[Staphylococcal toxic shock syndrome should be considered in the event of diffuse erythema with fever and shock]

Rational Design of Hit Compounds Targeting Staphylococcus aureus Threonyl-tRNA Synthetase

Staphylococcus aureus is one of the most dangerous nosocomial pathogens which cause a wide variety of hospital-acquired infectious diseases. S. aureus is considered as a superbug due to the development of multidrug resistance to all current therapeutic regimens. Therefore, the discovery of antibiotics with novel mechanisms of action to combat staphylococcal infections is of high priority for modern medicinal chemistry. Nowadays, aminoacyl-tRNA synthetases are considered as promising molecular targets for antibiotic development. In the present study, we used for the first time S. aureus threonyl-tRNA synthetase (ThrRS) as a molecular target. Recombinant S. aureus ThrRS was obtained in the soluble form in a sufficient amount for inhibitor screening assay. Using the molecular docking approach, we selected 180 compounds for investigation of inhibitory activity toward ThrRS. Among the tested compounds, we identified five inhibitors from different chemical classes decreasing the activity of ThrRS by more than 70% at a concentration of 100 μM. The most active compound 2,4-dibromo-6-{[4-(4-nitro-phenyl)-thiazol-2-yl]-hydrazonomethyl}-phenol has an IC₅₀ value of 56.5 ± 3.5 μM. These compounds are not cytotoxic toward eukaryotic cells HEK293 (EC₅₀ > 100 μM) and can be useful for further optimization and biological research.

Natural Products That Target Virulence Factors in Antibiotic-Resistant Staphylococcus aureus

The increase in the incidence of antibiotic-resistant Staphylococcus aureus (S. aureus) associated infections necessitates the urgent development of novel therapeutic strategies and antibacterial drugs. Antivirulence strategy is an especially compelling alternative strategy due to its low selective pressure for the development of drug resistance in bacteria. Plants and microorganisms are not only important food and medicinal resources but also serve as sources for the discovery of natural products that target bacterial virulence factors. This review discusses the mechanisms of the major virulence factors of S. aureus, including the accessory gene regulator quorum-sensing system, bacterial biofilm formation, α-hemolysin, sortase A, and staphyloxanthin. We also provide an overview of natural products isolated from plants and microorganisms with activity against the major virulence factors of S. aureus and their adjuvant effects on existing antibiotics to overcome antibiotic-resistant S. aureus. Finally, the limitations and solutions of these antivirulence compounds are discussed, which will help in the development of novel antibacterial drugs against antibiotic-resistant S. aureus.