P-1322. Transmission Dynamics of <i>Escherichia coli</i> Sequence Type 131 Amongst Community Dwelling Households: A Prospective Cohort Study

Abstract Background Escherichia coli sequence type 131 (E. coli ST131) is a global pandemic clone associated with the rapid dissemination of CTX-M–class extended spectrum β-lactamase (ESBL) genes, conferring resistance to several antibiotic classes, and is a major cause of both healthcare and community-acquired extraintestinal pathogenic E. coli (ExPEC) infections. The drivers of E. coli ST131 pandemicity are not well-understood. Figure 1. Prospective cohort study enrollment flowchart Methods Between February 2017 to November 2018, 34 hospitalized patients with E. coli positive cultures (including half with ST131-positive cultures) and their household coresidents were recruited to a prospective cohort study in which all household members provided up to 12 stool samples at 2-6 week intervals. The samples were screened for E. coli ST131 isolates using quantitative polymerase chain reaction (qPCR), and short-read whole genome sequencing (WGS) was conducted on all E. coli ST131-positive isolates. Figure 2. Model estimates of E. coli ST131 acquisition rate and carriage duration Results Nine individuals (7.25%) carried E. coli ST131 for a median of 86.35 days [80% CrI: 30.03-188.8] (over three times higher than the cohort average of 27.33 days [80% CrI: 20.00-36.74]) and at high densities. The household coresidents of these individuals acquired E. coli ST131 at approximately twice the rate of those who did not coreside with a persistent high-density carrier (0.031 per day [80% CrI: .012-.10] and 0.016 per day [0.006-0.05], respectively; Odds Ratio: 2.61 [95% CI: 1.36 to 5.00] (p &amp;lt; 0.01)). WGS analysis identified a high degree of sequence similarity between E. coli ST131 isolates obtained from different individuals and at multiple non-sequential timepoints in four of the nine families in which a high-density persistent carrier was resident, indicating potential repeated transmission events. Multivariate and univariate regression analysis of risk factors associated with E. coli ST131 acquisition Conclusion These findings indicate that a proportion of high-density asymptomatic carriers in the community may act as reservoirs for E. coli ST131, with frequent transmission to household contacts representing a key driver of E. coli ST131’s pandemic success. Further studies in other settings are needed to understand high-density persistent carrier status and address this potential community-level reservoir in order to contain this multi-resistant pathogen and reduce its clinical impact. Disclosures Paul Tambyah, MBBS (S'pore), Diplomate, American Board of Internal Medicine and Infectious Diseases, Moderna: Grant/Research Support|Sanofi-Pasteur: Grant/Research Support