Integrated Multivariate Analysis with Nondetects for the Development of Human Sewage Source-Tracking Tools Using Bacteriophages of Enterococcus faecalis.

We developed sewage-specific microbial source tracking (MST) tools using enterococci bacteriophages and evaluated their performance with univariate and multivariate analyses involving data below detection limits. Newly isolated Enterococci faecalis bacterial strains AIM06 (DSM100702) and SR14 (DSM100701) demonstrated 100% specificity and 90% sensitivity to human sewage without detecting 68 animal manure pooled samples of cats, chickens, cows, dogs, ducks, pigs, and pigeons. AIM06 and SR14 bacteriophages were present in human sewage at 2-4 orders of magnitude. A principal component analysis confirmed the importance of both phages as main water quality parameters. The phages presented only in the polluted water, as classified by a cluster analysis, and at median concentrations of 1.71 × 102 and 4.27 × 102 PFU/100 mL, respectively, higher than nonhost specific RYC2056 phages and sewage-specific KS148 phages (p < 0.05). Interestingly, AIM06 and SR14 phages exhibited significant correlations with each other and with total coliforms, E. coli, enterococci, and biochemical oxygen demand (Kendall's tau = 0.348 to 0.605, p < 0.05), a result supporting their roles as water quality indicators. This research demonstrates the multiregional applicability of enterococci hosts in MST application and highlights the significance of multivariate analysis with nondetects in evaluating the performance of new MST host strains.

Occurrence of bacteriophages infecting Aeromonas, Enterobacter, and Klebsiella in water and association with contamination sources in Thailand.

The co-residence of bacteriophages and their bacterial hosts in humans, animals, and environmental sources directed the use of bacteriophages to track the origins of the pathogenic bacteria that can be found in contaminated water. The objective of this study was to enumerate bacteriophages of Aeromonas caviae (AecaKS148), Enterobacter sp. (EnspKS513), and Klebsiella pneumoniae (KlpnKS648) in water and evaluate their association with contamination sources (human vs. animals). Bacterial host strains were isolated from untreated wastewater in Bangkok, Thailand. A double-layer agar technique was used to detect bacteriophages. All three bacteriophages were detected in polluted canal samples, with likely contamination from human wastewater, whereas none was found in non-polluted river samples. AecaKS148 was found to be associated with human fecal sources, while EnspKS513 and KlpnKS648 seemed to be equally prevalent in both human and animal fecal sources. Both bacteriophages were also present in polluted canals that could receive contamination from other fecal sources or the environment. In conclusion, all three bacteriophages were successfully monitored in Bangkok, Thailand. This study provided an example of bacteriophages for potential use as source identifiers of pathogen contamination. The results from this study will assist in controlling sources of pathogen contamination, especially in developing countries.