Antibacterial and antibiotic synergistic activities of the extract from Pithecellobium clypearia against clinically important multidrug-resistant gram-negative bacteria

Abstract

Abstract Introduction Multidrug-resistant Acinetobacter baumannii (MDRAB) and Pseudomonas aeruginosa (MDRPsA) have attracted widespread attention. Antibiotic adjuvants can give a second life to antibiotics that bacteria have developed resistance to. Pithecellobium clypearia is a medicinal plant used in China for treating various diseases, including infections. Pithecellobium clypearia may have the potential as an antibiotic adjuvant to enhance the effect of antibiotics. Methods The antibacterial and synergistic activities of extract from Pithecellobium clypearia (S20b) and antibiotics, alone and in combination with MDRAB and MDRPsA, were evaluated in vitro against 20 clinic multidrug-resistant isolates by the micro-dilution and checkerboard dilution methods. The compounds in S20b were analysed by RRLC-MS/MS. The mechanism of S20b was confirmed by transmission electron microscopy (TEM). Results S20b demonstrated potential inhibitory activity against MDRAB and MDRPsA and showed a synergistic effect of interaction with the antibiotics in this experiment. The TEM results confirmed that S20b could damage the bacterial cell wall. Moreover, the effects of S20b on the reversion resistance of A. baumannii and P. aeruginosa against the corresponding antibacterial agents could possibly be associated with the increase in bacterial membrane permeability. Conclusions S20b increased the efficiency of antibiotics against MDRAB and MDRPsA. This study is the first to demonstrate that S20b from Pithecellobium clypearia may have potential use as a therapeutic agent to against MDRAB and MDRPsA.