Study on Antibacterial Activity of Water Extract of Galla chinensis Against Carbapenemase-Producing Enterobacteriaceae

Carbapenemase-producing Enterobacteriaceae (CPE) represents a significant global public health concern, largely driven by factors including misuse of antibiotics and their inappropriate use in livestock. This study systematically evaluated the minimum inhibitory concentration (MIC) of Galla chinensis (GC) water extract against a range of CPE strains, aiming to assess its potential therapeutic application and efficacy against multidrug-resistant bacteria (MDR). MIC values for carbapenemase with different plasmids spanned between 3.9 and 500 mg/mL, while readings of 62.55–500 mg/L demonstrated no colonies. The growth curve analysis demonstrated that the GC extract significantly inhibited bacterial growth at both 1/4 and 1/2 MIC doses, completely inhibiting bacterial growth at 1 MIC (p < 0.01). Furthermore, the effect of 1/4 MIC was also statistically different; however, it may not provide a meaningful inhibitory effect. qRT-PCR analysis revealed an increase in the expression of carbapenemase genes, including pkPC2_InFII, pNDM5_IncX3, pIMP4_IncN, and pOXA48_IncX3 subsequent to GC extract treatment at 1/2 MIC. Transcriptomic analysis further revealed differential gene expression associated with bacterial resistance mechanisms. Consequently, the GC extract demonstrated pronounced antibacterial efficacy against CPE, exhibiting a significant ability to inhibit their growth and minimize the activity of vital resistance genes.