3D-printed porous titanium rods equipped with vancomycin-loaded hydrogels and polycaprolactone membranes for intelligent antibacterial drug release.

Implant-related infections pose significant challenges to orthopedic surgeries due to the high risk of severe complications. The widespread use of bioactive prostheses in joint replacements, featuring roughened surfaces and tight integration with the bone marrow cavity, has facilitated bacterial proliferation and complicated treatment. Developing antibacterial coatings for orthopedic implants has been a key research focus in recent years to address this critical issue. Researchers have designed coatings using various materials and antibacterial strategies. In this study, we fabricated 3D-printed porous titanium rods, incorporated vancomycin-loaded mPEG750-b-PCL2500 gel, and coated them with a PCL layer. We then evaluated the antibacterial efficacy through both in vitro and in vivo experiments. Our coating passively inhibits bacterial biofilm formation and actively controls antibiotic release in response to bacterial growth, providing a practical solution for proactive and sustained infection control. This study utilized 3D printing technology to produce porous titanium rod implants simulating bioactive joint prostheses. The porous structure of the titanium rods was used to load a thermoresponsive gel, mPEG750-b-PCL2500 (PEG: polyethylene glycol; PCL: polycaprolactone), serving as a novel drug delivery system carrying vancomycin for controlled antibiotic release. The assembly was then covered with a PCL membrane that inhibits bacterial biofilm formation early in infection and degrades when exposed to lipase solutions, mimicking enzymatic activity during bacterial infections. This setup provides infection-responsive protection and promotes drug release. We investigated the coating's controlled release, antibacterial capability, and biocompatibility through in vitro experiments. We established a Staphylococcus aureus infection model in rabbits, implanting titanium rods in the femoral medullary cavity. We evaluated the efficacy and safety of the composite coating in preventing implant-related infections using imaging, hematology, and pathology. In vitro experiments demonstrated that the PCL membrane stably protects encapsulated vancomycin during PBS immersion. The PCL membrane rapidly degraded at a lipase concentration of 0.2 mg/mL. The mPEG750-b-PCL2500 gel ensured stable and sustained vancomycin release, inhibiting bacterial growth. We investigated the antibacterial effect of the 3D-printed titanium material, coated with PCL and loaded with mPEG750-b-PCL2500 hydrogel, using a rabbit Staphylococcus aureus infection model. Imaging, hematology, and histopathology confirmed that our composite antibacterial coating exhibited excellent antibacterial effects and infection prevention, with good safety in trials. Our results indicate that the composite antibacterial coating effectively protects vancomycin in the hydrogel from premature release in the absence of bacterial infection. The outer PCL membrane inhibits bacterial growth and prevents biofilm formation. Upon contact with bacterial lipase, the PCL membrane rapidly degrades, releasing vancomycin for antibacterial action. The mPEG750-b-PCL2500 gel provides stable and sustained vancomycin release, prolonging its antibacterial effects. Our composite antibacterial coating demonstrates promising potential for clinical application.

Viewpoint: The impending pandemic of resistant organisms - a paradigm shift towards source control is needed.

The United States needs a paradigm shift in its approach to control infectious diseases. Current recommendations are often made in a siloed feedback loop. This may be the driver for such actions as the abandonment of contact precautions in some settings, the allowance of nursing home residents who are carriers of known pathogens to mingle with others in their facility, and the determination of an intervention's feasibility based upon budgetary rather than health considerations for patients and staff. Data from both the U.S. Veterans Health Administration and the U.K.'s National Health Service support the importance of carrier identification and source control. Both organizations observed marked decreases in methicillin-resistant Staphylococcus aureus (MRSA), but not methicillin-susceptible Staphylococcus aureus infections with the implementation of MRSA admission screening measures. Facilities are becoming over-reliant on horizontal prevention strategies, such as hand hygiene and chlorhexidine bathing. Hand hygiene is an essential practice, but the goal should be to minimize the risk of workers' hands becoming contaminated with defined pathogens, and there are conflicting data on the efficacy of chlorhexidine bathing in non-ICU settings. Preemptive identification of dedicated pathogens and effective source control are needed. We propose that the Centers for Disease Control and Prevention should gather and publicly report the community incidence of dedicated pathogens. This will enable proactive rather than reactive strategies. In the future, determination of a patient's microbiome may become standard, but until then we propose that we should have knowledge of the main pathogens that they are carrying.

