Burkholderia pseudomallei is a Gram-negative bacterium and the causative agent of melioidosis in humans and animals in the tropics. The clinical manifestations of melioidosis are diverse, ranging from localized infections to whole-body sepsis. The effective serological method is crucial for the point-of-care diagnosis of melioidosis. The aim of this study was to develop indirect immunofluorescence assay (IFA)-based methods for detecting immunoglobulin G (IgG) antibodies in melioidosis patients. These methods use whole-cell antigens made from recombinant E. coli strains that express major B. pseudomallei antigens, including TssM, OmpH, AhpC, BimA, and Hcp1. A total of 271 serum samples from culture-confirmed melioidosis patients (n = 81), patients with other known infections (n = 70), and healthy donors (n = 120) were tested. Our study showed that the recombinant TssM strain had the highest performance, with 92.6% sensitivity, 100% specificity, 100% positive predictive value, 96.9% negative predictive value, 97.8% efficiency, 97.0% accuracy, and no cross-reactivity. The method agreement analysis based on k efficiency calculations showed that all five IFA methods perfectly agreed with the standard culturing method, while the traditional indirect hemagglutination (IHA) method moderately agreed with the culture. In summary, our investigations showed that the TssM-IFA method could be used for melioidosis diagnosis.

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.

MicroRNA (miRNA)-guided gene silencing depends on the accurate assembly and regulation of the RNA-induced silencing complex (RISC), in which Argonaute-2 (Ago2) interacts with accessory proteins to facilitate complex stability and catalytic activity. Staphylococcal nuclease domain-containing protein 1 (SND1) is an important component of the RISC and a transcriptional co-regulator implicated in multiple cancers; however, the structural consequences of disease-associated SND1 mutations remain poorly understood. In this study, an integrated computational workflow combining protein–protein docking, molecular dynamics simulations, and free energy analyses was employed to investigate the potential structural effects of the SND1 S781F mutation on the SND1–Ago2 interaction. The wild-type complex was predicted to maintain a stable interaction network involving the Tudor domain of SND1 and methylated arginine residues of Ago2. In contrast, the S781F substitution was associated with altered intermolecular hydrogen bonding patterns, reduced predicted interaction stability, increased structural flexibility, altered correlated residue motions, and a broader free energy landscape, suggesting a less stable protein–protein interface. Although the mutant complex sampled a larger number of distinct intermolecular hydrogen bond interactions, these interactions exhibited lower occupancies and reduced persistence than those in the wild-type complex. Collectively, these computational findings suggest that the S781F mutation could act as a potential modulator of the local physicochemical environment, interaction stability, and conformational dynamics of the SND1–Ago2 surface. This study provides atomistic insights into the structural consequences of the S781F mutation and establishes a computational framework for future experimental validation of its role in miRNA-mediated gene regulation and cancer biology.