Synergistic Effect of Plant Compounds in Combination with Conventional Antimicrobials against Biofilm of Staphylococcus aureus, Pseudomonas aeruginosa, and Candida spp.

Abstract

Bacterial and fungal biofilm has increased antibiotic resistance and plays an essential role in many persistent diseases. Biofilm-associated chronic infections are difficult to treat and reduce the efficacy of medical devices. This global problem has prompted extensive research to find alternative strategies to fight microbial chronic infections. Plant bioactive metabolites with antibiofilm activity are known to be potential resources to alleviate this problem. The phytochemical screening of some medicinal plants showed different active groups, such as stilbenes, tannins, alkaloids, terpenes, polyphenolics, flavonoids, lignans, quinones, and coumarins. Synergistic effects can be observed in the interaction between plant compounds and conventional drugs. This review analyses and summarises the current knowledge on the synergistic effects of plant metabolites in combination with conventional antimicrobials against biofilms of Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. The synergism of conventional antimicrobials with plant compounds can modify and inhibit the mechanisms of acquired resistance, reduce undesirable effects, and obtain an appropriate therapeutic effect at lower doses. A deeper knowledge of these combinations and of their possible antibiofilm targets is needed to develop next-generation novel antimicrobials and/or improve current antimicrobials to fight drug-resistant infections attributed to biofilm.

Anti-Biofilm Activity of Oleacein and Oleocanthal from Extra-Virgin Olive Oil toward Pseudomonas aeruginosa

“…The low activities of these compounds against PA SW may be linked to differences among the bacterial strains in their genetic background and in the production of other polysaccharides (polysaccharide synthesis loci) and molecules (pyoverdine and rhamnolipids), as well as in the presence of extracellular DNA in the biofilm matrix. All these factors are mainly involved in the initial attachment of bacterial cells and early biofilm formation [30,31].…”

“…Indeed, the respiratory strain was able to produce more alginate than the surgical infection site's isolate (p = 0.048). Consequently, it is likely that the extracellular matrix of the biofilm of the strain isolated from the surgical infection site can include not only alginate but also other polysaccharides, such as pellicle polysaccharide, that are essential for late-stage biofilm formation and maturation [31,[35][36][37] and may be less susceptible to oleocanthal.…”

Rutin/Sulfobutylether-β-Cyclodextrin as a Promising Therapeutic Formulation for Ocular Infection

“…As a response to rising antibiotic resistance, new therapeutic strategies are in development. Over the years, interest in plant extracts and their metabolites has risen within the scientific community [ 12 , 13 ]. Rutin (RTN) ( Figure 1 ), which is a flavonoid isolated from plants or fruits, showed antibacterial activity against S. aureus , A. baumannii , and P. aeruginosa [ 14 ].…”