Anti-Bacterial Properties of Bletilla striata Dihydrophenanthrene Against Extended Spectrum β-Lactamases-Carrying and Carbapenem-Resistant Escherichia coli from Hospital Clinical Practice

Abstract

The present study was aimed at investigating anti-bacterial effects of Bletilla striata dihydrophenanthrene (DHP) on clinically isolated Escherichia coli (E. coli), including extended spectrum β-lactamases (ESBLs)-carrying E. coli and carbapenem-resistant E. coli (CRE). The minimum inhibitory concentrations (MIC) of two extracts, DHP and residual substances extracted by ethanol and n-butanol (NBE), were determined by the serial dilution method. The light absorption value of macromolecular substances, total leakage rate, and total protein content in the nutrient solution were determined by spectrophotometric analysis. Quantification of protein expression and drug susceptibility verification were determined by mass spectroscopy. In addition, the elimination of drug-resistant plasmids was evaluated. Our data showed that the DHP had a more powerful antibacterial effect on E. coli than that of NBE, with MICs of 0.82–1.38 mg/mL and 1.07–1.51 mg/mL, respectively. In addition, DHP enhanced the absorbance value of macromolecular substances, and increased protein expression in E. coli when compared with NBE. Moreover, NBE increased the total leakage rate of small molecule substances, total protein content, and reversed drug resistance when compared with DHP. Both NBE and DHP eliminated the banding patterns related to multidrugresistant plasmids, selectively inhibited bacterial growth and reversed multidrug resistance by regulating cell membrane permeability and protein expression levels in E. coli. The reversal of drug resistance may be mediated through elimination of drug-resistant plasmids in E. coli. Therefore, DHP and NBE may be promising antibacterial drug candidates, and DHP is more likely.