Evaluation of antibacterial potential of medicinal plant Spilanthes acmella Murr. and it’s in vitro raised callus against resistant organisms especially those harbouring bla genes

Alcoholic extracts of stem of an endangered medicinal plant Spilanthes acmella and its in vitro raised callus were evaluated for antibacterial potential against various gram positive and gram negative bacteria including resistant isolates harbouring bla genes by agar well diffusion method. The alcoholic extract of parent plant as well as its callus showed good antibacterial activity against gram positive and gram negative bacteria and also efficiently controlled the growth of most of the resistant bacteria harbouring bla genes. Minimum inhibitory concentrations (MIC) of the extracts was determined by broth microdilution method. MIC against gram positive bacteria ranged from 12.0 to 49.0 µg/ml, while MIC against gram negative bacteria ranged from 1.53 to 12.0 µg/ml and MIC against resistant bacteria harbouring bla genes ranged from 6.1 to 98.0 µg/ml. The present study shows that extracts of Spilanthes acmella contain good antibacterial activity which can be used to obtain novel antibacterial compounds for the treatment of infectious diseases that otherwise pose problem of drug resistance to currently used antimicrobials. This is the first report of antibacterial activity of S. acmella through in vitro callus and also it’s potential against gram negative bacteria harbouring bla genes.