Study of biofilm formation in indwelling catheters from patients with catheter-associated urinary tract infections

Background: Biofilms are communities of microorganisms that are enclosed in a matrix of exopolymers, contributing to chronic and recurring infections, particularly in indwelling medical devices such as urinary catheters, and have developed resistance to numerous antimicrobial drugs. Biofilms plays a crucial role in the pathogenesis of Catheter associated urinary tract infection (CAUTI), which in turn responsible for 40% of health care associated infections. Objective: The objective was to identify biofilm using phenotypic methods in urinary catheter isolates and compare these methods to choose a sensitive method with good reproducibility. Method: A total of 55 culture positive urinary isolates were identified by standard microbiological methods from 126 hospitalized patients catheterized for more than 48 hours and subjected to biofilm detection by phenotypic methods such as Tissue Culture Plate (TCP), Congo Red Agar (CR) and Tube Adherence (TA) method. Results: Out of 55, 15 (27.2%) showed biofilm formation by TCP method. Maximum biofilm production was seen in Escherichia coli (49%) followed by Klebsiella pneumoniae (27.2%). CR detected biofilm production in 45.4%, TA in 34.5% and TCP in 27.2% isolates. CR and TA methods were compared to TCP, as it is considered gold standard method and they both demonstrated a sensitivity of 86.6% and specificity of 65% and 72.5% respectively. Conclusion: TCP is a quantitative and reliable method for detection of biofilm with good reproducibility.Detection of biofilms can be recommended for chronic and recurrent infections before institution of empirical antibiotics especially in resource limited settings to effectively prevent health care associated infections.