From the Guidelines
When aspirating an abscess for culture, I recommend sending the specimen for aerobic and anaerobic culture, as well as Gram stain, as these are the most critical tests for identifying the causative organisms and guiding appropriate antibiotic therapy. According to the 2012 Infectious Diseases Society of America clinical practice guideline for the diagnosis and treatment of diabetic foot infections 1, obtaining an appropriate specimen for culture from almost all infected wounds is crucial. The guideline suggests cleansing and debriding the wound before obtaining the specimen, and then aspirating any purulent secretions using a sterile needle and syringe.
- Key laboratory tests for abscess culture include:
- Aerobic and anaerobic culture to identify the causative bacteria
- Gram stain to provide rapid information on the type of bacteria present
- The specimen should be collected using sterile technique and transported promptly to the laboratory in appropriate containers, such as aerobic and anaerobic transport media, as recommended by the guideline 1.
- It is essential to collect the specimen correctly to avoid contamination with normal skin flora and to ensure accurate culture results, which will guide targeted antibiotic therapy and improve clinical outcomes, as emphasized by the guideline 1.
From the Research
Recommended Labs for Aspirating Abscess for Culture
When aspirating an abscess for culture, the following labs are recommended:
- Aerobic culture: This is the most common type of culture and is recommended for all patients with abscesses 2
- Gram stain: This is a reliable indicator of sterile abscesses, abscesses in pure culture, and those in mixed anaerobic culture 3
- Blood culture: This is recommended for patients with immunocompromise, clinical suspicion of penetrating inoculation, or failed primary treatment 2
Special Considerations
- Anaerobic culture: This should not be routinely performed during the initial evaluation of patients with hematogenous musculoskeletal infection, but should be considered for patients with immunocompromise, clinical suspicion of penetrating inoculation, or failed primary treatment 2
- Fungal culture: This should not be routinely performed during the initial evaluation of patients with hematogenous musculoskeletal infection, but should be considered for patients with immunocompromise, clinical suspicion of penetrating inoculation, or failed primary treatment 2
- Acid-fast bacteria (AFB) culture: This should not be routinely performed during the initial evaluation of patients with hematogenous musculoskeletal infection, but should be considered for patients with immunocompromise, clinical suspicion of penetrating inoculation, or failed primary treatment 2
Specimen Collection and Transportation
- Aspirates of liquid specimen or tissue are always preferred to swabs 4
- Proper collection and transportation of specimens are crucial to avoid contamination by normal flora 4
- Unacceptable or inappropriate specimens, such as coughed sputum, throat swabs, feces, gastric aspirates, voided urine, and vaginal swabs, should not be used for culture 4