Detection of biofilm formation in staphylococcus aureus. Does it have a role in treatment of MRSA infections?

Staphylococcus aureus is a causative agent of many types of diseases throughout the world. Staphylococcal infections are of particular concern because of the causative bacteria offering resistance to a wide range of commonly used antibiotics. The formation of biofilm is the hallmark characteristic of S. aureus infection. Biofilms constitute reservoir of pathogens and are associated with resistance to antimicrobial agents and chronic infections. In this study 262 clinical strains of S. aureus were screened by tissue culture plate method, tube method and congo red agar method for biofilm formation. Antimicrobial sensitivity testing of these strains was done by Kirby bauer disc diffusion method. Tissue culture plate method detected 38 (14.51%) isolates as strong biofilm producers, 132 (50.38%) as moderate biofilm producers and 92 (35.11%) strains as nonproducers of biofilm. The congo red agar method had a low sensitivity and specificity of 67.65 and 89.13%. The tube method correlated well with tissue culture plate method with a sensitivity and specificity of 99.40 and 95.78% but the interpretation are observer dependent. Biofilm production was higher in methicillin resistant strains as compared to the methicillin sensitive strains of S. aureus. Biofilm producers were found to be more resistant to almost all the groups of antibiotics.