Management of Diabetic Foot Ulcers

Preparation and Technique for Obtaining Cultures

The Infectious Diseases Society of America recommends cleaning and debriding the wound before obtaining any sample to eliminate superficial contaminants and colonizers 1, 2, 3
Surgical debridement of necrotic and devitalized tissue is essential before taking a culture, as this is crucial for identifying the true pathogens 1, 2, 3
Never take cultures without first cleaning or debriding the wound, as this results in contamination with colonizing organisms 1, 2, 3
Obtain tissue through curettage by scraping the base of the debrided ulcer with a sterile dermal curette or scalpel 1, 2, 3
Alternatively, perform a biopsy of the debrided ulcer bed to obtain deep tissue 1, 2, 3
Aspirate any purulent secretion present using sterile needle and syringe 1, 2, 3
Avoid the use of swabs on the wound or wound drainage, as they provide less accurate results 1, 2, 3

Evaluate the presence of osteomyelitis through probe-to-bone test, plain radiographs, and inflammatory markers (ESR, CRP, or procalcitonina) 4, 5
If osteomyelitis is suspected, obtain bone cultures instead of just soft tissue, as these are more accurate for guiding therapy 4, 5
Bone cultures should be obtained intraoperatively during surgical debridement or percutaneously if no immediate surgery is planned 4, 5
Consider magnetic resonance imaging if the diagnosis of osteomyelitis remains doubtful after initial studies 4, 5

Send samples immediately in a sterile container or appropriate transport medium 1, 2, 3
Request aerobic and anaerobic cultures of all samples 1, 2, 3
Request Gram stain if possible for initial guidance 1, 2, 3
Use conventional microbiological techniques as the first line for pathogen identification, not molecular techniques initially 4, 5

Obtain cultures BEFORE starting antibiotics whenever possible, especially when multiresistant organisms are suspected 1, 2, 3
In moderate to severe infections (such as Wagner IV), cultures are mandatory to guide definitive therapy 6

Do not use swabs on non-debrided wounds - this only identifies colonizers, not true pathogens 1, 2, 3
Do not culture clinically non-infected lesions unless for specific epidemiological purposes 1, 2, 3
Do not obtain superficial cultures when osteomyelitis is suspected - bone culture is needed 4, 5

Expect polymicrobial infections in chronic or previously antibiotic-treated ulcers 1, 2, 3
Consider empirical coverage for MRSA while awaiting culture results, especially if there is a history of MRSA or high local prevalence 1, 2