Whole-genome surveillance supports hazard profiling of Escherichia coli lineages in recycled water treatment systems.

Whole-genome sequencing of 180 Escherichia coli isolates from a recycled water system revealed 88 sequence types with extensive strain heterogeneity, despite a >90% reduction in total E. coli loads.

• Why it matters: Conventional monitoring based on E. coli counts offers limited insight into strain diversity and public health hazards, which hampers effective risk assessment and management in recycled water systems.
• What they did: Researchers applied longitudinal whole-genome sequencing and developed a hazard framework incorporating virulence factors, antimicrobial resistance genes, and exposure context to classify isolates, finding 92.8% as low hazard and 7.2% as moderate hazard.
• The result: Genomic profiling uncovered population structure and hazard heterogeneity not detectable by traditional methods, supporting the integration of genomic data into hazard-informed monitoring to enhance risk-based management of recycled water.