Comparison of Candida Polymerase Chain Reaction Method and Blood Culture in Patients with High Risk of Candidemia in Intensive Care Unit

Abstract

Candida species are responsible for 70-90% of invasive fungal infections in the intensive care unit. Early diagnosis and treatment is important in candidemia. Improper diagnosis and treatment increases mortality and morbidity significantly. Because of the late results of blood cultures and low sensitivity of the serological tests when used alone, molecular methods should be investigated in this field. In this study, the results of the Candida real-time polymerase chain reaction (Rt-PCR) test, which was studied from blood culture and whole blood, were compared in patients with high candidemia risk who were followed in the General Surgery Intensive Care and Anesthesiology and Reanimation Unit of Cukurova University Faculty of Medicine. It was aimed to investigate the practical utility of Candida RT-PCR test, which is a rapid diagnosis method in patients with suspected candidemia. In our study, 90 patients with high risk of candidemia according to the criteria determined according to the guidelines were evaluated prospectively. Urine, perineum, axilla, tracheal aspirate culture and two sets of blood cultures were obtained from the patients. Blood sample was also drawn into an ethylenediaminetetraacetic acid (EDTA) tube and stored at -40°C for later Candida Rt-PCR study. In Candida Rt- PCR, species-specific primers were used to distinguish species. Candida score (CS) of the patients was calculated. Forty one (45.5%) of the patients were female and 49 (55.5%) were male. The median age of the patients was 61.5 years. Candida was positive in blood culture in three (3.3%) of the patients included in the study, while Candida Rt-PCR was positive in 17 (18.9%). Candida species detected in the blood culture and Rt-PCR test were compatible with each other. Rt-PCR was significantly more positive (p= 0.006). Candida Rt-PCR positivity was significantly higher in patients receiving total parenteral nutrition (p= 0.028), malignancy (p= 0.021), and history of surgery in the last three months (p=0.003). The difference in CS between patients with PCR positive and PCR negative was statistically significant (p= 0.015). Our study was conducted in a high-risk population for candidemia and the results of Candida Rt-PCR was found to be more positive than blood culture. Rt-PCR positivity and blood culture positivity were associated with high CS. In the light of these data, it was thought that it would be appropriate to use molecular methods in the diagnosis and support them with CS, especially in patients with high risk of candidemia. Considering that blood culture, which is the gold standard for the diagnosis of candidemia, gives late results and is 50% positive, using faster diagnostic methods for candidemia is important to reduce mortality and morbidity. The fast and good results of Candida PCR method have shown that it can be used in diagnosis. However, lack of standardization of primers used in PCR tests may cause false positives. Additional studies are needed in this respect.