A path forward for Staphylococcus aureus vaccine development.

The pursuit of a vaccine to quell Staphylococcus aureus disease has been unfruitful. In this Viewpoint, we explore the biological linkage between microbial niche acquisition and host immunity as a basis to guide future vaccine efforts.

Novel insights into vancomycin-loaded calcium sulfate and negative pressure wound therapy in preventing infections in open fractures.

BACKGROUND: Open fractures are challenging due to susceptibility to Staphylococcus aureus infections. This study examines the impact of Vancomycin-Loaded Calcium Sulfate (VLCS) and negative pressure wound therapy (NPWT) on macrophage behavior in enhancing healing and infection resistance. Both VLCS and NPWT were evaluated individually and in combination to determine their effects on macrophage polarization and infection resistance in open fractures. METHODS: Through single-cell RNA sequencing, genomic expressions in macrophages from open fracture patients treated with VLCS and NPWT were compared to a control group. The analysis focused on MBD2 gene changes related to macrophage polarization. RESULTS: Remarkable modifications in MBD2 expression in the treatment group indicate a shift towards M2 macrophage polarization. Additionally, the combined treatment group exhibited greater improvements in infection resistance and healing compared to the individual treatments. This shift suggests a healing-promoting atmosphere with improved infection resilience. CONCLUSIONS: VLCS and NPWT demonstrate the ability to alter macrophage behavior toward M2 polarization, which is crucial for infection prevention in open fractures. The synergistic effect of their combined use shows even greater promise in enhancing outcomes in orthopedic trauma care.

Immunoinformatic approach for multi-epitope vaccine design against Staphylococcus aureus based on hemolysin proteins.

Staphylococcus aureus is a common bacterium that causes a variety of infections in humans. This microorganism produces several virulence factors, including hemolysins, which contribute to its disease-causing ability. The treatment of S. aureus infections typically involves the use of antibiotics. However, the emergence of antibiotic-resistant strains has become a major concern. Therefore, vaccination against S. aureus has gained attention as an alternative approach. Vaccination has the advantage of stimulating the immune system to produce specific antibodies that can neutralize bacteria and prevent infection. However, developing an effective vaccine against S. aureus has proven to be challenging. This study aimed to use in silico methods to design a multi-epitope vaccine against S. aureus infection based on hemolysin proteins. The designed vaccine contained four B-cell epitopes, four CTL epitopes, and four HTL epitopes, as well as the ribosomal protein L7/L12 and pan-HLA DR-binding epitope, included as adjuvants. Furthermore, the vaccine was non-allergenic and non-toxic with the potential to stimulate the TLR2-, TLR-4, and TLR-6 receptors. The predicted vaccine exhibited a high degree of antigenicity and stability, suggesting potential for further development as a viable vaccine candidate. The population coverage of the vaccine was 94.4 %, indicating potential widespread protection against S. aureus. Overall, these findings provide valuable insights into the design of an effective multi-epitope vaccine against S. aureus infection and pave the way for future experimental validations.

Conserved moonlighting protein pyruvate dehydrogenase induces robust protection against Staphylococcus aureus infection.

Developing an effective Staphylococcus aureus (S. aureus) vaccine has been a challenging endeavor, as demonstrated by numerous failed clinical trials over the years. In this study, we formulated a vaccine containing a highly conserved moonlighting protein, the pyruvate dehydrogenase complex E2 subunit (PDHC), and showed that it induced strong protective immunity against epidemiologically relevant staphylococcal strains in various murine disease models. While antibody responses contributed to bacterial control, they were not essential for protective immunity in the bloodstream infection model. Conversely, vaccine-induced systemic immunity relied on γδ T cells. It has been suggested that prior S. aureus exposure may contribute to the reduction of vaccine efficacy. However, PDHC-induced protective immunity still facilitated bacterial clearance in mice previously exposed to S. aureus. Collectively, our findings indicate that PDHC is a promising serotype-independent vaccine candidate effective against both methicillin-sensitive and methicillin-resistant S. aureus isolates.

