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Effectiveness of β lactam antibiotics compared with antibiotics active against atypical pathogens in non-severe community acquired pneumonia: meta-analysis

BMJ 2005; 330 doi: (Published 24 February 2005) Cite this as: BMJ 2005;330:456
  1. Graham D Mills (millsg{at}, consultant physician1,
  2. Michael R Oehley, medical student2,
  3. Bruce Arrol, associate professor3
  1. 1 Respiratory and Infectious Diseases Department, Waikato Hospital, Private Bag 3200, Hamilton 2001, New Zealand,
  2. 2 University of Auckland School of Medicine, New Zealand,
  3. 3 Department of General Practice and Primary Health Care, University of Auckland, New Zealand
  1. Correspondence to: G D Mills
  • Accepted 29 November 2004


Objective To systematically compare β lactam antibiotics with antibiotics active against atypical pathogens in the management of community acquired pneumonia.

Data sources Medline, Embase, Cochrane register of controlled trials, international conference proceedings, drug registration authorities, and pharmaceutical companies.

Review methods Double blind randomised controlled monotherapy trials comparing β lactam antibiotics with antibiotics active against atypical pathogens in adults with community acquired pneumonia. Primary outcome was failure to achieve clinical cure or improvement.

Results 18 trials totalling 6749 participants were identified, with most patients having mild to moderate community acquired pneumonia. The summary relative risk for treatment failure in all cause community acquired pneumonia showed no advantage of antibiotics active against atypical pathogens over β lactam antibiotics (0.97, 95% confidence interval 0.87 to 1.07). Subgroup analysis was undertaken in those with a specific diagnosis involving atypical pathogens. We found a significantly lower failure rate in patients with Legionella species who were treated with antibiotics active against atypical pathogens (0.40, 0.19 to 0.85). Equivalence was seen for Mycoplasma pneumoniae (0.60, 0.31 to 1.17) and Chlamydia pneumoniae (2.32, 0.67 to 8.03).

Conclusions Evidence is lacking that clinical outcomes are improved by using antibiotics active against atypical pathogens in all cause non-severe community acquired pneumonia. Although such antibiotics were superior in the management of patients later shown to have legionella related pneumonia, this pathogen was rarely responsible for pneumonia within the included trials. β lactam agents should remain the antibiotics of initial choice in adults with non-severe community acquired pneumonia.


  • Contributors GDM conceived the study. GDM and MRO were involved in all stages of data collection, and data analysis. GDM and BA prepared the manuscript. GDM is guarantor.

  • Funding MRO was funded by a summer studentship from the Waikato District health board.

  • Conflict of interest GDM has received funding for research from Abbott, AstraZeneca, AventisPharma, Boehringer Ingelheim, GlaxoWellcome, ICOS, Merck&Co, Pfizer, and Roche. He has also been reimbursed by AventisPharma, Bristol-Myers Squibb, GlaxoWellcome, and Merck&Co for attending conferences. BA has received funding for research and conference attendance from the Future Forum, an educational cardiovascular forum funded by AstraZeneca.

  • Ethical approval Not required.

  • Accepted 29 November 2004
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