Study of the Relation between the Resonance Behavior of Thickness Shear Mode (TSM) Sensors and the Mechanical Characteristics of Biofilms

Microsystems for biofilm characterization and sensing - A review

Biofilms are the primary cause of clinical bacterial infections and are impervious to typical amounts of antibiotics, necessitating very high doses for elimination. Therefore, it is imperative to have suitable methods for characterization to develop novel methods of treatment that can complement or replace existing approaches using significantly lower doses of antibiotics. This review presents some of the current developments in microsystems for characterization and sensing of bacterial biofilms. Initially, we review current standards for studying biofilms that are based on invasive and destructive end-point biofilm characterization. Additionally, biofilm formation and growth is extremely sensitive to various growth and environmental parameters that cause large variability in biofilms between repeated experiments, making it very difficult to compare experimental repeats and characterize the temporal characteristics of these organisms. To address these challenges, recent developments in the field have moved toward systems and miniature devices that can aid in the non-invasive characterization of bacterial biofilms. Our review focuses on several types of microsystems for biofilm evaluation including optical, electrochemical, and mechanical systems. This review will show how these devices can lead to better understanding of the physiology and function of these communities of bacteria, which can eventually lead to the development of novel treatments that do not rely on high-dosage antibiotics.

Methods Used for the Eradication of Staphylococcal Biofilms

Staphylococcus aureus is considered one of the leading pathogens responsible for community and healthcare-associated infections. Among them, infections caused by methicillin-resistant strains (MRSA) are connected with ineffective or prolonged treatment. The therapy of staphylococcal infections faces many difficulties, not only because of the bacteria's resistance to antibiotics and the multiplicity of virulence factors it produces, but also due to its ability to form a biofilm. The present review focuses on several approaches used for the assessment of staphylococcal biofilm eradication. The methods described here are successfully applied in research on the prevention of biofilm-associated infections, as well as in their management. They include not only the evaluation of the antimicrobial activity of novel compounds, but also the methods for biomaterial functionalization. Moreover, the advantages and limitations of different dyes and techniques used for biofilm characterization are discussed. Therefore, this review may be helpful for those scientists who work on the development of new antistaphylococcal compounds.

Viscoelastic response of Escherichia coli biofilms to genetically altered expression of extracellular matrix components

How the viscoelastic properties of the extracellular matrix affect the various biological functions conferred by biofilms is an important question in microbiology. In this study, the viscoelastic response of Escherichia coli biofilms to the genetically altered expression of extracellular matrix components was studied. Biofilms of the wild type E. coli MG1655 and its mutant strains producing different amounts of extracellular matrix components (curli, colanic acid, and poly-β-1,6-N-acetyl-d-glucosamine) were used to examine the viscoelastic behavior of biofilms grown at the solid-atmosphere interface. The results suggest that the presence of curli proteins dominates biofilm mechanical behavior. The rheological data indicate that the cohesive energy of the biofilm was the highest in the wild type strain. The results demonstrate the importance of extracellular matrix composition for biofilm mechanical properties. We propose that by genetically altering the expression of extracellular matrix polymers, bacteria are able to modulate the mechanical properties of their local environment in accordance with bulk environmental conditions.