Evaluation of a real-time PCR assay for detection and quantification of bacterial DNA directly in blood of preterm neonates with suspected late-onset sepsis

• Published in: Critical care (London, England) Vol. 22; no. 1; p. 105
• Main Authors: van den Brand, Marre, van den Dungen, Frank A M, Bos, Martine P, van Weissenbruch, Mirjam M, van Furth, A Marceline, de Lange, Annemieke, Rubenjan, Anna, Peters, Remco P H, Savelkoul, Paul H M
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 22-04-2018; BioMed Central; BMC
• Subjects: Analysis; Bacteremia; Bacterial DNA load; Diagnosis; Health aspects; Infants (Premature); Late-onset sepsis; Molecular diagnosis; Neonatology; Real-time PCR; Sepsis; Staphylococcus aureus infections; Neonatology; Late-onset sepsis; Molecular diagnosis; Bacterial DNA load; Real-time PCR; Bacteremia
• ISSN: 1364-8535; 1466-609X; 1364-8535
• DOI: 10.1186/s13054-018-2010-4

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.
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.
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 log
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 log
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).
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.