The dominant role of biofilm-associated protein (Bap) in Staphylococcus aureus biofilm development prompted us to investigate Bap as a potential target for proteinase-mediated biofilm dispersion. Biofilm assay in microtitre plates showed that proteinase K hampered the early adhesion of cells as well as biofilm development. Proteinase K treatment of 24- and 48-h-old biofilms showed enhanced dispersion of bap-positive S. aureus biofilm; however, proteinase K did not affect the bap-negative S. aureus biofilm. When antibiotics were used in combination with proteinase K, significant enhancement in antibiotic action was noticed against bap-positive S. aureus biofilm. This study establishes that antibiotics in combination with proteinase K can be used for controlling S. aureus biofilms in whose development Bap surface protein has a major role. We propose that Bap protein could be a potential target for therapeutic control of S. aureus infections (for example, bovine mastitis).

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Streptococcus pyogenes is a notorious human pathogen responsible for a wide array of infections. The ability of S. pyogenes to form biofilms is an innate property during the pathogenesis of invasive infections. From the eleven M serotypes tested: M56, M74, M100, M65, M89 and st38 formed dense biofilms in 48 h. The present study is the first of its kind to report about the biofilm formation in the serotypes M56, M65 M74 M100 and st38. XTT reduction assay of the biofilms showed decreased metabolic activity with increase in incubation time. The surface architecture of the biofilms when observed by scanning electron microscopy (SEM) revealed the microcolony formation. Confocal laser scanning microscopy (CLSM) was used to compare the surface topography and thickness of biofilms between the biofilm formers with and without the addition of glucose. Interestingly a non-biofilm former (st2147) was induced to form biofilms with the addition of glucose. On correlating the drug (erythromycin) resistance of the various M serotypes with their biofilm forming ability we noticed that erythromycin sensitive strains were found to be good biofilm formers. We also noticed that biofilm formation in S. pyogenes is independent of sil gene.

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