Development of broad-spectrum antibiofilm drugs: strategies and challenges

Advancing Anti-Biofilm Strategies: Innovations to Combat Biofilm-Related Challenges and Enhance Efficacy

Biofilms are complex communities of microorganisms that can cause significant challenges in various settings, including industrial processes, environmental systems, and human health. The protective nature of biofilms makes them resistant to traditional anti-biofilm strategies, such as chemical agents, mechanical interventions, and surface modifications. To address the limitations of conventional anti-biofilm methods, researchers have explored emerging strategies that encompass the use of natural compounds, nanotechnology-based methods, quorum-sensing inhibition, enzymatic degradation, and antimicrobial photodynamic/sonodynamic therapy. There is an increasing focus on combining multiple anti-biofilm strategies to combat resistance and enhance effectiveness. Researchers are continuously investigating the mechanisms of biofilm formation and developing innovative approaches to overcome the limitations of conventional anti-biofilm methods. These efforts aim to improve the management of biofilms and prevent infections while preserving the environment. This study provides a comprehensive overview of the latest advancements in anti-biofilm strategies. Given the dynamic nature of this field, exploring new approaches is essential to stimulate further research and development initiatives. The effective management of biofilms is crucial for maintaining the health of industrial processes, environmental systems, and human populations.

The action of phytochemicals in biofilm control

Covering: 2009 to 2021Antimicrobial resistance is now rising to dangerously high levels in all parts of the world, threatening the treatment of an ever-increasing range of infectious diseases. This has becoming a serious public health problem, especially due to the emergence of multidrug-resistance among clinically important bacterial species and their ability to form biofilms. In addition, current anti-infective therapies have low efficacy in the treatment of biofilm-related infections, leading to recurrence, chronicity, and increased morbidity and mortality. Therefore, it is necessary to search for innovative strategies/antibacterial agents capable of overcoming the limitations of conventional antibiotics. Natural compounds, in particular those obtained from plants, have been exhibiting promising properties in this field. Plant secondary metabolites (phytochemicals) can act as antibiofilm agents through different mechanisms of action from the available antibiotics (inhibition of quorum-sensing, motility, adhesion, and reactive oxygen species production, among others). The combination of different phytochemicals and antibiotics have revealed synergistic or additive effects in biofilm control. This review aims to bring together the most relevant reports on the antibiofilm properties of phytochemicals, as well as insights into their structure and mechanistic action against bacterial pathogens, spanning December 2008 to December 2021.

Metal Complexes—A Promising Approach to Target Biofilm Associated Infections

Microbial biofilms are represented by sessile microbial communities with modified gene expression and phenotype, adhered to a surface and embedded in a matrix of self-produced extracellular polymeric substances (EPS). Microbial biofilms can develop on both prosthetic devices and tissues, generating chronic and persistent infections that cannot be eradicated with classical organic-based antimicrobials, because of their increased tolerance to antimicrobials and the host immune system. Several complexes based mostly on 3D ions have shown promising potential for fighting biofilm-associated infections, due to their large spectrum antimicrobial and anti-biofilm activity. The literature usually reports species containing Mn(II), Ni(II), Co(II), Cu(II) or Zn(II) and a large variety of multidentate ligands with chelating properties such as antibiotics, Schiff bases, biguanides, N-based macrocyclic and fused rings derivatives. This review presents the progress in the development of such species and their anti-biofilm activity, as well as the contribution of biomaterials science to incorporate these complexes in composite platforms for reducing the negative impact of medical biofilms.

5-hydroxymethyl-2-furaldehyde impairs Candida albicans - Staphylococcus epidermidis interaction in co-culture by suppressing crucial supportive virulence traits

