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Byline: Rossella Briancesco (Department of Environment and Primary Prevention, Istituto Superiore di Sanita, Rome, Italy); Anna Maria Coccia (Department of Environment and Primary Prevention, Istituto Superiore di Sanita, Rome, Italy); [...]

In this study, the performance of a new most probable number (MPN) test (Pseudalert®/Quanti-Tray®) for the enumeration of Pseudomonas aeruginosa from hospital waters was compared with both international and national membrane filtration-based culture methods for P. aeruginosa: ISO 16266:2006 and UK The Microbiology of Drinking Water - Part 8 (MoDW Part 8), which both use Pseudomonas CN agar. The comparison based on the calculation of mean relative differences between the two methods was conducted according to ISO 17994:2014. Using both routine hospital water samples (80 from six laboratories) and artificially contaminated samples (192 from five laboratories), paired counts from each sample and the enumeration method were analysed. For routine samples, there were insufficient data for a conclusive assessment, but the data do indicate at least equivalent performance of Pseudalert®/Quanti-Tray®. For the artificially contaminated samples, the data revealed higher counts of P. aeruginosa being recorded by Pseudalert®/Quanti-Tray®. The Pseudalert®/Quanti-Tray® method does not require confirmation testing for atypical strains of P. aeruginosa, saving up to 6 days of additional analysis, and has the added advantage of providing confirmed counts within 24-28 hours incubation compared to 40-48 hours or longer for the ISO 16266 and MoDW Part 8 methods. [ABSTRACT FROM AUTHOR]

Data on the occurrence of non-tuberculous mycobacteria (NTM), in parallel with those obtained for bacterial indicators and amoebae, are presented with the aim to collect information on the spread of NTM in drinking water distribution systems in Italy. Samples were collected from taps of hospitals and households in Central and Southern Italy. The concentration values obtained for the more traditional microbial parameters complied with the mandatory requirements for drinking water. Conversely, moderate-to-high microbial loads (till 300 CFU/L) were observed for the NTM. Positive samples were obtained from 62% of the investigated water samples. Analogous results were observed for amoebae showing a higher percentage of positive samples (76%). In terms of public health, the presence of mycobacteria in water distribution systems may represent a potential risk especially for vulnerable people such as children, the elderly or immunocompromised individuals.

This report presents a case study of a comprehensive sanitary survey on ca. 160 community drinking water supplies after a severe (post-Tsunami) flooding event in Sri Lanka. Sanitary inspection and microbiological and chemical water quality analyses were performed according to specifically-designed procedures established on the World Health Organization (WHO) guidelines. Significant hazards and critical points were identified in almost all the investigated water supplies. The overall results showed a significant level of microbiological and chemical risk associated with drinking water consumption within the investigated areas. The criteria and methods practised in this study are proposed as a model to assure an effective and reliable monitoring in post-emergencies involving possible deterioration of water quality and to identify health priorities related to water consumption.

The ISO reference method, defined by the European Drinking Water Directive for the enumeration of total coliforms and Escherichia coli in water intended for human consumption, has various limitations, especially related to discrepancies observed with the new taxonomic classification of the coliform group. A study was therefore performed to compare the above reference method with another rapid method, the DST/Colilert, and to evaluate the phenotypical characteristics of isolated microrganisms. The ISO reference method failed to detect a significant proportion of coliforms and E. coli in water and furthermore, it enumerated microrganisms belonging to other groups. The DST/Colilert method was found instead to be a suitable alternative method for the detection of bacterial indicators.