Community-acquired pneumonia: no clear role for sputum Gram's stain

Clinical bottom line (level 2a-)

  1. The role of sputum Gram's stain in the identifying the causative organism in community-acquired pneumonia is unclear.
Reed et al: Western Journal of Medicine 1996; 165: 197-204
Expires March 2003

The study

Systematic review of all diagnostic studies of
  • Patients: community-acquired pneumonia
  • Intervention: sputum Gram's stain
  • Outcome: detection of pneumococcus


    • Articles found in English using Medline, 1966 to 1993 (search terms: sputum, Gram's stain and pneumonia ) and searching bibliographies of retrieved articles

    Selection criteria: see above
    Appraisal criteria: 3 blinded reviewers looked for an independent reference standard, evidence of community-acquired pneumonia, and enough information to calculate 2x2 tables. Authors were contacted to obtained more information about blinding and other protocol issues.
    Articles excluded if:

    11 prospective studies and 1 retrospective chart review found involving 1322 patients.

    The evidence

    • Sensitivity ranged from 15% to 100% and specificity from 11% to 100%. Most studies had a sensitivity < 70%

    Comments

    1. 70% of patients were able to produce a purulent sputum sample. Such practical considerations further limit the clinical utility of the test.
    2. Limiting the search to Medline and the English language mean important studies may have been missed.
    3. Study size, blinding, the definition of a positive test or control for antibiotic use was not statistically related to test characteristics.

    Citation

    1. Reed WW, Byrd GS, Gates RJ, et al: Sputum Gram's stain in community-acquired pneumococcal pneumonia: a meta-analysis. Western Journal of Medicine 1996; 165: 197-204
    Search Terms: (sputum near culture) and pneumon* in Cochrane
    Contributor: Chris Ball and Clare Wotton, November 1999
    Reviewer: Mitsuhiro Kamei

    Clinical Question.
    Patient
    Intervention or Exposure
    Outcome