Antibacterial and Antivirulence Activities of Capparis spinosa L. against Acinetobacter baumannii and Streptococcus mutans

The urgent hunt for new antimicrobial medicines has been spurred on by the increasing threat of multidrug-resistant bacterial diseases. Against two therapeutically important pathogens, Acinetobacter baumannii and Streptococcus mutans, this work assessed the antibacterial and antivirulence effects of Capparis spinosa L. leaf and flower extract. Assessed were antibacterial effects using minimum bactericidal concentration (MBC), minimum inhibitory concentration (MIC), and disk diffusion tests. Furthermore, quantitative real-time PCR (qRT-PCR) examined the expression levels of the virulence-associated genes ompA and gtfB. Concerning concentration-dependent antibacterial activity, S. mutans shown more sensitivity than A. baumannii. For S. mutans, MIC values were 16 mg/mL and for A. baumannii they were 32 mg/mL. Significantly downregulation of ompA and gtfB at sub-inhibitory extract concentrations (p < 0.001) indicated by gene expression analysis suggested compromised adhesion and biofilm development capacity. These results show C. spinosa extract as a potential natural agent that not only prevents bacterial development but also disturbs important pathogenic processes. It is advised to investigate its active components and in vivo efficiency further.