Vaccine development to prevent Staphylococcus aureus surgical-site infections

Targeted Clindamycin Delivery Systems: Promising Options for Preventing and Treating Bacterial Infections Using Biomaterials

Targeted therapy represents a real opportunity to improve the health and lives of patients. Developments in this field are confirmed by the fact that the global market for drug carriers was worth nearly $40 million in 2022. For this reason, materials engineering and the development of new drug carrier compositions for targeted therapy has become a key area of research in pharmaceutical drug delivery in recent years. Ceramics, polymers, and metals, as well as composites, are of great interest, as when they are appropriately processed or combined with each other, it is possible to obtain biomaterials for hard tissues, soft tissues, and skin applications. After appropriate modification, these materials can release the drug directly at the site requiring a therapeutic effect. This brief literature review characterizes routes of drug delivery into the body and discusses biomaterials from different groups, options for their modification with clindamycin, an antibiotic used for infections caused by aerobic and anaerobic Gram-positive bacteria, and different methods for the final processing of carriers. Examples of coating materials for skin wound healing, acne therapy, and bone tissue fillers are given. Furthermore, the reasons why the use of antibiotic therapy is crucial for a smooth and successful recovery and the risks of bacterial infections are explained. It was demonstrated that there is no single proven delivery scheme, and that the drug can be successfully released from different carriers depending on the destination.

Biofunctional lipid nanoparticles for precision treatment and prophylaxis of bacterial infections

The lack of bacterial-targeting function in antibiotics and their prophylactic usage have caused overuse of antibiotics, which lead to antibiotic resistance and inevitable long-term toxicity. To overcome these issues, we develop neutrophil-bacterial hybrid cell membrane vesicle (HMV)-coated biofunctional lipid nanoparticles (LNP@HMVs), which are designed to transport antibiotics specifically to bacterial cells at the infection site for the effective treatment and prophylaxis of bacterial infection. The dual targeting ability of HMVs to inflammatory vascular endothelial cells and homologous Gram-negative bacterial cells results in targeted accumulation of LNP@HMVs in the site of infections. LNP@HMVs loaded with the antibiotic norfloxacin not only exhibit enhanced activity against planktonic bacteria and bacterial biofilms in vitro but also achieve potent therapeutic efficacy in treating both systemic infection and lung infection. Furthermore, LNP@HMVs trigger the activation of specific humoral and cellular immunity to prevent bacterial infection. Together, LNP@HMVs provide a promising strategy to effectively treat and prevent bacterial infection.

Staphylococcus aureus vaccine strategy: Promise and challenges

Staphylococcus aureus (S. aureus) is a leading and crucial infectious threat to global public health due to the widespread emergence of antibiotic-resistant strains such as Methicillin-Resistant S. aureus (MRSA). MRSA infects immunocompromised patients and healthy individuals and has rapidly spread from the healthcare setting to the outside community. The development of flawless vaccines become a medical need worldwide against multi-drug resistant S. aureus. Therefore, protection by an immune-based strategy may provide valuable measures to contain the spread of invasive S. aureus infections. Several vaccine candidates have been prepared which are either in the preclinical phase or in the early clinical phase, whereas several candidates have failed to show a protective efficacy in human subjects. Currently, research is focusing on identifying novel vaccine formulations able to elicit potent humoral and cellular immune responses. Several approaches have also been made to the development of monoclonal or polyclonal antibodies for passive immunization to protect against S. aureus infections. In recent years, a multi-epitope vaccine has emerged as a novel platform for subunit vaccine design by using computational approaches. Therefore, in this review, we have summarized and discussed the mechanistic overview of different strategies used to develop potential vaccine candidates and passive interventions which are in different stages of clinical trials to fight multi-drug resistant S. aureus infections.

Innovation for infection prevention and control-revisiting Pasteur's vision

Louis Pasteur has long been heralded as one of the fathers of microbiology and immunology. Less known is Pasteur's vision on infection prevention and control (IPC) that drove current infection control, public health, and much of modern medicine and surgery. In this Review, we revisited Pasteur's pioneering works to assess progress and challenges in the process and technological innovation of IPC. We focused on Pasteur's far-sighted conceptualisation of the hospital as a reservoir of microorganisms and amplifier of transmission, aseptic technique in surgery, public health education, interdisciplinary working, and the protection of health services and patients. Examples from across the globe help inform future thinking for IPC innovation, adoption, scale up and sustained use.

