Quantitative evaluation of bacteria adherent to polyelectrolyte HEMA‐based hydrogels

Abstract

The use of adhesive poly(HEMA)-based hydrogels is standard practice in dental restorative procedures. Microorganisms, which potentially can cause oral pathologies, may colonize these polymers. In the present work, bacterial adhesion to polymers prepared with 2-hydroxyethyl methacrylate (HEMA) and to different molar ratios of 2-acrylamido-2-methylpropane-sulfonic acid (AMPS) and/or to 2-methacryloyloxyethyl-tri-methyl-ammonium chloride (METAC) co-monomers were tested. A colorimetric assay system that utilizes the Microbo revelation medium (Microbo srl, Rome, Italy) for microbial counts is shown to be capable of counting the number of adherent bacterial cells without removing them from polymer surfaces. In conditions that mimic those present in the oral cavity, similar bacterial adhesion percentages on the same polymer were observed with the different bacteria belonging to both gram-positive and gram-negative genera, such as Streptococcus sobrinus and Streptococcus oralis (resident microorganisms in the oral cavity) and Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa (transient microorganisms in the oral cavity). It is determined that the physico-chemical characteristics of poly(HEMA)-based hydrogels are the major factors promoting bacterial adhesion, which increased with increasing water content in the swollen polymers, reaching maximal values on the cationic polymers.

Antibiotic Effect on Planktonic and Biofilm-Producing Staphylococci

“…Antibiotic killing potency decreased as biofilm age increased (from 6 to 24 or 48 h) for some antibiotics such as vancomycin, but that of rifampicin or tetracycline was not affected. Berlutti et al [26] presented an improved method called the BioTimer assay, which can be successfully applied to directly enumerate Staphylococcus in biofilms without any sample manipulation. The BTA method can be used to count Staphylococcus via a genus-specific correlation line that correlates the time required for BT-PR medium color switch with the initial concentration of planktonic bacteria.…”

A New Biosensor to Enumerate Bacteria in Planktonic and Biofilm Lifestyle

“…in the absence of living bacteria (Fig. 1, insert of Panel A ) (Berlutti et al, 2003). In the presence of bacteria, BT-PR reagent switches red-to-yellow due to metabolism of fermenting bacteria.…”

“…BTA has been successfully employed to estimate bacterial population colonizing a variety of abiotic materials. The first report concerned the evaluation of adhesion ability of different Gram-positive and Gram-negative species on different adhesive poly(HEMA)-based hydrogels to be utilized in dental restorative procedures (Berlutti et al, 2003). As matter of fact, the use of dental polymers is a standardized practice in dental restorative procedures.…”

“…Bacterial counts have deep implications in microbiological diagnosis and therapeutic treatments (Bryers, 2008), in water and food quality analysis (Ramalho et al, 2001;Lee et al, 2007;Rueckert et al, 2005), in environmental applications and consumers' safety. The standard method used to evaluate the number of bacteria, based on determination of Colony Forming Units (CFUs) (ISO method), can be considered fully appropriate only when bacteria are in planktonic lifestyle but it is unreliable to count bacteria in aggregated, adherent and biofilm lifestyle (Berlutti et al, 2003Frioni, 2010). Even if different analytical strategies have been attempted to enumerate bacteria in biofilm, the detection of the actual number of bacteria in aggregated, adherent and biofilm lifestyle is still a great challenge for microbiologists.…”

Detection of Staphilococcus aureus by Amoxicillin Modified Natural Phosphate Electrode: Analytical Application Potato Juice

“…The contaminated food has the same aspect (appearance, odor, taste) that the healthy food [7][8][9]. The placement of detector of this bacterium is essential in order to prevent the risks of contamination [10,11]. After the previously published work, which consisted in using the modified electrode AMX-NP for the detection and quantification of staphylococcus aurous [5], this work aims to use the same electrode in an analytical application, to face this analytical method under real conditions, In particular in potato juice.…”