J Appl Microbiol. 2026 Jul 17:lxag180. doi: 10.1093/jambio/lxag180. Online ahead of print.
ABSTRACT
AIMS: To develop a user-friendly and portable reference material (RM) for onsite validation of medical sterilization equipment, addressing the limitations of conventional biological indicators that require specialized laboratory facilities.
METHODS AND RESULTS: A lyophilized microsphere-based RM containing Bacillus atrophaeus spores was developed by optimizing lyoprotectant formulation. The RM demonstrated excellent homogeneity (F statistic < F critical) and satisfactory stability over 14 days at 4°C and 25°C, rigorously according to ISO 33405: 2024 standard method. When applied to validate UV sterilization devices by quantifying viable spore reduction, it further provided precise and reliable log reduction value measurements. The simple reconstitute-and-culture procedure enabled non-specialists to perform onsite checks. For instance, in UV validation, optimal conditions (e.g., ≥3-log reduction within 30 min at a distance of 150 cm) were easily determined using this RM. Preliminary assessments also confirmed its applicability for ozone and ethylene oxide sterilizers.
CONCLUSIONS: This study presents the first preparation of a convenient, lyophilized spore RM that fulfills ISO 33405: 2024 criteria. Its successful application in validating multiple sterilization modalities demonstrates significant potential for routine quality control and compliance testing in healthcare settings, particularly where advanced laboratory facilities are unavailable.
PMID:42467903 | DOI:10.1093/jambio/lxag180