Preoperative and perioperative risk factors, and risk score development for prosthetic joint infection due to Staphylococcus aureus: A multinational matched case-control study

OBJECTIVES

We aim to identify the preoperative and perioperative risk factors associated with post-surgical Staphylococcus aureus prosthetic joint infections (PJI), and to develop and validate risk-scoring systems, to allow a better identification of high-risk patients for more efficient targeted interventions.

METHODS

We performed a multicenter matched case-control study of patients who underwent a primary hip and knee arthroplasty from 2014 to 2016. Two multivariable models by logistic regression were performed, one for the preoperative and one for perioperative variables; also, predictive scores were developed and validated in an external cohort.

RESULTS

In total, 130 cases and 386 controls were included. The variables independently associated with S. aureus-PJI in the preoperative period were (adjusted OR; 95% CI): BMI >30 kg/m² (3.0; 1.9-4.8), resident in a long-term care facility (2.8; 1.05-7.5), fracture as reason for arthroplasty (2.7; 1.4-5.03), skin disorders (2.5; 0.9-7.04), previous surgery in the index joint (2.4; 1.3-4.4), male sex (1.9; 1.2-2.9) and ASA score 3-4 (1.8; 1.2-2.9). The AUROC curve was 0.73 (95% CI 0.68-0.78). In perioperative model, the risk factors were the previous ones plus surgical antibiotic prophylaxis administered out of the first 60 minutes before incision (5.9; 2.1-16.2), wound drainage for >72h after arthroplasty (4.5; 1.9-19.4) and use of metal bearing material vs. ceramic (1.9; 1.1-3.3). The AUROC curve was 0.78 (95% CI 0.72-0.83). The predictive scores developed were validated in the external cohort.

CONCLUSIONS

Predictive scores for S. aureus-PJI were developed and validated; this information would be useful for implementation of specific preventive measures.

Expert commentary on the challenges and opportunities for surgical site infection prevention through implementation of evidence-based guidelines in the Asia-Pacific Region

INTRODUCTION

Surgical site infections (SSIs) are a significant source of morbidity and mortality in the Asia-Pacific region (APAC), adversely impacting patient quality of life, fiscal productivity and placing a major economic burden on the country's healthcare system. This commentary reports the findings of a two-day meeting that was held in Singapore on July 30-31, 2019, where a series of consensus recommendations were developed by an expert panel composed of infection control, surgical and quality experts from APAC nations in an effort to develop an evidence-based pathway to improving surgical patient outcomes in APAC.

METHODS

The expert panel conducted a literature review targeting four sentinel areas within the APAC region: national and societal guidelines, implementation strategies, postoperative surveillance and clinical outcomes. The panel formulated a series of key questions regarding APAC-specific challenges and opportunities for SSI prevention.

RESULTS

The expert panel identified several challenges for mitigating SSIs in APAC; (a) constraints on human resources, (b) lack of adequate policies and procedures, (c) lack of a strong safety culture, (d) limitation in funding resources, (e) environmental and geographic challenges, (f) cultural diversity, (g) poor patient awareness and (h) limitation in self-responsibility. Corrective strategies for guideline implementation in APAC were proposed that included: (a) institutional ownership of infection prevention strategies, (b) perform baseline assessments, (c) review evidence-based practices within the local context, (d) develop a plan for guideline implementation, (e) assess outcome and stakeholder feedback, and (f) ensure long-term sustainability.

CONCLUSIONS

Reducing the risk of SSIs in APAC region will require: (a) ongoing consultation and collaboration among stakeholders with a high level of clinical staff engagement and (b) a strong institutional and national commitment to alleviate the burden of SSIs by embracing a safety culture and accountability.

