Invasive <scp> <i>E. coli</i> </scp> Disease in US Nursing Homes: Brief Report of Case Validation Findings

BACKGROUND: Invasive Escherichia coli disease (IED) causes significant morbidity, but little is known about its characteristics in nursing home (NH) populations. PARTICIPANTS AND SETTING: Adult long-stay NH residents with electronic health record (EHR) evidence of a positive E. coli infection from Medicare-certified skilled nursing facilities between 2017 and 2023 (excluding 2020-2021). METHODS: This retrospective case validation study collected NH EHR data on demographics, case definition, hospitalizations, emergency visits, antibiotic use, and discharge status. Each resident's NH Minimum Data Set assessment closest to the date of qualifying E. coli culture (QEC) was also reviewed. Our IED case definition combines E. coli culture confirmation from urine or blood with clinical signs consistent with invasive disease (i.e., sepsis) within 72 h. RESULTS: Among 90 IED cases, 77.8% were female, 73.3% white, and 70% dually eligible for Medicare and Medicaid. Most cases (85.7%) were admitted from acute care facilities. Over 90% of cases were confirmed from urine specimens alone, only 7.7% from blood cultures. Sepsis was documented in 54.4% of cases, with 33.3% specifically classified as "sepsis due to E. coli." End-organ dysfunction impacted 28% of patients, with acute kidney injury (15.6%) being most common. Over one-third (36.7%) were hospitalized within 30 days of diagnosis. Substantial antibiotic resistance was observed, with 61.5% of isolates resistant to ampicillin and over half resistant to fluoroquinolones. Urological risk factors included neurogenic bladder (20%) and obstructive uropathy (14%). Common comorbidities were hypertension (70%), diabetes (51.1%), and depression (47.8%). CONCLUSION: The results of this study indicate that NH residents who develop IED incur high rates of sepsis, hospitalization, and antibiotic resistance, highlighting the importance of improved laboratory reporting systems and thorough specimen collection to enhance earlier diagnosis and treatment of E. coli infections that can progress to this life-threatening disease.