The role of vaccines in fighting antimicrobial resistance (AMR)

Epidemiology of non-vaccine serotypes of Streptococcus pneumoniae before and after universal administration of pneumococcal conjugate vaccines

The universal administration of pneumococcal conjugate vaccines (PCVs) had been demonstrated as an effective way to prevent Streptococcus pneumoniae infection. However, the immunity induced by PCVs protected against the infections caused by vaccine serotypes, which were usually more frequent than non-vaccine serotypes (NVTs). The prevalence and pathogenicity of NVTs after universal vaccination have caused widespread concern. We reviewed the epidemiology of non-PCV13 S. pneumoniae before and after PCV13 introduction, and explored the potential reasons for the spread of NVTs. Emerging and spreading NVTs can be regarded as the focus for future serotype epidemiological survey and vaccine optimization.AbbreviationsIPD: invasive pneumococcal disease PCV: pneumococcal conjugate vaccines VT: vaccine serotypeNVT: non-vaccine serotype.

Value of pneumococcal vaccination in controlling the development of antimicrobial resistance (AMR): Case study using DREAMR in Ethiopia

BACKGROUND

Antimicrobial resistance (AMR) poses an imminent threat to global health security. Pneumococcal vaccination reduces disease incidence, prevents antibiotic use, and decreases antibiotic-resistant infections. However, the benefit of vaccination in reducing AMR has been poorly quantified to date.

METHODS

We developed an agent-based model, DREAMR (Dynamic Representation of the Economics of AMR) to evaluate the economic value of childhood immunization with the pneumococcal conjugate vaccine (PCV) in mitigating the development of AMR. Our model incorporates vaccination coverage, disease incidence, care seeking, and antibiotic use. Accumulation of AMR is simulated based on antibiotic exposure through pharmacokinetics and resulting pharmacodynamics. The model was applied to Ethiopia.

RESULTS

Introduction of PCV vaccination has helped slow the development of AMR by 14.77% for amoxicillin and 0.59% for ceftriaxone in Ethiopia since 2011. In addition to the benefit of reduction in disease incidence, PCV vaccination has averted approximately 718,100 antibiotic treatment failures and 9,520 AMR-related deaths (27.8% reduction) in Ethiopia between 2011 and 2017, resulting in savings of $32.7 million. Maintaining current PCV immunization coverage will contribute an additional $7.67 million in annual AMR cost savings over five years compared to no vaccination scenario, which could increase to $11.43 million by increasing PCV coverage to 85% by 2022.

CONCLUSIONS

This study is the first to demonstrate the broader economic value of pneumococcal vaccination in controlling the development of AMR in Africa. Vaccination not only saves lives by preventing illnesses, but also benefits society by reducing antibiotic utilization and treatment failures due to AMR.

Manifesto on the Value of Adult Immunization: "We Know, We Intend, We Advocate"

Immunization through vaccination is a milestone achievement that has made a tremendous contribution to public health. Historically, immunization programs aimed firstly to protect children, who were disproportionally affected by infectious diseases. However, vaccine-preventable diseases can have significant impacts on adult mortality, health, and quality of life. Despite this, adult vaccinations have historically been overlooked in favor of other health priorities, because their benefits to society were not well recognized. As the general population is aging, the issue of vaccination in older adults is gaining importance. In high-income countries, recommendations for the routine vaccination of older adults have been gradually introduced. The Italian National Immunization Plan is considered to be among the most advanced adult vaccination plans in Europe. However, available data indicate there is low adherence to vaccination recommendations in Italy. The COVID-19 pandemic has exposed the damage that can be caused by an infectious disease, especially among adults and individuals with comorbidities. The aim of this “Manifesto”, therefore, is to provide an overview of the existing evidence on the value of adult vaccination, in the Italian context, with a call to action to healthcare providers and health authorities.

Burden of invasive group B Streptococcus disease in non-pregnant adults: A systematic review and meta-analysis

Background

Streptococcus agalactiae or group B Streptococcus (GBS) has emerged as an important cause of invasive disease in adults, particularly among the elderly and those with underlying comorbidities. Traditionally, it was recognised as an opportunistic pathogen colonising and causing disease in pregnant women, neonates, and young infants. Reasons for the upsurge of invasive GBS (iGBS) among the elderly remain unclear, although it has been related to risk factors such as underlying chronic diseases, immunosenescence, impaired inflammatory response, and spread of virulent clones. Antibiotics are successfully as treatment or prophylaxis against iGBS. Several candidate vaccines against iGBS are under development.