Distribution and Antibiotic Resistance Patterns of Pathogenic Bacteria in Patients With Chronic Cutaneous Wounds in China

Background: To determine the distribution and antimicrobial susceptibility pattern of pathogenic bacteria in patients with chronic cutaneous wounds on a national scale. Methods: A retrospective study was conducted using the data recorded between January 1, 2018 and January1, 2020 in 195 hospitals across China. After screening the data, 815 patients with chronic wounds were finally analyzed. The data collected included information about the patients' general condition and local cutaneous wound assessments, especially microbial culture and antibiotic susceptibility tests. The analyses were performed using SPSS Version 26. Results: The study included 815 patients (290 [35.6%] females; 63 [50-74] years). The most common causes of chronic cutaneous wounds were diabetes (183, 22.5%), infection (178, 21.8%), and pressure (140, 17.2%). Among these, 521(63.9%) samples tested yielded microbial growth, including 70 (13.4%) polymicrobial infection and 451 (86.6%) monomicrobial infection. The positive rate of microbial culture was highest in wound tissue of ulcers caused by infection (87.6%), followed by pressure (77.1%), diabetes (68.3%), and venous diseases (67.7%). Bates-Jensen wound assessment tool (BWAT) scores >25 and wounds that lasted for more than 3 months had a higher positive rate of microbial culture. BWAT scores >25 and wounds in the rump, perineum, and feet were more likely to exhibit polymicrobial infection. A total of 600 strains were isolated, of which 46.2% (277 strains) were Gram-positive bacteria, 51.3% (308 strains) were Gram-negative bacteria, and 2.5% (15 strains) were fungi. The most common bacterial isolates were Staphylococcus aureus (29.2%), Escherichia coli (11.5%), Pseudomonas aeruginosa (11.0%), Proteus mirabilis (8.0%), and Klebsiella pneumoniae (5.8%). The susceptibility tests showed that 116 cultured bacteria were Multidrug resistant (MDR) strains. The resistance rates of S. aureus were 92.0% (161/175) to penicillin, 58.3% (102/175) to erythromycin, and 50.9% (89/175) to clindamycin. Vancomycin was the most effective antibiotic (0% resistance rate) against all Gram-positive bacteria. Besides, the resistance rates of E. coli were 68.1% (47/69) to ampicillin, 68.1% (47/69) to ciprofloxacin, 60.9% (42/69) to levofloxacin. However, all the isolated Gram-negative bacteria showed low resistance rates to tigecycline (3.9%) and amikacin (3.6%). Conclusions: The distribution of bacteria isolated from chronic cutaneous wounds varies with the BWAT scores, causes, duration, and the location of wounds. Multidrug resistance is a serious health issue, and therefore antibiotics used in chronic wounds must be under strict regulation. Our findings may help clinicians in making informed decisions regarding antibiotic therapy.

WHAT'S NEW IN INFECTION ON SURGICAL SITE AND ANTIBIOTICOPROPHYLAXIS IN SURGERY?

INTRODUCTION

Infection of the surgical site is the common complication, with significant rates of morbidity and mortality, representing a considerable economic problem for the health system.

OBJECTIVE

To carry out a narrative review of the literature on surgical site infection and the principles of antibiotic prophylaxis to update the knowledge of its use in surgery.

METHOD

Medline, Ovid, Google Scholar, National Library of Medicine (PubMed), Cochrane and SciELO were used for the research. The keywords used were "anti-bacterial agents"; "antibioticoprophylaxis" AND "surgical wound infection". The inclusion criteria were articles of recent publication, with full texts available and performed in humans.

RESULT

A total of 29 articles were evaluated and selected according to the eligibility criteria.

CONCLUSION

Infection of the surgical site is the most common postoperative complication. The key point of its prevention is the combination of several interventions that aim to reduce risk factors, such as: compliance with the new guidelines of the Center for Disease Control and Prevention; the principles of the use of prophylactic antibiotics; factors and risk index of the surgical site; administration time; duration and dosage of antibiotics. These data are available in this article.

Evaluation of Bacterial RNA Polymerase Inhibitors in a Staphylococcus aureus-Based Wound Infection Model in SKH1 Mice

Chronic wounds infected with pathogens such as Staphylococcus aureus represent a worldwide health concern, especially in patients with a compromised immune system. As antimicrobial resistance has become an immense global problem, novel antibiotics are urgently needed. One strategy to overcome this threatening situation is the search for drugs targeting novel binding sites on essential and validated enzymes such as the bacterial RNA polymerase (RNAP). In this work, we describe the establishment of an in vivo wound infection model based on the pathogen S. aureus and hairless Crl:SKH1-Hrhr (SKH1) mice. The model proved to be a valuable preclinical tool to study selected RNAP inhibitors after topical application. While rifampicin showed a reduction in the loss of body weight induced by the bacteria, an acceleration of wound healing kinetics, and a reduced number of colony forming units in the wound, the ureidothiophene-2-carboxylic acid 1 was inactive under in vivo conditions, probably due to strong plasma protein binding. The cocrystal structure of compound 1 with RNAP, that we hereby also present, will be of great value for applying appropriate structural modifications to further optimize the compound, especially in terms of plasma protein binding.

