Interference in Staphylococcus aureus biofilm and virulence factors production by human probiotic bacteria with antimutagenic activity

Abstract

Given that Staphylococcus aureus, an opportunistic pathogen, is one of the main etiological agents that causes various hospital and community infections associated with the production of virulence factors, emerging treatment strategies target to attenuate the activity of these factors can be promising to combat antibiotic-resistant strains. In this perspective, we investigated the antipathogenic potential against three S. aureus strains of chloroform extracts of cell-free culture supernatant from the probiotic bacteria Lactobacillus casei and Lactobacillus acidophilus, as well as its suitability as an alternative antimutagenic agent. Both extracts did not display antibacterial activity but significantly reduced the bacterial biofilm formation at different stages 3 h (up to 73%), 6 h (up to 45%), and 24 h (up to 46%). Moreover, the extracts decrease the virulence factors production, hemolysin (up to 67%), and coagulase (delayed coagulation), as well as the cell metabolism in the biofilm (up to 65%), disrupting a preformed biofilm (up to 46%), all devoid of affecting its growth suggesting that the inhibition could be mediated by Quorum sensing (QS). The extract’s effect on biofilm disruption and metabolic activity seems to be strain dependent. The 2,5-diketopiperazines present in the extracts showed the ability to bind to the QS regulatory proteins SarA and AgrA in molecular docking studies. In the mutagenicity assay, both probiotic bacteria were able to remove the mutagen, and this capacity increased with the bacteria concentration.