title: BAL neutrophils, serum procalcitonin, and C-reactive protein to predict bacterial infection in the immunocompromised host.
abstract: BACKGROUND
  Bacterial pulmonary infection is a common life-threatening complication in immunocompromised patients. The results of BAL cultures are not immediately available, and their microbiological yield might be limited by empiric antibiotic prescriptions. We evaluated clinical signs and symptoms, leukocyte counts, C-reactive protein (CRP) levels, procalcitonin levels, and BAL fluid neutrophil percentages as potential markers for bacterial infection in a cohort of immunocompromised patients with pulmonary complications.
  
  
  METHODS
  One hundred seven consecutive patients who had been referred for bronchoscopy due to suspected pulmonary infection were included in this study. Based on clinical, laboratory, radiologic, microbiological, and histologic results, patients were classified as having proven bacterial infection (n = 27), possible bacterial infection (n = 11), and no bacterial infection (n = 69).
  
  
  RESULTS
  Most common underlying conditions were hematologic malignancy (n = 62) and solid organ transplantation (n = 20). Clinical parameters were similar in patients with and without bacterial infection (difference was not significant). The percentage of BAL fluid neutrophils had the highest area under the curve (0.818; 95% confidence interval [CI], 0.700 to 0.935; p < 0.001), followed by absolute neutrophil counts (0.797; 95% CI, 0.678 to 0.916; p < 0.001), procalcitonin level (0.746; 95% CI, 0.602 to 0.889; p = 0.001), and CRP level (0.688; 95% CI, 0.555 to 0.821; p = 0.015) to predict proven bacterial infection (in opposition to no or possible bacterial infection) in the receiver operating characteristic analysis. Conversely, neither infiltrates (p = 0.123) nor leukocyte counts (p = 0.429) were useful in diagnosing bacterial infection. The percentage of BAL fluid neutrophils and procalcitonin level were independent predictors of bacterial infection in the multivariate regression.
  
  
  CONCLUSIONS
  Neutrophil percentage in BAL fluid, procalcitonin level, and CRP level might be potentially useful to differentiate bacterial infection from nonbacterial conditions in immunocompromised hosts with pulmonary complications.
authors.affiliation: University of Massachusetts Medical School, 55 Lake Ave North, Worcester, MA 01655, USA. dstolz@uhbs.ch
authors.forename: Daiana
authors.initials: D
authors.lastname: Stolz
authors.forename: Andreas
authors.initials: A
authors.lastname: Stulz
authors.forename: Beat
authors.initials: B
authors.lastname: Müller
authors.forename: Alois
authors.initials: A
authors.lastname: Gratwohl
authors.forename: Michael
authors.initials: M
authors.lastname: Tamm
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification; D001424:Bacterial Infections / Q000175:diagnosis / Q000276:immunology / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology*; D001999:Bronchoscopy; D002097:C-Reactive Protein / Q000378:metabolism*; D002116:Calcitonin / Q000097:blood*; D015740:Calcitonin Gene-Related Peptide; D016001:Confidence Intervals; D004269:DNA, Bacterial / Q000032:analysis; D005260:Female; D005500:Follow-Up Studies; D006023:Glycoproteins; D006801:Humans; D016867:Immunocompromised Host; D007124:Immunoenzyme Techniques; D007958:Leukocyte Count; D008163:Luminescent Measurements; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000502:physiology*; D016133:Polymerase Chain Reaction; D011379:Prognosis; D011446:Prospective Studies; D011498:Protein Precursors / Q000097:blood*; D012372:ROC Curve; D012141:Respiratory Tract Infections / Q000175:diagnosis / Q000276:immunology / Q000378:metabolism
chemical_list: D015415:Biomarkers; C000606589:CALCA protein, human; D004269:DNA, Bacterial; D006023:Glycoproteins; D011498:Protein Precursors; D002116:Calcitonin; D002097:C-Reactive Protein; D015740:Calcitonin Gene-Related Peptide