title: Polymicrobial bloodstream infections in the neonatal intensive care unit are associated with increased mortality: a case-control study.
abstract: BACKGROUND
  Polymicrobial infections in adults and children are associated with increase in mortality, duration of intensive care and healthcare costs. Very few studies have characterized polymicrobial bloodstream infections in the neonatal unit. Considerable variation has been reported in incidence of polymicrobial infections and associated clinical outcomes. We characterized the risk factors and outcomes of polymicrobial bloodstream infections in our neonatal units in a tertiary hospital in North America.
  
  
  METHODS
  In a retrospective case control study design, we identified infants in the neonatal intensive care unit with positive blood cultures at Texas Children's Hospital, over a 16-year period from January 1, 1997 to December 31, 2012. Clinical data from online databases were available from January 2009 to December 2012. For each polymicrobial bloodstream infection (case), we matched three infants with monomicrobial bloodstream infection (control) by gestational age and birth weight.
  
  
  RESULTS
  We identified 2007 episodes of bloodstream infections during the 16 year study period and 280 (14%) of these were polymicrobial. Coagulase-negative Staphylococcus, Enterococcus, Klebsiella and Candida were the most common microbial genera isolated from polymicrobial infections. Polymicrobial bloodstream infections were associated with more than 3-fold increase in mortality and an increase in duration of infection. Surgical intervention was a significant risk factor for polymicrobial infection.
  
  
  CONCLUSIONS
  The frequency and increased mortality emphasizes the clinical significance of polymicrobial bloodstream infections in the neonatal intensive care unit. Clinical awareness and focused research on neonatal polymicrobial infections is urgently needed.
authors.affiliation: Section of Neonatology, Department of Pediatrics, Texas Children's Hospital & Baylor College of Medicine, 6621, Fannin, MC: WT 6-104, Houston, TX 77030, USA. mohanv@bcm.edu.
authors.forename: Mohan
authors.initials: M
authors.lastname: Pammi
authors.forename: Danni
authors.initials: D
authors.lastname: Zhong
authors.forename: Yvette
authors.initials: Y
authors.lastname: Johnson
authors.forename: Paula
authors.initials: P
authors.lastname: Revell
authors.forename: James
authors.initials: J
authors.lastname: Versalovic
mesh_terms: D016470:Bacteremia / Q000097:blood / Q000175:diagnosis* / Q000401:mortality*; D001724:Birth Weight; D002175:Candida; D016022:Case-Control Studies; D060085:Coinfection / Q000175:diagnosis* / Q000401:mortality*; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D007709:Klebsiella; D008297:Male; D012189:Retrospective Studies; D012307:Risk Factors; D013210:Staphylococcus; D013781:Texas; D016896:Treatment Outcome