Prevalence of bloodstream pathogens is higher in neonatal encephalopathy cases vs. controls using a novel panel of real-time PCR assays.

Cally J Tann,Jennifer J Kurinczuk,Nigel Klein,Jackson Were,Peter Nkurunziza,Margaret Nakakeeto,Alison M Elliott,Nicola J Robertson,Barbara A Willey,Kathryn A Harris,James Oweka,Peter Hughes,Natasha Nyombi

doi:10.1371/journal.pone.0097259

Abstract

BackgroundIn neonatal encephalopathy (NE), infectious co-morbidity is difficult to diagnose accurately, but may increase the vulnerability of the developing brain to hypoxia-ischemia. We developed a novel panel of species-specific real-time PCR assays to identify bloodstream pathogens amongst newborns with and without NE in Uganda.MethodologyMultiplex real-time PCR assays for important neonatal bloodstream pathogens (gram positive and gram negative bacteria, cytomegalovirus (CMV), herpes simplex virus(HSV) and P. falciparum) were performed on whole blood taken from 202 encephalopathic and 101 control infants. Automated blood culture (BACTEC) was performed for all cases and unwell controls.Principal FindingsPrevalence of pathogenic bacterial species amongst infants with NE was 3.6%, 6.9% and 8.9%, with culture, PCR and both tests in combination, respectively. More encephalopathic infants than controls had pathogenic bacterial species detected (8.9%vs2.0%, p = 0.028) using culture and PCR in combination. PCR detected bacteremia in 11 culture negative encephalopathic infants (3 Group B Streptococcus, 1 Group A Streptococcus, 1 Staphylococcus aureus and 6 Enterobacteriacae). Coagulase negative staphylococcus, frequently detected by PCR amongst case and control infants, was considered a contaminant. Prevalence of CMV, HSV and malaria amongst cases was low (1.5%, 0.5% and 0.5%, respectively).Conclusion/SignificanceThis real-time PCR panel detected more bacteremia than culture alone and provides a novel tool for detection of neonatal bloodstream pathogens that may be applied across a range of clinical situations and settings. Significantly more encephalopathic infants than controls had pathogenic bacterial species detected suggesting that infection may be an important risk factor for NE in this setting.

Highlights

Identification of bloodstream infections in newborns, either alone or as a co-morbidity amongst infants affected by conditions such as neonatal encephalopathy (NE), is problematic
Of the 101 control infants, none was positive for pathogenic bacterial species on blood culture (BC) but two were positive on PCR, giving a prevalence of neonatal bacteremia amongst the control group of 2.0% (2/101)
Four control infants were clinically unwell on recruitment, so BCs were performed in addition to PCR; all 4 were negative on both tests

Summary

Introduction

Identification of bloodstream infections in newborns, either alone or as a co-morbidity amongst infants affected by conditions such as neonatal encephalopathy (NE), is problematic. In preclinical studies exposure to bacterial endotoxin has been shown to increase vulnerability of the developing brain to perinatal hypoxia-ischemia [1,2,3]. Clinical studies have yet to precisely define the relationship between perinatal infections and neonatal encephalopathy (NE). Fetal exposure to inflammation and, or, infection has been found to increase brain vulnerability to hypoxia-ischemia via stimulation of toll-like receptors, immune and inflammatory responses, chemotaxis and cell death[4,5,6]. In neonatal encephalopathy (NE), infectious co-morbidity is difficult to diagnose accurately, but may increase the vulnerability of the developing brain to hypoxia-ischemia.

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