title: Procalcitonin to predict bacterial coinfection in infants with acute bronchiolitis: a preliminary analysis.
abstract: OBJECTIVE
  The aim of this study was to conduct a preliminary analysis of serum procalcitonin (PCT) to predict bacterial coinfection in infants with acute bronchiolitis.
  
  
  METHODS
  Retrospective cohort chart review of 40 infants admitted with acute bronchiolitis to the pediatric intensive care unit. Logistic regression models were used to determine the association of PCT and white blood count with presence of bacterial coinfection defined by either positive culture or chest radiograph result.
  
  
  RESULTS
  Fifteen (38%) of 40 patients had a diagnosis of bacterial coinfection by positive culture (9/15) or chest radiograph (6/15). Procalcitonin (P < 0.0001) was significantly associated with bacterial coinfection. A cutoff value of 1.5 ng/mL had sensitivity of 0.80, specificity of 1.00, and area under the operating curve of 0.88. White blood count (P = 0.06) was borderline significant with sensitivity of 0.33, specificity of 0.96, and area under the operating curve of 0.67. Three of 15 patients were later found to have bacterial coinfection with initial PCT of less than 1.5 ng/mL. None had follow-up PCT measurements taken. Thirty-five of 40 were prescribed empiric antibiotic therapy, including 20 of 25 patients without evidence of bacterial coinfection. None had a PCT of greater than 1.5 ng/mL. If a PCT cutoff of greater than 1.5 ng/mL had been used, 57% fewer patients would have received antibiotics with a 45% reduction in antimicrobial charges.
  
  
  CONCLUSIONS
  An elevated PCT may assist clinicians in determining presence of bacterial coinfection at admission in infants with acute bronchiolitis. Implementation of a PCT cutoff of 1.5 ng/mL at admission may prevent unnecessary antibiotic use with associated cost savings. Serial PCT levels may increase sensitivity. Further validation is warranted.
authors.affiliation: From the *Division of Pediatric Critical Care Medicine, Department of Pediatrics, University of Kentucky Chandler Medical Center; †College of Public Health, Department of Biostatistics, ‡Pharmacy Services, University of Kentucky; and §Division of Neonatology, Department of Pediatrics, University of Kentucky Chandler Medical Center, Lexington, KY.
authors.forename: James L
authors.initials: JL
authors.lastname: Laham
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Breheny
authors.forename: Brian M
authors.initials: BM
authors.lastname: Gardner
authors.forename: Henrietta
authors.initials: H
authors.lastname: Bada
mesh_terms: D000208:Acute Disease; D016470:Bacteremia / Q000097:blood* / Q000175:diagnosis; D015415:Biomarkers / Q000097:blood; D001988:Bronchiolitis / Q000097:blood*; D002116:Calcitonin / Q000097:blood*; D015740:Calcitonin Gene-Related Peptide; D060085:Coinfection / Q000097:blood* / Q000175:diagnosis; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006023:Glycoproteins; D006801:Humans; D007223:Infant; D015278:Intensive Care Units, Pediatric; D008297:Male; D011237:Predictive Value of Tests; D011379:Prognosis; D011498:Protein Precursors / Q000097:blood*; D012372:ROC Curve; D012189:Retrospective Studies
chemical_list: D015415:Biomarkers; C000606589:CALCA protein, human; D006023:Glycoproteins; D011498:Protein Precursors; D002116:Calcitonin; D015740:Calcitonin Gene-Related Peptide