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Thorax doi:10.1136/thoraxjnl-2012-203106
  • Respiratory infection
  • Original article

Contribution of host, bacterial factors and antibiotic treatment to mortality in adult patients with bacteraemic pneumococcal pneumonia

  1. Birgitta Henriques Normark1,3,6
  1. 1Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
  2. 2Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
  3. 3Swedish Institute for Communicable Disease Control, Solna, Sweden
  4. 4Department of Communicable Diseases Control and Prevention, Stockholm, Sweden
  5. 5Department of Medicine, Infectious Disease Unit, Karolinska University Hospital, Stockholm, Sweden
  6. 6Department of Laboratory Medicine, Division of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden
  1. Correspondence to Dr Pontus Naucler, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Nobels väg 16, KI Solna Campus, Box 280, Stockholm SE-171 77, Sweden; pontus.naucler{at}ki.se
  • Received 7 December 2012
  • Revised 21 January 2013
  • Accepted 2 February 2013
  • Published Online First 26 February 2013

Abstract

Rationale Host and bacterial factors as well as different treatment regimens are likely to influence the outcome in patients with bacteraemic pneumococcal pneumonia.

Objectives To estimate the relative contribution of host factors as well as bacterial factors and antibiotic treatment to mortality in bacteraemic pneumococcal pneumonia.

Methods A cohort study of 1580 adult patients with community-acquired bacteraemic pneumococcal pneumonia was conducted between 2007 and 2009 in Sweden. Data on host factors and initial antibiotic treatment were collected from patient records. Antibiotic resistance and serotype were determined for bacterial isolates. Logistic regression analyses were performed to assess risk factors for 30-day mortality.

Results Smoking, alcohol abuse, solid tumour, liver disease and renal disease attributed to 14.9%, 13.1%, 13.1%, 8.0% and 7.4% of the mortality, respectively. Age was the strongest predictor, and mortality increased exponentially from 1.3% in patients <45 years of age to 26.1% in patients aged ≥85 years. There was considerable confounding by host factors on the association between serotype and mortality. Increasing age, liver disease and serotype were associated with mortality in patients admitted to the ICU. Combined treatment with β-lactam antibiotics and macrolide/quinolone was associated with reduced mortality in patients in the ICU, although confounding could not be ruled out.

Conclusions Host factors appear to be more important than the specific serotype as determinants of mortality in patients with bacteraemic pneumococcal pneumonia. Several host factors were identified that contribute to mortality, which is important for prognosis and to guide targeted prevention strategies.