A rapid method for Candida DNA preparation from sputum, and its clinical application

The analysis and identification of Candida in sputum specimens is of significance in clinical settings. The aim of this study was to assess the feasibility of a previously validated rapid method for preparing Candida DNA in conjunction with pretreatment with Sputasol (Aiyan Biotechnology, Shanghai, China) for detecting Candida in sputum specimens.

The study included 181 patients with respiratory diseases who were hospitalized at the Bethune International Peace Hospital between 9 and 29 January 2020. Sputum specimens were collected retrospectively, and sputum culture results and related clinical information were extracted from electronic medical records. The sputum samples were pre-treated with Sputasol digest and subjected to rapid DNA sample preparation, and duplex polymerase chain reaction (PCR) for detecting Candida.

Out of the 181 sputum specimens, 65 tested positive for Candida through PCR, and 32 were positive through fungal culture. The samples that tested positive through fungal culture were also positive through PCR, and the identified species were completely consistent. Conversely, all samples that tested negative through PCR were also negative through fungal culture. The two assays showed moderate agreement, with a Kappa value of 0.554. The false-positive results of PCR Candida detection may be attributed to antifungal treatment and higher sensitivity.

The rapid Candida DNA sample preparation technique combined with duplex PCR for Candida detection is a sensitive method for identifying Candida in sputum. It is necessary to combine PCR results with comprehensive clinical judgment for deriving conclusions. Further studies are needed to verify its clinical value.