Acacia ehrenbergiana (Hayne) and Prosopis juliflora Extracts Promote the Survival of Caenorhabditis elegans Infected with Methicillin-Resistant Staphylococcus aureus

Background: Staphylococcus aureus (S. aureus) is a leading cause of skin and soft tissue infections, with antibiotic-resistant strains causing potentially life-threatening diseases. This study explored the antimicrobial potential of Acacia ehrenbergiana (Hayne) and Prosopis juliflora using a Caenorhabditis elegans (C. elegans) in vivo model infected with methicillin-susceptible (MSSA) and methicillin-resistant (MRSA) S. aureus strains. Methods: Wild-type C. elegans were exposed to MSSA strain ATCC 25923 and MRSA strains ATCC BF195 and ATCC BC 3820 using an agar-based killing assay. The impact of ethanol extracts from A. ehrenbergiana and P. juliflora on the survival of infected C. elegans was assessed by analyzing the survival rates of infected and non-infected worms. The effects of the plant extracts on C. elegans feeding rate and colonization of MSSA and MRSA in the worm's gut were also examined. Additionally, in vitro assays were conducted to assess the bactericidal and/or bacteriostatic effects of the plant extracts. Results: Exposure to MSSA and MRSA strains significantly reduced C. elegans lifespan, with a mean time to death (TDmean) of 72 ± 1.3 h. Treatment with 100–500 μg/ml of either plant extract increased C. elegans survival by 65–70%. The extracts did not affect C. elegans pharyngeal pumping. Colony-forming Unit (CFU) assays showed a significant reduction in MSSA and MRSA colonization in the worm intestine with P. juliflora, but not A. ehrenbergiana extracts. In vitro Minimum Inhibitory Concentration (MIC) assays indicated that neither extract had direct bactericidal activity, suggesting the observed reduction in bacterial infection in worms was likely due to enhanced host immune response rather than direct antibacterial effects. Conclusion: These findings suggest that A. ehrenbergiana and P. juliflora extracts enhance C. elegans survival upon infection through indirect mechanisms, possibly involving immune system activation. This study highlights the potential of these extracts as antibacterial agents against MSSA and MRSA strains.