Practice Perfect 755
Swabbing Wounds: Don’t Do It!

This one is for all of our medicine friends with whom we work side-by-side. Recently I was consulted on a patient with a diabetic foot infection in the hospital. The patient had already been admitted for a few days, and the medicine resident who consulted me described how they had swabbed the wound in the emergency room. Inwardly, I groaned, thinking how this was an erroneous action that no longer has a place in modern patient care. I’m not sure why this practice remains so common. Perhaps it’s convenience. Or maybe those outside the regular care of foot complications just don’t know. Maybe it’s a combination.

As lower extremity experts, most of us are aware that swabbing the surface of a foot ulcer is simply sampling surface contamination and does not accurately characterize the infecting agents.

Swabbing the wound, taking a surface sample for C&S in the emergency room is an erroneous action that no longer has a place in modern patient care.

The Message: Stop Swabbing the Surface!

I find in working with medical residents, it is often much easier to achieve satisfactory communication than with their attendings, for the simple reason that their lack of experience and status as learners makes them more open-minded. Perhaps this is an example we should all follow. My conversations with them are highly productive, but all good questioning residents ask the important question: what does the research literature say?

Chakraborti C, Le C, Yanofsky A. Sensitivity of superficial cultures in lower extremity wounds. J Hosp Med. 2010 Sep;5(7):415-420.

This systematic review included studies that examined surface swab cultures in comparison with deep tissue cultures of infected wounds. They found a pooled sensitivity of 49% and specificity 62% (pooled positive likelihood ratio 1.1 and negative likelihood ratio 0.67) that superficial swabs correlated with the deeper tissues.

Lipsky BA, Berendt AR, Cornia PB, Pile JC, Peters EJ, Armstrong DG, Deery HG, Embil JM, Joseph WS, Karchmer AW, Pinzur MS. 2012 Infectious Diseases Society of America clinical practice guideline for the diagnosis and treatment of diabetic foot infections. Clin Infect Dis. 2012 Jun;54(12):e132-173.

Studies like the above led the Infectious Disease Society of America to this statement in their clinical practice guideline (recommendation 18), “We recommend sending a specimen for culture that is from deep tissue, obtained by biopsy or curettage after the wound has been cleansed and debrided. We suggest avoiding swab specimens, especially of inadequately debrided wounds, as they provide less accurate results.” This is considered a strong recommendation based on moderate quality evidence, according to the IDSA.

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If we shouldn’t swab the surface, what should we do? Simple. Debride the wound completely and take a deep tissue sample to send for gram stain, culture and sensitivity. This has the best chance to accurately diagnose the actual infecting organism(s) as well as increase the likelihood of capturing organisms living in deeper tissues such as anaerobes. Most medical doctors are not surgeons, so this is the very reason to consult your friendly neighborhood podiatrist!

Best wishes.

Jarrod Shapiro, DPM
PRESENT Practice Perfect Editor
jarrod@podiatry.com
References
  1. Chakraborti C, Le C, Yanofsky A. Sensitivity of superficial cultures in lower extremity wounds. J Hosp Med. 2010 Sep;5(7):415-420.
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  2. Lipsky BA, Berendt AR, Cornia PB, Pile JC, Peters EJ, Armstrong DG, Deery HG, Embil JM, Joseph WS, Karchmer AW, Pinzur MS. 2012 Infectious Diseases Society of America clinical practice guideline for the diagnosis and treatment of diabetic foot infections. Clin Infect Dis. 2012 Jun;54(12):e132-173.
    Follow this link

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