Comparative evaluation of Candida DNA, mannan, anti-mannan antibodies and (1-3)-b-D-glucan in the diagnosis of candidaemia

Abstract number: p864

Khan  Z.U., Alam  F., Mustafa  A.S.

Background and objective: 

A delayed diagnosis of candidaemia is associated with high mortality, and therefore, early diagnosis and institution of appropriate therapy is essential to improve prognosis. The aim of this study was to evaluate sensitivity of four currently available assays, namely Platelia Candida Ag for the detection of mannan, Platelia Candida Ab for the detection of anti-mannan antibodies, snPCR for the detection of DNA, and Fungitell for detection of (1–3)-b-D-glucan in the diagnosis of candidaemia.

Methods: 

Thirty-two sera samples from 27 culture confirmed cases of candidaemia, 10 sera from Candida vaginitis patients, and 30 sera from healthy controls were included in the study. The ELISA-based tests were performed as per the instructions provided by the manufacturers. The cut-off values for each test were determined by determining mean + 3 standard deviation of the control sera. DNA was extracted from the sera using standard techniques and PCR was performed with generic as well as species-specific primers for C. albicans, C. parapsilosis, C. glabrata, and C. tropicalis.

Results: 

In candidaemia patients, the sensitivity and negative predictive value for the assys were as follows: Platelia mannan 84%, and 86%, anti-mannan antibody 56% and 68%, (1–3)-b-D-glucan 75% and 67%, and Candida snPCR 88% and 88%, respectively. When the tests were combined, the sensitivity for mannan and anti-mannan improved to 94% and mannan and (1–3)-b-D-glucan to 97%.

Conclusions: 

The results of the study suggest that the combined detection of mannan and anti-mannan antibodies or mannan and (1–3)-b-D-glucan may contribute to the early and sensitive diagnosis of candidaemia or invasive candidiasis.. However, performance of snPCR offered an advantage over mannan and glucan tests since it was species-specific and detected 4 (12%) patients who were infected with more than one species. This observation has therapeutic implications, since Candida species have different anti-fungal susceptibility profiles.

Acknowledgement: 

Supported by College of Graduate Studies, Kuwait University, Kuwait.