Objectives

To conduct a systematic review of the current literature on invasive GBS in order to determine disease incidence and case fatality ratio (CFR) among non-pregnant adults. Additionally, information on risk factors, clinical presentation, serotype distribution, and antimicrobial resistance was also retrieved.

Methods

Between January and June 2020, electronic searches were conducted in relevant databases: MEDLINE, EMBASE, Global Health, and SCOPUS. Studies were included in the systematic review if they met the inclusion/exclusion criteria. The authors assessed the selected studies for relevance, risk of bias, outcome measures, and heterogeneity. Meta-analyses on incidence and CFR were conducted after evaluating the quality of methods for assessment of exposure and outcomes.

Results

Pooled estimates of iGBS incidence in non-pregnant adults 15 years and older were 2.86 cases per 100.000 population (95% CI, 1.68–4.34). Incidence rates in older adults were substantially higher, 9.13 (95%CI, 3.53–17.22) and 19.40 (95%CI, 16.26–22.81) per 100.000 population ≥50 and ≥ 65 years old, respectively. Incidence rates ranged from 0.40 (95% CI, 0.30–0.60) in Africa to 5.90 cases per 100.000 population (95% CI, 4.30–7.70) in North America. The overall CFR was and 9.98% (95% CI, 8.47–11.58). CFR was highest in Africa at 22.09% (95% CI, 12.31–33.57). Serotype V was the most prevalent serotype globally and in North America accounting for 43.48% (n = 12926) and 46,72% (n = 12184) of cases, respectively. Serotype Ia was the second and serotype III was more prevalent in Europe (25.0%) and Asia (29.5%). Comorbidities were frequent among non-pregnant adult iGBS cases. Antimicrobial resistance against different antibiotics (i.e., penicillin, erythromycin) is increasing over time.

Conclusions

This systematic review revealed that iGBS in non-pregnant adults has risen in the last few years and has become a serious public health threat especially in older adults with underlying conditions. Given the current serotype distribution, vaccines including serotypes predominant among non-pregnant adults (i.e., serotypes V, Ia, II, and III) in their formulation are needed to provide breadth of protection. Continued surveillance monitoring potential changes in serotype distribution and antimicrobial resistance patterns are warranted to inform public health interventions.

Bacterial Outer Membrane Vesicles as a Versatile Tool in Vaccine Research and the Fight against Antimicrobial Resistance

Gram-negative bacteria include a number of pathogens that cause disease in humans and animals. Although antibiotics are still effective in treating a considerable range of infections caused by Gram-negative bacteria, the alarming increase of antimicrobial resistance (AMR) induced by excessive use of antibiotics has raised global concerns. Therefore, alternative strategies must be developed to prevent and treat bacterial infections and prevent the advent of a postantibiotic era. Vaccines, one of the greatest achievements in the history of medical science, hold extraordinary potential to prevent bacterial infections and thereby reduce the need for antibiotics. Novel bacterial vaccines are urgently needed, however, and outer membrane vesicles (OMVs), naturally produced by Gram-negative bacteria, represent a promising and versatile tool that can be employed as adjuvants, antigens, and delivery platforms in the development of vaccines against Gram-negative bacteria. Here, we provide an overview of the many roles OMVs can play in vaccine development and the mechanisms behind these applications. Methods to improve OMV yields and a comparison of different strategies for OMV isolation aiming at cost-effective production of OMV-based vaccines are also reviewed.

Healthy Ageing and Vaccines: Application of the P4 Medicine Concept to Immunizations

In today's tormented world, it appears useful to take advantage of communication channels to promote life-course immunization and affirm its major role in healthy ageing. Instead of developing the argument of chronological age, we demonstrate the life-course principle here based on the P4 medicine concept. Are vaccines "preventive, personalized, predictive, and participatory?" Based on detailed analysis of research findings, we successively demonstrate the seminal role of vaccines on preventable infectious diseases, post-sepsis functional decline, non-communicable diseases (cardio-neuro-vascular, respiratory, and renal diseases), community protection, antimicrobial resistance, and perhaps even old-age dementia. Healthy ageing and the promotion of immunization are closely dependent on health literacy and provision of information by skilled health-care professionals. However, personal autonomy and individual freedom are influenced by psycho-cognitive hurdles (cultural approaches, beliefs, emotions, and behaviours), the opinions of the public/family/friends, and the increasing role of social media, which challenges scientific evidence. A similar phenomenon exists when dealing with the issue of healthy ageing, whose success depends greatly on life-course immunization.

