β-1,3 glucan as a test for central venous catheter biofilm infection

Abstract

Biofilms are microbial communities that are associated with solid surfaces such as intravascular catheters. Candida species are a major cause of medical device-associated infections. Twenty percent to 70% of all candidemias are associated with this biofilm process. Diagnosis and effective treatment of Candida device-associated infections requires removal of the involved device. The ability to identify a biofilm device infection before catheter removal may obviate removal of a substantial number of devices. Prior studies in our laboratory identified cell wall changes (specifically, increased β-1,3 glucan) associated with biofilm, compared with planktonic C. albicans. Both in vitro and in vivo (catheter) biofilm models were used to determine whether biofilm cells secreted more β-1,3 glucan and whether these differences could be used to discern the presence of a Candida biofilm infection with 3 species (C. albicans, C. glabrata, and C. parapsilosis). A limulus lysate assay was used to quantify β-1,3 glucan in supernatants from planktonic or biofilm cultures and in the serum of rats with an intravascular catheter biofilm infection or disseminated candidiasis. β-1,3 glucan was detected from both in vitro and in vivo models from each condition. However, the concentrations of β-1,3 glucan from the biofilm conditions were 4-10-fold greater in vitro (P < .001) and were 10-fold greater in vivo (P < .001), despite equal or fewer numbers of cells in the biofilm conditions. These results suggest the secreted polysaccharide β-1,3 glucan may serve as a useful tool for the diagnosis of Candida biofilm and device-associated infections. © 2007 by the Infectious Diseases Society of America. All rights reserved.