Usefulness of a semi-quantitative procalcitonin test kit for early diagnosis of neonatal sepsis

Introduction: This study was designed to determine the sensitivity and specificity of a semi-quantitative procalcitonin (PCT) test kit for the diagnosis of neonatal sepsis.

Methods: Infants admitted to the neonatal intensive care unit with signs suggestive of sepsis were recruited into the study. Prior to commencement on antibiotics, the following investigations were carried out on each of these infants: blood culture and sensitivity, PCT semi-quantitation and C-reactive protein (CRP) estimation. Infants already on antibiotics, or who developed signs of sepsis within 72 hours of discontinuation of antibiotics, were excluded from the study.

Results: Of the 87 infants recruited, 18 (20.7 percent) were confirmed to have sepsis based on positive blood culture results. At a PCT cut-off level of greater than or equal to 2 ng/ml, the sensitivity of the PCT-Q kit in detecting neonatal sepsis at the onset of symptoms was 88.9 percent and its specificity was 65.2 percent. The sensitivity of CRP for diagnosis of sepsis was 55.6 percent and its specificity was 89.9 percent.

Conclusion: The semi-quantitative PCT test kit is of moderate sensitivity but poor specificity for early diagnosis of neonatal sepsis. A negative PCT test result may help to "rule out", while a raised CRP result helps to "rule in", the possibility of sepsis.