Characterization, validation and application of a DNA microarray for the detection of mandatory and other waterborne pathogens

Molecular Diagnostic Tools Applied for Assessing Microbial Water Quality

Microbial water quality is of vital importance for human, animal, and environmental health. Notably, pathogenically contaminated water can result in serious health problems, such as waterborne outbreaks, which have caused huge economic and social losses. In this context, the prompt detection of microbial contamination becomes essential to enable early warning and timely reaction with proper interventions. Recently, molecular diagnostics have been increasingly employed for the rapid and robust assessment of microbial water quality implicated by various microbial pollutants, e.g., waterborne pathogens and antibiotic-resistance genes (ARGs), imposing the most critical health threats to humans and the environment. Continuous technological advances have led to constant improvements and expansions of molecular methods, such as conventional end-point PCR, DNA microarray, real-time quantitative PCR (qPCR), multiplex qPCR (mqPCR), loop-mediated isothermal amplification (LAMP), digital droplet PCR (ddPCR), and high-throughput next-generation DNA sequencing (HT-NGS). These state-of-the-art molecular approaches largely facilitate the surveillance of microbial water quality in diverse aquatic systems and wastewater. This review provides an up-to-date overview of the advancement of the key molecular tools frequently employed for microbial water quality assessment, with future perspectives on their applications.

Detection of cholera toxin with surface plasmon field-enhanced fluorescent spectroscopy

In this work, a biosensor based on surface plasmon field-enhanced florescence spectroscopy (SPFS) method was successfully constructed to detect the truncated form of cholera toxin, that is, its beta subunit (CTX-B). CTX-B is a relatively small molecule (12 kDa) and it was chosen as model analyte for the detection of protein toxins originated from waterborne pathogens. Recognition layer was prepared on gold-coated LaSFN9 glasses modified with 11-mercaptoundecanoic acid (11-MUA). Biotin-conjugated anti-CTX-B polyclonal antibody (B-Ab) was immobilized on streptavidin (SA) layer constructed on the 11-MUA-modified surface. CTX-B amount was determined with direct assay using B-Ab in surface plasmon resonance (SPR) mode and with sandwich assay in SPFS mode using Cy5-conjugated anti-CTX-B polyclonal antibody. Minimum detected CTX-B concentrations were 10 and 0.01 μg/ml with SPR and SPFS, respectively, showing the sensitivity of the SPFS system over the conventional one. The detection was done in 2-6 h, which was faster than both culture and polymerase chain reaction (PCR)-based methods. Stability tests were performed with SA-coated sensors (excluding B-Ab). In this form, the layer was stable after 30 days of storage in phosphate-buffered saline (PBS; 0.01 M, pH = 7.4) at +4°C. B-Ab layer was formed immediately on them before each measurement.

Microbiological Hygiene Quality of Thermal Muds: A Pilot Study in Pelotherapy Facilities of the Euganean Thermal District (NE Italy)

Evaluation of hygienic aspects of thermal mud microbiology is still neglected. This study evaluates the microbiological hygiene quality of thermal muds, providing a comprehensive assessment of the whole mud cultivation chain. Maturing mud, peloid and used mud samples were collected twice in a year from 30 SPAs of the Euganean Thermal District, NE Italy. Samples were processed with an ad hoc laboratory method. The following indicator parameters were assessed: Total Count at 22, 37 and 55 °C; total coliforms; Escherichia coli; enterococci; Staphylococcus aureus; Pseudomonas aeruginosa; sulfite-reducing clostridia; dermatophytes. Statistical significance of differences between the two sampling campaigns and correlation between temperature and indicator parameters were evaluated. One-hundred eighty samples were analyzed. Widespread presence of environmental species was found, as well as hints of possible microorganism transfer from the patient's skin to the mud. Proper setting of thermal water temperature resulted critical, in terms of hygienic quality. Although optimal maturation should be granted (thermal water at 30-42 °C), a pasteurization step at 60-65 °C is strongly recommended to sanitize peloids before pelotherapy. Facilities re-using thermal muds should also implement a regeneration step at ≥65 °C. Core evaluation of thermal mud hygienic quality could encompass the following guidelines: absence (i.e., 0 colony forming units (CFU)/g) of E. coli, P. aeruginosa, S. aureus and dermatophytes.