Abstract
Staphylococcus aureus (S. aureus) is a global health threat accompanied by increasing in drug resistance. To combat this challenge, there is an urgent need to find alternative antimicrobial agents against S. aureus. This study investigated the antimicrobial efficacy of carnosol against S. aureus using an in vitro model. The effects of carnosol were determined based on the antimicrobial effects or formation and disruption of biofilms. Finally, metabolomics of S. aureus grown as planktonic cells and biofilms with carnosol treatment were analyzed using gas chromatography-mass spectrometry. The minimum inhibitory concentrations (MICs) of carnosol were 32 to 256 μg/mL against the sixteen tested S. aureus strains. Among the biofilms, we observed a reduction in bacterial motility of the S. aureus, biofilm development and preformed biofilm after carnosol treatment. Moreover, the significantly altered metabolic pathways upon carnosol treatment in S. aureus planktonic cells and biofilms were highly associated with the perturbation of glyoxylate and dicarboxylate metabolism, glycine, serine and threonine metabolism, arginine and proline metabolism, alanine, aspartate and glutamate metabolism, arginine biosynthesis, and aminoacyl-tRNA biosynthesis. In addition, glutathione metabolism, D-glutamine and D-glutamate metabolism were significantly changed in the biofilms. This study establishes the antibacterial and antibiofilm properties of carnosol, and will provide an alternative strategy for overcoming the drug resistance of S. aureus.
Highlights
Staphylococcus aureus (S. aureus) is one of the major gram-positive opportunistic pathogens associated with hospital-acquired infections and food-borne illnesses worldwide (Knox et al, 2015)
These results showed that carnosol inhibited Staphylococcal biofilm formation
The prevalence of drug-resistant bacterial infections has become a major threat to human health
Summary
Staphylococcus aureus (S. aureus) is one of the major gram-positive opportunistic pathogens associated with hospital-acquired infections and food-borne illnesses worldwide (Knox et al, 2015). The emergence and spread of methicillin-resistant S. aureus (MRSA) strains and the formation of biofilms make S. aureus one of the most difficult challenges to control Most microorganisms can exist in two forms: a planktonic form or as a biofilm. Once microorganisms form a biofilm, their genetic expression changes rapidly, which makes them physiologically and metabolically distinct from their corresponding planktonic cells (Kaiser et al, 2017). Biofilms often exhibit a strong inherent resistance to antimicrobial drugs, which makes the control of biofilm infections very difficult, and this may be further troubled if the pathogenic microorganism is resistant to multiple agents
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