Active surveillance of multidrug-resistant organism colonization in a tertiary hospital in Northern Greece.

Multidrug-resistant organisms (MDROs) pose a growing threat in healthcare settings. Timely detection through active surveillance is essential for infection prevention and antimicrobial stewardship. This study investigated the prevalence and microbiological profile of MDRO colonization among hospitalized patients at AHEPA University Hospital in Thessaloniki, Greece. A prospective surveillance study was conducted from October 2024 to January 2025 across multiple hospital wards. Screening swabs from the rectum, groin, and nares were obtained upon admission or during hospitalization. Microbiological analysis targeted key MDROs, including Klebsiella pneumoniae, Pseudomonas aeruginosa, vancomycin-resistant enterococci (VRE), Candida auris, and methicillin-resistant Staphylococcus aureus (MRSA). Among 1206 patients screened, 308 (25.5%) tested positive for at least one MDRO. Rectal swabs yielded the highest detection rates, predominantly identifying K. pneumoniae and VRE. Candida auris was most frequently isolated from groin swabs, while nasal swabs rarely detected MDROs. Internal medicine wards exhibited the highest colonization burden. Contact tracing and prolonged hospitalization were the most common indications for screening. This study highlights the high prevalence and diverse spectrum of MDRO colonization in a Greek tertiary hospital. Targeted screening- especially of rectal and groin sites-facilitates early detection and effective infection control. Continued surveillance is essential to mitigate MDRO transmission.