Mortality in infections caused by metallo-β-lactamase- versus serine carbapenemase-producing Enterobacterales: a systematic review and meta-analysis.
Fiorela G Mulellari, Shahd Mohammad, Luena Seferasi et al.
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In 30 seconds
This systematic review and meta-analysis examined whether mortality differs between hospitalized adults aged ≥16 years with infections caused by metallo-β-lactamase (MBL)- versus serine β-lactamase (SBL)-producing Enterobacterales. It included 17 observational studies (n = 2429). Pooled crude mortality showed no clear difference between groups (OR 0.77, 95% CI 0.57-1.03; I 2 = 29.6%). An exploratory synthesis of adjusted hazard ratios suggested a difference (aHR 0.67, 95% CI 0.48-0.92; I 2 = 5.6%), but was limited by residual confounding and differences in adjustment. Overall certainty of evidence was very low.
Key findings
- Across studies, pooled crude mortality did not clearly differ for MBL- versus SBL-producing infections (OR 0.77, 95% CI 0.57-1.03; I 2 = 29.6%).
- Exploratory pooling of adjusted hazard ratios suggested a mortality difference (aHR 0.67, 95% CI 0.48-0.92; I 2 = 5.6%), with important methodological caveats.
- Adjusted odds ratios were summarized descriptively because mortality timepoints, comparators, and adjustment methods differed.
Why it matters
These findings caution against using carbapenemase class alone to infer prognosis in hospitalized adults with CPE infection. The review highlights that outcomes may also reflect patient characteristics, infection severity, circulating clones, and access to timely active therapy. The very low certainty means the available evidence cannot establish a reliable mortality difference between MBL- and SBL-producing infections.
What to keep in mind
Evidence came from observational studies and was rated very low certainty. Adjusted estimates were limited by residual confounding, heterogeneous adjustment models, and derivation or inversion of some estimates; treatment reporting was also heterogeneous.