Trends in the Antimicrobial Resistance Pattern of Bacterial Gram-Negative Pathogens in Elderly Patients Admitted to the Intensive Care Unit

Antimicrobial resistance (AMR) remains a public health problem in European Union countries, and elderly patients represent a vulnerable category due to aging and its associated risk factors. In this research, we investigated the trend of the antimicrobial resistance pattern of Gram-negative pathogens isolated in samples collected from elderly patients (over 65 years) hospitalized in the intensive care unit (ICU) between 2022 and 2024. A total of 2510 samples, including blood, tracheal aspirate, sputum, urine, pus/wound swabs, exudates, intravascular catheters, cerebrospinal fluid, and sterile fluids, were collected from 1864 elderly patients. Almost two-thirds of clinical specimens were harvested from the respiratory tract. The most frequently reported pathogens from 3094 Gram-negative bacterial isolates were <i>Klebsiella</i> spp., <i>Acinetobacter</i> spp., and <i>Escherichia coli</i>. During the studied period, almost 40% of all the <i>Klebsiella</i> spp. strains were multidrug-resistant (MDR)/extensively drug-resistant (XDR), with a significant increase in the resistance to cephalosporins (<i>p</i> ≤ 0.05), fluoroquinolones (<i>p</i> ≤ 0.05), and carbapenems (imipenem-(<i>p</i> ≤ 0.05), ertapenem-<i>p</i> < 0.001). The proportion of carbapenem-non susceptible <i>Klebsiella</i> spp. rose from 24.41% in 2023 to 32.48% in 2024, <i>p</i> = 0.01. Two-thirds of <i>Acinetobacter</i> spp. isolates were MDR/XDR, and over 80% were carbapenem-non-susceptible in 2023-2024. The results draw attention to the need to quickly adopt measures to reduce the prevalence, limit the transmission of MDR/XDR pathogens, and improve therapeutic protocols in this age category.