The World Needs a Staph Vaccine-New Research Could Bring It a Step Closer.

This Medical News article discusses recent findings that help explain Staphylococcus aureus vaccine failures.

Dynamical analysis of methicillin-resistant Staphylococcus aureus infection in North Cyprus with optimal control: prevalence and awareness.

The number of Methicillin-resistant Staphylococcus aureus (MRSA) cases in communities and hospitals is on the rise worldwide. In this work, a nonlinear deterministic model for the dynamics of MRSA infection in society was developed to visualize the significance of awareness in interventions that could be applied in the prevention of transmission with and without optimal control. Positivity and uniqueness were verified for the proposed corruption model to identify the level of resolution of infection factors in society. Furthermore, how various parameters affect the reproductive number R 0 and sensitivity analysis of the proposed model was explored through mathematical techniques and figures. The global stability of model equilibria analysis was established by using Lyapunov functions with the first derivative test. A total of seven years of data gathered from a private hospital consisting of inpatients and outpatients of MRSA were used in this model for numerical simulations and for observing the dynamics of infection by using a non-standard finite difference (NSFD) scheme. When optimal control was applied as a second model, it was determined that increasing awareness of hand hygiene and wearing a mask were the key controlling measures to prevent the spread of community-acquired MRSA (CA-MRSA) and hospital-acquired MRSA (HA-MRSA). Lastly, it was concluded that both CA-MRSA and HA-MRSA cases are on the rise in the community, and increasing awareness concerning transmission is extremely significant in preventing further spread.

Staphylococcus aureus screening and preoperative decolonisation with Mupirocin and Chlorhexidine to reduce the risk of surgical site infections in orthopaedic surgery: a pre-post study.

BACKGROUND: Nasal carriage of Staphylococcus aureus is a risk factor for surgical site infections (SSI) in orthopaedic surgery. The efficacy of decolonisation for S. aureus on reducing the risk of SSI is uncertain in this speciality. The objective was to evaluate the impact of a nasal screening strategy of S. aureus and targeted decolonisation on the risk of S. aureus SSI. METHODS: A retrospective pre-post and here-elsewhere study was conducted between January 2014 and June 2020 in 2 adult orthopaedic surgical sites (North and South) of a French university hospital. Decolonisation with Mupirocin and Chlorhexidine was conducted in S. aureus carriers starting February 2017 in the South site (intervention group). Scheduled surgical procedures for hip, knee arthroplasties, and osteosyntheses were included and monitored for one year. The rates of S. aureus SSI in the intervention group were compared to a historical control group (South site) and a North control group. The risk factors for S. aureus SSI were analysed by logistic regression. RESULTS: A total of 5,348 surgical procedures was included, 100 SSI of which 30 monomicrobial S. aureus SSI were identified. The preoperative screening result was available for 60% (1,382/2,305) of the intervention group patients. Among these screenings, 25.3% (349/1,382) were positive for S. aureus and the efficacy of the decolonisation was 91.6% (98/107). The rate of S. aureus SSI in the intervention group (0.3%, 7/2,305) was not significantly different from the historical control group (0.5%, 9/1926) but differed significantly from the North control group (1.3%, 14/1,117). After adjustment, the risk factors of S. aureus SSI occurrence were the body mass index (ORaper unit, 1.05; 95%CI, 1.0-1.1), the Charlson comorbidity index (ORaper point, 1.34; 95%CI, 1.0-1.8) and operative time (ORaper minute, 1.01; 95%CI, 1.00-1.02). Having benefited from S. aureus screening/decolonisation was a protective factor (ORa, 0.24; 95%CI, 0.08-0.73). CONCLUSIONS: Despite the low number of SSI, nasal screening and targeted decolonisation of S. aureus were associated with a reduction in S. aureus SSI.

