Extraintestinal Invasive Escherichia coli Infections in the US

Extraintestinal invasive Escherichia coli infections are a leading cause of sepsis and hospitalization, further complicated by increasing rates of antimicrobial resistance.

To describe the US epidemiology of invasive E coli infections and their clinical and molecular features.

This cohort study used active laboratory- and population-based surveillance data from 9 US sites with a total population of more than 7.2 million people for invasive E coli in normally sterile body sites, collected from June to August 2023 from medical records and isolate characterization. Data were analyzed from November 2023 to February 2024.

Laboratory-confirmed identification of any E coli organism isolated from a normally sterile body site obtained from a resident of the surveillance area.

Outcomes of interest were population-based and site-specific incidence rate estimates of E coli infections, demographic and clinical characteristics, antimicrobial susceptibility profiles, and predicted O serotypes by in silico serotyping.

Among 1345 cases of E coli infection in 1334 unique case-patients, the median (IQR) age was 68 (55-79) years, and 762 case-patients (57.1%) were female; 1223 infections (90.9%) were from blood and 122 infections (9.1%) were from other sterile sites. The overall estimated annual incidence rate was 74.7 per 100 000 population (surveillance site range, 51.4-96.0 per 100 000 population). Estimated incidence rates were higher among cases in patients aged 60 years or older compared with younger patients (225.0 vs 30.6 per 100 000 population), although rates were similar for females and males aged 60 years or older (224.5 vs 224.0 per 100 000 population). The most common underlying medical condition reported was diabetes (457 patients [34.0%]). Pyelonephritis (267 infections [19.9%]) and lower urinary tract infections (495 infections [36.8%]) were the most frequently associated infection types. In total, 1279 cases (95.1%) were hospitalized for less than 30 days after isolate collection; 106 case-patients (7.9%) died. Overall, 185 infections (13.8%) were due to extended-spectrum β-lactamase-producing E coli; 275 of 1061 isolates (25.9%) were resistant to ciprofloxacin and 370 of 1286 (28.8%) were resistant to trimethoprim-sulfamethoxazole. Of 846 sequenced isolates, the most prevalent O serotypes were O25B (137 isolates [16.2%]), O2 (93 isolates [11.0%]), and O6 (84 isolates [9.9%]).

This cohort study using population-based public health surveillance data identified a substantial burden of invasive E coli disease, especially in older people, with high rates of antimicrobial resistance. These results can help inform national public health prevention efforts.