Phytochemical study and evaluation of the antibacterial and anti-biofilm activities of ethanolic extracts of Lavandula mairei and Pulicaria mauritanica in the fight against nosocomial infections

The rise of multi-resistant strains in nosocomial infections poses a severe public health challenge, largely driven by biofilm formation, which sustains infections in hospital settings. Medicinal plants offer a potential solution to combat these resistant infections. This study investigates the antibacterial and anti-biofilm properties of two Moroccan plants: Lavandula mairei Humbert and Pulicaria mauritanica Coss. The chemical composition of these plants was analyzed through phytochemical screening, mineral analysis, infrared spectroscopy, and HPLC-UV. The Minimum Inhibitory Concentration (MIC) was performed by microdilution in order to evaluate the antibacterial activity of the extracts against the bacterial strains: Staphylococcus aureus, Escherichia coli, Bacille cereus, Acinetobacter baumannii and Pseudomonas aeruginosa. The anti-biofilm activity was measured by evaluating the biomass of the biofilm formed by P. aeruginosa and E. coli using the crystal violet staining method. The screening phytochemical tests revealed that both plants contain tannins, flavonoids, sterols, and triterpenes, but lack alkaloids and saponins. Mineral analysis showed high levels of essential elements such as calcium, potassium, and zinc, with heavy metals within safe limits. Thermogravimetric analysis indicated dehydration and organic matter loss at specific temperature ranges. HPLC-UV identified phenolic compounds, including quercetin and caffeic acid, with higher concentrations in Pulicaria mauritanica. relative to antibacterial activity, MIC against the bacterial strains tested, demonstrated varying efficacy across bacterial strains. Anti-biofilm activity against P. aeruginosa revealing a reduction in biofilm biomass. These findings highlight the potential of Lavandula mairei and Pulicaria mauritanica as natural alternatives to address antibiotic resistance in nosocomial infections.