Using contact network dynamics to implement efficient interventions against pathogen spread in hospital settings: A modelling study.

BACKGROUND: Long-term care facilities (LTCFs) are hotspots for pathogen transmission. Infection control interventions are essential, but the high density and heterogeneity of interindividual contacts within LTCF may hinder their efficacy. Here, we explore how the patient-staff contact structure may inform effective intervention implementation. METHODS AND FINDINGS: Using an individual-based model (IBM), we reproduced methicillin-resistant Staphylococcus aureus colonisation transmission dynamics over a detailed contact network recorded within a French LTCF of 327 patients and 263 staff over 3 months. Simulated baseline cumulative colonisation incidence was 21 patients (prediction interval: 11, 31) and 35 staff (prediction interval: 19, 54). We examined the potential impact of 3 types of interventions against transmission (reallocation reducing the number of unique contacts per staff, reinforced contact precautions, and hypothetical vaccination protecting against acquisition), targeted towards specific populations. All 3 interventions were effective when applied to all nurses or healthcare assistants (median reduction in MRSA colonisation incidence up to 35%), but the benefit did not exceed 8% when targeting any other single staff category. We identified "supercontactor" individuals with most contacts ("frequency-based," overrepresented among nurses, porters, and rehabilitation staff) or with the longest cumulative time spent in contact ("duration-based," overrepresented among healthcare assistants and patients in elderly care or persistent vegetative state (PVS)). Targeting supercontactors enhanced interventions against pathogen spread in the LTCF. With contact precautions, targeting frequency-based staff supercontactors led to the highest incidence reduction (20%, 95% CI: 19, 21). Vaccinating a mix of frequency- and duration-based staff supercontactors led to a higher reduction (23%, 95% CI: 22, 24) than all other approaches. Although based on data from a single LTCF, when varying epidemiological parameters to extend to other pathogens, our results suggest that targeting supercontactors is always the most effective strategy, indicating this approach could be applied to prevent transmission of other nosocomial pathogens. CONCLUSIONS: By characterising the contact structure in hospital settings and identifying the categories of staff and patients more likely to be supercontactors, with either more or longer contacts than others, interventions against nosocomial spread could be more effective. We find that the most efficient implementation strategy depends on the intervention (reallocation, contact precautions, vaccination) and target population (staff, patients, supercontactors). Importantly, both staff and patients may be supercontactors, highlighting the importance of including patients in measures to prevent pathogen transmission in LTCF.

The efficacy of an alcohol-based nasal antiseptic versus mupirocin or iodophor for preventing surgical site infections: A meta-analysis.

BACKGROUND: Nasal decolonization of Staphylococcus aureus is a proven strategy to reduce surgical site infections (SSI). Recently updated guidelines expanded nasal decolonization beyond traditionally high-risk populations to include the option for alcohol-based antiseptics (ABAs). We assessed the efficacy of a novel ABA for reducing SSI compared to mupirocin and iodophor. METHODS: A literature search in Google Scholar, PubMed, MEDLINE, and Cochrane databases was completed of studies reporting SSI outcomes in hospitals using an ABA. Primary meta-analyses were conducted to analyze ABA clinical efficacy versus no intervention (7 studies); subanalyses compared the ABA to mupirocin (3 studies) or iodophor (2 studies). RESULTS: One hundred forty-seven nasal decolonization titles for SSI prevention were identified, of which 7 were accepted. In the studies selected, 16,212 patients were included: 7,983 (49.24%) control group, and 8,129 (50.14%) intervention group. Significant effect sizes (measured as odds ratios [ORs]) and z-scores were found in all 3 meta-analyses: (OR = 3.178, z = 4.743, P < .001) in ABA clinical efficacy, (OR = 4.110, z = 3.167, P < .01) in ABA versus mupirocin, and (OR = 3.043, z = 3.155, P < .01) in ABA versus iodophor. Funnel plots for each demonstrated a lack of bias. CONCLUSIONS: Statistically significant positive effects were identified in all 3 meta-analyses. An ABA appears to be a viable alternative to mupirocin or iodophors to reduce SSIs.

