Carbapenemase production and in-hospital mortality associated with multidrug-resistant bacteria: a retrospective study conducted in Granada, Spain

Multidrug-resistant bacteria (MDR) represent a significant global health concern and vary in specific settings. Spain reported several annual deaths attributed to MDR bacteria, mainly carbapenemase-producing Enterobacterales. We aimed to characterise the incidence and temporal trends of MDR bacterial infections or colonisations reported within the province of Granada (data from five hospitals), and to investigate factors linked to clinical vulnerability. We conducted an observational retrospective study (2014–2022) using the Andalusian Epidemiological Surveillance System. We employed descriptive, bivariate analyses and geographical mapping. Multivariable logistic regression models were adjusted to identify factors associated with (1) carbapenemase-production and (2) in-hospital mortality. We included 1482 patients. The main microorganisms identified were <i>Klebsiella spp.</i>, <i>Escherichia spp</i>. and <i>Acinetobacter baumannii</i>. Carbapenemases were detected in 23% of cases, and were associated with higher in-hospital mortality rates (OR: 1.92; 95% confidence interval (95% CI): 1.31–2.81) and male sex (OR: 1.50; 95% CI: 1.01–2.23). The overall in-hospital mortality rate was estimated at 18.1%. Infections caused by <i>A. baumannii</i> (OR: 2.11; 95% CI: 1.41–3.13) or carbapenemase-producing <i>Klebsiella pneumoniae</i> (OR: 2.11; 95% CI: 1.28–3.45) were associated with increased mortality. These findings contribute to our understanding of the characteristics associated with carbapenemase-producing and early mortality resulting from MDR bacteria. This study offers insights into the factors associated with clinical vulnerability, which may improve future preventive measures.