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Open Access Research article

Polymicrobial bloodstream infections in the neonatal intensive care unit are associated with increased mortality: a case-control study

Mohan Pammi1*, Danni Zhong2, Yvette Johnson1, Paula Revell3 and James Versalovic3

Author Affiliations

1 Section of Neonatology, Department of Pediatrics, Texas Children’s Hospital & Baylor College of Medicine, 6621, Fannin, MC: WT 6-104, Houston, TX 77030, USA

2 Section of Neonatology, Department of Pediatrics, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530021, China

3 Department of Pathology, Texas Children’s Hospital & Baylor College of Medicine, Houston, TX 77030, USA

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BMC Infectious Diseases 2014, 14:390  doi:10.1186/1471-2334-14-390

Published: 14 July 2014

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.

Conclusion

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.

Keywords:
Neonate; Infant; NICU; Sepsis; Polymicrobial; Mortality