Evaluation of biofilm formation by three different methods and its antibiogram with special reference to indwelling medical devices from a tertiary care hospital

Introduction and objective: Biofilms represent the exopolysaccharides produced by the bacteria on various indwelling devices in which they remain enmeshed. These bacteria are highly resistant to antimicrobial agents causing chronic and recurrent infections. So the present study was undertaken to detect biofilms from clinical isolates by three different methods with its antibiotic resistance pattern and association with various indwelling devices.Material and methods: The study was carried out in the Department of Microbiology, Indian Institute of Medical Science and Research Jalna over a period of three months .This is a cross-sectional type of observational study. A total of 112 clinical isolates were first identified by standard microbiological tests and then screened for biofilm formation by 1)Tube method,2)Tissue culture method and 3) Congo red agar method. Their antibiotic sensitivity pattern was determined using Kirby Bauer Disc Diffusion method and association with indwelling medical devices was observed prospectively& retrospectively.Results :Out of the 112 clinical isolates,we found 50.9% isolates produced biofilm by tissue culture method,33(29.46%) by tube method and only16(14.25%) by Congo red agar method.The predominant biofilm producer was Pseudomonas(70%) followed by Staphylococcus aureus(61.1%), Klebsiella (45.83%),Coagulase negative Staphylococcus(42.85%)and then E coli(32.14%).All the biofilm producing strains were highly resistant to commonly used antibiotics and there was a strong association between biofilm production and indwelling medical devices used for the diagnostic or therapeutic intervention.Conclusions: Tissue culture method was the most sensitive method for detection of biofilms. As the resistance of these isolates was very high, all the isolates from the medical devices should be screened both for biofilm production and their antibiotic sensitivity testing should be performed for better patients compliance and outcome. DOI:10.21276/APALM.1630