Transmission dynamics of Escherichia coli sequence type 131 in households-a one health prospective cohort study.

Escherichia coli sequence type 131 (ST131) is a major cause of community-onset, multidrug-resistant extraintestinal infections. The transmission and carriage dynamics associated with E. coli ST131's global prevalence remain poorly understood. Here, we identify a group of persistent, high-density carriers of E. coli ST131 in the community. In this prospective cohort study in Singapore, we enrolled index patients with prior extraintestinal E. coli infections (17 with ST131, 17 with other sequence types) and their household coresidents. We collected sequential stool samples from 135 human participants and six companion animals and environmental swabs from 34 households. We identified nine carriers that persistently carried E. coli ST131 in high densities (57.79% of E. coli isolates per sample) for a median carriage duration of 86.35 days (80% credible interval (CrI) 30.03 to 188.80). Persistent carriers and their coresidents carried genetically similar E. coli ST131 isolates (median single nucleotide polymorphism distance 2, interquartile range 2 to 7), but persistent carriers harboured greater diversity, suggesting that they were the source of inter-individual transmissions. Our results highlight asymptomatic, persistent carriers as potential reservoirs sustaining community E. coli ST131 transmissions, offering a potential target for public health interventions such as vaccination to limit the spread of multidrug resistance.