Assessing the feasibility of reusing oral nutritional supplements in a quaternary intensive care unit

Background Healthcare generates substantial carbon emissions and waste, and sustainability initiatives increasingly aim to reduce environmental impact without compromising care. In our Intensive Care Unit (ICU), unused oral nutritional supplements (ONS) are routinely discarded, contributing to financial and carbon waste. Reuse may offer benefits but must be balanced against infection prevention requirements. This study assessed microbiological contamination of ONS to inform feasibility of a safe reuse program. Methods In our ICU, three ONS products were sampled using standardised surface-swabbing. Twenty "ingoing" products entering patient rooms and twenty cleaned, unconsumed "outgoing" products leaving patient rooms were cultured for both total organisms and Enterobacterales. Values were calculated as colony forming units (CFU) per centimetre-squared (CFU/cm 2 ) and compared with food-surface contamination thresholds. Group differences were analysed using non-parametric statistical tests. Results Forty ONS items were sampled (20 ingoing, 20 outgoing). Outgoing products had significantly lower overall bacterial counts than ingoing products (median 0.27 CFU/cm 2 versus 0.00 CFU/cm 2 ; p < 0.001). Enterobacterales were uncommon at baseline – only detected on four (20%) products – and absent on all outgoing samples. There was no significant difference observed between the three different product types. Conclusions Cleaning unopened ONS after ICU room exposure resulted in significantly reduced bacterial burden, with no Enterobacterales detected, supporting the feasibility of safe reuse. These findings suggest that reusing unopened ONS could deliver meaningful financial and carbon savings while upholding infection prevention measures essential for patient safety.