This study aims at checking the inhibitory effects of different plant extracts on biofilm forming microorganisms isolated from clinical setting. A total of 60 samples including 30 from oral sites and 30 from urine and wounds were collected and 50 morphologically different strains were isolated. Six highly resistant strains were characterized morphologically, physiologically, biochemically and genetically. Isolated strains were tested for biofilm formation using test tube assay, Congo red assay and liquid-interface coverslip assay. Antibacterial activity of aqueous and methanolic extracts of 5 different plants including Camellia sinensis (green tea), Syzygium aromaticum (clove), Musa sepientum (banana), Mentha piperita (peppermint) and Allium sativum (Garlic) was determined both individually and in combination against selected strains in both planktonic and biofilm mode. 16srRNA sequencing identified strains as Providencia stuartii, Shigella sonnei, Escherichia coli, Bacillus cereus_, Enterobacter aerogenes and Macrococcus caseolyticus. Significant biofilm formation was observed by each of the three methods for all strains except for E. coli and P. stuartii. Aqueous extract of A. sativum showed highest antibacterial activity against all strains with MIC ranging from 75-735 mg ml^-1 and MBC from 255-740 mg ml^-1. Aqueous extracts of M. sepientum exhibited maximum biofilm reduction in B. cereus. Reported knowledge of medicinal plants as antibacterial and antibiofilm agents against both highly contagious and antibiotic resistant gram positive and the gram negative isolates provide novel information necessary to control their formation in clinical setting. Hence, there is an increasing need to research new substances with the ability to inhibit these strains.

Key words: A. sativum, Biofilm formation, Methanolic extracts, Plant extracts