Molecular approaches in the diagnosis of sepsis in neutropenic patients with haematological malignances.

INTRODUCTION: Sepsis is a major cause of significant morbidity and mortality in neutropenic patients. Blood culture remains the gold standard in the microbiological diagnosis of bacterial or fungal bloodstream infections, but it has clear limits of rapidity and sensitivity. The objective of the study was to compare the real-time polymerase chain reaction (RT-PCR) with automated blood cultures (BC) method in detection in whole blood of pathogens in febrile neutropenic patients with hematological malignancies.
METHODS: A total of 166 consecutive febrile neutropenic patients were enrolled. Blood samples for cultures and SeptiFast testing were obtained at the onset of fever, before the implementation of empirical antibiotic therapy.
RESULTS: Forty (24.1%) samples out of the 166 blood samples tested, were positive by at least one method. Twenty-three (13.9%) samples were positive by blood culture and 38 (22.9%) by multiplex real-time PCR. The analysis of concordance evidenced a low correlation between the two methods (n = 21; 52.5%), mainly due to samples found negative by culture but positive with the Septi-Fast assay. Sensitivity, specificity, and positive and negative predictive values of RT-PCR were 91.3%, 88.1%, 55.3%, and 98.4%, respectively, compared with BC. DISCUSSION: Multiplex real-time PCR assay improved detection of the most bacteria associated with febrile neutropenia episodes. Further studies are needed to assess the real advantages and clinical benefits that molecular biology tests can add in diagnosis of sepsis.