Development of Microbial Source Tracking (MST) Approach to Support Public Health Policy

Microbiological water quality is a key element in everyday public health decisions. It relies on regulatory values of indicator bacteria concentration as measured by standard microbiological methods. Alongside the standard methods, advanced molecular tools, known as Microbial Source Tracking (MST) emerge to attribute fecal water contamination to their host species. We initiated an MST testing framework in Israel, targeting human, ruminant, bovine, porcine, and waterfowl fecal contamination. The following aspects were included:

1)Local validation and implementation of MST assays developed in other geographical regions around the world, tracing human, ruminant, bovine and porcine presence (Appl Environ Microbiol 2015. 81(15): 5037-47).

2) Development of new MST assays targeting avian species using Next Generation Sequencing (NGS) platforms, to extend the MST battery profile in a bird migratory region. Six new qPCR assays were developed, targeting Lactobacillus, Gallibacterium, Fusobactericeae and Firmicutes, with high specificity values while demonstrating variable sensitivity levels (Front Microbiol. 2016. 7: 145).

3) Construction of a methodical scheme to correlate between culture-based methods and qPCR results at low bacterial concentration.

En route to practical MST implementation we explored the reliability of tests for association between culture-based enumeration and qPCR repetitions at low bacterial load. This allows identification of the critical count where qPCR repetitions are required to achieve reliable positive detection.

Environmental data obtained from standard routine monitoring together with MST data were proven to effectively support public health decisions, example of such occasions will be further discussed.