Dissemination of metallo-β-lactamases in gram-negative bacteria and impact on in-hospital mortality

a descriptive study in a university hospital in Northeastern Brazil

Abstract

Objective: to describe the epidemiological and microbiological profile and clinical outcomes of patients infected with Metallo-β-lactamases (MBL)-producing
or dual-carbapenemase gram-negative bacteria at Hospital Universitário Walter Cantídio (HUWC/UFC), Fortaleza-CE, in 2025. Methods: descriptive and retrospective study, approved by the Ethics Committee (protocol 6.717.757). Patients with positive cultures between January and December 2025 were included. Microbial identification and antimicrobial susceptibility testing were performed using the Vitek-2® System, with interpretation according to the
2025 BrCAST criteria. Data were collected via REDCap and analyzed using R (v4.4.1). Results: forty-three unique patients were identified, with 68 isolates distributed across ten bacterial species. Male predominance, with a median age of 56 years. Klebsiella pneumoniae accounted for more than half of the isolates. The ndm gene was the most prevalent, followed by imp. Samples were predominantly from blood and urine, originating from eight (8) hospital wards. The number of in-hospital deaths was 15. Conclusion: the findings demonstrate active and diverse presence of MBL-producing bacteria at HUWC, with significant mortality, reinforcing the need for systematic microbiological surveillance.