Nationwide Burden of Metallo-β-Lactamase Genes in Brazilian Clinical Klebsiella pneumoniae Isolates: A Systematic Review and Meta-Analysis.

Background: Class B carbapenemases confer high-level resistance to carbapenems in Klebsiella pneumoniae. In Brazil, data on the national burden and geographic distribution of these genes among clinical K. pneumoniae isolates are sporadic. We performed a systematic review and meta-analysis to estimate the prevalence of MβL genes in Brazilian clinical K. pneumoniae. Methods: We searched SciELO, PubMed, ScienceDirect and LILACS for original studies published between 2006 and 2024 reporting molecular detection of MβL in clinical K. pneumoniae isolates from Brazil. Articles were independently screened, along with the extracted data and appraised study quality using Joanna Briggs Institute checklists. A random-effects meta-analysis estimated the pooled prevalence of MβL producers and assessed heterogeneity and publication bias. Results: Fifteen studies including 3.533 clinical K. pneumoniae isolates met inclusion criteria. Overall, 402 isolates (11.4%) harbored MβL genes, yielding a pooled prevalence of 44.6%. Subgroup analysis demonstrated highest prevalence in the Southeast. bla_NDM was the dominant variant (present in 14/15 studies), with bla_VIM and bla_IMP rarely detected. Meta-regression revealed an inverse association between sample size and reported prevalence, and no significant publication bias was observed. Conclusions: MβLs, particularly NDM, are widespread in Brazilian clinical K. pneumoniae but show marked regional heterogeneity driven by differences in study design, laboratory capacity, and outbreak dynamics. Urgent expansion of standardized and multicenter molecular surveillance, including allele-specific detection, and strengthened laboratory infrastructure are needed and may inform targeted infection-control and antimicrobial-stewardship interventions.