Creation and validation of an extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-E) clinical risk scoring tool for select Enterobacterales in non-urinary isolates.

BACKGROUND

Infections caused by extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E) are increasing in the United States. Although many risk factor scoring tools exist, many are specific to bloodstream isolates and may not represent all patient populations. The purpose of this study was to create and validate an institution-specific scoring tool for select ESBL-E of non-urinary origin based on previously identified risk factors.

METHODS

This retrospective, case-control analysis included inpatient adults at an academic medical center from July 2021 through August 2023 with a documented ESBL-E or non-ESBL-E infection of non-urinary origin. Patients with ESBL-E isolates were matched in a 1:1 ratio to non-ESBL-E isolates by organism and specimen type. Points for each risk factor were assigned by dividing their respective regression coefficient by half of the smallest regression coefficient and rounding to the nearest integer (prior ESBL-E within the past 12 months: 6 points, urinary catheter: 3 points, central venous catheter: 2 points, cirrhosis: 2 points). Sensitivities, specificities, positive predictive values (PPV), and negative predictive values (NPV) were calculated for each score, and discriminatory power was assessed via the receiver operating characteristic (ROC)-area under the curve (AUC).

RESULTS

Of the 1139 identified cultures, 140 patients met the criteria for inclusion into the ESBL-E case arm, thus 140 patients with non-ESBL-E cultures were matched as controls. Baseline characteristics were relatively similar between the groups. A score of 0 was associated with low risk of ESBL-E (PPV 0.31, NPV 0.36), whereas scores between 2 and 5 were considered moderate risk (PPV 0.56, NPV 0.55), and scores ≥6 were associated with high risk (PPV 0.91, NPV 0.56). The ROC curve AUC was 0.705.

CONCLUSIONS

The majority of ESBL-E risk factor scoring tools are specific to isolates causing bloodstream infections. This institution-specific scoring tool may be used to tailor empiric antimicrobial regimens and decrease unnecessary exposure to carbapenems in non-ESBL-E infections of non-urinary origin.