Polymicrobial biofilms involving fungal-bacterial interactions are stated to modulate host immune response and exhibit enhanced antibiotic resistance. In this milieu, clinically important opportunistic pathogens Candida albicans and Staphylococcus epidermidis associate synergistically and instigate implant and blood stream infections. Impediment of virulence traits that support successive pathogenic lifestyle and inter-kingdom interactions without altering the microbial growth represents an attractive alternate strategy. To accomplish this objective, 5-hydroxymethyl-2-furaldehyde (5HM2F), a reported antibiofilm agent against C. albicans, was considered for this study. 5HM2F significantly repressed the biofilm formation of S. epidermidis and mixed-species at 300 μg/mL and 400 μg/mL, respectively without modulating the growth. Microscopic analyses and phenotypic assays explicated the competency of 5HM2F to impede biofilm formation, hyphal growth, initial attachment, intercellular adhesion, and fungal-bacterial interaction. Further, 5HM2F greatly reduced the secreted hydrolases production. Reduced content of biofilm matrix components upon 5HM2F treatment was believed to be the underlying reason for enhanced antibiotic and/antifungal susceptibility. Additionally, qPCR analysis correlated well with in vitro bioassays wherein, 5HM2F was identified to repress the expression of important genes associated with hyphal morphogenesis, adhesion, biofilm formation and virulence in both mono-species and mixed-species. Reduced virulence and colonization of mono-species and mixed-species in 5HM2F treated Caenorhabditis elegans substantiated the antibiofilm and antivirulence potential of 5HM2F. Overall, this study proposes 5HM2F as a potent therapeutic candidate against single and mixed-species biofilm infections of C. albicans and S. epidermidis.

Challenges and New Therapeutic Approaches in the Management of Chronic Wounds

Chronic non-healing wounds are estimated to cost the US healthcare $28-$31 billion per year. Diabetic ulcers, arterial and venous ulcers, and pressure ulcers are some of the most common types of chronic wounds. The burden of chronic wounds continues to rise due to the current epidemic of obesity and diabetes and the increase in elderly adults in the population who are more vulnerable to chronic wounds than younger individuals. This patient population is also highly vulnerable to debilitating infections caused by opportunistic and multi-drug resistant pathogens. Reduced microcirculation, decreased availability of cytokines and growth factors that promote wound closure and healing, and infections by multi-drug resistant and biofilm forming microbes are some of the critical factors that contribute to the development of chronic non-healing wounds. This review discusses novel approaches to understand chronic wound pathology and methods to improve chronic wound care, particularly when chronic wounds are infected by multi-drug resistant, biofilm forming microbes.

Umbelliferone Impedes Biofilm Formation and Virulence of Methicillin-Resistant Staphylococcus epidermidis via Impairment of Initial Attachment and Intercellular Adhesion

Staphylococcus epidermidis is an opportunistic human pathogen, which is involved in numerous nosocomial and implant associated infections. Biofilm formation is one of the prime virulence factors of S. epidermidis that supports its colonization on biotic and abiotic surfaces. The global dissemination of three lineages of S. epidermidis superbugs highlights its clinical significance and the imperative need to combat its pathogenicity. Thus, in the current study, the antibiofilm activity of umbelliferone (UMB), a natural product of the coumarin family, was assessed against methicillin-resistant S. epidermidis (MRSE). UMB exhibited significant antibiofilm activity (83%) at 500 μg/ml concentration without growth alteration. Microscopic analysis corroborated the antibiofilm potential of UMB and unveiled its potential to impair intercellular adhesion, which was reflected in auto-aggregation and solid phase adherence assays. Furthermore, real time PCR analysis revealed the reduced expression of adhesion encoding genes (icaD, atlE, aap, bhp, ebh, sdrG, and sdrF). Down regulation of agrA and reduced production of secreted hydrolases upon UMB treatment were speculated to hinder invasive lifestyle of MRSE. Additionally, UMB hindered slime synthesis and biofilm matrix components, which were believed to augment antibiotic susceptibility. In vivo assays using Caenorhabditis elegans divulged the non-toxic nature of UMB and validated the antibiofilm, antivirulence, and antiadherence properties of UMB observed in in vitro assays. Thus, UMB impairs MRSE biofilm by turning down the initial attachment and intercellular adhesion. Altogether, the obtained results suggest the potent antibiofilm activity of UMB and the feasibility of using it in clinical settings for combating S. epidermidis infections.

Patient compliance with antimicrobial drugs: A Chinese survey

BACKGROUND

Antimicrobial therapy is among the mainstream treatment modalities employed in clinical settings. Antimicrobial sensitivity of the pathogen and patient compliance are key determinants of the efficacy of antimicrobial therapy.

