A Systematic Review and Meta-Analysis of the Risk of Mortality Associated with Methicillin-Resistant Staphylococcus aureus Clones.

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most pervasive pathogens, accounting for more deaths annually than some major infectious diseases. Its clinical significance lies not only in the ever-expansion of its antimicrobial resistance spectrum, but also its evolving clonal structure. In this systematic review and meta-analysis, we aimed to quantify mortality associated with MRSA clones and evaluate the contribution of specific molecular features to outcome variation.

Methods: We searched PubMed, Scopus, Web of Science, and Google Scholar for studies reporting mortality among patients with MRSA infection and associated molecular typing data, including clonal complex, sequence type and SCCmec type. Results were presented in thematic narratives, tables and figures. A random-effects meta-analysis was performed to estimate pooled mortality and prevalence proportions.

Results: Twenty-seven included studies reported on MRSA isolates from 12 different countries. The overall pooled mortality was 22.47% (95% CI: 17.31-28.07), with the highest mortality observed in Europe. Among MRSA clonal complexes, the highest mortality was observed among CC5 (50.75%), followed by CC8 (37.56%). Although ST72 (66.16%) was the most prevalent sequence type, the highest mortality rates were observed in ST764 (38.74%) and ST1 (38.72%). SCCmec type IV (36.95%) was dominant but had a lower mortality rate (18.71%) compared to types II (39.09%) and III (27.52%).

Conclusions: The clear dominance and lethality of specific lineages affirm the clinical utility of molecular diagnostics in guiding treatment and predicting outcomes. These insights call for an expansion of MRSA typing programs in hospital laboratories and national surveillance systems.