Prevalence, Clinical Characteristics, and Mortality Impact of Metallo-β-Lactamase-Producing Enterobacter Cloacae Complex Infections: A Retrospective Cohort Study

Metallo-β-lactamase (MBL)-producing Enterobacter cloacae complex (ECC) is an emerging threat associated with limited treatment options and increased mortality. This study aimed to describe the clinical and molecular characteristics, risk factors, and outcomes of MBL-producing ECC infections in Taiwan. We conducted a retrospective cohort study at a tertiary hospital in central Taiwan from July 2022 to December 2023. Hospitalized patients with ECC infections were included. MBL production was determined using multiplex PCR for blaIMP-1, blaIMP-2, blaVIM, and blaNDM genes. We compared clinical characteristics, antibiotic susceptibility profiles, and outcomes between MBL-producing and non-MBL-producing ECC infections. Among 239 patients with ECC infections, 9.2% (22/239) were MBL-producing. blaNDM was the predominant MBL gene (72.7%, 16/22). MBL-producing ECC showed significantly lower antibiotic susceptibility compared to non-MBL-producing ECC, except for amikacin and tigecycline. Patients with MBL-producing ECC infections had higher rates of ICU admission (50.0% vs 11.1%, p<0.001), prolonged hospitalization exceeding four weeks (54.5% vs 29.5%, p=0.030), and 30-day all-cause mortality (22.7% vs 5.1%, adjusted HR 2.95, 95% CI: 1.02-8.52, p=0.035). MBL production was an independent risk factor for mortality in bloodstream infections. MBL-producing ECC infections are associated with high antibiotic resistance, increased healthcare resource utilization, and significantly higher mortality, particularly in bloodstream infections. The predominance of blaNDM among MBL genes aligns with recent regional trends. These findings underscore the urgent need for enhanced surveillance, rapid diagnostics, and targeted management strategies to address this emerging threat.