Epidemiology and outcomes associated with MBL-producing Enterobacterales: A systematic literature review

The increasing prevalence of infections due to metallo-β-lactamase (MBL)-producing Enterobacterales poses a serious concern given the limited treatment options available. This systematic literature review (SLR) describes the molecular epidemiology, geographical distribution, and clinical outcomes of such infections. Systematic searches of literature published between January 2013 and May 2023 were performed, and 39 studies with an MBL sample size of ≥25 isolates and ≥2 well-defined outcomes were eligible. Most of the studies were from Asia (21/39) followed by Europe (11/39) and evaluated more than two species (24/39). Overall, the percentage of MBL-producing isolates ranged from 6.8%-100.0%. Among 6620 MBL-producers, the majority were from Europe (3837/6620; 58.0%), followed by Asia (2079/6620; 31.4%). New Delhi MBL (NDM)-producers (5668/6620; 85.6%) were the most frequent across all regions, with NDM-1 as the common variant. The majority of IMP-producing isolates (586/592; 99.0%) came from Asia, while the majority of VIM-producing isolates were found in Europe (322/371; 86.8%). Studies focused on MBL-specific outcomes (n = 28) reported reduced susceptibility (<80.0%) to most antimicrobials except for colistin and tigecycline. Six studies reported significantly longer hospital and/or ICU stay due to MBL-Enterobacterales compared to other infection groups. Common mortality measures reported were overall mortality (18.8%-57.0%; 9 studies), in-hospital mortality (11.1%-55.3%; 6 studies), and 30-day mortality (0%-36.4%; 7 studies). Previous antibiotic use (9 studies) and hospital and/or ICU stay (8 studies) were common risk factors for colonization/infection and mortality. Reporting of MBL prevalence across regions will provide a better understanding of the infection burden and prevent further spread.