A bacterial wound culture is a test that detects and identifies bacteria that cause infections (pathogenic) in a wound. Any wound may become infected with a variety of bacteria. A culture helps to determine whether a wound has become infected, which type(s) of bacteria are causing the infection, and which antibiotic would best treat the infection and help heal the wound.
Wounds may be superficial breaks in the skin such as scrapes, cuts and scratches or may involve deeper tissues such as incisions, bites, punctures or burns. (Read the article on Wound and Skin Infections.) A culture is performed by collecting a sample of fluid, cells or tissue from the wound and placing it on or in appropriate nutrient media. The media encourages the growth of bacteria that may be present, allowing for further testing and identification.
Typically, only one kind of pathogenic bacteria is causing the infection in a wound. However, there may be several types of normal skin bacteria present in the culture. Separating the various types of bacteria and identifying the pathogenic bacteria requires one or more days to perform.
A Gram stain is usually performed to help determine the type of bacteria present and provide a rapid result to the healthcare practitioner. The shape and color (morphology and staining characteristics) also help determine what other tests may need to be performed to definitively identify the cause of infection.