Development of a vaccine against Staphylococcus aureus invasive infections: Evidence based on human immunity, genetics and bacterial evasion mechanisms

Invasive Staphylococcus aureus infections are a leading cause of morbidity and mortality in both hospital and community settings, especially with the widespread emergence of virulent and multi-drug resistant methicillin-resistant S. aureus strains. There is an urgent and unmet clinical need for non-antibiotic immune-based approaches to treat these infections as the increasing antibiotic resistance is creating a serious threat to public health. However, all vaccination attempts aimed at preventing S. aureus invasive infections have failed in human trials, especially all vaccines aimed at generating high titers of opsonic antibodies against S. aureus surface antigens to facilitate antibody-mediated bacterial clearance. In this review, we summarize the data from humans regarding the immune responses that protect against invasive S. aureus infections as well as host genetic factors and bacterial evasion mechanisms, which are important to consider for the future development of effective and successful vaccines and immunotherapies against invasive S. aureus infections in humans. The evidence presented form the basis for a hypothesis that staphylococcal toxins (including superantigens and pore-forming toxins) are important virulence factors, and targeting the neutralization of these toxins are more likely to provide a therapeutic benefit in contrast to prior vaccine attempts to generate antibodies to facilitate opsonophagocytosis.

Antimicrobial approaches in the prevention of Staphylococcus aureus infections: a review

Background

The prophylactic application of antimicrobials that are active against Staphylococcus aureus can prevent infections. However, implementation in clinical practice is limited. We have reviewed antimicrobial approaches for the prevention of S. aureus infections.

Methods

We searched the Cochrane Central Register of Controlled Trials, PubMed/MEDLINE and EMBASE databases and trial registries using synonyms for S. aureus, infections and prevention as search terms. We included randomized controlled trials and systematic reviews only.

Results

Most studies were conducted with mupirocin. Mupirocin is effective in preventing S. aureus infections in patients receiving dialysis treatment and in surgical patients, particularly if the patients are carriers of S. aureus. The combination of mupirocin and chlorhexidine, but not chlorhexidine alone, is also effective against S. aureus infections. So far, vaccines have not proven successful in protecting against S. aureus infections. Regarding prophylactic povidone-iodine and systemic antibiotics, there is limited evidence supporting their effectiveness against S. aureus infections. Antimicrobial honey has not been proven to be more effective or non-inferior to mupirocin in protecting against S. aureus infections.

Conclusions

The current evidence supports the use of mupirocin as prophylaxis for preventing infections with S. aureus, particularly in carriers and in the surgical setting or in patients receiving dialysis treatment. Other antimicrobial agents have not been sufficiently proven to be effective so far, or have been proven ineffective. New trials with vaccines and anti-staphylococcal peptides are currently underway and may lead to new preventive strategies in the future.

Rapid and Broad Immune Efficacy of a Recombinant Five-Antigen Vaccine against Staphylococcus Aureus Infection in Animal Models

Staphylococcus aureus (S. aureus) is a leading cause of both healthcare-and community-associated infections globally, which result in severe disease and readily developing antibiotic resistance. Developing an efficacious vaccine against S. aureus is urgently required. In the present study, we selected five conserved antigens, including the secreted factors α-hemolysin (Hla), staphylococcal enterotoxin B (SEB) and the three surface proteins staphylococcal protein A (SpA), iron surface determinant B N2 domain (IsdB-N2) and manganese transport protein C (MntC). They were all well-characterized virulence factor of S. aureus and developed a recombinant five-antigen S. aureus vaccine (rFSAV), rFSAV provided consistent protection in S. aureus lethal sepsis and pneumonia mouse models, and it showed broad immune protection when challenged with a panel of epidemiologically relevant S. aureus strains. Meanwhile, rFSAV immunized mice were able to induce comprehensive cellular and humoral immune responses to reduce bacterial loads, inflammatory cytokine expression, inflammatory cell infiltration and decrease pathology after challenge with a sub-lethal dose of S. aureus. Moreover, the importance of specific antibodies in protection was demonstrated by antibody function tests in vitro and in vivo. Altogether, our data demonstrate that rFSAV is a potentially promising vaccine candidate for defensing against S. aureus infection.