Evaluation of the efficacy of a new inactivated vaccine against Staphylococcus aureus, Echerchia coli and Mycoplasma bovis mastitis in cows.

Staphylococcus aureus, Escherichia coli and Mycoplasma bovis are the most commonly isolated mastitis pathogens. The aim of this study was to evaluate the efficacy of a new mixed vaccine against mastitis caused by  Staphylococcus aureus, Escherichia coli, and Mycoplasma bovis. For this purpose, a mixed inactivated vaccine was administered subcutaneously to 24 heifers as one dose (2 mL) on the 45th day before birth and the second dose 21 days later. In 9 heifers, 2 mL of PBS was administered as placebo instead of vaccine. Then, heifers were divided into 3 groups as 7 vaccinated and 3 unvaccinated animals. Staphylococcus aureus, Escherichia coli, and Mycoplasma bovis were administered to the groups through intramammary route. Three vaccinated heifers were considered the common control without bacteria in all groups. The parameters considered to assess the effect of vaccination were clinical findings, bacterial count in milk, somatic cell count, and antibody titers. Clinical signs were observed only in the unvaccinated placebo group. Bacteria count and somatic cell count in milk increased in vaccinated and unvaccinated heifers. However, this increase was less in vaccinated animals and gradually returned to the normal level. In the unvaccinated heifers, it was ever high. Serum antibody titers were measured before and after vaccination. Antibody titers were high in vaccinated heifers after vaccination and were negative in unvaccinated heifers. In conclusion, the mixed vaccine had beneficial effect against Staphylococcus aureus, Escherichia coli, and Mycoplasma bovis mastitis and stimulated the immune response of vaccinated heifers.

IL-10 inhibition during immunization improves vaccine-induced protection against Staphylococcus aureus infection.

Staphylococcus aureus is a major human pathogen. An effective anti-S. aureus vaccine remains elusive as the correlates of protection are ill-defined. Targeting specific T cell populations is an important strategy for improving anti-S. aureus vaccine efficacy. Potential bottlenecks that remain are S. aureus-induced immunosuppression and the impact this might have on vaccine-induced immunity. S. aureus induces IL-10, which impedes effector T cell responses, facilitating persistence during both colonization and infection. Thus, it was hypothesized that transient targeting of IL-10 might represent an innovative way to improve vaccine efficacy. In this study, IL-10 expression was elevated in the nares of persistent carriers of S. aureus, and this was associated with reduced systemic S. aureus-specific Th1 responses. This suggests that systemic responses are remodeled because of commensal exposure to S. aureus, which negatively implicates vaccine function. To provide proof of concept that targeting immunosuppressive responses during immunization may be a useful approach to improve vaccine efficacy, we immunized mice with T cell-activating vaccines in combination with IL-10-neutralizing antibodies. Blocking IL-10 during vaccination enhanced effector T cell responses and improved bacterial clearance during subsequent systemic and subcutaneous infection. Taken together, these results reveal a potentially novel strategy for improving anti-S. aureus vaccine efficacy.

Investigation of cross-opsonic effect leads to the discovery of PPIase-domain containing protein vaccine candidate to prevent infections by Gram-positive ESKAPE pathogens.

