Predictive performance of weekly rectal surveillance cultures and extra-rectal colonization for carbapenem-resistant Enterobacterales infections in a resource-limited ICU with KPC and NDM co-circulation

BACKGROUND Carbapenem-resistant Enterobacterales (CRE) cause hard-to-treat infections. Rectal surveillance is widely used to detect carriers, but its predictive value where different carbapenemases co-circulate is unclear. We assessed whether CRE rectal and extra-rectal colonization predicts subsequent infection in an intensive care unit with concurrent KPC and NDM circulation.

METHODS We performed a retrospective observational study in a 60-bed adult intensive care unit in Buenos Aires, Argentina, from July 2016 to September 2019. All patients underwent weekly rectal surveillance, and extra rectal samples were taken when clinically indicated. Following up lasted 90 days from the first positive culture or from admission for non-carriers. Outcomes were any CRE infection and bacteremia. We estimated predictive values and fitted multivariable logistic regression models.

RESULTS We included 495 patients, median age 66 years, 58% male. Of them, 66% had rectal colonization and 8% had extrarectal colonization. CRE rectal carriage showed low PPV for any infection, about 10%, with high NPV near 94%, and it was not independently associated with infection (aOR 1.9 [0.9-4.4], p=0.1). CRE extra-rectal colonization was an independent predictor of any CRE infection (aOR 3.4 [1.4-7.9] p<0.01) and bacteremia (aOR 3.3 [1.3-8.9] p<0.05), with specificity >93% but sensitivity ≈ 20%.

CONCLUSIONS In this mixed KPC and NDM CRE setting, weekly rectal surveillance was not a predictor of later infection, while extra rectal colonization retained independent predictive value for overall infection and for bacteremia.