The primary objective of this study is to characterize the contemporary extremity wound “bioburden” at the time of definitive wound coverage/closure of severe extremity military and civilian wounds. We will analyze routine tissue samples collected as part of standard of care employing both standard tissue culture microbiology and modern polymerase chain reaction (PCR) technologies.
Secondary objectives of the study are to determine: (a) the correlation of the identified wound pathogens at the time of wound closure/coverage with subsequent deep wound infections; (b) the correlation of the PCR results with those obtained from standard hospital microbiology; and (c) the efficacy, if any, of antibiotics used in the care of the wound.
Infection remains the most common and significant complication following high energy fractures, with rates ranging from 25 – 40%. Up to 15% of recent combat casualties develop osteomyelitis.The large traumatic wounds are inoculated with environmental bacteria at the time of injury and are exposed to host and hospital flora colonization during the initial treatment course. In contrast to significant advances made in related extremity trauma care disciplines, the strategies that address the prevention of deep infection following severe open fracture wounds have remained constant for the past 20 years. Few surgeons sample the wound bioburden at the time of closure, typically related to the unreliable results from the routine microbiology at predicting subsequent failure due to infection. Evidence supports the initial administration of systemic antibiotics as effective in reducing the infection rate in open fracture care. Many patients with severe extremity wounds are multiple trauma patients, faced with recovery from head, chest and abdominal injuries associated with the extremity injury. These patients are at risk for the development of nosocomial infections and for infection with resistant pathogens. Prolonged or repeated systemic antibiotic exposure is avoided, if possible, in this cohort. The long term impact of systemic antibiotic therapy on severe extremity wounds is currently unknown and may be counter-productive. When antibiotics are administered, a directed therapy approach is preferred. Tissues in the zone of injury are often hypoperfused and the antibiotic concentration in the critical injured tissues is less than the desired therapeutic level. The wound bacteria and fungi can attach to soft tissues, bone or metal implants and initiate biofilm production. Biofilm colonies are increasingly recognized as the likely source of chronic and implant related infections. Traditional antibiotics are unable to penetrate the biofilm meaning multi-component therapies that prevent biofilm development are needed. Over the next decade, the treatment of the severe wound is expected to dramatically change. Local wound anti-microbial therapies employing bio-degradable micro or nanospheres, ceramics or chitosan sponges may likely replace systemic therapy. These local antibiotic treatments might be potentiated by combining them with biofilm disbursing agents (bismuth thiols).
Principal Investigator: Thomas Higgins
Department: Orthopedic Surgery