Twenty-Year Public Health Impact of 7- and 13-Valent Pneumococcal Conjugate Vaccines in US Children

Pneumococcal conjugate vaccines (PCVs) have been used in the United States since 2000. To assess the cumulative 20-year effect of PCVs on invasive pneumococcal disease (IPD) incidence among children <5 years of age, we analyzed Active Bacterial Core Surveillance data, conducted a literature review, and modeled expected and observed disease. We found that PCVs have averted >282,000 cases of IPD, including ≈16,000 meningitis, ≈172,000 bacteremia, and ≈55,000 bacteremic pneumonia cases. In addition, vaccination has prevented 97 million healthcare visits for otitis media, 438,914-706,345 hospitalizations for pneumonia, and 2,780 total deaths. IPD cases declined 91%, from 15,707 in 1997 to 1,382 in 2019. Average annual visits for otitis media declined 41%, from 78 visits/100 children before PCV introduction to 46 visits/100 children after PCV13 introduction. Annual pneumonia hospitalizations declined 66%-79%, from 110,000-175,000 in 1997 to 37,000 in 2019. These findings confirm the substantial benefits of PCVs for preventing IPD in children.

Strategies to Improve Antimicrobial Utilization with a Special Focus on Developing Countries

Antimicrobial resistance (AMR) is a high priority across countries as it increases morbidity, mortality and costs. Concerns with AMR have resulted in multiple initiatives internationally, nationally and regionally to enhance appropriate antibiotic utilization across sectors to reduce AMR, with the overuse of antibiotics exacerbated by the COVID-19 pandemic. Effectively tackling AMR is crucial for all countries. Principally a narrative review of ongoing activities across sectors was undertaken to improve antimicrobial use and address issues with vaccines including COVID-19. Point prevalence surveys have been successful in hospitals to identify areas for quality improvement programs, principally centering on antimicrobial stewardship programs. These include reducing prolonged antibiotic use to prevent surgical site infections. Multiple activities centering on education have been successful in reducing inappropriate prescribing and dispensing of antimicrobials in ambulatory care for essentially viral infections such as acute respiratory infections. It is imperative to develop new quality indicators for ambulatory care given current concerns, and instigate programs with clear public health messaging to reduce misinformation, essential for pandemics. Regular access to effective treatments is needed to reduce resistance to treatments for HIV, malaria and tuberculosis. Key stakeholder groups can instigate multiple initiatives to reduce AMR. These need to be followed up.

Prescription Antibiotic Use Among the US population 1999-2018: National Health and Nutrition Examination Surveys

Background

Antibiotic resistance has been identified as a public health threat both in the United States and globally. The United States published the National Strategy for Combating Antibiotic Resistance in 2014, which included goals to reduce inappropriate outpatient antibiotic use.

Methods

This cross-sectional study was conducted using National Health and Nutrition Examination Surveys (NHANES) years 1999–2018. Weighted prevalence of past 30-day nontopical outpatient antibiotic use was calculated, as well as the change in prevalence from 1999–2002 to 2015–2018 and 2007–2010 to 2015–2018, both overall and for subgroups. Associations with past 30-day nontopical outpatient antibiotic use in 2015–2018 were examined using predictive margins calculated by multivariable logistic regression.

Results

The overall prevalence of past 30-day nontopical outpatient antibiotic use adjusted for age, sex, race/ethnicity, poverty status, time of year of the interview, and insurance status from 1999–2002 to 2015–2018 changed significantly from 4.9% (95% CI, 3.9% to 5.0%) to 3.0% (95% CI, 2.6% to 3.0%), with the largest decrease among children age 0–1 years. From 2007–2010 to 2015–2018, there was no significant change (adjusted prevalence ratio [adjPR], 1.0; 95% CI, 0.8 to 1.2). Age was significantly associated with antibiotic use, with children age 0–1 years having significantly higher antibiotic use than all other age categories >6 years. Being non-Hispanic Black was negatively associated with antibiotic use as compared with being non-Hispanic White (adjPR, 0.6; 95% CI, 0.4 to 0.8).

Conclusions

While there were declines in antibiotic use from 1999–2002 to 2015–2018, there were no observed declines during the last decade.

