Abstract
<title>Abstract</title> <p> Background Integrating clinical surveillance with environmental cultures and healthcare-worker (HCW) hand sampling may help target infection prevention and control (IPC) action, but environmental or hand recovery alone does not establish transmission. We assessed unit-level IPC priorities in a Mongolian tertiary hospital and contextualised the institutional profile using national surveillance. Methods We combined a retrospective analysis of anonymised, IPC-reviewed, laboratory-positive healthcare-associated infection (HAI) records from 28 December 2022 to 31 December 2025 with a cross-sectional survey conducted in six units from 16 June to 3 July 2025. The survey sampled 131 high-touch surfaces, nine field-negative controls, and 68 HCW hand imprints. Cross-sectional isolates underwent MALDI-TOF mass spectrometry identification and VITEK 2 susceptibility testing. Monthly phenotype-confirmed MDRO-positive HAI records were analysed by negative-binomial regression with patient-days as an offset. Results Across 43,922 admissions and 275,922 patient-days, 2,458 HAIs were recorded (8.91 per 1,000 patient-days). Of 1,819 IPC-classified MDRO-positive HAI cases, 91.6% occurred in four service categories. Among 1,999 organisms recovered from these records, MRSA (32.3%) and ESBL-producing <italic>Escherichia coli</italic> (23.4%) predominated; <italic>Acinetobacter baumannii</italic> was most frequent in intensive care. After exclusion of six data-incomplete 2023 months, the temporal model did not provide evidence of an increase (incidence-rate ratio per year 1.08, 95% confidence interval 0.98–1.18; p = 0.11). Twenty-two of 131 surfaces (16.8%) were MDRO-positive, and 23 of 68 HCW hand imprints (33.8%) were MRSA-positive. Surgery Unit I and the intensive care unit were ranked top priority, and the Stroke Unit high priority. Conclusions Integrated surveillance identified a small number of units where clinical burden overlapped with environmental-surface and HCW-hand contamination. These findings support risk-stratified IPC and antimicrobial stewardship while remaining insufficient to infer directional transmission or clonal linkage. </p>