High diversity of strain clonality and metallo-β-lactamases genes among carbapenem-resistant Enterobacterales in Taiwan.

Abstract

Purpose: This study aimed to investigate the genetic and clinical characteristics of carbapenem-resistant Enterobacterales (CRE) isolates carrying metallo-β-lactamases (MBLs) genes.

Methods: A total of 146 non-duplicated isolates of CRE were collected in 2022. Their ceftazidime/avibactam (CZA) susceptibilities were determined using the E test. The phenotypic identification of carbapenemases was conducted using the modified carbapenem inactivation method, followed by sequencing of the five common carbapenemase genes (bla_KPC, bla_NDM, bla_VIM, bla_IMP, and bla_OXA-48). Multilocus sequence typing of selected Klebsiella pneumoniae, Escherichia coli, and Enterobacter cloacae complex isolates were performed.

Results: Among the 146 CRE isolates, 52 (35.6%) were resistant to CZA. MBL-encoding genes were detected in 46 (31.5%) of all tested CRE isolates, with 82.6% (n = 38) of them exhibiting resistance to CZA. Fourteen isolates were resistant to CZA without any detected MBL genes. The most commonly identified MBL genes were bla_IMP (n = 20), followed by bla_NDM (n = 19), and bla_VIM (n = 5). In CZA-R, the most common definite antibiotic before the CZA E test was CZA (n = 18), followed by tigecycline (n = 13), and fluroquinolone (n = 10). The 14-day and 30-day mortality rates were 9.0% (n = 13) and 22.8% (n = 34), and were associated with intensive care unit admission at onset (P = 0.029 and P = 0.001, respectively). The sequence types of CRE isolates carrying MBLs were diverse without major clones.

Conclusion: The continuous emergence of MBL gene-encoding CRE with multiple clones has led to reduced CZA susceptibilities and worse outcomes.