There is an increasingly growing demand for nonantibiotic strategies to overcome drug resistance in bacterial biofilm infections. Here, a novel “gas-sensitized hyperthermia” strategy is proposed for appreciable bacteria killing by the smart design of a metal-organic framework (MOF)–sealed Prussian blue–based nanocarrier (MSDG). Once the biofilm microenvironment (BME) is reached, the acidity-activated MOF degradation allows the release of diallyl trisulfide and subsequent glutathione-responsive generation of hydrogen sulfide (H ₂ S) gas. Upon near-infrared irradiation, H ₂ S-sensitized hyperthermia arising from MSDG can efficiently eliminate biofilms through H ₂ S-induced extracellular DNA damage and heat-induced bacterial death. The generated H ₂ S in the biofilm can stimulate the polarization of macrophages toward M2 phenotype for reshaping immune microenvironment. Subsequently, the secretion of abundant regeneration-related cytokines from M2 macrophages accelerates tissue regeneration by reversing the infection-induced pro-inflammatory environment in an implant-related infection model. Collectively, such BME-responsive nano-antibacterials can achieve biofilm-specific H ₂ S-sensitized thermal eradiation and immunomodulatory tissue remodeling, thus realizing the renaissance of precision treatment of refractory implant–related infections.

Staphylococcal aureus (S. aureus) has become the leading causative pathogen of Prosthetic Joint Infection (PJI), which is the most devastating complication after arthroplasty surgeries. Due to the biofilm formation ability and emergence of multiple-drugs resistance strains of S. aureus, it has become an urgency to find new anti-staphylococcal agents to establish effective prophylaxis and treatment strategy for PJI. Extracted from a traditional Chinese herb, berberine is proved active in inhibiting S. aureus, while whether it exerts the same effect on PJI-related S. aureus remains unknown. This study aims to investigate the antimicrobial activity of berbrine against clinical derived PJI-related S. aureus and whether its inhibiting efficacy is associated with subtypes of S. aureus. Eighteen PJI-associated S. aureus were collected and their Multi-locus Sequence Types (MLST) and susceptibility to berberine both in planktonic and biofilm form were investigated. Additionally, one S. aureus strain (ST1792) was selected from the group and its transcriptomic profiling in berberine incubation was performed. The statistical analyses were conducted using Student’s t-test with SPSS 24.0(SPSS, IBM, USA). The data were expressed as the means ± standard deviation. Values of p < 0.05 were considered statistically significant. It was found out that the Minimum Inhibitory Concentration values of PJI-related S. aureus varied in a broad range (from 64 to 512 μg/ml) among different MLST subtypes and the bacteria were able to regain growth after 24 h in berberine of MIC value or higher concentrations. In addition, sub-inhibitory concentrations of berberine surprisingly enhanced biofilm formation in some S. aureus strains. Traditional medicine is utilised by a large number of individuals, which provides abundant resources for modern medical science. In our study, berberine was found bactericidal against PJI related S. aureus, however, its antibacterial property was impacted by the MLST subtypes of the bacteria, both in planktonic and biofilm growth forms.

Implant-associated infections (IAIs) caused by S. aureus can result in serious challenges after orthopedic surgery. Due to biofilm formation and antibiotic resistance, this refractory infection is highly prevalent, and finding drugs to attenuate bacterial virulence is becoming a rational alternative strategy. In S. aureus, the SaeRS two-component system (TCS) plays a key role in the production of over 20 virulence factors and the pathogenesis of the bacterium. Here, by conducting a structure-based virtual screening against SaeR, we identified that fenoprofen, a USA Food and Drug Administration (FDA)-approved nonsteroid anti-inflammatory drug (NSAID), had excellent inhibitory potency against the response regulator SaeR protein. We showed that fenoprofen attenuated the virulence of S. aureus without drug resistance. In addition, it was helpful in relieving osteolysis and restoring the walking ability of mice in vitro and in implant-associated infection models. More importantly, fenoprofen treatment suppressed biofilm formation and changed the biofilm structure, which caused S. aureus to form loose and porous biofilms that were more vulnerable to infiltration and elimination by leukocytes. Our results reveal that fenoprofen is a potent antivirulence agent with potential value in clinical applications and that SaeR is a drug target against S. aureus implant-associated infections.

Biofilms formed by Staphylococcus aureus are one of the predominant causes of implant-associated infections (IAIs). Previous studies have found that S. aureus nucleases nuc1 and nuc2 modulate biofilm formation. In this study, we found low nuc1/nuc2 expression and high biofilm-forming ability among IAI isolates. Furthermore, in a mouse model of exogenous IAIs, Δnuc1/2 exhibited higher bacterial load on the surface of the implant than that exhibited by the other groups (WT, Δnuc1, and Δnuc2). Survival analysis of the hematogenous IAI mouse model indicated that nuc1 is a virulence factor related to mortality. We then detected the influence of nuc1 and nuc2 on biofilm formation and immune evasion in vitro. Observation of in vitro biofilm structures with scanning electron microscopy and evaluation of bacterial aggregation with flow cytometry revealed that both nuc1 and nuc2 are involved in biofilm structuring and bacterial aggregation. Unlike nuc1, which is reported to participate in immune evasion, nuc2 cannot degrade neutrophil extracellular traps. Moreover, we found that nuc1/nuc2 transcription is negatively correlated during S. aureus growth, and a possible complementary relationship has been proposed. In conclusion, nuc1/nuc2 are complementary genes involved in biofilm formation in exogenous IAIs. However, nuc2 contributes less to virulence and is not involved in immune evasion.

Background: This study assessed the distribution characteristics of pathogens isolated from cases of orthopedic infections and focused on the antimicrobial susceptibility of the main pathogens. Methods: This retrospective study involved patients with orthopedic infection in a tertiary medical center located in Shanghai, China, from 2008 to 2021.Pathogen information and the basic information of patients were identified from clinical microbiology laboratory data and the institutional medical record system. Results: In total, the pathogen information of 2821 patients were enrolled in the study. S. aureus (37.71%) was the main causative pathogen responsible for orthopedic infection. Gender, pathogens distribution and polymicrobial infection rates were significantly different (P < 0.05) among patients with different orthopedic infection diseases.The trends in the distribution of pathogens in the total cohort, implant-related infection group (Group A), non-implant-related infection group (Group B), and the sub-group of cases with arthroplasty showed significant linear changes over time. And the polymicrobial infection rates of the total cohort (from 17.17% to 11.00%), Group B(from 24.35% to 14.47%), and the sub-group of cases with internal fixation (from 10.58% to 4.87%) decreased significantly. The antimicrobial susceptibility showed changing trends with time for some main pathogens, especially for S.aureus and Enterobacter spp. Conclusions: Our research indicated that the pathogen distribution and antimicrobial susceptibility in orthopedic infections changed over time. And the distribution of pathogens varied significantly among different types of orthopedic infectious diseases. These findings may serve as a reference for prophylaxis and empirical treatment strategies of orthopedic infection.