Prevalence and Impact of Multidrug-Resistant Bacteria in Solid Cancer Patients with Bloodstream Infection: a 25-Year Trend Analysis.

The study aimed to describe the epidemiology of multidrug-resistant (MDR) bacteria among solid cancer (SC) patients with bloodstream infections (BSIs), evaluating inappropriate empiric antibiotic treatment (IEAT) use and mortality trends over a 25-year period. All BSI occurrences in adult SC patients at a university hospital were analyzed across five distinct five-year intervals. MDR bacteria were classified as extended-spectrum beta-lactamases (ESBL)-producing and/or Carbapenem-resistant Enterobacterales, non-fermenting Gram-negative bacilli (GNB) resistant to at least three antibiotic classes, methicillin-resistant Staphylococcus aureus (MRSA), and Vancomycin-resistant Enterococci. A multivariate regression model identified the risk factors for MDR BSI. Of 6,117 BSI episodes, Gram-negative bacilli (GNB) constituted 60.4% (3,695/6,117), being the most common are Escherichia coli with 26.8% (1,637/6,117), Klebsiella spp. with 12.4% (760/6,117), and Pseudomonas aeruginosa with 8.6% (525/6,117). MDR-GNB accounted for 644 episodes (84.8% of MDR or 644/759), predominantly ESBL-producing strains (71.1% or 540/759), which escalated significantly over time. IEAT was administered in 24.8% of episodes, mainly in MDR BSI, and was associated with higher mortality (22.9% vs. 14%, P < 0.001). Independent factors for MDR BSI were prior antibiotic use [odds ratio (OR) 2.93, confidence interval (CI) 2.34-3.67], BSI during antibiotic treatment (OR 1.46, CI 1.18-1.81), biliary (OR 1.84, CI 1.34-2.52) or urinary source (OR 1.86, CI 1.43-2.43), admission period (OR) 1.28, CI 1.18-1.38, and community-acquired infection (OR 0.57, CI 0.39-0.82). The study showed an increase in MDR-GNB among SC patients with BSI. A quarter received IEAT, which was linked to increased mortality. Improving risk assessment for MDR infections and the judicious prescription of empiric antibiotics are crucial for better outcomes.