Unlocking the molecular realm: advanced approaches for identifying clinically and environmentally relevant bacteria

Rapid, effective, and specific identification of clinical and environmental bacterial pathogens is of major importance for their control. Traditionally, bacteria have been identified by phenotypic methods based on morphological, biochemical, and metabolic properties. While these methods are very useful in clinical practice, they have limitations including a poor ability to differentiate within and between species and time-consuming workflows. Newly developed molecular methods can greatly improve the accuracy of taxonomic characterization, identifying specific strains of medical or environmental importance. However, due to high costs and the need for trained professionals, these methods are not yet routine in diagnostic laboratories. Thus, disseminating knowledge on advances in molecular identification techniques is pivotal to make these methodologies accessible. The objective of this work was to review and discuss current molecular techniques for bacteria identification aiming to track and monitor microbial agents in clinical and environmental samples.

Sponge-based microfluidic sampling for potentiometric ion sensing.

This work demonstrates an application of the new materials, sponges, for the use in microfluidic solution sampling integrated with ion-selective electrodes. The microfluidic sponge-based sampling was developed and studied as novel sampling and sample handling method to serve as alternative for microfluidic paper- and textile-based sampling for ion analysis in various environmental (Cd2+, Pb2+ and pH) and clinically (K+, Na+, Cl-) relevant samples. Three types of polyurethane, cellulose and natural sponges were used as substrates for microfluidic solution sampling. Polyurethane based sponge was found to have low heavy metal sorption capacity thus it was recognized as suitable for microfluidic sampling coupled with solid-state as well as solid-contact ion-selective electrodes. The application of sponge-based microfluidic sampling, contrary to previous findings of paper- and textile-based microfluidic sampling, allowed measurements of heavy metals without prior modification of the sampling substrate. Finally, the determination of potassium, sodium and chloride in wastewater sludge and sweat samples done with sponge-based microfluidic sampling integrated with ISEs was found similar to analysis done by ICP-OES and IC.

Textile-based sampling for potentiometric determination of ions.

Potentiometric sensing utilizing textile-based micro-volume sampling was applied and evaluated for the determination of clinically (Na(+), K(+), Cl(-)) and environmentally (Cd(2+), Pb(2+) and pH) relevant analytes. In this technological design, calibration solutions and samples were absorbed into textiles while the potentiometric cells (ion-selective electrodes and reference electrode) were pressed against the textile. Once the liquid, by wicking action, reached the place where the potentiometric cell was pressed onto the textile, hence closing the electric circuit, the potentiometric response was obtained. Cotton, polyamide, polyester and their blends with elastane were applied for micro-volume sampling. The textiles were found to influence the determination of pH in environmental samples with pH close to neutral and Pb(2+) at low analyte concentrations. On the other hand, textile-based micro-volume sampling was successfully applied in measurements of Na(+) using solid-contact sodium-selective electrodes utilizing all the investigated textiles for sampling. It was found that in order to extend the application of textile-based sampling toward environmental analysis of ions it will be necessary to tailor the physio-chemical properties of the textile materials. In general, textile-based sampling opens new possibilities for direct chemical analysis of small-volume samples and provide a simple and low-cost method to screen various textiles for their effects on samples to identify which textiles are the most suitable for on-body sensing.