Invasive candidiasis are the most common form of fungal infection in critically ill patients, particularly intra-abdominal candidiasis (IAC), which is associated with high morbidity and mortality. The current diagnostic gold standard relies on conventional fungal culture, which has a long turnaround time and may delay targeted antifungal therapy. Non-culture-based assays such as 1,3-β-D-glucan lack specificity for early and definitive diagnosis. Molecular diagnostics, including PCR, offer faster and more specific detection, but their clinical use remains limited.

The CandID PLUS PCR assay targets major Candida species and has not yet been evaluated on peritoneal fluid.

The CANDIDIAG study aims to assess the feasibility and diagnostic performance of the CandID PLUS PCR in detecting Candida spp. in peritoneal fluid from ICU patients with suspected IAC.

This study constitutes a post-hoc analysis of the pBDG2 study (Prospective evaluation of the peritoneal 1.3 Beta-D-glucan for the diagnosis of intra-abdominal candidiasis in the critically ill patients) registered with the number NCT 03997929). Therefore, all patients have been already recruited. For the CANDIDIAG study, we will use the biological collection of peritoneal fluid issue from the pBDG2 study. All patients with confirmed intra-abdominal candidiasis are identified. We will test de CandID PCR, retrospectively, on their peritoneal fluid and compared the results with the fungal culture.

Inclusion Criteria:

• adult critically ill patient
• with confirmed intra-abdominal candidiasis (culture positive with Candida albicans, glabrata, parapsilosis, tropicalis, krusei, and dubliniensis)
• enrolled in the pBDG2 study (NCT 03997929)
• intra-abdominal candidiasis documented at

Exclusion Criteria:

• Declined to participate
• intra-abdominal candidiasis caused by other candida species

The pBDG2 study enrolled 199 ICU patients across four participating centers. Inclusion criteria were: adult ICU patients with suspected intra-abdominal infection likely due to Candida spp., requiring emergency abdominal surgery.

Among the enrolled patients, 88 were diagnosed with confirmed intra-abdominal candidiasis based on positive fungal culture.

Only these 88 patients will be eligible for inclusion in the CANDIDIAG study. This constitutes a post-hoc analysis of a predefined subpopulation from the pBDG2 cohort.

Participating centers included the University Hospitals of Nancy, Dijon, Strasbourg, and the Regional Hospital Center of Metz (CHR Metz)