Inhibition of Staphylococcus aureus biofilm formation by gurmarin, a plant-derived cyclic peptide

Abstract

Staphylococcus aureus (Sa) is an opportunistic pathogen capable of causing various infections ranging from superficial skin infections to life-threatening severe diseases including pneumonia and sepsis. Sa produces biofilms readily on biotic and abiotic surfaces. Biofilm cells are embedded in a protective polysaccharide matrix and show an innate resistance to antibiotics, disinfectants, and clearance by host defenses. Additionally, biofilms serve as a source for systemic dissemination. Moreover, infections associated with biofilms may result in longer hospitalizations, a need for surgery, and may even result in death. Agents that inhibit the formation of biofilms and virulence without affecting bacterial growth to avoid the development of drug resistance could be useful for therapeutic purposes. In this regard, we identified and purified a small cyclic peptide, gurmarin, from a plant source that inhibited the formation of Sa biofilm under in vitro growth conditions without affecting the viability of the bacterium. The purified peptide showed a predicted molecular size of ~4.2 kDa on SDS-PAGE. Transcriptomic analysis of Sa biofilm treated with peptide showed 161 differentially affected genes at a 2-fold change, and some of them include upregulation of genes involved in oxidoreductases and downregulation of genes involved in transferases and hydrolases. To determine the inhibitory effect of the peptide against Sa biofilm formation and virulence in vivo, we used a rat-implant biofilm model. Sa infected implants with or without peptide were placed under the neck skin of rats for seven days. Implants treated with peptide showed a reduction of CFU and lack of edema and sepsis when compared to that of control animals without peptide. Taken together, gurmarin peptide blocks Sa biofilm formation in vitro and in vivo and can be further developed for therapeutic use.

Evaluation of anti-quorum sensing and antibiofilm effects of secondary metabolites from Gambeya lacourtiana (De Wild) Aubr. & Pellegr against selected pathogens

“…Swarming motility is also necessary for the dispersion of biofilms. Biofilms consist of extracellular matrix made up of self-produced substances, such as lipids, proteins and polysaccharides that protects the bacteria from disinfectants, antibiotics and host defence systems and contribute to increase resistance, and different antimicrobials that are capable of inhibiting biofilms and reducing virulence without killing the bacteria are important antimicrobial therapeutics [ 47 , 48 ]. The ability of the test compounds to inhibit biofilm formation at low concentrations (sub-MIC), is a very good indication of their possible potential application to overcome microbial resistance developed by biofilms embedded pathogen cells.…”

Evaluation of Antimicrobial Properties and Potential Applications of Pseudomonas gessardii M15 Rhamnolipids towards Multiresistant Staphylococcus aureus

“…The biofilm-adhered stain was resolubilized in ethanol, and the plates were incubated at RT for 30 min. Biofilm inhibition was quantified by measuring OD 570 [ 32 ]. The inhibition was calculated by comparing absorbance at 570 nm of the biofilm in the control with the absorbance of the treated condition.…”

Oreoch-1: A Peptide from Oreochromis niloticus as a Potential Tool against Staphylococci

“…S. aureus colonizes about 30% of the human population; simultaneously, it is a leading cause of bacteremia, infective endocarditis, and skin, soft tissue, osteoarticular, and device-related infections [4]. Its ability to infect and develop biofilm on prosthetic devices within the host is a well-established virulent trait, making patient management more challenging [5,6]. Biofilm is a complex community of sessile bacteria encased in a dense extracellular matrix of water, nutrients, polysaccharides, DNA, and proteins which provides protection from the immune system and drugs, hence significantly limiting the available treatment options [7].…”