Staphylococcus epidermidis biofilm growth in response to glucose: Implications for diabetic implantable device infections

Abstract

The association between high bacterial infection rates and diabetes mellitus (DM) has been well established, where DM specifically predisposes individuals to frequent and severe biofilm-associated implantable device infections (IDI). Diabetic hyperglycemia, or elevated blood sugar, is accepted to contribute to this phenomenon and thus has prompted questions regarding how biofilm development is enhanced in a glucose-rich environment. Staphylococcus epidermidis is the species responsible for most IDI, however, few studies have evaluated the effect of excess glucose on the biofilm formation of this bacterium and have not considered how low oxygen and pH, the physiologically relevant characteristics of IDI, may affect results. Here, S. epidermidis was grown in media containing 0, 20, 200, and 2000 mg/dL of glucose under aerobic and anaerobic conditions. Biofilm mass was quantified using the microtiter crystal violet assay and media pH was measured prior to and following biofilm growth. Glucose significantly increased biofilm mass only in anaerobic conditions at 2000 mg/dL, where increasing glucose concentrations corresponded with progressive media acidification. These data identify a relationship between oxygen condition, reduced pH, and enhanced S. epidermidis biofilm mass under excess glucose conditions, and thus provide insight into different variables that may contribute to the link between IDI and DM.