Cellulitis: the commonest infecting organisms were Staphylococcus and Streptococcus.

Clinical bottom line (level 4)

  1. Fine needle aspiration led to a positive culture in around a third of patients with cellulitis. Contaminants were common.
  2. The commonest infecting organisms were Staphylococcus (56%) and Streptococcus (24%).
  3. Patients who had antibiotics previously were more likely to have positive cultures.
Sigurdsson and Gudmundsson: Scandinavian Journal of Infectious Diseases 1989; 21: 537-542
Expires November 2004

The study

Prospective cohort study with unblinded, unobjective outcomes, not adjusted for confounding factors, not validated in an independent set of patients.

Setting: emergency department, Iceland

89 patients (aged ?, ?% male) with 94 cases of probable cellulitis (defined as an acute spreading inflammation of the skin and subcutaneous tissues characterised by three or more of: swelling, erythema, tenderness and increased skin warmth)

Excluded if
  • <18 years old
  • impetigo, folliculitis, carbuncles and surgical wound infections


    • All patients had fine needle aspiration.


    Outcomes studied:
  • positive cultures
  • contaminants
  • Staphylococcus
  • Staph aureus
  • Staph epidermidis
  • Streptococcus
  • Strep pyogenes
  • Klebsiella
  • other (Morganella morgagni, Pseudomonas aeruginosa, Peptococcus)

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    positive cultures ? 34/89 38%
    (28% to 48%)
    contaminants ? 8/89 9.0%
    (3.0% to 15%)
    Staphylococcus ? 19/34 56%
    (39% to 73%)
    Staph aureus ? 11/34 32%
    (17% to 48%)
    Staph epidermidis ? 8/34 24%
    (9.3% to 38%)
    Streptococcus ? 8/34 24%
    (9.3% to 38%)
    Strep pyogenes ? 5/34 15%
    (2.8% to 27%)
    Klebsiella ? 2/34 5.9%
    (0.0% to 14%)
    other (Morganella morgagni, Pseudomonas aeruginosa, Peptococcus) ? 4/34 12%
    (0.9% to 23%)

    prognostic factor for
    positive cultures     		time to outcome unadjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    prior antibiotics ? 1.89
    (1.07 to 3.35)     		4
    (2 to 52)

    • Total positive cultures = 42 - contaminants were mainly Staph epidermidis.

    Comments

    1. Failure to adjust for confounding factors (e.g. underlying disease, duration of cellulitis) makes these risk factors much less certain. There are few better studies of this area, however.

    Citation

    1. Sigurdsson AF, and Gudmundsson S: The etiology of bacterial cellulitis as determined by fine-needle aspiration. Scandinavian Journal of Infectious Diseases 1989; 21: 537-542
    Search Terms: cellulitis diagnosis
    Contributor: John Epling and Chris Ball, November 2000
    Reviewer: Asim J. Jani

    Clinical Question.
    Patient cellulitis
    Intervention or Exposure prevalence
    Outcome positive culture