Intensive care unit-acquired rectal colonization and subsequent infections with carbapenem-resistant bacteria: a cross-sectional study.

Purpose: Nosocomial infections caused by carbapenem-resistant bacteria (CRB) present a worldwide threat. We examined the incidence and clinical outcomes of ICU-acquired gastrointestinal colonization with CRB detected through routine weekly surveillance of rectal swabs.

Methods: This retrospective study included adult patients admitted to the ICU between January 1, 2020 and December 31, 2022, whose rectal swab cultures yielded CRB colonization after at least 72 h of ICU admission.

Results: Of 4,673 eligible patients, 493 had at least one positive rectal swab culture for CRB (prevalence 10.5%) after a mean of 17.8 days from ICU admission. The most common CRB species was Klebsiella pneumoniae (41.8%), followed by Acinetobacter baumannii (32.3%), Pseudomonas aeruginosa (21.3%) and Escherichia coli (8.1%). Following colonization, 240 patients (48.7%) developed CRB infections after a mean of 11.4 days and 29.2 days from the first positive rectal culture and from ICU admission, respectively. The overall agreement between the baseline rectal and final cultures was 82.1%. CRB-infected patients had higher frequencies of burns at baseline (p < 0.001), carbapenem (p = 0.015) and colistin (p < 0.001) use during ICU stay, need for intubation (p = 0.002) and nasogastric tube (p = 0.021), prolonged ICU stay (p < 0.001), and mortality (p = 0.006).

Conclusion: Our findings showed that nearly one in every 10 ICU patients acquired CRB colonization despite preventive efforts, ending up with CRB infections in nearly half.