In vivo Antibacterial Activity of Green Algae Ulva reticulata against Staphylococcus aureus in Drosophila Model of Infection

Background: Expansion of multi-drug resistant bacteria in social communities and health facilities has been widely reported. To overcome this ever-growing problem, new antibiotics with novel mechanisms of action are urgently required. Purpose: This research was carried out aiming to investigate the in vivo antibacterial effect of green algae Ulva reticulata against Staphylococcus aureus in fruit flies (Drosophila melanogaster) model of infection. Methods: Sample was dried and extracted with ethanol using maceration method. Wild type and mutant fruit flies were infected with S. aureus and subjected to survival and bacterial load analysis in the presence or absence of tetracycline or Ulva reticulata extract at different concentrations. All data were statistically analyzed. Results: Infection of D. melanogaster with S. aureus was characterized by two notable trends: reduction of host survival and increasing level of bacterial growth in the host during the course of infection. Such events were further augmented in mutant flies lacking normal immune responses. Nonetheless, improved survival rates and reduction of bacterial load were observed in wild type and immunodeficient mutant flies challenged with S. aureus in the presence of either tetracycline or ethanolic extracts of green algae Ulva reticulata. Conclusion: Taken together, our results suggest that Ulva reticulata yielded antistaphylococcal activity in vivo thus would be a prospective source for harvesting wide spectrum antibacterial compounds.