Transmission dynamics of Escherichia coli ST131 in Singapore households

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. We collected up to twelve sequential stool samples from 135 human participants and six companion animals and environmental swabs from 34 households, sequencing up to ten isolates per sample. Each household included an index patient with prior extraintestinal E. coli infection (17 with ST131, 17 with other sequence types) and their coresidents. While most participants carried E. coli ST131 intermittently, we identified a subset of participants 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). Coresiding with a persistent carrier was associated with an almost-doubled risk of acquiring E. coli ST131 (3.13% daily risk (80% CrI 1.22 to 10.14) versus 1.57% (80% CrI 0.65 to 5.19)). Persistent carriers and their coresidents carried genetically similar ST131 isolates, but persistent carriers harboured greater diversity, suggesting that they were the source of inter-individual transmissions. Our results demonstrate that asymptomatic, persistent carriers represent potential reservoirs sustaining community E. coli ST131 transmissions. In identifying this subgroup, we highlight a potential target for public health interventions such as vaccination to limit the spread of multidrug resistance.