In vitro biofilm production of Candida bloodstream isolates: any association with clinical characteristics?

Abstract

Candida spp. are a leading cause of bloodstream infection (BSI) and are associated with high mortality rates. Biofilm production is a virulence factor of Candida spp., and has been linked with poor clinical outcome. The aim of our study was to assess biofilm production of Candida bloodstream isolates at our institute, and to determine whether in vitro biofilm production is associated with any clinical characteristics of infection. During the four-year study period, 93 cases of Candida BSI were analysed. The most frequently isolated species was C. albicans (66.7 %), followed by C. glabrata (9.7 %), C. parapsilosis (9.7 %), C. tropicalis (9.7 %) and C. krusei (4.3 %). Biofilm production was more prevalent among non-albicans Candida spp. (77.4 %) than C. albicans (30.6 %) (P50.02). Abdominal surgery was identified as a risk factor of BSI caused by biofilm producing non-albicans Candida isolates. No risk factors predisposing to bloodstream infection caused by a biofilm producing C. albicans isolate were identified. Biofilm production was not verified as a risk factor of mortality.

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

“…These observations are consistent with the findings published by Tumbarello et al (2012), who showed 51% mortality in the biofilm‐producer group compared with isolates not producing biofilm (32%) based on XTT assay . In contrast, Pongrácz et al (2016) and Muñoz et al (2018) did not confirm biofilm production as a risk factor for mortality . In the present study, 30‐day mortality caused by Candida isolates producing biofilms was significantly higher comparing isolates with low and intermediate/high metabolic activity; in addition, intermediate/high metabolic activity proved to be a significant predictor of mortality in multivariate analysis.…”

“…Based on a recent epidemiological meta‐analysis, the incidence of candidaemia in Europe is 3.88 cases per 100 000 corresponding to approximately 79 cases per day . According to a number of studies, patients infected by biofilm‐producing isolates have a worse prognosis; however, contradicting studies also exist . This controversy is probably due, at least partly, to variability in the cut‐off values used to distinguish low from intermediate and high biofilm producers The other possible reason may be the high variability of the examined patient populations …”

“…Biofilm formation is a key virulence factor for Candida species; it serves as a focus in bloodstream infections, protects the fungal cells against the immune response; furthermore, the presence of biofilms is associated with reduced susceptibility to antimicrobial agents . Until recently, data on the clinical impact of Candida biofilm on mortality were scarce and there were more contradictions than answers due to the diverse experimental settings and variable patient populations . Several studies drew attention to the problems possibly arising from the variability of biofilm detection methods and the poorly standardised cut‐off points to distinguish biofilm‐producer isolates from strains with low biofilm production capability .…”

“…Nonetheless, the association of clinical variables with biofilm mass and metabolic activity at the same time is less studied . Hence, reports on the association of Candida biofilms with mortality are frequently contradictory; several studies showed that biofilm production is linked to significantly higher mortality, while other results do not support this observation . In this study, we used XTT and crystal violet assays to simultaneously assess the clinical impact of biofilm development on mortality, in patients with candidaemia.…”

“…9 Until recently, data on the clinical impact of Candida biofilm on mortality were scarce and there were more contradictions than answers due to the diverse experimental settings and variable patient populations. [10][11][12] Several studies drew attention to the problems possibly arising from the variability of biofilm detection methods and the poorly standardised cut-off points to distinguish biofilm-producer isolates from strains with low biofilm production capability. [10][11][12][13] Generally, two simple rapid screening platforms are used to examine biofilm production, that is quantification of biomass production using crystal violet-based staining 14 and quantification of the metabolic activity of sessile cells using XTT (2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) reduction assay.…”