# Resveratrol: A Review on the Biological Activity and Applications
## 13 Antimicrobial Activity  
RSV manifests antimicrobial action opposite to a remarkably extensive spectrum of bacterial and fungal species. It has the ability to modify the bacterial expression of a virulence nature, affecting the cell cycle, promoting decreased toxin formation, suppressing biofilm generation, limited motility, and influencing the quorum sensing (QS) for both health benefits and as a natural food preservative [236]. In association with regular antibiotics, RSV stimulates the activity of aminoglycosag against _Staphylococcus aureus_ while it inhibits the noxious activity of fluoroquinolones against _S. aureus_ and _Escherichia coli_. Moreover, topical administration of this nutraceutical has proven beneficial in acne lesions provoked by _Propioniibacterium acnes_. Recent data illustrate that the synergic combination of RSV with specific antibiotics may increase their antimicrobial potency, alleviating the crescent issue of antimicrobial resistance [237; 238].  
The virulence factors of methicillin-resistant _S. aureus_ (MRSA) clinical isolates, such as hemolysis, hemagglutination, protease, biofilm, and lecithinase, were significantly inhibited by \(t\)RSV 50 \(\mu\)g/mL and curcumin 20 \(\mu\)g/mL in vitro separate administration.  
Consequently, \(t\)RSV and curcumin could be used as an alternative therapy against bacterial resistance to antibiotics [239].  
RSV inhibits _E. coli_ virulence factors and cell growth by increasing DNA fragmentation, blocking Z-ring formation, and fitsZ gene expression. In addition, RSV administration increased cell elongation and ROS production in _E. coli_[240].  
RSV and polymycin B act synergistically against multidrug-resistant (MDR) Gram-negative _Klebsiella pneumoniae_ and _E. coli_ bacterial strains. Minimum inhibitory concentrations (MICs) of polymycin B were significantly lowered by RSV (32 ug/mL to 128 ug/mL, optimal concentrations depending on bacteria). The study evidenced that the sensitivity of MDR Gram-negative bacterial strains to polymycin B can be increased by RSV treatment [241].  
Typical bacterial infection produced by MDR _Pseudomonas aeruginosa_ is very difficult to treat, using polymyxins as the last alternative therapy, with unfavorable pharmacodynamics and PK, improbable to attain effective blood levels. Well-tolerated RSV had a synergic effect combined with polymyxin B therapy when analyzed in vitro on antibacterial and anti-biofilm activities [242]. It was also established that Chilean RWs have an antibacterial effect against _Helicobacter pylori_ due to the existence of RSV in their composition [243; 244].  
A recent in vitro study highlighted that RSV, chlorhexidine digluconate (CHX), and benzalkonium chloride (BZK) co-administration could be successfully applied against nosocomial pathogens responsible for healthcare-associated infections, such as _Burkholedia_ spp., _K. pneumoniae_, _P. aeruginosa_, _Stenotrophomonas maltophilia_, and _Candida albicans_ clinical isolates [245].  
RSV treatment (50 and 100 ug/mL) can also inhibit motility, QS system, and biofilm formation of _Aeromonas hydrophilic_, a Gram-negative aquatic bacterium responsible for septicemia in humans [246].  
_C. albicans_ is the principal candidiasis-inducing fungal pathogen in humans, and one of its most critical virulence elements is its capacity to synthesize biofilms. The antifungal effects of RSV (10-20 ug/mL) alter the morphological transition of _C. albicans_ following several hypha-inducing circumstances and reduce the growth of the yeast form and mycelia. Therefore, RSV has promising anti-_Candida_ actions via suppressing existing or in the formation process _C. albicans_ biofilms [247; 248].