Molecular microbiological methods in the diagnosis of neonatal sepsis

Abstract

Neonatal sepsis is a major cause of neonatal mortality and morbidity. The current gold standard for diagnosis of sepsis, namely blood culture, suffers from low sensitivity and a reporting delay of approximately 48-72 h. Rapid detection of sepsis and institution of antimicrobial therapy may improve patient outcomes. Rapid and sensitive tests that can inform clinicians regarding the institution or optimization of antimicrobial therapy are urgently needed. The ideal diagnostic test should have adequate specificity and negative predictive value to reliably exclude sepsis and avoid unnecessary antibiotic therapy. We comprehensively searched for neonatal studies that evaluated molecular methods for diagnosis of sepsis. We identified 19 studies that were assessed with respect to assay methodology and diagnostic characteristics. In addition, we also reviewed newer molecular microbiological assays of relevance that have not been fully evaluated in neonates. Molecular methods offer distinct advantages over blood cultures, including increased sensitivity and rapid diagnosis. However, diagnostic accuracy and cost-effectiveness should be established before implementation in clinical practice.

Figure 1. Molecular methods in the diagnosis of sepsis

MALDI-TOF MS: Matrix-assisted laser desorption ionization time-of-flight mass spectrometry; PNA: Peptide nucleic acid.

Figure 2. Peptide nucleic acid FISH

(A) A mixed culture of Escherichia coli and Pseudomonas aeruginosa was fixed to the slide and hybridized with the E. coli/P. aeruginosa probes. E. coli appears green and P. aeruginosa red. (B) A mixed culture of Staphylococcus aureus and Staphylococcus epidermidis was fixed to the slide and hybridized with specific PNA FISH probes. S. aureus appears green and S. epidermidis red. (C) A mixed culture of Candida albicans, Candida tropicalis and Candida glabrata was fixed to the slide and Yeast Traffic Light probe was applied. C. albicans appears green, C. tropicalis yellow and C. glabrata red. PNA FISH images were supplied by AdvanDx, MA, USA.