Minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) determination

MIC and MBC of SBT@AgNPs against different bacterial strains was evaluated by broth dilution method as proposed by National Committee for Clinical Laboratory Standards (CLSI 2019). Briefly, wide range dilutions (1–128 μg/ml) of SBT@AgNPs were prepared and 100 μl of each dilution was incubated with 100 μl of log culture (10⁵–10⁶ CFU/ml) of K. pneumoniae, P. aeruginosa, E. coli and S. aureus in a 96 well microtitre plate for 18–24 h at 37 °C. Minimum dilution of SBT@AgNPs showing no visible turbidity in broth was termed as MIC of SBT@AgNPs against tested pathogen. For MBC, contents from each well were plated on separate nutrient agar plates and incubated overnight at 37 °C. Next day, lowest concentration of SBT@AgNPs showing no growth on nutrient agar plate was termed as MBC of SBT@AgNPs against tested pathogen.