Community-acquired pneumonia: microbiology results were used infrequently to change antibiotic regimens

Clinical bottom line (level 4)

  1. One in ten patients with community aquired pneumonia have changes based on microbiology results.
  2. Half of sputum smears, a third of sputum cultures and a tenth of blood cultures identify a potentially infectious organism in patients with community-acquired pneumonia.
  3. One in seven patients fail to respond to the initial empiric course of antibiotics.
Sanyal et al: American Journal of Respiration and Critical Care Medicine 1999; 160: 346-348
Expires March 2003

The study

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

Setting: acute hospital, USA

184 patients (aged 18 to 99; mean 62, % male) with community-acquired pneumonia

Excluded if
  • HIV or AIDS
  • malignancy
  • sickle cell anaemia
  • neutropenia or other immunosuppressed state
  • splenectomy
  • intravenous drug use
  • bronchiectasis
  • discharged from acute care hospital within preceding 12 weeks
  • not treated according to American Thoracic Society Guidelines, 1993


    • Patients with severe pneumonia received ceftazidime or ticarcillin/clavulanate. Patients with non-severe pneumonia received cefuroxime and erythromycin.


    Outcomes studied:
  • positive sputum smear
  • positive sputum culture
  • positive blood culture
  • failed response to first antibiotic regimen
  • antibiotics changed on the basis of culture results

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    positive sputum smear ? 60/116 52%
    (43% to 61%)
    positive sputum culture ? 40/116 35%
    (26% to 43%)
    positive blood culture ? 19/174 11%
    (6.3% to 16%)
    failed response to first antibiotic regimen ? 25/184 14%
    (8.6% to 19%)
    antibiotics changed on the basis of culture results ? 3/25 12%
    (0.0% to 25%)

    Comments

    1. The number of deaths is too small to support the conclusion that there is no significant difference between empirical changes in antibiotics and microbiologically informed changes.

    Citation

    1. Sanyal S, Smith PR, Saha AC, et al: initial microbiologic studies did not affect outcome in adults hospitalized with community-acquired pneumonia. American Journal of Respiration and Critical Care Medicine 1999; 160: 346-348
    Contributor: Chris Ball and Clare Wotton, November 1999
    Reviewer: Paul Sullivan

    Clinical Question.
    Patient community aquired pneumonia
    Intervention or Exposure microbiology specimens guiding changes
    Comparison empiric changes
    Outcome mortality, morbidity