Comparison of two models of biofilm formation on reusable stainless steel medical device material.

BACKGROUND: Reusable medical devices require reprocessing before subsequent patient use. Inadequate reprocessing can create suitable conditions for contaminating microbes to form biofilm. Despite this threat, there is a lack of guidance for medical device manufacturers to make biofilm assessment on their device labelling and instructions for use. Currently, there are no US Food and Drug Administration-recognized standardized models for biofilm formation on medical devices or device materials.

AIM: To assess established standard methods for their suitability to be used as validation tools for medical device manufacturers and regulatory agencies.

METHODS: Pseudomonas aeruginosa biofilms were grown using a drip flow reactor and a CDC biofilm reactor (CDC-BR) biofilm reactor on stainless steel coupons as a medical device material surrogate surface. Growth duration, extraction procedure, and extraction medium were optimized within the parameters of the experiments. Suitability of the models was determined by the comparison of colony-forming units (cfu), protein concentration, and total organic carbon.

FINDINGS: Data revealed that both the models developed similar levels of biofilm as quantified by cfu, despite different shear stress conditions. The results showed that protein and total organic carbon are potential analytes to quantify the biofilm biomass under the conditions tested. Additionally, results of each assay display low variability across multiple biofilm replicates.

CONCLUSION: Both models develop reproducible biofilm with a similar level of cfu but different levels of total organic carbon and protein. Our findings indicate that the CDC biofilm reactor and drip flow reactor provide reliable platforms for studying biofilm growth on medical device materials.