Wet Environmental Surveillance of Antimicrobial Resistance Genes in High-Risk Hospital Units

Background/Objectives: Hospital water and wastewater environments are potential reservoirs for antimicrobial resistance genes (ARGs), particularly in high-risk clinical units. This study examined site-specific ARG DNA detection patterns in wet and waste-associated sites of a haematology ward and an intensive care unit (ICU) to identify environmental hotspots that may inform targeted infection prevention and control (IPC) interventions. Methods: A descriptive point-prevalence environmental study was conducted in May 2025 in a tertiary acute-care hospital. Samples were collected after routine cleaning and during usual clinical activity. Real-time PCR assays were used to detect bla_TEM, bla_SHV, bla_CTX-M, bla_OXA-48-like, bla_VIM, bla_NDM, bla_IMP, bla_KPC, and mcr-1. Analytical summaries included samples meeting predefined quality-control criteria. Ct signals were categorised descriptively; Ct values ≤ 40 were considered positive, with Ct values 36-40 classified as very low molecular signals, whereas Ct values > 40 were considered negative. Results: The analytical dataset comprised 60 samples: 31 from haematology and 29 from ICU. At least one included ARG signal was detected in 40/60 samples (66.7%), including 23/31 haematology samples (74.2%) and 17/29 ICU samples (58.6%), bla_TEM (51.7%) and bla_SHV (43.3%) were most frequent. Sink drains showed the broadest multi-gene profiles, especially combinations of ESBL- and carbapenemase-associated genes. Haematology showed broader carbapenemase-associated diversity, whereas ICU detections clustered in patient-room sink drains and sluice-room wastewater infrastructure. Conclusions: ARG DNA signals were unevenly distributed, with sink drains representing most frequently positive sampling sites for multi-gene detection. This molecular, single-timepoint environmental study does not demonstrate viable organisms, colonisation, or transmission; however, point-prevalence environmental assessments may identify wet and wastewater-associated hotspots that can inform targeted IPC interventions against the spread of multidrug-resistant microorganisms.