Comparison of Methods of Biofilm Detection in Urinary Candida Isolates and Evaluating its Role in Persistent Candiduria

Abstract

Introduction: Candiduria is a common finding in catheterised patients with increasing trend of non albicans Candida species. Biofilm formation on indwelling catheters leads to persistent colonisation ending up in infection in immunocompromised patients. Aim: This study was conducted with the aim of identification of Candida species isolated from urine samples of catheterised patients; comparison of three phenotypic methods for biofilm detection in these Candida isolates and evaluating the role of biofilm in persistent candiduria. Materials and Methods: A prospective study was conducted in Microbiology Department. Total 50 non repeat urine samples were selected from the patient’s sample received in the laboratory routinely. Samples with significant number of pus cells and budding yeast cells in direct microscopy and significant count of Candida species in culture from catheterised patients were subjected to HiChrom agar for species identification and tube method, congo red agar and tissue culture plate method for biofilm detection. Diagnostic test analysis was done for the three biofilm detection methods taking tissue culture plate methods as gold standard. Chi-square analysis was performed for comparison of persistent candiduria with duration of catheterisation and biofilm. Results: Sensitivity and specificity for tube method was 100% and 0% respectively and 26.53% and 100% respectively for Congo red agar. A significant difference was found in persistent candiduria in patients with duration of catheterisation of one week and those with more than one week (χ2 =0.0047 p-value=0.9) and also in proportion of biofilm positive Candida isolates in these two group of patients χ2 =4.56, p-value=0.9). Conclusion: Tube method showed excellent sensitivity while congo red agar had better specificity. This study shows that Candida colonisation and biofilm formation is associated with persistent candiduria.

Keywords

• catheter
• colonising
• hospitalised