Progression from carbapenemase-producing Enterobacterales colonisation to subsequent clinical isolation in a Korean regional surveillance cohort: a retrospective cohort study

Abstract

Carbapenemase-producing Enterobacterales (CPE) colonisation may progress to clinical infection. We aimed to determine the incidence of and risk factors for progression from CPE colonisation to clinical isolation in a regional surveillance cohort. From the 2024 mandatory CRE surveillance registry, we identified 6340 patients including 8012 records and 337 facilities. Of these, 3164 patients had a rectal swab or stool sample as the index specimen and were classified as colonised, and 2483 (78.5%) had CPE confirmed by molecular testing and constituted the analytic cohort. The outcome was isolation of a carbapenem-resistant Enterobacterales isolate from a clinical specimen more than 48 h after the index specimen. Of 2483 CPE colonised patients, 103 (4.1%) progressed to clinical isolation over 459,899 person-days of observation, an incidence rate of 0.22 per 1000 person-days (95% confidence interval [CI] 0.18–0.27). The median time to progression was 44 days (interquartile range, 20–123), and the Kaplan–Meier cumulative incidence was 1.7% (95% CI 1.3–2.3) at 30 days, 3.3% (2.6–4.1) at 90 days and 4.0% (3.2–4.9) at 180 days. The respiratory tract (40/103, 38.8%) and urinary tract (30/103, 29.1%) were the common sources. KPC-type carbapenemase (adjusted hazard ratio [aHR] 3.74, 95% CI 1.64–8.54, P = 0.002), fluoroquinolone exposure (aHR 2.09, 95% CI 1.38–3.15, P < 0.001) and cephalosporin exposure (aHR 1.98, 95% CI 1.33–2.96, P < 0.001) were independently associated with progression. The incidence rate was 0.260 per 1000 person-days in KPC carriers against 0.065 in non-KPC carriers (rate ratio 4.00, 95% CI 1.75–9.12; log-rank P < 0.001). Clinical CPE isolation followed colonisation in 4.1% of carriers, with almost three-quarters of events inside 90 days. KPC-type carbapenemase, fluoroquinolone exposure, and cephalosporin exposure were independently associated with a higher risk of clinical isolation, supporting targeted surveillance and antimicrobial stewardship for KPC-carrying colonisers.