Biofilms, Biomaterials, and Device-related Infections

The chapter “A History of Biomaterials” at the start of this book documents the development and design of indwelling materials for medical and dental purposes. The primary design criteria in the choice of materials were pragmatic and based on the necessary mechanical properties required to fashion a functional device. Orthopedic implants require strong materials for load bearing, articulating surfaces such as joints require durability and resistance to wear, stents and shunts require flexibility and patency, and sutures require a high tensile strength, yet must also be flexible enough for intricate manipulation. Indwelling devices, however, increase the risk of infection. Catheter-associated urinary tract infection (CAUTI), the most common health care-associated infection, accounted for nearly 40% of all nosocomial infections worldwide (Hooton et al., 2010). Prolonged catheter use is the primary risk factor for developing CAUTI (www. cdc.gov/hai/ca_uti/uti.html). Additionally, the incidence of prosthetic joint (hip and knee) infections (PJIs) and cardiovascular implantable device (CID) infections is increasing dramatically (Xu et al., 2017). CIDs include cardiovascular implantable electronic devices and ventricular assist devices, and implantation is increasing with an aging population. Although estimates vary with the types of devices, host factors and underlying diseases, infection rates generally increase with duration. While for some procedures, such as orthopedic joint arthroplasty, surgical-site infection rates are low (1%–2%) (Kurtz et al., 2012), the ever-growing number of patients undergoing these procedures translates to large numbers of infection each year. By 2020, estimates suggest that there will be 70,000 cases of infection in the United States alone (Kurtz et al., 2012). Infection of artificial joints is especially devastating, since oral or intravenous antibiotic therapy frequently fails to resolve the infection, leaving the only course of action to surgical debridement, or partial or total revision. The formation of microbial biofilms on these devices contributes significantly to device-related surgical site infections rendering these infections extremely difficult to treat with conventional topical or systemic antibiotic therapy.