BACKGROUND: Enterococcus faecium and Staphylococcus aureus are the Gram-positive pathogens of the ESKAPE group, known to represent a great threat to human health due to their high virulence and multiple resistances to antibiotics. Combined, enterococci and S. aureus account for 26% of healthcare-associated infections and are the most common organisms responsible for blood stream infections. We previously showed that the peptidyl-prolyl cis/trans isomerase (PPIase) PpiC of E. faecium elicits the production of specific, opsonic, and protective antibodies that are effective against several strains of E. faecium and E. faecalis. Due to the ubiquitous characteristics of PPIases and their essential function within Gram-positive cells, we hypothesized a potential cross-reactive effect of anti-PpiC antibodies. RESULTS: Opsonophagocytic assays combined with bioinformatics led to the identification of the foldase protein PrsA as a new potential vaccine antigen in S. aureus. We show that PrsA is a stable dimeric protein able to elicit opsonic antibodies against the S. aureus strain MW2, as well as cross-binding and cross-opsonic in several S. aureus, E. faecium and E. faecalis strains. CONCLUSIONS: Given the multiple antibiotic resistances S. aureus and enterococci present, finding preventive strategies is essential to fight those two nosocomial pathogens. The study shows the potential of PrsA as an antigen to use in vaccine formulation against the two dangerous Gram-positive ESKAPE bacteria. Our findings support the idea that PPIases should be further investigated as vaccine targets in the frame of pan-vaccinomics strategy.

[Intraosseous vancomycin in total knee arthroplasty]. / Vancomicina intraósea en artroplastía total de rodilla.

INTRODUCTION: intravenous antibiotic prophylaxis has significantly reduced the incidence of periprosthetic joint infection (PJI) in knee surgeries. However, for patients colonized with methicillin-resistant Staphylococcus aureus (MRSA) or those at risk of colonization, prophylaxis should include vancomycin. Intraosseous (IO) administration of vancomycin could enhance its effectiveness in total knee arthroplasty (TKA). MATERIAL AND METHODS: a retrospective review was conducted, including 143 patients at risk of PJI scheduled for TKA who received IO vancomycin along with intravenous (IV) cefazolin, referred to as group I (GI), between May 2021 and December 2022. The occurrence of complications in the first three postoperative months was evaluated. Results were compared with 140 patients without risk factors who received standard IV prophylaxis, designated as group II (GII). RESULTS: in GI, 500 mg of IO vancomycin was administered, injected into the proximal tibia, in addition to standard IV prophylaxis. In GII, patients received only IV cefazolin. The incidence of complications was 1.64% in GI and 1.4% in GII. The PJI rate at 90 postoperative days was 0.69% in GI and 0.71% in GII. CONCLUSIONS: IO vancomycin administration, along with standard IV prophylaxis, provides a safe and effective alternative for patients at risk of MRSA colonization. This approach minimizes complications associated with IV vancomycin use and addresses logistical challenges of timely administration.

INTRODUCCIÓN: la profilaxis antibiótica intravenosa ha reducido significativamente la incidencia de infección articular periprotésica (IAP) en cirugías de rodilla. No obstante, para pacientes colonizados con Staphylococcus aureus resistente a meticilina (SARM) o aquellos con riesgo de colonización, la profilaxis debe incluir vancomicina. La administración intraósea de vancomicina podría potenciar su efectividad en la artroplastía total de rodilla. MATERIAL Y MÉTODOS: se realizó una revisión retrospectiva que incluyó a 143 pacientes en riesgo de IAP programados para artroplastía total de rodilla que recibieron vancomicina intraósea junto a cefazolina intravenosa (IV), a quienes denominamos grupo I (GI), entre mayo de 2021 y diciembre de 2022. Se evaluó la aparición de complicaciones en los primeros tres meses postoperatorios. Los resultados se compararon con 140 pacientes sin factores de riesgo que recibieron profilaxis intravenosa estándar, denominados grupo II (GII). RESULTADOS: en el GI, se administraron 500 mg de vancomicina intraósea, inyectados en la tibia proximal, además de la profilaxis intravenosa estándar. En el GII, los pacientes recibieron sólo cefazolina intravenosa. La incidencia de complicaciones fue de 1.64% en el GI y de 1.4% en el GII. La tasa de IAP a los 90 días postoperatorios fue de 0.69% en el GI y de 0.71% en el GII. CONCLUSIONES: la administración de vancomicina intraósea, junto con la profilaxis intravenosa estándar, ofrece una alternativa segura y eficaz para pacientes con riesgo de colonización por SARM. Este enfoque minimiza las complicaciones asociadas con el uso intravenoso de vancomicina y soluciona los desafíos logísticos de la administración oportuna.

