When and How to Perform Cultures on Chronic Wounds?

Purpose: The purpose of this Evidence-Based Report Card was to examine current best evidence related to when and how to perform cultures on chronic wounds to guide clinicians in determining the appropriate treatment.
Question: (1) When should cultures be performed on chronic wounds? and (2) What is the best method or technique to perform a culture on a chronic wound?
Search Strategy: A search of the literature was performed, resulting in 45 publications relevant to the topic. Following a review of titles and abstracts, 7 studies were identified that met inclusion criteria. Key search terms used were "chronic wound," "chronic infected wound," "wound culture," "specimen collection," and "wound swab." Strength of the evidence was rated based on the methodology from Essential Evidence Plus: Levels of Evidence and Oxford Center for Evidence-Based Medicine, adapted by Gray and colleagues.
Findings: Seven studies were identified as pertinent to the topic on wound culture and meeting inclusion criteria. The study designs included 1 randomized controlled trial, 1 quasi-experimental comparative study, 1 systematic review, 1 scoping literature review, 1 integrative literature review, and 2 professional organization expert panel reviews (consensus statement and position statement). Of the 7 studies, 3 studies suggest that 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. Four studies report that a quantitative culture of wound tissue is the gold standard to obtain a wound culture, but the swab method is an acceptable alternative option. Two articles demonstrate the Levine technique is more reliable than the Z-technique to determine microbial load in the wound bed. The strength of the evidence was identified as 2 level A studies, 1 level B study, and 4 level C studies. Using Johns Hopkins methodology, the quality of the studies was deemed either high quality or good quality.
Conclusion/recommendation: Evidence indicates that identification of potential chronic wound infection should be considered early using clinical signs such as pain, necrotic tissue, delayed healing, and wound deterioration (in addition to classic signs of infection) to determine the need for collecting a culture (Strength of Recommendation Taxonomy [SORT] level 2); and when a culture is deemed necessary, swab culture using the Levine method is a clinically practical alternative if performed correctly (SORT level 1).