What type of culture is ordered for a wound?

Appropriate Wound Culture Collection Techniques

For infected wounds, the preferred collection methods in order of preference are: deep tissue biopsy, tissue curettage, or needle aspiration, with swab cultures using the Levine technique being an acceptable alternative when other methods are not feasible. 1

Proper Wound Culture Collection Protocol

When to Culture

• Cultures should only be collected from clinically infected wounds 2, 1
• Culturing clinically uninfected lesions is unnecessary unless done as part of infection control surveillance 2
• Cultures should be obtained prior to starting antibiotics when possible 1
• Blood cultures should be performed for patients with severe infections, especially if systemically ill 2

Preferred Collection Methods (in order of preference)

1. Deep tissue biopsy - gold standard for wound bioburden identification 1
2. Tissue curettage - scraping with a sterile dermal curette or scalpel blade 2
3. Needle aspiration - useful for purulent collections or areas of cellulitis 2
4. Swab using Levine technique - acceptable alternative when other methods aren't feasible 1

Proper Collection Technique

1. Cleanse and debride the wound before obtaining specimens 2, 1
   • Remove necrotic tissue and callus
   • Clean with sterile saline
2. For open wounds, obtain tissue specimens from the debrided base 2
3. Avoid swabbing undebrided ulcers or wound drainage 2
4. If swabbing is the only option:
   • Use a swab designed for both aerobic and anaerobic organisms 2
   • Apply the Levine technique (press swab into wound bed with rotation) 1
5. Clearly identify samples with specimen type and anatomic location 2
6. Promptly send specimens to the laboratory in appropriate sterile containers or transport media 2, 1
   • For anaerobic specimens, use anaerobic transport tubes with at least 0.5g of tissue 1

Common Pitfalls to Avoid

• Inappropriate culturing: Culturing uninfected wounds leads to unnecessary antibiotic use 1
• Poor specimen collection: Swabbing surface exudate rather than viable tissue may miss deep tissue pathogens 2
• Delayed transport: Specimens should be transported promptly to preserve organism viability 2, 1
• Inadequate debridement: Failure to clean and debride before collection can lead to misleading results 2, 1
• Missing anaerobes: Failing to use appropriate anaerobic collection methods will miss potentially important pathogens 1

Clinical Considerations

• Recent evidence suggests properly performed swab cultures and tissue biopsies yield similar results for common wound pathogens 3
• Swabs with vacuum transport containers may offer advantages in recovering anaerobes 4
• For diabetic foot infections, tissue specimens are strongly preferred over swab cultures 2
• Culture results should guide antibiotic selection and narrowing of therapy once available 1

By following these evidence-based guidelines for wound culture collection, clinicians can obtain accurate microbiological data to guide appropriate antimicrobial therapy, improving patient outcomes while minimizing unnecessary antibiotic use.