Pollution by Antibiotics and Antimicrobial Resistance in LiveStock and Poultry Manure in China, and Countermeasures

The demand for animal protein has increased considerably worldwide, especially in China, where large numbers of livestock and poultry are produced. Antibiotics have been widely applied to promote growth and prevent diseases. However, the overuse of antibiotics in animal feed has caused serious environmental and health risks, especially the wide spread of antimicrobial resistance (AMR), which seriously affects animal and human health, food safety, ecosystems, and the sustainable future development of animal protein production. Unfortunately, AMR has already become a worldwide challenge, so international cooperation is becoming more important for combatting it. China’s efforts and determination to restrict antibiotic usage through law enforcement and effective management are of significance. In this review, we address the pollution problems of antibiotics; in particular, the AMR in water, soil, and plants caused by livestock and poultry manure in China. The negative impact of widespread and intensive use of antibiotics in livestock production is discussed. To reduce and mitigate AMR problems, we emphasize in this review the development of antibiotic substitutes for the era of antibiotic prohibition.

Serum Antibody Responses against Carbapenem-Resistant Klebsiella pneumoniae in Infected Patients

Capsular polysaccharide (CPS) heterogeneity within carbapenem-resistant Klebsiella pneumoniae (CR-Kp) strain sequence type 258 (ST258) must be considered when developing CPS-based vaccines. Here, we sought to characterize CPS-specific antibody responses elicited by CR-Kp-infected patients. Plasma and bacterial isolates were collected from 33 hospital patients with positive CR-Kp cultures. Isolate capsules were typed by wzi sequencing. Reactivity and measures of efficacy of patient antibodies were studied against 3 prevalent CR-Kp CPS types (wzi29, wzi154, and wzi50). High IgG titers against wzi154 and wzi50 CPS were documented in 79% of infected patients. Patient-derived (PD) IgGs agglutinated CR-Kp and limited growth better than naive IgG and promoted phagocytosis of strains across the serotype isolated from their donors. Additionally, poly-IgG from wzi50 and wzi154 patients promoted phagocytosis of nonconcordant CR-Kp serotypes. Such effects were lost when poly-IgG was depleted of CPS-specific IgG. Additionally, mice infected with wzi50, wzi154, and wzi29 CR-Kp strains preopsonized with wzi50 patient-derived IgG exhibited lower lung CFU than controls. Depletion of wzi50 antibodies (Abs) reversed this effect in wzi50 and wzi154 infections, whereas wzi154 Ab depletion reduced poly-IgG efficacy against wzi29 CR-Kp We are the first to report cross-reactive properties of CPS-specific Abs from CR-Kp patients through both in vitro and in vivo models.IMPORTANCE Carbapenem-resistant Klebsiella pneumoniae is a rapidly emerging public health threat that can cause fatal infections in up to 50% of affected patients. Due to its resistance to nearly all antimicrobials, development of alternate therapies like antibodies and vaccines is urgently needed. Capsular polysaccharides constitute important targets, as they are crucial for Klebsiella pneumoniae pathogenesis. Capsular polysaccharides are very diverse and, therefore, studying the host's capsule-type specific antibodies is crucial to develop effective anti-CPS immunotherapies. In this study, we are the first to characterize humoral responses in infected patients against carbapenem-resistant Klebsiella pneumoniae expressing different wzi capsule types. This study is the first to report the efficacy of cross-reactive properties of CPS-specific Abs in both in vitro and in vivo models.

Antimicrobial Stewardship: Fighting Antimicrobial Resistance and Protecting Global Public Health

Antimicrobial resistance (AMR) is a serious threat to global public health. It increases morbidity and mortality, and is associated with high economic costs due to its health care burden. Infections with multidrug-resistant (MDR) bacteria also have substantial implications on clinical and economic outcomes. Moreover, increased indiscriminate use of antibiotics during the COVID-19 pandemic will heighten bacterial resistance and ultimately lead to more deaths. This review highlights AMR's scale and consequences, the importance, and implications of an antimicrobial stewardship program (ASP) to fight resistance and protect global health. Antimicrobial stewardship (AMS), an organizational or system-wide health-care strategy, is designed to promote, improve, monitor, and evaluate the rational use of antimicrobials to preserve their future effectiveness, along with the promotion and protection of public health. ASP has been very successful in promoting antimicrobials' appropriate use by implementing evidence-based interventions. The "One Health" approach, a holistic and multisectoral approach, is also needed to address AMR's rising threat. AMS practices, principles, and interventions are critical steps towards containing and mitigating AMR. Evidence-based policies must guide the "One Health" approach, vaccination protocols, health professionals' education, and the public's awareness about AMR.

