Clinical Outcomes and Treatment Strategies in Patients With Non-Carbapenemase-producing Carbapenem-Resistant Versus Carbapenem-Susceptible Enterobacterales Infections

Background: Carbapenem-resistant Enterobacterales (CRE) are difficult to treat and can cause significant morbidity and mortality, however most data reflect carbapenemase-producing infections. Objective: Our objective was to evaluate clinical outcomes of non-carbapenemase-producing CRE (nCP-CRE) compared with carbapenem-susceptible Enterobacterales (CSE) infections. Methods: This was a retrospective, multicenter, observational study (January 1, 2018 to December 31, 2020). The primary outcome was clinical success at 30 days with secondary outcomes, including clinical success at 90 days, clinical success based on treatment for nCP-CRE, persistent bacteremia, intensive care unit (ICU) admission, length of stay, and rate of Clostridioides difficile or multidrug resistant infections. Results: The final analysis included 211 patients: 142 (67%) with CSE and 69 (33%) with nCP-CRE infections. Prior carbapenem exposure was more common with nCP-CRE (15% vs 4%, P = 0.01). Clinical success at 30 days was similar between groups (77% vs 74%, P = 0.73). There were no differences in secondary outcomes. There was an overall low use of carbapenems (empiric 6%, definitive 7%). Most nCP-CRE infections were treated with a monotherapy carbapenem-sparing regimen (empiric 88%, definitive 90%). Limitations include the retrospective design and the high rate of urinary infections. Conclusion and Relevance: Our study found no difference in clinical outcomes between nCP-CRE and CSE infections. Application of this study with future studies would help in determining optimal regimens for these infections.