Pleural effusion: empyema: commonly caused by Strep. pneumoniae and Staph. aureus.

Clinical bottom line (level 4)

  1. Aerobic or mixed aerobic/anaerobic infections were the commonest causes of empyema.
  2. Streptococcus pneumoniae and Staphylococcus aureus were the commonest infectious organisms (about two thirds of all infections).
Brook and Frazier: Chest 1993; 103 (5): 1502-1507
Expires October 2003

The study

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

Setting: two military hospitals, USA

197 patients (aged range 5 months to 78 years; mean 37, 72% male) empyema (diagnosed if evacuation of gross pus from pleural space)

Excluded if
  • no bacterial growth
  • tuberculosis or non-bacterial infection



    • Factors studied:

    Most patients received antimicrobials.


    Outcomes studied:
  • aerobic infection
  • mixed infection
  • anaerobic infection
  • aerobes: Streptococcus pneumoniae
  • Staphylococcus aureus
  • Escherichia coli
  • Klebsiella pneumoniae
  • Haemophilus influenzae
  • anaerobes: anaerobic cocci
  • Prevotella and Porphyromonas species
  • Bacteroides fragilis
  • Fusobacterium

    • All patients had aerobic and anaerobic cultures for up to five days.

    The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    aerobic infection ? 127/197 64%
    (58% to 71%)
    mixed infection ? 45/197 23%
    (17% to 29%)
    anaerobic infection ? 25/197 13%
    (8% to 17%)
    aerobes: Streptococcus pneumoniae ? 70/197 36%
    (29% to 42%)
    Staphylococcus aureus ? 58/197 29%
    (23% to 36%)
    Escherichia coli ? 17/197 8.6%
    (4.7% to 13%)
    Klebsiella pneumoniae ? 16/197 8.1%
    (4.3% to 12%)
    Haemophilus influenzae ? 12/197 6.1%
    (2.8% to 9.4%)
    anaerobes: anaerobic cocci ? 36/197 18%
    (13% to 24%)
    Prevotella and Porphyromonas species ? 24/197 12%
    (7.6% to 17%)
    Bacteroides fragilis ? 22/197 11%
    (6.8% to 16%)
    Fusobacterium ? 20/197 10%
    (5.9% to 14%)

    Citation

    1. Brook I, and Frazier EH: aerobic and anaerobic microbiology of empyema: a retrospective review in two military hospitals. Chest 1993; 103 (5): 1502-1507
    Search Terms: reference from Pleural effusion chapter in 'Quick Consult Manual to Evidence-based Medicine': publd Lippincott-Raven, 1997
    Contributor: Chris Ball and Clare Wotton, October 2000
    Reviewer:

    Clinical Question.
    Patient pleural effusion and empyema
    Intervention or Exposure prevalence
    Outcome aerobic/ anaerobic bacteria