Diagnosis of Neonatal Bacterial Sepsis by Polymerase Chain Reaction

Role of polymerase chain reaction as an early diagnostic tool for neonatal bacterial sepsis

BACKGROUND

Neonatal bacterial sepsis is a challenging disease that needs to be detected early. As it is a life-threatening condition, the use of an approach that could be more rapid than standard culture and identification techniques for detection of neonatal sepsis would be highly desirable.

OBJECTIVE

The aim of this work was to assess the effectiveness of the PCR technique compared with blood culture for the early detection of bacterial sepsis.

PARTICIPANTS AND METHODS

This study included 50 neonates with suspected sepsis. A blood sample was collected and divided into two parts: one part was subjected to broad-range 16S rDNA detection by PCR (runtime 6 h) and the other part was inoculated onto blood culture bottles (monitored for 6 days). In addition, some risk factors associated with clinical sepsis were explored.

RESULTS

Twenty-four neonates (48%) were positive for bacterial DNA by PCR and 17 cases (34%) had a positive blood culture. Seventeen neonates were positive for both blood culture and bacterial DNA. There was no statistical significance between both methods and the risk factors studied, except for sex and blood culture. The results of PCR in the detection of bacterial sepsis when compared with blood culture showed 100% sensitivity, 78.79% specificity, 70.83% positive predictive value, and 100% negative predictive value. An excellent agreement was found between the two methods (κ=0.716, P<0.001).

CONCLUSION AND RECOMMENDATIONS

The PCR detected a higher rate of sepsis in neonates than blood culture. Therefore, PCR is useful for the rapid and accurate diagnosis of bacterial infection, with a significant impact on the current inappropriate and unnecessary use of antibiotics in the treatment of newborns. We recommend using broad-range PCR to rapidly diagnose infants with sepsis.

Diagnosis of neonatal sepsis by broad-range 16S real-time polymerase chain reaction

BACKGROUND

The standard diagnostic test (blood culture) for suspected neonatal sepsis has limitations in sensitivity and specificity, and 16S polymerase chain reaction (PCR) has been suggested as a new diagnostic tool for neonatal sepsis.

OBJECTIVES

To develop and evaluate a new real-time PCR method for detection of bacterial DNA in blood samples collected from infants with suspected neonatal sepsis.

METHODS

Immediately after blood culture, a study sample of 0.5-1.0 ml whole blood was collected and used for a novel 16S real-time PCR assay. All positive samples were sequenced. Detailed case studies were performed in all cases with conflicting results, to verify if PCR could detect pathogens in culture negative sepsis.

RESULTS

368 samples from 317 infants were included. When compared with blood culture, the assay yielded a sensitivity of 79%, a specificity of 90%, a positive predictive value of 59%, and a negative predictive value of 96%. Seven of the 31 samples with a positive PCR result and a negative blood culture had definite or suspected bacterial sepsis. In five samples, PCR (but not blood culture) could detect a pathogen that was present in a blood culture collected more than 24 h prior to the PCR sample.

CONCLUSIONS

This study presents an evaluation of a new real-time PCR technique that can detect culture-positive sepsis, and suggests that PCR has the potential to detect bacteria in culture-negative samples even after the initiation of intravenous antibiotics.