Candida biofilm production is associated with higher mortality in patients with candidaemia.

Background: Candidaemia is a common life-threatening disease among hospitalised patients, but the effect of the Candida biofilm-forming ability on the clinical outcome remains controversial.

Objective: The aim was to determine the impact of biofilms, specifically focusing on biofilm mass and metabolic activity, on the mortality in candidaemia.

Patients/methods: The clinical data of patients (n = 127) treated at the University of Debrecen, Clinical Centre, between January 2013 and December 2018, were investigated retrospectively. Biofilm formation was assessed using the crystal violet and XTT assays, measuring the biofilm mass and metabolic activity, respectively. Isolates were classified as low, intermediate and high biofilm producers both regarding biofilm mass and metabolic activity. The susceptibility of one-day-old biofilms to fluconazole, amphotericin B, anidulafungin, caspofungin and micafungin was evaluated and compared to planktonic susceptibility.

Results: Intermediate/high biofilm mass was associated with significantly higher mortality (61%). All Candida tropicalis, Candida parapsilosis and Candida glabrata isolates originating from fatal infections were intermediate/high biofilm producers, whereas this ratio was 85% for Candida albicans. Solid malignancy was associated with intermediate/high biofilm producers (P = .043). The mortality was significantly higher in infections caused by Candida strains producing biofilms with intermediate/high metabolic activity (62% vs. 33%, P = .010). The ratio of concomitant bacteraemia was higher for isolates forming biofilms with low metabolic activity (53% vs 28%, P = .015).

Conclusions: This study provides evidence that the Candida biofilms especially with intermediate/high metabolic activity are related to higher mortality in candidaemia.