Persistence of Immune Responses Through 36 Months in Healthy Adults After Vaccination With a Novel Staphylococcus aureus 4-Antigen Vaccine (SA4Ag)

Background

Staphylococcus aureus causes serious health care- and community-associated disease, requiring improved preventive measures such as vaccines. The investigational S. aureus 4-antigen vaccine (SA4Ag), comprising capsular polysaccharide serotypes 5 and 8 (CP5 and CP8) conjugated to CRM₁₉₇, recombinant mutant clumping factor A (rmClfA), and recombinant manganese transporter protein C (rP305A or rMntC), was well tolerated, inducing robust functional immune responses to all 4 antigens through 12 months postvaccination. This is a serological extension study through 36 months postvaccination.

Methods

In 2 previous studies, healthy adults received SA4Ag, SA3Ag (without rMntC), or placebo; serology was also assessed at ~24 and ~36 months postvaccination. Functional immune responses (antibody responses that facilitate killing of S. aureus or neutralize S. aureus virulence mechanisms) were assessed with opsonophagocytic activity killing assays (CP5 or CP8) and a fibrinogen-binding inhibition assay (ClfA). A competitive Luminex immunoassay assessed ClfA and rMntC responses. Adverse events within 48 hours of blood draw were recorded.

Results

Four hundred forty subjects (18-64 years old, 255; 65-85 years old, 185) were enrolled. At 24 and 36 months postvaccination, subjects receiving SA4Ag had substantially higher geometric mean titers (GMTs) for CP5, CP8, and ClfA vs baseline; geometric mean fold rises (GMFRs) from baseline to month 36 were 2.7-8.1. For rMntC, 36-month GMTs declined from peak levels but remained above baseline for all SA4Ag groups; GMFRs from baseline to month 36 were 1.8 and 1.5 in the younger and older cohorts, respectively.

Conclusions

Persistent functional immune responses to S. aureus antigens were observed through 36 months in healthy adults.

ClinicalTrialsgov

NCT01643941 and NCT01364571.

Surgical Infections and Antibiotic Stewardship: In Need for New Directions

BACKGROUND AND AIMS

Patients undergoing surgery are prone to infections, either at the site of surgery (superficial or organ-space) or at remote sites (e.g. pneumonia or urinary tract). Surgical site infections are associated with substantial morbidity and mortality, increased length of hospital stay and represent a huge burden to the health economy across all healthcare systems. Here we discuss recent advances and challenges in the field of surgical site infections.

MATERIAL AND METHODS

Review of pertinent English language literature.

RESULTS

Numerous guidelines and recommendations have been published in order to prevent surgical site infections. Compliance with these evidence-based guidelines vary and has not resulted in any major decrease in the surgical site infection rate. To date, most efforts to reduce surgical site infection have focused on the role of the surgeon, but a more comprehensive approach is necessary.

CONCLUSION

Surgical site infections need to be addressed in a structured way, including checklists, audits, monitoring, and measurements. All stakeholders, including the medical profession, the society, and the patient, need to work together to reduce surgical site infections. Most surgical site infections are preventable-and we need a paradigm shift to tackle the problem.

