Phytochemical screening and bactericidal activity of three Algerian medicinal plant extracts against nosocomial multidrug-resistant enterobacteria

The emergence of multidrug-resistant bacterial strains represents a major global public health challenge. In this context, the search for bioactive compounds from natural sources has gained increasing attention. The present study aimed to investigate the phytochemical composition of hydro-methanolic extracts obtained by maceration from the leaves of Laurus nobilis L. and Rosmarinus officinalis L., as well as the roots of Glycyrrhiza glabra L., and to evaluate their antibacterial activity against Escherichia coli and Klebsiella pneumoniae, two pathogens frequently associated with nosocomial infections. Antibacterial activity was assessed using both agar diffusion and liquid culture methods. Phytochemical screening revealed the presence of saponins, terpenoids, alkaloids, tannins, and flavonoids at varying concentrations among the three plant extracts. The results showed significant antibacterial activity (P < 0.01), with inhibition zone diameters of 18 ± 0.2 mm, 23 ± 0.4 mm, and 16 ± 0.6 mm against E. coli, and 17 ± 0.4 mm, 21 ± 0.6 mm, and 19 ± 0.9 mm against K. pneumoniae, respectively. Furthermore, the MBC/MIC ratio indicated a bactericidal effect against both multidrug-resistant strains. Overall, these findings demonstrate that the studied plant extracts are rich in bioactive compounds with notable antibacterial properties, highlighting their potential as promising alternative agents for combating antibiotic-resistant infections.