Biofilm growth on orthopedic implantable materials: static or dynamic condition what is the most appropriate methodological tools to study device-related infections?

Aim Study of biofilm growth under static and dynamic conditions to evaluate the most suitable orthopedic materials on the prevention of device-related infections. Method Biofilms of Staphylococcus epidermidis (ATCC 35984) icaA and icaD genes positive and Pseudomonas aeruginosa (DSM 939) were generated under static and dynamic conditions, adding the bacterial inocula on titanium, carbon, polycarbonate and carbon-peek coupons housed in flat bottom test tubes or in the CDC Biofilm Reactor (CBR) system respectively. Biofilm growth was evaluated by MTT assay after 48 hours. Results Results of dynamic model showed a better capacity of S.epidermidis to grow with a rotation between 120-60 rpm on each tested materials (Mann-Whitney test, p-value < 0,05) than P.aeruginosa. Titanium was thematerial on which the bacterial strains adhered less, whereas carbon and polycarbonate allowed greatest adherence of P.aeruginosa (Mann-Whitney test, p-value < 0,05). Results of static model showed that both species grew on each materials without distinction (Kruskal-Wallis test, p-value 0,95). S.epidermidis growth was better also under static condition. Conclusions the static model was not able to evaluate the different adhesion capacity of the strains to the materials, confirming the dynamic model is the most suitable tool for the study of orthopedic materials on the prevention of device-related infections. This research was funded by the University of Pisa, PRA 2017_18 Project