BACKGROUND : Rapid and accurate diagnosis of neonatal sepsis is highly warranted because of high associated
morbidity and mortality. The aim of this study was to evaluate the performance of a novel multiplex PCR assay for
diagnosis of late-onset sepsis and to investigate the value of bacterial DNA load (BDL) determination as a measure
of infection severity.
METHODS : This cross-sectional study was conducted in a neonatal intensive care unit. Preterm and/or very low birth
weight infants suspected for late-onset sepsis were included. Upon suspicion of sepsis, a whole blood sample was
drawn for multiplex PCR to detect the eight most common bacteria causing neonatal sepsis, as well as for blood
culture. BDL was determined in episodes with a positive multiplex PCR.
RESULTS : In total, 91 episodes of suspected sepsis were investigated, and PCR was positive in 53 (58%) and blood
culture in 60 (66%) episodes, yielding no significant difference in detection rate (p = 0.17). Multiplex PCR showed a
sensitivity of 77%, specificity of 81%, positive predictive value of 87%, and negative predictive value of 68%
compared with blood culture. Episodes with discordant results of PCR and blood culture included mainly detection
of coagulase-negative staphylococci (CoNS). C-reactive protein (CRP) level and immature to total neutrophil (I/T)
ratio were lower in these episodes, indicating less severe disease or even contamination. Median BDL was high (4.1
log10 cfu Eq/ml) with a wide range, and was it higher in episodes with a positive blood culture than in those with a
negative blood culture (4.5 versus 2.5 log10 cfu Eq/ml; p < 0.0001). For CoNS infection episodes BDL and CRP were
positively associated (p = 0.004), and for Staphylococcus aureus infection episodes there was a positive association
between BDL and I/T ratio (p = 0.049).
CONCLUSIONS : Multiplex PCR provides a powerful assay to enhance rapid identification of the causative pathogen in
late-onset sepsis. BDL measurement may be a useful indicator of severity of infection.
Additional file 1: Detection of pathogens in blood by blood culture
and PCR for polymicrobial infection episodes.