OBJECTIVE

In this study, we sought to investigate the factors that affect patient compliance to antimicrobial therapy in a Chinese teaching hospital to enhance patient compliance and to prevent abuse and misuse of antibiotics by patients.

METHODS

A questionnaire survey was conducted among patients willing to answer all the questions who were prescribed antimicrobial drugs orally, and for whom at least half of the duration of therapy was not under the supervision of a doctor or nurse. Data analyses were performed using Kruskal-Wallis test and multivariate logistic regression.

RESULTS

A total of 720 patients participated in the survey; of these, 714 patients provided complete data and were included in the analysis. Up to 86.97% of patients showed noncompliance to antimicrobial therapy (total compliance score < 8), whereas 13.03% of patients showed good compliance (total compliance score = 8). On multivariate analyses, understanding of the treatment was an important factor associated with compliance.

CONCLUSIONS

A range of factors were associated with compliance to antimicrobial therapy, including understanding of the treatment, gender, age, home address, education level, and family income.

Changing facades of Vibrio cholerae: An enigma in the epidemiology of cholera

Cholera, caused by the Gram-negative bacterium Vibrio cholerae, has ravaged humanity from time immemorial. Although the disease can be treated using antibiotics along with administration of oral rehydration salts and controlled by good sanitation, cholera is known to have produced mayhems in ancient times when little was known about the pathogen. By the 21st century, ample information about the pathogen, its epidemiology, genetics, treatment and control strategies was revealed. However, there is still fear of cholera outbreaks in developing countries, especially in the wake of natural calamities. Studies have proved that the bacterium is mutating and evolving, out-competing all our efforts to treat the disease with previously used antibiotics and control with existing vaccines. In this review, the major scientific insights of cholera research are discussed. Considering the important role of biofilm formation in the V. cholerae life cycle, the vast availability of next-generation sequencing data of the pathogen and multi-omic approach, the review thrusts on the identification of suitable biofilm-inhibiting targets and the discovery of anti-biofilm drugs from nature to control the disease.

Effect of Tamarindus indica L. and Manihot esculenta Extracts on Antibiotic-resistant Bacteria

Background:

The chemical composition of plants used in traditional medicine exhibits biologically active compounds, such as tannins, flavonoids, and alkaloids and becomes a promising approach to treat microbial infections, mainly with drug-resistant bacteria.

Objective:

The aim of the present study was to evaluate the hydroethanolic leaf extracts of Tamarindus indica (tamarind) and Manihot esculenta (cassava) as antimicrobial potential against Pseudomonas aeruginosa clinical isolated and Methicillin-resistant Staphylococcus aureus.

Materials and Methods:

Hydroethanolic leaf extracts were prepared and characterized by high-performance liquid chromatography/diode array detection, Fourier transform infrared, 1,1-diphenyl-2-picrylhydrazyl, and ultraviolet-visible methods. The antimicrobial activity against four strains of clinical relevance was evaluated by the microdilution method at minimum inhibitory concentrations.

Results:

Phenolic compounds such as flavonoids were detected in the plant extracts. T. indica extract at 500 μg/mL showed antimicrobial activity against S. aureus and P. aeruginosa; however, M. esculenta showed only activity against P. aeruginosa in this concentration.

Conclusions:

Our results suggested that polyphenols and flavonoids present in T. indica leaf extracts are a potential source of antimicrobial compound. The T. indica extract showed antibacterial activity against S. aureus and P. aeruginosa while M. esculenta had effect only on P. aeruginosa meropenem resistant.

SUMMARY

Antibacterial effect of T. indica and M. esculenta leaf extract was evaluated.

T. indica extract displayed activity against S. aureus and P. aeruginosa strains.

M. esculenta showed effect on P. aeruginosa meropenem resistant.

Abbreviations Used: BHI: Agar brain heart infusion, CAPES: Coordination for the improvement of higher education personnel, DPPH: 1,1-diphenyl-2-picrylhydrazyl, FAPITEC/SE: Foundation for support to research and technological innovation of the state of sergipe, FTIR: Fourier transform infrared spectroscopy, HPLC: High-performance liquid chromatography, KBr: Potassium bromide, MIC: Minimum inhibitory concentration, MRSA: Methicillin-resistant Staphylococcus aureus, RSC: Radical scavenging capacity, UV-vis: Ultraviolet-visible.