A prospective hospital study of the aetiology of community-acquired pneumonia

Med J Aust. 1989 Jul 17;151(2):87-91. doi: 10.5694/j.1326-5377.1989.tb101168.x.


In a one-year prospective study of 106 adults (mean age, 60 years) who were admitted to hospital with community-acquired pneumonia, an aetiological diagnosis was made in 82 (77%) patients. Streptococcus pneumoniae was considered to be responsible for 44 (42%) and respiratory viruses for 19 (18%) infections. Other aetiological agents that were found in a smaller number of patients included Haemophilus influenzae (9% of patients), enteric Gram-negative bacilli (8% of patients), Staphylococcus aureus (3% of patients), Legionella spp. (3% of patients), Mycobacterium tuberculosis (3% of patients), Mycoplasma pneumoniae (8% of patients) and Chlamydia psittaci (5% of patients). The mortality was 10% and was related significantly to increasing age and to coexisting heart and lung disease. Antibiotic treatment that was commenced before admission to hospital and investigations were undertaken reduced significantly the isolation rate of susceptible bacterial pathogens. The Gram-stained smear of sputum was valuable in establishing a tentative diagnosis of bacterial pneumonia. The most-useful tests in making an early diagnosis proved to be those which detected pneumococcal and mycoplasmal antigens, blood cultures and culture of sputum for appropriate bacterial pathogens.

Publication types

  • Comparative Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Anti-Bacterial Agents / therapeutic use
  • Bacterial Infections / complications*
  • Evaluation Studies as Topic
  • Female
  • Humans
  • Male
  • Middle Aged
  • Pneumonia / drug therapy
  • Pneumonia / epidemiology
  • Pneumonia / etiology*
  • Pneumonia / mortality
  • Pneumonia, Pneumococcal / diagnosis
  • Pneumonia, Pneumococcal / etiology
  • Predictive Value of Tests
  • Prospective Studies
  • South Australia
  • Streptococcus pneumoniae / immunology
  • Streptococcus pneumoniae / isolation & purification
  • Virus Diseases / complications*


  • Anti-Bacterial Agents