Search Results (3)

Background/Objective:Staphylococcus aureus produces staphyloferrin A (Sfna) siderophores to sequester host iron during infection and rapid cell proliferation We examined drug susceptibility, siderophore production, and genome sequencing of clinical isolates of S. aureus. Methods: A total of 100 specimens, including pus, sputum, hemoculture, urine, tissue, fluid, and skin scrap specimens, were grown in iron-deprived Luria broth agar. The isolates were investigated for spectral signature using MALDI–TOF/MS, while antibiotic susceptibility and siderophore content were assessed using the chrome azurol S method. Whole genome and partial 16S rRNA DNA sequences were employed, and VITEK/MS revealed specific spectra. Results: Clindamycin, erythromycin, gentamicin, linezolid, moxifloxacin, oxacillin, trimethoprim/sulfamethoxazole, and vancomycin (100%) were the most common antibiotics to which the S. aureus isolates were susceptible. Sfna was not detectable in fluid and skin scrap isolates, which were encoded by sfnaB, sfnaD, and sfnaB/sfnaD genes. However, they were detectable in pus (73.8%), sputum (85.3%), hemoculture (50.0%), and urine (85.7%) isolates. The aureus subspecies, JKD6159, SA268, and MN8, were found to be 72.73% according to genome sequencing. Conclusion: most staphylococci in the isolates, including S. aureus JKD6159, SA268, and MN8, were sensitive to antibiotics and were detected by MALDI–TOF/MS, resulting in the production of Sfna encoded by sfna genes. Full article

Background and Objectives: The imminent threat of antibiotic resistance has spurred studies of nonconventional antimicrobial approaches. Gallium utilization is a promising and emerging approach to treating a variety of resistant bacteria using “Trojan horse” strategies to disrupt iron-dependent processes and biofilms. This study utilized experimental evolution to test the evolvability of gallium resistance in Staphylococcus aureus and resistance traits potentially correlated with metals, antibiotics and polyfluorinated compounds, as well as its genomics foundations. Methods: Whole-genome sequencing was utilized to reveal functional networks of mutations associated with gallium resistance. Additionally, scanning electron microscopy (SEM) observation was utilized to visualize distinct morphological changes on the surface of gallium-resistant populations and compare with the control populations. Results: As demonstrated by these studies, S. aureus evolved resistance to gallium after 20 days of selection. Furthermore, these populations displayed resistance traits correlated with heavy metals and polyfluorinated compounds. In contrast, the gallium-resistant populations were very sensitive to antibiotics. Whole-genome analysis revealed significant polymorphisms in the gallium (III)-resistant populations for example, polymorphisms in staphyloferrinA export MFS transporter/D ornithine citrate ligase (sfaA/sfaD), teichoic acid D Ala esterase (fmtA), DUF3169 family protein (KQ76_RS01520) and adenine phosphoribosyltransferase (KQ76_RS08360), while polymorphisms in the ABC transporter permease subunit (pstC) and acyltransferase family protein (KQ76_RS04365) were unique to the control populations. The polymorphisms directly affected the cells’ morphology. SEM images showed significant external ultrastructural changes in the gallium-selected bacterial cells compared to the control cells. Conclusions: Our study confirmed that using gallium as an antimicrobial can have significant health and environmental implications. Full article

Siderophores are organic ligands involved in dissolved iron (dFe) speciation in the oceans. Their study is crucial for a better understanding of the biogeochemical cycle of Fe in the marine environment, particularly in certain areas, such as the Southern Ocean, where Fe deficiency limits marine productivity. In this study, an analytical method is proposed for the extraction and pre-concentration of siderophores from seawater samples by solid phase extraction (SPE) and subsequent analysis by high-performance liquid chromatography—electrospray ionization—mass spectrometry (HPLC-ESI-MS/MS). Two siderophores were used as standards: Ferrioxamine E, a commercially available hydroxamate siderophore, and a staphyloferrin A-like compound with two citric acid units, synthesized in our laboratories by solid-phase peptide synthesis. A central composite design, considering different pH (2, 3.5, and 5) and sample loading volume (50, 125 and 200 mL) as variables, was used to optimize the extraction yield with SPE C18 cartridges. Tests were conducted on samples of artificial seawater spiked with siderophore standards. Ferrioxamine E showed high extraction yields in all tests carried out. On the contrary, the extraction of staphyloferrin A-like compound was significantly affected by both pH and loading volume. Full article