Rates of carbapenem resistant Enterobacterales (CRE)-related infections in the United States have continued to rise, leading to significant morbidity and mortality. Klebsiella pneumoniae carbapenemases (KPC) have been the most common carbapenemase in the United States; over time, however, a shift has occurred in some regions.

A multicenter, retrospective observational study was performed across a large-scale healthcare system of 33 acute care hospitals in the southwestern United States, primarily Arizona. Patients were included if they were ≥ 18 years old with resistance to at least one carbapenem from January 1st, 2023 to July 31st, 2023.

Among 169 included patients, the most common CRE species was Klebsiella pneumoniae (82 %) with the most common identified carbapenemase being metallo beta lactamase (MBL) (76 %), the majority of which were New Delhi metallo-beta-lactamases (NDMs). Multivariable logistic regression was performed to determine risk factors for treatment failure regarding CRE infections. This model found renal replacement therapy [OR 2.44 (95 % CI 1.04–5.71)], prior hospitalization within 90 days of index culture [OR 2.69 (95 % CI 1.12–6.47), and admission to the ICU [OR 5.55 (95 % CI 2.58–11.93)] to be statistically significant risk factors for treatment failure.

Our study highlights the alarming rise of NDM-producing CRE’s in the southwestern US, primarily Arizona, along with the importance of closely assessing patient risk factors in view of deciding on appropriate empiric therapy.