5-Dodecanolide interferes with biofilm formation and reduces the virulence of Methicillin-resistant Staphylococcus aureus (MRSA) through up regulation of agr system

Methicillin resistant Staphylococcus aureus (MRSA) is a predominant human pathogen with high morbidity that is listed in the WHO high priority pathogen list. Being a primary cause of persistent human infections, biofilm forming ability of S. aureus plays a pivotal role in the development of antibiotic resistance. Hence, targeting biofilm is an alternative strategy to fight bacterial infections. The present study for the first time demonstrates the non-antibacterial biofilm inhibitory efficacy of 5-Dodecanolide (DD) against ATCC strain and clinical isolates of S. aureus. In addition, DD is able to inhibit adherence of MRSA on human plasma coated Titanium surface. Further, treatment with DD significantly reduced the eDNA synthesis, autoaggregation, staphyloxanthin biosynthesis and ring biofilm formation. Reduction in staphyloxanthin in turn increased the susceptibility of MRSA to healthy human blood and H2O2 exposure. Quantitative PCR analysis revealed the induced expression of agrA and agrC upon DD treatment. This resulted down regulation of genes involved in biofilm formation such as fnbA and fnbB and up regulation of RNAIII, hld, psmα and genes involved in biofilm matrix degradation such as aur and nuc. Inefficacy of DD on the biofilm formation of agr mutant further validated the agr mediated antibiofilm potential of DD. Notably, DD was efficient in reducing the in vivo colonization of MRSA in Caenorhabditis elegans. Results of gene expression studies and physiological assays unveiled the agr mediated antibiofilm efficacy of DD.