Antimicrobial Resistance Profiles of Multidrug-Resistant Pathogens in a Military Hospital: A Three-Year Study

The global rise of multidrug-resistant (MDR) microorganisms poses a significant threat to public health by limiting effective treatment options. This study aimed to assess the incidence, resistance profiles, and distribution of MDR organisms within the 424 General Military Training Hospital in Thessaloniki, Greece, over a three-year period (2021-2023). A total of 7,856 microbial isolates were collected, of which 131 were confirmed as MDR and analyzed further. Isolates were obtained from a variety of clinical specimens, including blood, urine, bronchial lavage, sputum, catheters, and wound secretions, originating from several hospital departments such as the ICU, emergency department, and general surgery. Microbial identification and antimicrobial susceptibility testing were conducted using the Vitek 2-Compact system (BioMérieux, Marcy-l'Étoile, France), following Clinical and Laboratory Standards Institute (CLSI) guidelines. <i>Klebsiella pneumoniae</i> was the most frequently isolated MDR pathogen, followed by <i>Acinetobacter baumannii</i> and <i>Pseudomonas aeruginosa</i>. Notably, <i>Klebsiella pneumoniae</i> demonstrated increasing resistance over time, especially against carbapenems and third-generation cephalosporins. <i>Acinetobacter baumannii</i> showed persistently high resistance, while <i>Pseudomonas aeruginosa</i> maintained a more moderate profile. Urine and blood were the most common sources of MDR isolates, with <i>Klebsiella pneumoniae</i> predominating. <i>Acinetobacter baumannii</i> was more often found in respiratory samples, whereas <i>Pseudomonas aeruginosa</i> appeared mostly in wound cultures. The ICU and emergency department were identified as key locations for MDR pathogen isolation. Although monthly variations were observed, no consistent seasonal trends were noted. These findings emphasize the urgent need for targeted antimicrobial stewardship, stricter infection control practices, and continuous surveillance to prevent further escalation of MDR infections in healthcare settings.