Exploring Virulence Factors and Alternative Therapies against Staphylococcus aureus Pneumonia

Pneumonia is an acute pulmonary infection associated with high mortality and an immense financial burden on healthcare systems. Staphylococcus aureus is an opportunistic pathogen capable of inducing S. aureus pneumonia (SAP), with some lineages also showing multidrug resistance. Given the high level of antibiotic resistance, much research has been focused on targeting S. aureus virulence factors, including toxins and biofilm-associated proteins, in an attempt to develop effective SAP therapeutics. Despite several promising leads, many hurdles still remain for S. aureus vaccine research. Here, we review the state-of-the-art SAP therapeutics, highlight their pitfalls, and discuss alternative approaches of potential significance and future perspectives.

Communicating Benefits from Vaccines Beyond Preventing Infectious Diseases

Despite immunisation being one of the greatest medical success stories of the twentieth century, there is a growing lack of confidence in some vaccines. Improving communication about the direct benefits of vaccination as well as its benefits beyond preventing infectious diseases may help regain this lost confidence. A conference was organised at the Fondation Merieux in France to discuss what benefits could be communicated and how innovative digital initiatives can used for communication. During this meeting, a wide range of indirect benefits of vaccination were discussed. For example, influenza vaccination can reduce hospitalisations and deaths in older persons with diabetes by 45% and 38%, respectively, but the link between influenza and complications from underlying chronic non-communicable diseases such as diabetes is frequently underestimated. Vaccination can reduce antimicrobial resistance (AMR), which is growing, by reducing the incidence of infectious disease (though direct and indirect or herd protection), by reducing the number of circulating AMR strains, and by reducing the need for antimicrobial use. Disease morbidity and treatment costs in the elderly population are likely to rise substantially, with the ageing global population. Healthy ageing and life-course vaccination approaches can reduce the burden of vaccine-preventable diseases, such as seasonal influenza and pneumococcal diseases, which place a significant burden on individuals and society, while improving quality of life. Novel disease surveillance systems based on information from Internet search engines, mobile phone apps, social media, cloud-based electronic health records, and crowd-sourced systems, contribute to improved awareness of disease burden. Examples of the role of new techniques and tools to process data generated by multiple sources, such as artificial intelligence, to support vaccination programmes, such as influenza and dengue, were discussed. The conference participants agreed that continual efforts are needed from all stakeholders to ensure effective, transparent communication of the full benefits and risks of vaccination.

Antibiotic Resistance: Moving From Individual Health Norms to Social Norms in One Health and Global Health

Antibiotic resistance is a problem for human health, and consequently, its study had been traditionally focused toward its impact for the success of treating human infections in individual patients (individual health). Nevertheless, antibiotic-resistant bacteria and antibiotic resistance genes are not confined only to the infected patients. It is now generally accepted that the problem goes beyond humans, hospitals, or long-term facility settings and that it should be considered simultaneously in human-connected animals, farms, food, water, and natural ecosystems. In this regard, the health of humans, animals, and local antibiotic-resistance-polluted environments should influence the health of the whole interconnected local ecosystem (One Health). In addition, antibiotic resistance is also a global problem; any resistant microorganism (and its antibiotic resistance genes) could be distributed worldwide. Consequently, antibiotic resistance is a pandemic that requires Global Health solutions. Social norms, imposing individual and group behavior that favor global human health and in accordance with the increasingly collective awareness of the lack of human alienation from nature, will positively influence these solutions. In this regard, the problem of antibiotic resistance should be understood within the framework of socioeconomic and ecological efforts to ensure the sustainability of human development and the associated human-natural ecosystem interactions.

