Distinct expression trend of signature antigens of Staphylococcus aureus osteomyelitis correlated with clinical outcomes

The impact of methicillin resistance on clinical outcome among patients with Staphylococcus aureus osteomyelitis: a retrospective cohort study of 482 cases

This study was designed to evaluate the impact of methicillin resistance on the outcomes among patients with S. aureus osteomyelitis. We reviewed all extremity osteomyelitis patients treated in our clinic center between 2013 and 2020. All adult patients with S. aureus pathogen infection were included. Clinical outcome in terms of infection control, length of hospital stay, and complications were observed at the end of a 24-month follow-up and retrospectively analyzed between populations with/without methicillin resistance. In total, 482 osteomyelitis patients due to S. aureus were enrolled. The proportion of methicillin-resistant S. aureus (MRSA) was 17% (82) and 83% (400) of patients had Methicillin-sensitive S. aureus (MSSA). Of 482 patients, 13.7% (66) presented with infection persistence after initial debridement and antibiotic treatment (6 weeks), needed repeated debridement, 8.5% (41) had recurrence after all treatment end and a period infection cure, complications were observed in 17 (3.5%) patients (pathologic fracture; 4, nonunion; 5, amputation; 8) at final follow-up. Following multivariate analysis, we found patients with S. aureus osteomyelitis due to MRSA are more likely to develop a persistent infection (OR: 2.26; 95% CI 1.24-4.13) compared to patients with MSSA. Patients infected with MRSA also suffered more complications (8.5% vs. 2.5%, p = 0.015) and longer hospital stays (median: 32 vs. 23 days, p < 0.001). No statistically significant differences were found in recurrence. The data indicated Methicillin resistance had adverse clinical implication for infection persistence among patients with S. aureus osteomyelitis. These results will help for patients counsel and preparation for treatment.

LncRNA NONHSAT009968 inhibits the osteogenic differentiation of hBMMSCs in SA-induced inflammation via Wnt3a

Osteomyelitis is one of the most challenging diseases in the field of orthopedics for its complex pathogenesis and unsatisfactory treatment. The mechanism underlying its occurrence and development is still unclear. In our previous study, we found that long non-coding RNA (lncRNA) NONHSAT009968 inhibited the ability of osteogenic differentiation in staphylococcal protein A (SPA)-treated human bone marrow mesenchymal stem cells (hBMMSCs), but the underlying mechanism remains unclear. The current study was aimed at elucidating the possible mechanism of NONHSAT009968 in regulating osteogenic differentiation and bone defect repairability of hBMMSCs under infection. It was revealed that Wnt3a played a key role in promoting osteogenic differentiation of hBMMSCs treated with SPA in vitro. In addition, NONHSAT009968 inhibited osteogenic differentiation of hBMMSCs treated with SPA via Wnt3a, both in vivo and in vitro. In sum, the results suggested that lncNONHSAT009968 inhibited osteogenic differentiation of hBMMSCs in SA-induced inflammation through Wnt3a, which may have affected the occurrence and development of osteomyelitis. This study might provide novel insights regarding osteomyelitis and infectious bone defects.

StaphAIR: A Label-Free Antigen Microarray Approach to Detecting Anti-Staphylococcus aureus Antibody Responses in Orthopedic Infections

Arrayed imaging reflectometry (AIR) is an optical biosensor platform for simple, multiplex measurement of antigen-specific antibody responses in patient blood samples. Here, we report the development of StaphAIR, an 8-plex Staphylococcus aureus antigen array on the AIR platform for profiling antigen-specific anti-S. aureus humoral immune responses. Initial validation experiments with mouse and humanized monoclonal antibodies against the S. aureus autolysin glucosaminidase (Gmd) domain, and subsequent testing with dilution series of pooled positive human serum confirmed analytically robust behavior of the array, with all antigens displaying Langmuir-type dose-response curves. Testing a cohort of 82 patients with S. aureus musculoskeletal infections (MSKI) and 30 healthy individuals enabled discrimination of individual patient responses to different S. aureus antigens, with statistical significance between osteomyelitis patients and controls obtained overall for four individual antigens (IsdA, IsdB, Gmd, and SCIN). Multivariate analyses of the antibody titers obtained from StaphAIR revealed its utility as a potential diagnostic tool for detecting S. aureus MSKI (area under the receiver operating characteristic curve (AUC) > 0.85). We conclude that StaphAIR has utility as a high-throughput immunoassay for studying and diagnosing osteomyelitis in patients.