Exposure of Staphylococcus aureus to silver(I) induces a short term protective response

Abstract

The Ag(I) ion has well established antibacterial and antifungal properties. Exposure of Staphylococcus aureus to MIC 80 AgNO 3 (3 lg/ml) lead to an increase in the activity of superoxide dismutase, glutathione reductase and catalase at 30 min but activity declined by 60 min. In addition, exposure of cells to this metal ion for 1 h lead to increased expression of a number of proteins such as elongation factors Ts, Tu and G, fructose-bisphosphate aldolase and triosephosphate isomerase but their expression declined following 4 h exposure. ATP binding cassette transporter protein and oligoendopeptidase F showed increased expression at 4 h. While Ag(I) is a potent antimicrobial agent this work demonstrates that S. aureus can mount a short-term protective response to exposure to the metal ion but that this is eventually overcome.

Novel silver(I) complexes of coumarin oxyacetate ligands and their phenanthroline adducts: Biological activity, structural and spectroscopic characterisation

“…Full analytical and IR, 1 H, 13 C NMR and UV-Vis spectroscopic data are presented in Section S3, Supplementary material with selected data for representative complexes given in Table S8 and Tables 3-6. 2.2.3. Synthesis of 1,10-phenanthroline adducts of silver(I) complexes of 2-(2-oxo-2H-chromen-substituted-yl)oxy acetic acid-based ligands (34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44) A literature method was adopted for the synthesis of these adducts [21]. All of the following reactions were carried out under dark conditions to obtain suitable complexes for structure elucidation studies.…”

“…All of the following reactions were carried out under dark conditions to obtain suitable complexes for structure elucidation studies. The experimental data recorded for phen adducts (34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44) are given in Section S4 in Supplementary material with selected data for representative complexes given in Tables 3-6.…”

“…The ligands (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22), Ag(I) complexes (23-33), phenanthroline adducts (34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44) and commercially available drugs, gentamycin and vancomycin, were screened for their antimicrobial activity. S. aureus (NCIMB 12702) was obtained from the National Collection of Industrial, Marine and Food.…”

“…Previous studies have shown that silver(I) complexes of coumarin-3carboxylates and coumarin-4-carboxylates have excellent activity against MRSA and P. aeruginosa respectively [21,33,34]. Exposure of S. aureus to silver nitrate has been shown to lead to a transient increase in superoxide dismutase (SOD) activity and catalase activity which may indicate that the silver compound induces oxidative stress in the cell [35]. A more recent paper has shown that silver enhances antibiotic activity against Gram-negative bacteria by interfering with cellular processes and sensitizing the cells towards current antibiotics [36].…”

Proteomic analysis of the proteins released from Staphylococcus aureus following exposure to Ag(I)

“…The cell pellets were washed twice in phosphate buffered saline (PBS, 5 ml) and resuspended in either dH 2 O or AgNO 3 (3.0 lg/ml (17.6 lM), Sigma-Aldrich) and incubated at 37°C and 200 rpm for a further 0.5, 1, 2 or 4 h. A concentration of 3.0 lg/ml was chosen as this had previously been established to be the MIC 80 value (Smith et al, 2012). Cells were harvested as before and the supernatants collected.…”