From the Guidelines
To order a wound culture properly, obtain a tissue specimen for culture by scraping with a sterile scalpel or dermal curette (curettage) or biopsy from the base of a debrided ulcer, as this method provides more accurate results than a superficial wound swab 1. When collecting a wound culture, it is essential to follow proper procedures to ensure accurate identification of causative organisms and appropriate antibiotic selection.
- First, cleanse the wound with sterile saline to remove surface contaminants, avoiding antiseptics which can inhibit bacterial growth.
- Then, obtain a tissue specimen for culture by scraping with a sterile scalpel or dermal curette (curettage) or biopsy from the base of a debrided ulcer, as recommended by the most recent guidelines 1.
- For deep wounds, aspirate any purulent material using a sterile needle and syringe.
- Label the specimen with patient information, wound location, current antibiotic therapy, and collection time.
- Transport the sample to the laboratory promptly in an appropriate transport medium to maintain organism viability.
- Complete the laboratory requisition form with relevant clinical information, including suspected pathogens, current antibiotics, and immunocompromised status. This procedure is crucial for minimizing contamination with normal skin flora, which could lead to misleading results and inappropriate treatment 1. It is also important to note that special anaerobic transport containers must be used for anaerobic organisms, as these bacteria die when exposed to oxygen 1.
From the Research
Proper Procedure for Ordering a Wound Culture
To order a wound culture, the following steps should be considered:
- The decision to perform a wound culture should be based on clinical suspicion of infection, as indiscriminate and routine wound cultures are not recommended 2.
- A culture is indicated to identify the causative organisms and to guide antibiotic therapy when clinical suspicion of an infection exists 2.
- The Levine technique is considered a reliable method for determining microbial load in the wound bed, and swab culture is an acceptable alternative option to quantitative culture of wound tissue 3.
- Classic signs of infection may not always be present, but culturing may be indicated when additional signs such as pain, necrotic tissue, prolonged or delayed healing, and wound bed deterioration occur 3.
When to Perform a Wound Culture
Consider performing a wound culture in the following situations:
- When there are clinical signs of infection, such as increased redness, swelling, or purulent discharge 2.
- When there are additional signs such as pain, necrotic tissue, prolonged or delayed healing, and wound bed deterioration 3.
- When the patient has a history of previous infections or antibiotic use 4.
Methods for Performing a Wound Culture
The following methods can be used to perform a wound culture:
- Swab culture: This is the most frequently employed method of confirming wound infection in the United States, but a standardized procedure is lacking 2.
- Quantitative culture of wound tissue: This is considered the gold standard to obtain a wound culture, but it may not always be practical or necessary 3.
- Levine technique: This is a reliable method for determining microbial load in the wound bed 3.