Quantifying risk of disease due to extended-spectrum β-lactamase producing Enterobacteriaceae in patients who are colonized at ICU admission.

Background: The prevalence of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) has globally increased and spread to the community. No clinical score is available to select carriers in whom these organisms can be empirically targeted at ICU admission.

Methods: We prospectively assessed between 2009 and 2017 the prevalence of ESBL-PE infection in carriers at ICU admission. A logistic regression was used to determine independent risk factors associated with ESBL-PE infection, and to build a clinical risk score.

Results: Of the 8,061 admissions over the study 7-year period, 745 (9%) patients were ESBL-PE carriers at admission, of whom 395 had infections at ICU admission including 59 (15%) who had culture-proven ESBL-PE related infection. By multivariable analysis, age >60 years, cirrhosis, being on broad-spectrum antibiotics within the past three months, urinary or intra-abdominal source of infection, and the absence of chronic pulmonary disease, were the five independent factors associated with ESBL-PE infection in carriers. A clinical risk score ranging from 0 to 7 was built based on these variables, with an area under the receiver operating characteristic curve (ROC) of 0.82 (95% CI 0.78-0.86); p <0.001. The prevalence of ESBL-PE infection for clinical risk scores of 0-1, 2-3, 4-5, or 6-7 was 0%, 4%, 26%, and 49%, respectively. The negative predictive value when Mondor ESBL risk score is <4 was 97%.

Conclusion: ESBL-PE related infection was not common in carriers at ICU admission. A clinical risk score may spare ESBL-PE carriers with lower risk of ESBL-PE infection at ICU admission unnecessary empiric carbapenem therapy.