Genetic Attributes of E. coli Isolates from Chlorinated Drinking Water

Area of Science:

• Environmental microbiology
• Public health
• Genomics

Background:

• Escherichia coli (E. coli) in water sources can indicate fecal contamination and pose health risks.
• E. coli strains can be commensals, pathogens, or free-living, with varying implications for human health and water safety.

Purpose of the Study:

• To genetically characterize E. coli isolates from treated drinking water in Australia.
• To determine the likely source and potential health risks associated with these E. coli strains.

Main Methods:

• Whole genome sequencing was employed to determine phylogenetic groups and multi-locus sequence types.
• In silico screening for virulence and antibiotic resistance genes was performed.

Main Results:

• Four E. coli isolates were identified as potential human pathogens, but not in high numbers.
• Nine isolates were classified as free-living, water-associated strains.
• Only 14% of isolates belonged to host-associated phylogenetic group B2, and only one isolate carried antibiotic resistance genes.

Conclusions:

• The genetic profiles suggest that recent human fecal contamination was not the primary source of E. coli in the studied drinking water.
• The majority of isolates were not associated with significant human health risks.