Challenges for Clinical Development of Vaccines for Prevention of Hospital-Acquired Bacterial Infections

Increasing antibiotic resistance in bacteria causing endogenous infections has entailed a need for innovative approaches to therapy and prophylaxis of these infections and raised a new interest in vaccines for prevention of colonization and infection by typically antibiotic resistant pathogens. Nevertheless, there has been a long history of failures in late stage clinical development of this type of vaccines, which remains not fully understood. This article provides an overview on present and past vaccine developments targeting nosocomial bacterial pathogens; it further highlights the specific challenges associated with demonstrating clinical efficacy of these vaccines and the facts to be considered in future study designs. Notably, these vaccines are mainly applied to subjects with preexistent immunity to the target pathogen, transient or chronic immunosuppression and ill-defined microbiome status. Unpredictable attack rates and changing epidemiology as well as highly variable genetic and immunological strain characteristics complicate the development. In views of the clinical need, re-thinking of the study designs and expectations seems warranted: first of all, vaccine development needs to be footed on a clear rationale for choosing the immunological mechanism of action and the optimal time point for vaccination, e.g., (1) prevention (or reduction) of colonization vs. prevention of infection and (2) boosting of a preexistent immune response vs. altering the quality of the immune response. Furthermore, there are different, probably redundant, immunological and microbiological defense mechanisms that provide protection from infection. Their interplay is not well-understood but as a consequence their effect might superimpose vaccine-mediated resolution of infection and lead to failure to demonstrate efficacy. This implies that improved characterization of patient subpopulations within the trial population should be obtained by pro- and retrospective analyses of trial data on subject level. Statistical and systems biology approaches could help to define immune and microbiological biomarkers that discern populations that benefit from vaccination from those where vaccines might not be effective.

Vaccinomics to design a novel single chimeric subunit vaccine for broad-spectrum immunological applications targeting nosocomial Enterobacteriaceae pathogens

Healthcare associated infections (HAIs) are major cause of elevated mortality, morbidity, and high healthcare costs. Development of a vaccine targeting these pathogens could benefit in reducing HAIs count and excessive use of antibiotics. This work aimed to design a multi-epitope based prophylactic/ therapeutic vaccine directing against carbapenem resistant Enterobacter cloacae and other leading nosocomial members of Enterobacteriaceae group. Based on subtractive proteomics and immunoinformatics in-depth investigation of E. cloacae reference proteome, we prioritize four targets: outer membrane usher protein-lpfC, putative outer membrane protein A-OmpA, putative outer membrane protein-FimD, and arginine transporter fulfilling criteria of vaccine candidacy. A multi-epitope peptide vaccine construct is then formulated comprising predicted epitopes with potential to evoke both innate and adaptive immunity and B-subunit of cholera toxin as an adjuvant. The construct is modelled, loop refined, improved for stability via disulfide engineering and optimized for codon usage as per Escherichia coli expression system to ensure its maximum expression. Cross-conservation analysis carried out to evaluate broad-spectrum applicability by providing cross protection against nosocomial pathogens. A blind docking method is applied further to predict predominant binding mode of the construct with TLR4 innate immune receptor, followed by molecular dynamics simulation protocol to probe complex dynamics and exposed topology of the construct epitopes for recognition and immune processing by the host. Towards the end, binding free energies of the vaccine construct-TLR4 receptor were estimated to test docking predictions and affirm complex stability. We believe these findings to be highly useful for vaccinologists in making a highly effective vaccine for E. cloacae specifically, and other notorious Enterobacteriaceae nosocomial pathogens in general.

Effectiveness and cost-effectiveness of a Clostridium difficile vaccine candidate in a hospital setting

Toxoid vaccines against Clostridium difficile infections (CDI) appear promising in reducing the risk of developing toxin-mediated symptoms. We sought to evaluate the effectiveness and cost-effectiveness of a vaccine candidate in a hospital setting. We developed an agent-based simulation model of nosocomial CDI in a 300-bed hospital. Targeting high-risk patients for vaccination, we estimated the reduction of symptomatic CDI. Using the net reduction of CDI-associated isolation days, we evaluated the vaccine's cost-effectiveness from a healthcare provider perspective over a 2-year period with an average monthly incidence of 5 cases per 10,000 patient-days pre-vaccination. Assuming a vaccine efficacy in the range 60-90%, vaccinating 40% of high-risk patients pre-admission reduced symptomatic CDI by 16.6% (95% CI: 15.2, 17.9). When the vaccine coverage increased to 80%, the reduction of symptomatic CDI was 34.6% (95% CI: 33.7, 35.9). For a willingness to pay (WTP) of CDN$1000 (corresponding to the average costs of case isolation per day), vaccine was cost-effective for vaccination costs per individual (VCPI) up to CDN$111 in the scenario of 40% vaccine coverage. With the same WTP, vaccine was cost-effective for VCPI up to CDN$121 when the vaccine coverage increased to 80%. A significant portion (~80%) of hospital colonization is caused by environmental transmission of C. difficile, which markedly reduced the effectiveness of vaccine below its assumed efficacy. However, due to the number of CDI-associated isolation days averted, vaccination of high-risk patients can be cost-effective depending on the WTP and the VCPI.

