In vitro Screening of Some Indian Medicinal Plants for Their Activity against Extended Spectrum Beta Lactamases

Abstract

Context: Extended Spectrum Beta Lactamases (ESBLs) play an important role in pathogenesis of various infections by enabling the bacterial species to be resistant to β-lactam antibiotics including extended-spectrum cephalosporins. Plants were selected on the basis of their traditional applications.  Objective: Our investigation screens and evaluates15 Indian medicinal plants for antimicrobial efficacy and synergistic potential against ESBLs producing bacteria. Materials and Methods: 6 bacterial strains were screened for their ability to release ESBLs. Plant extracts in methanol and aqueous solvents were screened for their effect on ESBLs producing bacteria. Antimicrobial-linked ESBLs inhibition activity and minimum inhibitory concentration (MIC) of extracts were evaluated by agar well diffusion and microdilution method. Synergistic interactions between plant extracts exhibiting good antimicrobial activity and extended spectrum cephalosporins were explored by Checkerboard method. Results: Three strains were detected as ESBL positive. The results of susceptibility assay clearly showed strong ESBLs inhibitory effect of Crinum latifolium, Oroxylem indicum, Punica granatum, Sapindus emarginatus and Terminalia chebula and their MIC values ranged from 1.87-30 mg/ml. In vitro interactions between plant extracts and antibiotics cefotaxime and ceftaizidime evaluated in terms of fractional inhibitory concentration (FIC) indices indicated synergism. Discussion and Conclusion: Higher resistance of ESBLs positive strains to β-lactam antibiotics encourages us to search the novel ESBLs inhibitors. Maximum 10-fold decline in the MIC of antibiotics cefotaxime and ceftaizidime was achieved in combination with plant extracts. Owing to enormous clinical significance of ESBL-producing organisms coupled with limited therapeutic options, the results revealed by present study are of paramount importance.