Abstract
The bioactive algal components that contribute to their antimicrobial properties have garnered significant attention, particularly in light of the rising incidence of antibiotic resistance. The current study aimed to evaluate the antibacterial activity of a Petalonia fascia methanolic extract and to explore the potentiation action of extract–antibiotic combinations with the available antibiotics, as well as the effects of their mixture on multidrug-resistant (MDR) bacteria, namely, five methicillin-resistant Staphylococcus aureus (MRSA) strains. The algal crude extract displayed antibacterial activity against all assayed isolates, with an inhibition zone ranging from 16 to 21 mm and the best spectrum of bactericidal effect with a ratio of MBC/MIC < 4 obtained on the five tested bacterial strains. Amoxicillin–extract mixtures decreased the bacterial growth rate dramatically on all five S. aureus isolates in a time-dependent manner. These results indicate the ability of the extract to modulate antibiotic activity. However, the possibility of its use to solve the issue of antibiotic-resistant bacterial strains and their application as therapeutic agents against infectious diseases warrants further investigation.