Commentary: Why Has Uptake of Pneumococcal Vaccines for Children Been So Slow? The Perils of Undervaluation

Pediatric pneumococcal disease exacts a substantial burden on global health, much of which is vaccine-preventable. Despite this considerable burden and the demonstrably high efficacy of pneumococcal conjugate vaccines (PCVs), the overall level of PCV uptake remains concerningly low, especially compared with that of other childhood-recommended vaccines, such as tuberculosis and polio. A broad set of plausible explanations exists for this low uptake, including logistical challenges, psychosocial factors and affordability. One additional and systematic cause of low uptake, which is the focus of our discussion, is economists' and policymakers' tendency to undervalue vaccination in general by adopting a narrow health sector perspective when performing economic evaluations of vaccines. We present an alternative, societal framework for economic evaluations that encompasses a broader set of socioeconomic benefits in addition to health benefits. Quantifying a more comprehensive taxonomy of PCV's benefits will help to address potential undervaluation and may be sufficient not only to justify recommendation and reimbursement but also to stimulate efforts and investment toward closing coverage gaps.

Biomarkers for Detecting Resilience against Mycobacterial Disease in Animals

Paratuberculosis and bovine tuberculosis are two mycobacterial diseases of ruminants which have a considerable impact on livestock health, welfare, and production. These are chronic "iceberg" diseases which take years to manifest and in which many subclinical cases remain undetected. Suggested biomarkers to detect infected or diseased animals are numerous and include cytokines, peptides, and expression of specific genes; however, these do not provide a strong correlation to disease. Despite these advances, disease detection still relies heavily on dated methods such as detection of pathogen shedding, skin tests, or serology. Here we review the evidence for suitable biomarkers and their mechanisms of action, with a focus on identifying animals that are resilient to disease. A better understanding of these factors will help establish new strategies to control the spread of these diseases.

Implication of the knowledge and perceptions of veterinary students of antimicrobial resistance for future prescription of antimicrobials in animal health, South Africa

Understanding the knowledge and perceptions of veterinary students of antimicrobial resistance (AMR) as potential future prescribers of antimicrobials may serve as an opportunity to improve stewardship of AMR. Pre-final (n = 42) and final (n = 29) year veterinary students of the University of Pretoria completed questionnaires to determine their knowledge and perceptions of AMR. Of the 71 respondents, mixed practice (48%) and small animal practice (45%) were the most preferred career choices post-graduation, with the field of gross pathology being the least preferred. Over 80% of the respondents believed that veterinary practitioners' misuse of antimicrobials contributes to AMR and a higher percentage (98.6%) believed that farmers' misuse of antimicrobials encourages the development of AMR, in particular, in food animals (60.6%) compared to companion animals (50.7%). Agreement in the ranking of abuse of antimicrobials between pre-final and final year students was fair (36.4%; kappa 0.3), and the most abused antimicrobials in descending order listed by the students were tetracyclines, penicillins, sulphonamides and aminoglycosides. There was wide disparity between training and potential field application, as well as variations in the correct matching of antimicrobials to their respective antibiotic classes. Responses to the clinical application of antimicrobials also varied widely. Despite the apparent teaching of AMR to veterinary students, gaps may exist in the translation of theoretical concepts to clinical applications, hence the need for focused and targeted antimicrobial prescription and stewardship training to bridge these potential identified gaps.

Immunization with proline rich region of pneumococcal surface protein A has no role in protection against Streptococcus pneumoniae serotype 19F

Pneumococcal surface protein A (PspA) is one of the major virulence factors expressed by almost all pneumococcal serotypes and was suggested to be a promising universal vaccine candidate for all pneumococcal sero-groups. Here, we expressed and purified the proline-rich region (PR) of PspA and tested it as a recombinant vaccine against infection caused by a clinical isolate (SP₁₉) of Streptococcus pneumoniae serotype 19F. Our results showed that BALB/c mice immunized with recombinant proline-rich (rPR) region showed a significant higher antibody titre against rPR region compared to control non-immunized group. However, immunized mice or mice recived polyclonal antibodies against rPR region challenged via the intra-peritoneal route with a lethal dose of SP₁₉ isolate showed no significant difference in survival compared to control non-immunized group. These results suggested that, immunization of BALB/c mice with rPR region of PspA is not protective against infection caused by serotype 19F in a mouse model.

