The rise of antimicrobial resistance necessitates the search for novel therapeutic agents. This study investigated the antibacterial potential of Capparis decidua stem extracts against multidrug-resistant bacterial strains. Ethanolic extract (EECD) and its derived fractions—chloroform-soluble (CSF), acetone-soluble (ASF), and acetone-insoluble (AIF)—were evaluated using agar well diffusion and broth dilution methods.

Results demonstrated that both EECD and CSF exhibited significant antimicrobial activity. The CSF fraction showed superior efficacy, particularly against Escherichia coli, with a maximum zone of inhibition (ZOI) of 26.28 mm and a minimum inhibitory concentration (MIC) of 204.6 µg mL⁻¹. The EECD was most effective against E. coli (ZOI: 22.42 mm; MIC: 242.3 µg mL⁻¹), followed by Bacillus subtilis. In contrast, the ASF and AIF fractions displayed markedly lower activity. The ethanolic extract showed the least inhibition against Pseudomonas aeruginosa (ZOI: 14.65 mm).

The findings confirm that Capparis decidua stem possesses potent antibacterial compounds, especially within its chloroform-soluble fraction. This validates its traditional medicinal use and highlights its promise as a source for developing complementary antimicrobial agents against drug-resistant pathogens.