An Investigation on Biofilm Formation and Expression of the icaA Gene among Staphylococcus aureus Strains Treated with Garlic Extract and Ciprofloxacin

Staphylococcus aureus is a bacterial pathogen that is responsible for a broad range of human infections. Infections caused by drug-resistant S. aureus are a global health threat. Biofilm formation capability of S. aureus, which is an important factor in infection establishment and drug resistance and thus therapeutic failure, is mainly mediated by ica operon, which is responsible for the production of polysaccharide intercellular adhesions. Inhibition of bacterial biofilm as a promising antibacterial approach has gained attention recently. In addition, several natural compounds, especially of plant origin, have displayed anti-biofilm potential against bacteria. Allicin is the major bioactive compound found in garlic (Allium sativum) and is responsible for its antimicrobial activity. Thus, this study aimed to evaluate the effects of garlic extract in combination with ciprofloxacin on the biofilm formation of pathogenic S. aureus. Antimicrobial effects and minimum inhibitory concentration (MIC) of either the agent alone or in combination were determined, and the bacterial biofilm formation and expression of the icaA gene were investigated. The results showed that garlic extract in combination with ciprofloxacin had a strong biofilm inhibitory potential and reduced biofilm formation by 54-61% compared to the control. The reduction of bacterial biofilm can be attributed to the reduction of the icaA gene, which was reduced by 59-65%. Thus, this study showed that garlic extract can be used as a promising anti-biofilm agent in combination with antibiotics and can be a good candidate to combat bacterial infections.