Prevention of microbiological contamination of drugs during their preparation for anaesthesia in the operating theatre: the Non-Touch trial

BACKGROUND: Aseptic techniques for preparing and administering injectable medicines remain under-studied, yet poor handling contributes substantially to healthcare-associated infections. Lipid-based formulations such as propofol pose an especially high risk of microbial contamination. The aseptic Non-Touch syringe preparation method may mitigate this risk but has not yet been evaluated. AIM: This study aimed to develop and assess a procedure to reduce contamination of drugs in syringes in operating theatres and intensive care units. METHODS: We evaluated the aseptic Non-Touch method across 950 syringes in both preclinical and clinical settings. First, 450 syringes underwent membrane filtration and bacterial culture; 50 prefilled 0.9% sodium chloride syringes served as negative controls. A subset of 150 syringes was further tested using Bactec blood culture analytics. In a subsequent clinical experiment, 300 preservative-free propofol syringes were prepared by specialist anaesthesiology nurses, with holding times of 1, 2, and 6 h prior to culture. FINDINGS: In preclinical trials, the Non-Touch method yielded a contamination rate of 0.67% (3/450) by culture and 2.7% (4/150) by Bactec (odds ratio: 4.1; adapted 95% confidence interval: 0.67-22.34); all negative controls remained sterile. In clinical experiments, two out of 300 propofol preparations (0.67%) were contaminated. Extending the interval between preparation and culture up to 6 h had no effect on contamination rates. CONCLUSION: The Non-Touch method demonstrated consistently low bacterial contamination (<1%) in both laboratory and clinical environments. Moreover, propofol syringe sterility was maintained for ≥6 h post preparation. These findings support further evaluation of Non-Touch as a practical strategy to enhance injection safety in routine anaesthetic and critical care settings.