Comparison of broad range 16S rDNA PCR to conventional blood culture for diagnosis of sepsis in the newborn

Abstract

Neonatal sepsis is a significant cause of morbidity and mortality in neonates. The gold standard for detecting bacterial sepsis is blood culture. However, it has low sensitivity and a reporting delay of approximately 48–72 h. Molecular assays for the detection of bacterial DNA represent possible new diagnostic tools for early identification of a bacterial cause. This study aimed at comparing a broad range 16S rDNA PCR to conventional blood culture for detecting bacterial DNA in blood samples from neonates with suspected sepsis. Fifty neonates with suspected sepsis, admitted at Neonatal Intensive Care Unit of Ain Shams University Hospitals, were included in this study. From each neonate, a minimum of 2–3 ml blood was collected by standard sterile procedures, 1 ml for conventional blood culture and 1–2 ml EDTA blood for PCR. The isolated microorganisms were identified by conventional microbiological methods. Thirty neonates (60%) gave positive blood culture results. The most frequently isolated microorganisms were Staphylococcus aureus (n= 17, 56.7%), followed by Coagulase negative Staphylococci (n=7, 23.3%),  Escherichia coli (n= 4, 13.3%), and Candida spp. (n=2, 6.7%). Twenty-eight (56%) neonates gave positive bacterial blood culture while 35 (70%) neonates gave positive PCR results. Considering the blood culture as the gold standard in diagnosis of bacterial neonatal sepsis, the sensitivity, specificity, positive predictive value and negative predictive value of PCR in detecting bacteremia relative to blood cultures were 20/28 (71.42%), 7/22 (31.81%), 20/35 (57.14%) & 7/15 (46.66%), respectively. In conclusion, PCR approach appears to be a relatively easy, reliable and valuable complementary method for diagnosis of neonatal sepsis for samples obtained during antimicrobial treatment especially when routine cultures remain negative. Staphylococci spp. has played an important role in causing neonatal sepsis. So, implementation of simple infection control measures such as hand washing, barrier nursing and promotion of clean deliveries should be considered to reduce neonatal sepsis

Keywords: Neonatal sepsis; Conventional blood culture; Broad range 16S DNA PCR