Bloodstream Infections Caused by Gram-Negative Bacteria in Geriatric Patients: Epidemiology, Antimicrobial Resistance and The Factors Affecting Mortality

Bloodstream infections (BSIs) are an important cause of morbidity and mortality in geriatric patients. We retrospectively analyzed the cases of geriatric patients who developed BSIs due to gram-negative bacteria in order to evaluate the epidemiology, antimicrobial resistance, and the factors affecting mortality. The cases of 110 patients aged ≥ 65 years admitted to our hospital between January 1, 2017, and December 31, 2022 were assessed; 70 (63.6%) of the BSIs were healthcare-associated BSIs. The urinary system was the most common detectable source of infection at 43.6%. The most frequently isolated bacteria were Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae, in that order. Carbapenem resistance was detected in 17 patients (15.5%), and extended-spectrum beta-lactamase (ESBL) production from Enterobacterales family members was detected in 37 (51.4%) patients. Multivariate analysis revealed that (i) the probability of mortality in the patients with total bilirubin was increased by approx. sixfold and (ii) the likelihood of mortality for those with a Pitt bacteremia score (PBS) ≥ 4 points was approx. 17 times higher. PBS and simplified qPitt scores can help predict mortality and manage geriatric patients. There is a significant increase in mortality among patients with procalcitonin (PCT) levels at ≥ 2 nm/ml.