Biosurfactant complexed with arginine has antibiofilm activity against methicillin-resistant Staphylococcus aureus.

Aim: The present study investigated the antimicrobial effectiveness of a rhamnolipid complexed with arginine (RLMIX_Arg) against planktonic cells and biofilms of methicillin-resistant Staphylococcus aureus (MRSA). Methodology: Susceptibility testing was performed using the Clinical & Laboratory Standards Institute protocol: M07-A10, checkerboard test, biofilm in plates and catheters and flow cytometry were used. Result: RLMIX_Arg has bactericidal and synergistic activity with oxacillin. RLMIX_Arg inhibits the formation of MRSA biofilms on plates at sub-inhibitory concentrations and has antibiofilm action against MRSA in peripheral venous catheters. Catheters impregnated with RLMIX_Arg reduce the formation of MRSA biofilms. Conclusion: RLMIX_Arg exhibits potential for application in preventing infections related to methicillin-resistant S. aureus biofilms.

[Box: see text].

Efficacy of Commercially Available Irrigation Solutions on Removal of Staphylococcus Aureus and Biofilm From Porous Titanium Implants: An In Vitro Study.

BACKGROUND: Periprosthetic joint infection remains a major problem. The bactericidal efficacy of commercial irrigation solutions for the treatment of infection is not well established in the presence of porous titanium (Ti) implants. This study compared the in vitro efficacy of five irrigation solutions on infected three-dimensional-printed porous Ti discs. METHODS: Titanium discs (2 × 4 mm, 400, 700, and 1,000 µm) were infected with S. aureus (1 × 106 colony-forming unit/mL) and incubated for 3 hours or 3 days to create acute or chronic infection with biofilm. Discs were irrigated with saline, antibiotic, or antiseptic solutions, then repeatedly sonicated. Sonicates were cultured for bacterial quantification. Statistical analyses were performed using one-way analysis of variance (ANOVA), followed by Tukey-Kramer post hoc testing (P < .05 significance). Biofilms were visualized by scanning electron microscopy. RESULTS: Saline irrigation was ineffective in both groups. In acute infections with 400 µm pores, differences were found with saline versus solution #3 (P = .015) and #4 (P = .015). Solution #4 had the lowest bacterial counts for all pore sizes. For biofilm, irrigation with saline, solutions #1, #2, and #3 inadequately cleared bacteria in all pore sizes. Lower remaining concentrations were observed in #4 with 400µm pores compared to saline (P = .06) and #2 (P = .039). The scanning electron microscopy showed a reduction of biofilm in samples washed with #4. CONCLUSIONS: Irrigation of infected porous Ti discs with saline, solutions #1 and #2 failed to reduce the bacterial load. The 400 µm discs consistently had more bacteria despite irrigation, highlighting the difficulty of removing bacteria from small pores. Solutions #3 and #4 reduced bacteria acutely, but only #4 demonstrated efficacy in clearing biofilm compared to saline. These results should be considered when treating periprosthetic joint infection in the presence of porous components and the potential presence of biofilm.

A highly neutralizing human monoclonal antibody targeting a novel linear epitope on staphylococcal enterotoxin B.

