Adaption of the Roche Septifast system for the early detection of neonatal sepsis in very low birthweight infants

Introduction: The gold standard for diagnosis of bacterial sepsis is a positive blood culture. However, results are usually not available before to 48 to 72h and pathogens are detected in only 25% of patients. Molecular assays for the detection of DNA in the blood have been tested as new diagnostic tools for early identification of bacterial sepsis in adults. Objective: To adapt and evaluate a commercially available PCR system for use in neonatology by using small blood volumes.

Materials and Methods: Blood specimens of 38 VLBW infants (mean±SD, range: 829g±242, 350–1150g) with clinical sepsis suspicion were analyzed using the Roche Septifast PCR system and a modified DNA extraction protocol to decrease blood volume requirements to 0,1ml. Results: Patients were divided in 3 groups: Group 1 (negative group, n=21) represents patients with a negative blood culture and no further clinical or laboratory signs of infection. In Group 2, blood culture was positive and patients had signs of sepsis and were treated with antimicrobial agents (blood culture positive sepsis group; n=11). Group 3 represents patients with clinical and laboratory signs of sepsis but with negative blood culture results (clinical sepsis group; n=6). In the negative group, 5 of 21 infants had a positive PCR result (potential contamination). All pathogens detected in the blood culture in Group 2 were equally detected by means of PCR. Four of six patients had a positive PCR results in Group 3.

Disscussion and Conclusion: The results indicate a 100% sensitivity and 76% specificity of the PCR system for detection of blood culture positive sepsis episodes in our study patients. The detection of bacteria improved in the group with culture negative clinical sepsis by use of PCR. These are the first data on the clinical utility of the commercially available multiplex real-time Septifast PCR test for the detection of blood stream pathogens in VLBW infants using a modified sample handling and DNA extraction protocol.