Drug Susceptibility, Siderophore Production, and Genome Analysis of Staphylococcus aureus Clinical Isolates from a University Hospital in Chiang Mai, Thailand

<b>Background/Objective:</b><i>Staphylococcus aureus</i> 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 <i>S. aureus</i>. <b>Methods:</b> 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. <b>Results:</b> Clindamycin, erythromycin, gentamicin, linezolid, moxifloxacin, oxacillin, trimethoprim/sulfamethoxazole, and vancomycin (100%) were the most common antibiotics to which the <i>S. aureus</i> isolates were susceptible. Sfna was not detectable in fluid and skin scrap isolates, which were encoded by <i>sfnaB</i>, <i>sfnaD</i>, and <i>sfnaB</i>/<i>sfnaD</i> 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. <b>Conclusion:</b> most staphylococci in the isolates, including <i>S. aureus</i> JKD6159, SA268, and MN8, were sensitive to antibiotics and were detected by MALDI-TOF/MS, resulting in the production of Sfna encoded by <i>sfna</i> genes.