From the Guidelines
The best technique to collect a wound culture sample from an abscess is to first clean the abscess surface with sterile saline or antiseptic solution, then aspirate pus using a sterile needle and syringe after the abscess has been incised and drained, as recommended by the most recent guidelines 1. When collecting the sample, it is essential to obtain material from the deepest portion of the abscess cavity rather than from the surface or margins to ensure that the causative organisms are captured rather than surface contaminants. Some key points to consider when collecting a wound culture sample include:
- Avoid using topical antiseptics like povidone-iodine or chlorhexidine immediately before collection as they can inhibit bacterial growth in the culture 1.
- Transfer the aspirated material immediately into appropriate culture transport media, such as an anaerobic transport tube if anaerobic organisms are suspected.
- The sample should be sent to the laboratory promptly, ideally within 2 hours of collection, to maximize the chances of isolating the true pathogen and preserving both aerobic and anaerobic organisms. Proper specimen collection is crucial because inaccurate results can lead to inappropriate antibiotic therapy and treatment failure, ultimately affecting morbidity, mortality, and quality of life. The most recent and highest quality study 1 supports the use of tissue specimens for culture, which provides more accurate results than superficial swabs, and recommends collecting a soft tissue specimen after cleansing and debridement to avoid contamination.
From the Research
Wound Culture Sample Collection from Abscess
- The best technique to collect a wound culture sample from an abscess is not explicitly stated in the provided studies, but some studies suggest that a quantitative culture of wound tissue is the gold standard, while the swab method is an acceptable alternative option 2.
- The Levine technique is reported to be more reliable than the Z-technique to determine microbial load in the wound bed 2.
- There is no compelling evidence for routine cultures or empiric treatment with antibiotics in immunocompetent patients with no confounding risk factors 3.
- Assessment of infection does not significantly differ when culture results from swabs or biopsies are available, but there is substantial variability between individual experts 4.
- Cultures of tissue or blood in patients with cellulitis are usually positive in less than 40% of cases, regardless of the technique used, except for Hemophilus influenzae cellulitis in pediatric patients, where blood cultures are positive in more than two-thirds of cases 5.
- The goal of culturing abscesses is to identify the offending pathogen, and Gram stain, culture, and antibiotics are necessary in certain cases, such as immunocompromised patients or abscesses with specific characteristics 5.