Extracts of Selected South African Medicinal Plants Mitigate Virulence Factors in Multidrug-Resistant Strains of .

The emergence of multidrug-resistant (MDR) remains a global health threat due to its alarming rates of becoming resistant to antibiotics. Therefore, identifying plant-based treatment options to target this pathogen's virulence factors is a priority. This study examined the antivirulence activities of twelve plant extracts obtained from three South African medicinal plants (, and ) against carbapenem-resistant (CBR) and extended-spectrum beta-lactamase (ESBL) positive strains. The plant extracts (ethyl acetate, dichloromethane, methanol, and water) were validated for their inhibitory activities against bacterial growth and virulence factors such as biofilm formation, exopolysaccharide (EPS) production, curli expression, and hypermucoviscosity. The potent extract on biofilm was observed with a scanning electron microscope (SEM), while exopolysaccharide topography and surface parameters were observed using atomic force microscopy (AFM). Chemical profiling of the potent extract was analysed using liquid chromatography-mass spectrometry (LC-MS). Results revealed a noteworthy minimum inhibitory concentration (MIC) value for the dichloromethane extract at 0.78 mg/mL on CBR- . (ethyl acetate) showed the highest cell attachment inhibition (67.25%) for CBR- SEM correlated the findings, evidenced by a significant alteration of the biofilm architecture. The highest EPS reduction of 34.18% was also noted for (ethyl acetate) and correlated by noticeable changes observed using AFM. (ethyl acetate) further reduced hypermucoviscosity to the least length mucoid string (1 mm-2 mm) at 1.00 mg/mL on both strains. (aqueous) showed biofilm inhibition of 45.91% for the ESBL-positive and inhibited curli expression at 0.50 mg/mL in both strains as observed for (aqueous) extract. Chemical profiling of (ethyl acetate), (aqueous), and (aqueous) identified diterpene (10.29%), hydroxy-dimethoxyflavone (10.24%), and 4,5-dicaffeoylquinic acid (13.41%), respectively, as dominant compounds. Overall, the ethyl acetate extract of revealed potent antivirulence properties against the studied MDR strains. Hence, it is a promising medicinal plant that can be investigated further to develop alternative therapy for managing -associated infections.