title: Quantitative versus qualitative cultures of respiratory secretions for clinical outcomes in patients with ventilator-associated pneumonia.
abstract: BACKGROUND
  Ventilator-associated pneumonia (VAP) is a common infectious disease in intensive care units (ICUs). The best diagnostic approach to resolve this condition remains uncertain.
  
  
  OBJECTIVE
  To evaluate whether quantitative cultures of respiratory secretions are effective in reducing mortality in immunocompetent patients with VAP, compared with qualitative cultures. We also considered changes in antibiotic use, length of ICU stay and mechanical ventilation.
  
  
  METHODS
  We searched The Cochrane Library, Cochrane Central Register of Controlled Trials (CENTRAL) Issue 2, 2011, which contains the Acute Respiratory Infections Group's Specialised Register, MEDLINE (1966 to June Week 4, 2011), EMBASE (1974 to June 2011) and LILACS (1982 to June 2011).
  
  
  METHODS
  Randomised controlled trials (RCTs) comparing respiratory samples processed quantitatively or qualitatively, obtained by invasive or non-invasive methods from immunocompetent patients with VAP and which analysed the impact of these methods on antibiotic use and mortality rates.
  
  
  METHODS
  Two review authors independently reviewed and trials identified in the search results and assessed studies for suitability, methodology and quality. We analysed data using Review Manager software. We pooled the included studies to yield the risk ratio (RR) for mortality and antibiotic change with 95% confidence intervals (CI).
  
  
  RESULTS
  Of the 4459 references identified from the electronic databases, five RCTs (1367 patients) met the inclusion criteria. Three studies compared invasive methods using quantitative cultures versus non-invasive methods using qualitative cultures, and were used to answer the main objective of this review. The other two studies compared invasive versus non-invasive methods, both using quantitative cultures. We combined all five studies to compare invasive versus non-invasive interventions for diagnosing VAP. The studies that compared quantitative and qualitative cultures (1240 patients) showed no statistically significant differences in mortality rates (RR 0.91; 95% CI 0.75 to 1.11). The analysis of all five RCTs showed there was no evidence of reduction in mortality in the invasive group versus the non-invasive group (RR 0.93; 95% CI 0.78 to 1.11). There were no significant differences between the interventions with respect to the number of days on mechanical ventilation, length of ICU stay or antibiotic change.
  
  
  CONCLUSIONS
  There is no evidence that the use of quantitative cultures of respiratory secretions results in reduced mortality, reduced time in ICU and on mechanical ventilation, or higher rates of antibiotic change when compared to qualitative cultures in patients with VAP. Similar results were observed when invasive strategies were compared with non-invasive strategies.
authors.affiliation: Department of Pulmonary Medicine - Pavilhão Pereira Filho - Santa Casa de Porto Alegre, Federal University of Health Sciences ofPorto Alegre (UFCSPA) and Feevale University, Porto Alegre, Brazil.
authors.forename: Danilo Cortozi
authors.initials: DC
authors.lastname: Berton
authors.forename: Andre C
authors.initials: AC
authors.lastname: Kalil
authors.forename: Paulo José Zimermann
authors.initials: PJ
authors.lastname: Teixeira
mesh_terms: D000328:Adult; D001431:Bacteriological Techniques / Q000379:methods*; D018893:Bronchoalveolar Lavage / Q000379:methods / Q000401:mortality; D001999:Bronchoscopy / Q000379:methods / Q000401:mortality; D006801:Humans; D007121:Immunocompetence; D007362:Intensive Care Units / Q000706:statistics & numerical data; D007902:Length of Stay; D053717:Pneumonia, Ventilator-Associated / Q000382:microbiology* / Q000401:mortality; D016032:Randomized Controlled Trials as Topic; D012137:Respiratory System / Q000378:metabolism*