ntra-abdominal candidiasis is a serious infection common in critically ill patients, often leading to high mortality if not treated quickly. Standard antifungal treatments may be less effective due to growing resistance and poor drug penetration into the abdominal cavity. In critically ill patients, drug levels can vary widely due to factors like surgery, inflammation, fluid resuscitation, or extracorporeal support, increasing the risk of underdosing. Rezafungin is a new antifungal agent with a long half-life and broad activity against Candida species, offering potential advantages in this setting. However, there is currently no data on its concentration or effectiveness in the peritoneal fluid of patients with intra-abdominal sepsis. Its long half-life, coupled with repeated pharmacokinetic variations in critical care settings and the risk of insufficient concentrations, may hinder its use in this population.

Inclusion Criteria:

• age > 18 years
• with a suspected intra-abdominal candidiasis requiring abdominal surgery
• and receiving the administration of rezafungin as first-line empirical antifungal treatment just before or within 1 hour the abdominal surgery
• and having abdominal drain for at least 2 days after the surgery

Exclusion Criteria:

• death expected within 24h
• decline to participate

This is a prospective PK study of critically ill adult patients with proven or suspected intra-abdominal candidiasis who are admitted to the surgical ICU at the university hospital of Nancy (France).

Adult critically ill patients with suspected intra-abdominal candidiasis requiring abdominal surgery and administration of rezafungin as first-line empirical antifungal treatment just before the abdominal surgery, abdominal drain for at least 2 days after the surgery.

Intra-abdominal candidiasis is defined following the 2024 consensus of FUNDICU