Immunization Against Staphylococcus aureus Infections

Background: Infections caused by Staphylococcus aureus continue to plague surgical patients, whether as surgical site infections or other nosocomial infections that complicate surgical care. The only meaningful methods available to decrease the risk of developing such infections are topical skin antisepsis (pre-operative skin preparation) and peri-operative antibiotic prophylaxis, neither of which offer a panacea. Alternatives to the latter are sought so as to minimize antibiotic selection pressure as a factor in the increasing problem of antimicrobial drug resistance. This review considers the possibility that immunization against S. aureus may offer a viable alternative for prophylaxis. Methods: Review and synthesis of pertinent English-language medical literature. Results: Vaccination against viral pathogens has been in successful clinical use for more than two centuries and was instrumental in the eradication of smallpox and the near-elimination of diseases such as poliomyelitis. Vaccinations against a limited number of bacterial pathogens (e.g., Bordetella pertussis, Clostridium tetanii, Corynebacterium diphtheriae, Haemophilus influenzae type b, Neisseria meningiditis, Streptococcus pneumoniae) have also been introduced with success, whereas others against bacteria are in development (C. difficile, Pseudomonas aeruginosa, S. aureus). Vaccination against S. aureus infection is in current veterinary use (e.g., to prevent mastitis among dairy cattle) but has not been successful to date in human beings despite multiple attempts, although development continues. Conclusions: Because of its complex microbiology, including multiple virulence factors and the ability to evade host immune surveillance, S. aureus presents numerous antigenic targets for vaccine development. Failure of two prior single-antigen vaccines in clinical trials has led to the consensus that future vaccine candidates must be directed against multiple antigens. Two distinct four-antigen vaccines are in clinical trials, but efficacy is yet to be determined.

Recent advances in Staphylococcus aureus infection: focus on vaccine development

Staphylococcus aureus normally colonizes the nasal cavity and pharynx. After breaching the normal habitat, the organism is able to cause a number of infections at any site of the body. The development of antibiotic resistance has created a global challenge for treating infections. Therefore, protection by vaccines may provide valuable measures. Currently, several vaccine candidates have been prepared which are either in preclinical phase or in early clinical phase, whereas several candidates have failed to show a protective efficacy in human subjects. Approaches have also been made in the development of monoclonal or polyclonal antibodies for passive immunization to protect from S. aureus infections. Therefore, in this review we have summarized the findings of recently published scientific literature to make a concise report.

Studying Biofilm and Clinical Issues in Orthopedics

The association between biofilm-forming microorganisms and prosthetic joint infection influences all aspect of management including approaches to diagnosis, management and prevention. This article will provide an overview of new anti-biofilm strategies for management of prosthetic joint infection.

Molecular epidemiology and expression of capsular polysaccharides in Staphylococcus aureus clinical isolates in the United States

Staphylococcus aureus capsular polysaccharides (CP) are important virulence factors under evaluation as vaccine antigens. Clinical S. aureus isolates have the biosynthetic capability to express either CP5 or CP8 and an understanding of the relationship between CP genotype/phenotype and S. aureus epidemiology is valuable. Using whole genome sequencing, the clonal relatedness and CP genotype were evaluated for disease-associated S. aureus isolates selected from the Tigecycline Evaluation and Surveillance Trial (T.E.S.T) to represent different geographic regions in the United States (US) during 2004 and 2009–10. Thirteen prominent clonal complexes (CC) were identified, with CC5, 8, 30 and 45 representing >80% of disease isolates. CC5 and CC8 isolates were CP type 5 and, CC30 and CC45 isolates were CP type 8. Representative isolates from prevalent CC were susceptible to in vitro opsonophagocytic killing elicited by anti-CP antibodies, demonstrating that susceptibility to opsonic killing is not linked to the genetic lineage. However, as not all S. aureus isolates may express CP, isolates representing the diversity of disease isolates were assessed for CP production. While approximately 35% of isolates (primarily CC8) did not express CP in vitro, CP expression could be clearly demonstrated in vivo for 77% of a subset of these isolates (n = 20) despite the presence of mutations within the capsule operon. CP expression in vivo was also confirmed indirectly by measuring an increase in CP specific antibodies in mice infected with CP5 or CP8 isolates. Detection of antigen expression in vivo in relevant disease states is important to support the inclusion of these antigens in vaccines. Our findings confirm the validity of CP as vaccine targets and the potential of CP-based vaccines to contribute to S. aureus disease prevention.

