Evaluation of semi-nested polymerase chain reaction (PCR) and mannan antigen detection compared to blood culture for diagnosis of candidemia

Invasive Candida infections have emerged as an important pathogen in the last decade, especially in immunocompromized patients. The aim of the present study was to evaluate the detection of Candida species in blood samples from pediatric patients with sepsis by blood culture method versus antigen detection method by enzyme linked immunosorbent assay (ELISA) and molecular method by polymerase chain reaction (PCR). This cross-sectional study was carried out on children at Mansoura University Children Hospital (MUCH) with the presence of clinical signs suggesting sepsis with absence of prior antifungal therapy. Laboratory diagnosis included blood culture, mannan antigen detection of Candida species by ELISA and semi-nested PCR. Candida species were detected by blood culture in 15.6% of the children and was detected by PCR and antigen detection in 20% for each. Candidemia was more frequently detected among patients with central venous lines (38.5%), children with Diabetes Mellitus (DM) (23.1%) and children with frequent blood transfusions (15.4%). However, these risk factors were not statistically significant. Mortality rate among children with candidemia was 42.9%. The sensitivity, specificity, and accuracy of antigen detection method by ELISA compared to culture, were 71.4, 89.5 and 86.7%, respectively. The sensitivity, specificity and accuracy of semi-nested PCR compared to culture were 85.7, 92.1 and 91.1% respectively. It can be concluded from this study that Candida species is a frequent pathogen associated with pediatric sepsis. Blood culture though is a reliable laboratory method for its diagnosis may lack sensitivity and requires prolonged time. Semi-nested PCR for detection of candidemia is sensitive, specific and accurate method. Mannan antigen detection by ELISA is rapid and easy; however, it may lacks specificity; it can be used as a preliminary method for screening. Further studies are recommended to detect the appropriate laboratory algorithm for early diagnosis of candidemia to start antifungal therapy appropriately.