Staphylococcal Enterotoxin B (SEB), produced by Staphylococcus aureus (S. aureus), is a powerful superantigen that induces severe immune disruption and toxic shock syndrome (TSS) upon binding to MHC-II and TCR. Despite its significant impact on the pathogenesis of S. aureus, there are currently no specific therapeutic interventions available to counteract the mechanism of action exerted by this toxin. In this study, we have identified a human monoclonal antibody, named Hm0487, that specifically targets SEB by single-cell sequencing using PBMCs isolated from volunteers enrolled in a phase I clinical trial of the five-antigen S. aureus vaccine. X-ray crystallography studies revealed that Hm0487 exhibits high affinity for a linear B cell epitope in SEB (SEB138-147), which is located distantly from the site involved in the formation of the MHC-SEB-TCR ternary complex. Furthermore, in vitro studies demonstrated that Hm0487 significantly impacts the interaction of SEB with both receptors and the binding to immune cells, probably due to an allosteric effect on SEB rather than competing with receptors for binding sites. Moreover, both in vitro and in vivo studies validated that Hm0487 displayed efficient neutralizing efficacy in models of lethal shock and sepsis induced by either SEB or bacterial challenge. Our findings unveil an alternative mechanism for neutralizing the pathogenesis of SEB by Hm0487, and this antibody provides a novel strategy for mitigating both SEB-induced toxicity and S. aureus infection.

Recommendations for the Prevention and Management of Deep Brain Stimulation Infections Based on 26-Year Single-Center Experience.

INTRODUCTION: Infections related to deep brain stimulation (DBS) can lead to discontinuation of the treatment and increased morbidity. Various measures of reducing infection rates have been proposed in the literature, but scientific consensus is lacking. The aim of this study was to report a 26-year single center experience of DBS infections and provide recommendations for the prevention and management of them. METHODS: The retrospective analysis consisted of 978 DBS surgeries performed at Oulu University Hospital (OUH) from 1997 to 2022. This included 342 primary or reimplantations of DBS electrodes and 559 primary or reimplantations of implantable pulse generator (IPG). Infections within approximately 1 year after the surgery without secondary cause were considered surgical-site infections (SSIs). χ2 test was used to compare infection rates before and after 2013, when the systematic implementation of infection prevention measures was started. RESULTS: A total of 35 DBS implants were found to be infected. The number of SSIs was 30, of which 29 were originally operated in OUH leading to a center-specific infection rate of 3.1%. Of the SSIs, 17.2% occurred after IPG replacement. Staphylococcus aureus was found in 75.0% of cultures and 32.1% were mixed infections. The treatment of SSIs included aggressive surgical revision combined with cefuroxime and vancomycin antibiotics, as most patients in the initial conservative treatment group eventually required surgical revision. A statistically significant difference in infection rates before and after the implementation of preventative measures was not observed (risk ratio 2.20, 95% confidence interval 0.94-5.75, p = 0.051), despite over two-fold difference in the incidence of SSIs. CONCLUSION: Our findings show that the rates of surgical infections are low in modern DBS, but due to their serious consequences, preventative measures should be implemented. We highlight that mixed infections should be accounted for in the antibiotic selection. Furthermore, our treatment recommendation includes aggressive surgical revision combined with antibiotic treatment.

In vivo mRNA expression of a multi-mechanistic mAb combination protects against Staphylococcus aureus infection.

Single monoclonal antibodies (mAbs) can be expressed in vivo through gene delivery of their mRNA formulated with lipid nanoparticles (LNPs). However, delivery of a mAb combination could be challenging due to the risk of heavy and light variable chain mispairing. We evaluated the pharmacokinetics of a three mAb combination against Staphylococcus aureus first in single chain variable fragment scFv-Fc and then in immunoglobulin G 1 (IgG1) format in mice. Intravenous delivery of each mRNA/LNP or the trio (1 mg/kg each) induced functional antibody expression after 24 h (10-100 µg/mL) with 64%-78% cognate-chain paired IgG expression after 3 days, and an absence of non-cognate chain pairing for scFv-Fc. We did not observe reduced neutralizing activity for each mAb compared with the level of expression of chain-paired mAbs. Delivery of the trio mRNA protected mice in an S. aureus-induced dermonecrosis model. Intravenous administration of the three mRNA in non-human primates achieved peak serum IgG levels ranging between 2.9 and 13.7 µg/mL with a half-life of 11.8-15.4 days. These results suggest nucleic acid delivery of mAb combinations holds promise and may be a viable option to streamline the development of therapeutic antibodies.