Safety, tolerability, and immunogenicity of a novel 4-antigen Staphylococcus aureus vaccine (SA4Ag) in healthy Japanese adults

A novel Staphylococcus aureus 4-antigen vaccine (SA4Ag) is under development, comprising capsular polysaccharide serotypes 5 and 8 (CP5 and CP8) conjugated to CRM197, recombinant protein clumping factor A (rmClfA), and recombinant manganese transporter protein C (MntC). We evaluated SA4Ag safety, tolerability, and immunogenicity in Japanese adults aged 20 to 64 and 65 to 85 years. A total of 136 healthy Japanese adults (68 per age group) were randomized 1:1 to receive single-dose SA4Ag or placebo intramuscularly (Day 1). Safety assessments included reactogenicity and adverse events. The ability of the vaccine to induce immune responses that are considered functional due to their ability to facilitate the killing of S. aureus or neutralize S. aureus virulence mechanisms was assessed using 5 different antigen-specific assays. SA4Ag was well tolerated in both age groups, with no safety concerns. At Day 29, > 85% of SA4Ag recipients in each age group achieved predefined thresholds for each antigen. Antibody geometric mean-fold rises from baseline to Day 29 in SA4Ag groups were: > 80 and > 30 for CP5 and CP8 (opsonophagocytic activity assay), > 10 for ClfA (fibrinogen-binding inhibition assay), and > 15 and > 7 for ClfA and MntC (competitive Luminex® immunoassay), respectively. Antibody titers decreased through Month 12 but remained well above baseline and placebo levels. SA4Ag had an acceptable safety profile and induced rapid and robust functional immune responses in both age groups. These results support ongoing development of SA4Ag for the prevention of invasive S. aureus disease in elective-surgery patients in Japan, North America, and Europe.

The role of vaccines in fighting antimicrobial resistance (AMR)

The problem of antimicrobial resistance (AMR) and the associated morbidity and mortality due to antibiotic resistant bacterial pathogens is not new. However, AMR has been increasing at an alarming rate with appearances of diseases caused by bacteria exhibiting resistance to not just one but multiple classes of antibiotics. The World Health Organization (WHO) supported by governments, health ministries and health agencies has formulated global action plans to combat the rise in AMR, supporting a number of proven initiatives such as antimicrobial stewardship, investments in development of new classes of antibiotics, and educational programs designed to eliminate inappropriate antibiotic use. Vaccines as tools to reduce AMR have historically been under-recognized, yet the positive effect in reducing AMR has been well established. For example Haemophilus influenzae type B (Hib) as well as Streptococcus pneumoniae (pneumococcal) conjugate vaccines have impressive track records in not only preventing life threatening diseases caused by these bacteria, but also reducing antibiotic use and AMR. This paper will describe the drivers of antibiotic use and subsequent development of AMR; it will make the case how existing vaccines are already participating in combatting AMR, describe future prospects for the role of new vaccines in development to reduce AMR, and highlight challenges associated with future vaccine development to combat AMR.

Immunomimetic Designer Cells Protect Mice from MRSA Infection

Many community- and hospital-acquired bacterial infections are caused by antibiotic-resistant pathogens. Methicillin-resistant Staphylococcus aureus (MRSA) predisposes humans to invasive infections that are difficult to eradicate. We designed a closed-loop gene network programming mammalian cells to autonomously detect and eliminate bacterial infections. The genetic circuit contains human Toll-like receptors as the bacterial sensor and a synthetic promoter driving reversible and adjustable expression of lysostaphin, a bacteriolytic enzyme highly lethal to S. aureus. Immunomimetic designer cells harboring this genetic circuit exhibited fast and robust sense-and-destroy kinetics against live staphylococci. When tested in a foreign-body infection model in mice, microencapsulated cell implants prevented planktonic MRSA infection and reduced MRSA biofilm formation by 91%. Notably, this system achieved a 100% cure rate of acute MRSA infections, whereas conventional vancomycin treatment failed. These results suggest that immunomimetic designer cells could offer a therapeutic approach for early detection, prevention, and cure of pathogenic infections in the post-antibiotic era.

Video Abstract

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A closed-loop gene network with bacterial sense-and-destroy actuation

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Direct diagnosis of implant-associated infections through blood biomarkers

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Early prevention of MRSA infection, as well as biofilm formation, in vivo

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Curing acute MRSA infections as an alternative to antibiotic therapy

The newly filed patent applications for vaccines against staphylococcus aureus

Staphylococcus aureus (S. aureus) frequently causes life threatening disease. To release the threat, vaccine has been proposed as a preventive intervention against the cause. However, the development of the vaccines is still in early stages. Thus, highlighting the related newly filed patent applications would stimulate further developments.

Surgical infection

Real and present danger