OMPs commonly reported in water. Results demonstrated that OMPs removal is dependent on biofilm thickness and bacterial cell density, microbial community composition and physicochemical properties of OMPs. Effective removals of ammonium and organic carbon (COD, >50%), acetaminophen (70%) and triclosan (99%) were obtained even at early stages of biofilm development (thickness < 0.33 mm, 2.9 ×105 cell mL−1). An increase in biofilm thickness and cell density (1.02 mm, 2.2 ×106 cell mL−1) enhanced the system performance. MABR achieved over 90% removal of nonpolar, hydrophobic and hydrophilic OMPs and 22–69% removal of negatively charged and acidic OMPs. Relative abundances of Zoogloea, Aquabacterium, Leucobacter, Runella, and Paludilbaculum bacteria correlated with the removal of certain OMPs. In addition, MABR achieved up to 96% nitrification and 80% overall COD removal by the end of the experiment. The findings from this study demonstrated MABRs to be a feasible option to treat municipal wastewater polluted by OMPs.
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•Optimal MABR performance obtained at thicknesses > 0.87 mm and 1.2 × 106 cells mL-1.•MABR achieved > 90% removal of nonpolar, uncharged OMPs included in Group 1.•MABR achieved 22–69% removal of acidic, ionic, hydrophobic OMPs of Group 2.•The MABR removed less than 15% of highly recalcitrant OMPs included in Group 3.•Zoogloea, Leucobacter, Runella relative abundance correlated with OMP removal.
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