Clinical diagnosis of neonatal sepsis is difficult even in the most sophisticated settings. Many technical pitfalls raise questions regarding blood culture reliability in diagnosis of neonatal sepsis. Detection of microbial DNA rather than the microorganisms themselves is a new era has been introduced in diagnostic microbiology that allows effective and rapid diagnosis of many diseases; it is suggested to represent a rapid and sensitive method in diagnosing bacterial sepsis in neonates.
Aim of the study: To evaluate the role of Broad Range 16 S rDNA PCR in diagnosis of sepsis in newborn infants and to compare the results of PCR with the conventional blood culture.
Patients and Methods: 58 newborn infant with clinically suspected sepsis were included in the present work. Complete blood picture and C-reactive protein level were done. Concomitant blood culture and 16S rDNA gene PCR amplification were done to all newborn infants included in this study.
Results: blood cultures were positive in only 28(48.2%) of cases. With the molecular method of broad range 16S rDNA PCR, the detection of bacteria in this study was improved to 38 (65.5%) of these patients. Compared to blood culture, the diagnosis of bacterial sepsis in the newborn by PCR revealed 96.4% sensitivity, 66.6% specificity, 72.9% positive predictive value and 95.2% negative predictive value. Out of 58 newborn infants included in this study 41 patients had suspected early onset sepsis (EOS) (< 7 days) and 17 patients had suspected late onset sepsis (≥ 7 days). The sensitivity, specificity, PPV, and NPV of PCR for the diagnosis of EOS were similar to those of late-onset sepsis. Of the patients with suspected EOS, 16 (39%) mothers had received antibiotics within 72 hours before delivery and maternal antibiotic drug use did not alter the performance of PCR.
Conclusions and Recommendations:
The benefit of PCR is its rapid availability of results with a high negative predictive value. As a tool to ‘rule out sepsis’, PCR can be easily incorporated into the hospital setting for newborn infants admitted to the NICU for sepsis evaluation. PCR seems to perform well in patients either with suspected EOS or late onset sepsis, irrespective of antibiotic drug use in the mother. Future studies are needed to incorporate PCR to provide us with additional valuable information regarding identification of definitive bacterial species and guide the clinical antibiotic selection.
Key words: Neonatal sepsis, Broad Range 16 S rDNA PCR