In Vitro Investigation to Determine if Vitamin E-Blended UHMWPE Has the Ability to Prevent Bacterial Attachment and Biofilm Formation

Introduction:

Periprosthetic infections that accompany the use of total joint replacement devices cause unwanted and catastrophic outcomes for patients and clinicians. These infections become particularly problematic in the event that bacterial biofilms form on an implant surface. Previous reports have suggested that the addition of Vitamin E to ultra-high-molecular-weight polyethylene (UHMWPE) may prevent the adhesion of bacteria to its surface and thus reduce the risk of biofilm formation and subsequent infection.^1–3 In this study, Vitamin E was blended with two types of UHMWPE material. It was hypothesized that the Vitamin E blended UHMWPE would resist the adhesion and formation of clinically relevant methicillin-resistant Staphylococcus aureus (MRSA) biofilms.

Methods and Materials:

Five sample types were manufactured, machined and sterilized (Table 1). To determine if MRSA biofilms would be reduced or prevented on the surface of the Vitamin E (VE) loaded samples (HXL VE 150 kGy and HXL VE 75 kGy) in comparison to the other three clinically relevant material types, each was tested for biofilm formation using a flow cell system.⁴

Direct Bacterial Quantification – An n = 7 samples of each material type were placed individually into a chamber of the flow cell. A solution of 10% modified brain heart infusion (BHI) broth containing 10⁵ MRSA cells/mL was flowed through each chamber. Using previously established protocols,^4–7 after 48 hours of growth, each sample was removed, and the number of colony forming units (CFU) determined using a 10-fold dilution series.

SEM Imaging – Using the same protocol as above, after the 48-hour incubation period, an n = 7 of each material type were fixed in 2.5% glutaraldehyde, dehydrated in ascending concentrations of ethanol, coated with carbon and imaged using scanning electron microscopy (SEM).

Results:

Results indicated that the Vitamin E blended materials did not resist the attachment/formation of MRSA biofilms to any greater degree than the other three material types. All materials had greater than 10⁷ CFU/cm² (Figure 1). SEM images corroborated with the quantification data (Figure 2).

Discussion:

In contrast to previously published results,^1–3 these data indicated that Vitamin E blended UHMWPE may not have the ability to prevent biofilm formation of a clinical MRSA isolate from occurring.