Cellulitis: swabbing breaks in the skin were the best way to culture pathogens.

Clinical bottom line (level 4)

  1. Swabbing of any breaks in the skin in patients with cellulitis was the best way of culturing a pathogen - around 40% were positive.
  2. More invasive techniques were not very helpful.
Hook et al: Archives of Internal Medicine 1986; 146: 295-297
Expires June 2004

The study

Case series with objective outcomes, not adjusted for confounding factors, not validated in an independent set of patients.

Setting: emergency department, university hospital, USA

50 patients (aged range 23 to 84 years; mean 50, 76% male) cellulitis

Excluded if
  • <16 years old
  • cellulitis of head/neck
  • history of antibiotic use in last week
  • allergy to lidocaine
  • other diagnosis likely





    • Outcomes studied:
  • punch biopsy (number positive)
  • needle aspiration
  • blood culture
  • primary lesion swab

    • Patients with diabetes mellitus or venous insufficiency were not excluded.
    • All patients had:
      • primary lesion culture (swab, no cleaning of any break in the skin, including ulcers, fissures and abrasions in continuity with cellulitis)
      • needle aspiration culture (povidone-iodine scrub followed by alcohol, 18-20g needle on 5-10ml syringe, non-bacteriostatic saline injected if initial aspiration was dry, if both aspirations unsuccessful, tip of the needle was cultured.)
      • punch biopsy culture - 4mm, full thickness punch biopsy in all patients after cleansing as in aspiration above and anaesthesia with lidocaine
      • blood culture - standard technique after cleansing venipuncture site with povidone-iodine

    The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    punch biopsy (number positive) ? 10/50 20%
    (8.9% to 31%)
    needle aspiration ? 5/50 10%
    (1.7% to 18%)
    blood culture ? 2/50 4.0%
    (0.0% to 9.4%)
    primary lesion swab ? 21/50 42%
    (28% to 56%)

    • All patients who had positive aspirates or biopsies grew the same organism on primary lesion swab culture.
    • The majority of infecting organisms were Staphylococcus or Streptococcus.
    • WBC, degree of fever, and ESR did not predict positive cultures.

    Comments

    1. It is unclear whether any patient had changes made in antibiotic therapy based on these culture results.

    Citation

    1. Hook EW, Hooton TM, Horton CA, et al: Microbiologic evaluation of cutaneous cellulitis in adults. Archives of Internal Medicine 1986; 146: 295-297
    Contributor: John Epling and Chris Ball, June 2000
    Reviewer:

    Clinical Question.
    Patient cellulitis
    Intervention or Exposure microbiologic evaluation
    Outcome diagnosis