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Objectives: A great setback in concern with public health is the development of emerging bacterial resistance towards conventional antibiotics making it a huge issue in the medical sector. To combat bacterial resistance, innovative strategies have been developed. One of the significant strategies is to target the bacterial pathogenicity through inhibition of quorum sensing (QS) mechanism among bacteria. QS is cell density dependent molecular communication prevailing in bacteria trends to express several genes conferring for its virulence, biofilm formation, antibiotic resistance, motility and plant-bacterial interactions etc. Methods: The current study investigates the anti-QS activity of red seaweed, against the targeted test pathogens Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter sp. and E. coli. Results and conclusion: At the concentration of 100 mg/mL of red seaweed extract, the biofilm was effectively reduced in Acinetobacter sp. and E. coli with 36 % and 40 % respectively. The exo polymeric substance (EPS) quantification from test pathogens in the presence of algal extract has declined to 40.8 % in Acinetobacter sp. and 14.8 % in E. coli reduction compared to S. aureus and K. pneumonia. Furthermore, the QS dependent motility activities are also reduced with the effect of algal extract. The efflux pump expression, being the noteworthy factor for antibiotic resistance has been inhibited by algal extract. The bioactive compounds from the algal extract A. fragilissima such as Melamine, Silicic acid, diethyl bis(trimethylsilyl) ester, Trimethyl [4-(1-methyl-1-methoxyethyl) phenoxy] silane, Benzo[h]quinoline, 2,4-dimethyl, Pyrazol-3(2H)-one, 4-nitro and 1,2-Bis(trimethylsilyl)benzene etc. Among them, Melamine showed high peak area and may responsible for the anti-QS activity and helps to overcome antibiotic resistance of the opportunistic pathogens. The QS dependent phenotypic expression among the test pathogens has been interrupted by the bioactive components of A. fragilissima.

Staphylococcus aureus is a versatile pathogen known to cause hospital- and community-acquired, foodborne, and zoonotic infections. The clinical infections by S. aureus cause an increase in morbidity and mortality rates and treatment costs, aggravated by the emergence of drug-resistant strains. As a multi-faceted pathogen, it is imperative to consolidate the knowledge on its pathogenesis, including the mechanisms of virulence regulation, development of antimicrobial resistance, and biofilm formation, to make it amenable to different treatment strategies. Nanomaterials provide a suitable platform to address this challenge, with the potential to control intracellular parasitism and multidrug resistance where conventional therapies show limited efficacy. In a nutshell, the first part of this review focuses on the impact of S. aureus on human health and the role of virulence factors and biofilms during pathogenesis. The second part discusses the large diversity of nanoparticles and their applications in controlling S. aureus infections, including combination with antibiotics and phytochemicals and the incorporation of antimicrobial coatings for biomaterials. Finally, the limitations and prospects using nanomaterials are highlighted, aiming to foster the development of novel nanotechnology-driven therapies against multidrug-resistant S. aureus.