The Genomics of Streptococcus Pneumoniae Carriage Isolates from UK Children and Their Household Contacts, Pre-PCV7 to Post-PCV13

We used whole genome sequencing (WGS) analysis to investigate the population structure of 877 Streptococcus pneumoniae isolates from five carriage studies from 2002 (N = 346), 2010 (N = 127), 2013 (N = 153), 2016 (N = 187) and 2018 (N = 64) in UK households which covers the period pre-PCV7 to post-PCV13 implementation. The genomic lineages seen in the population were determined using multi-locus sequence typing (MLST) and PopPUNK (Population Partitioning Using Nucleotide K-mers) which was used for local and global comparisons. A Roary core genome alignment of all the carriage genomes was used to investigate phylogenetic relationships between the lineages. The results showed an influx of previously undetected sequence types after vaccination associated with non-vaccine serotypes. A small number of lineages persisted throughout, associated with both non-vaccine and vaccine types (such as ST199), or that could be an example of serotype switching from vaccine to non-vaccine types (ST177). Serotype 3 persisted throughout the study years, represented by ST180 and Global Pneumococcal Sequencing Cluster (GPSC) 12; the local PopPUNK analysis and core genome maximum likelihood phylogeny separated them into two clades, one of which is only seen in later study years. The genomic data showed that serotype replacement in the carriage studies was mostly due to a change in genotype as well as serotype, but that some important genetic lineages, previously associated with vaccine types, persisted.

Defining and combating antibiotic resistance from One Health and Global Health perspectives

Several interconnected human, animal and environmental habitats can contribute to the emergence, evolution and spread of antibiotic resistance, and the health of these contiguous habitats (the focus of the One Health approach) may represent a risk to human health. Additionally, the expansion of resistant clones and antibiotic resistance determinants among human-associated, animal-associated and environmental microbiomes have the potential to alter bacterial population genetics at local and global levels, thereby modifying the structure, and eventually the productivity, of microbiomes where antibiotic-resistant bacteria can expand. Conversely, any change in these habitats (including pollution by antibiotics or by antibiotic-resistant organisms) may influence the structures of their associated bacterial populations, which might affect the spread of antibiotic resistance to, and among, the above-mentioned microbiomes. Besides local transmission among connected habitats-the focus of studies under the One Health concept-the transmission of resistant microorganisms might occur on a broader (even worldwide) scale, requiring coordinated Global Health actions. This Review provides updated information on the elements involved in the evolution and spread of antibiotic resistance at local and global levels, and proposes studies to be performed and strategies to be followed that may help reduce the burden of antibiotic resistance as well as its impact on human and planetary health.

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.

A Modular Vaccine Platform Combining Self-Assembled Peptide Cages and Immunogenic Peptides

Subunit vaccines use delivery platforms to present minimal antigenic components for immunization. The benefits of such systems include multivalency, self-adjuvanting properties, and more specific immune responses. Previously, the design, synthesis, and characterization of self-assembling peptide cages (SAGEs) have been reported. In these, de novo peptides are combined to make hubs that assemble into nanoparticles when mixed in aqueous solution. Here it is shown that SAGEs are nontoxic particles with potential as accessible synthetic peptide scaffolds for the delivery of immunogenic components. To this end, SAGEs functionalized with the model antigenic peptides tetanus toxoid632-651 and ovalbumin323-339 drive antigen-specific responses both in vitro and in vivo, eliciting both CD4+ T cell and B cell responses. Additionally, SAGEs functionalized with the antigenic peptide hemagglutinin518-526 from the influenza virus are also able to drive a CD8+ T cell response in vivo. This work demonstrates the potential of SAGEs to act as a modular scaffold for antigen delivery, capable of inducing and boosting specific and tailored immune responses.

Reduction in antimicrobial resistance by the way of extensive vaccination

In recent years, antibiotic-resistant bacteria emerged as a great problem leading to treatment failures and an increase in the cost of healthcare. There is a growing belief in the use of vaccines to reduce the antimicrobial resistance (AMR). The vaccination could prevent the possibilities of infection that are known to induce AMR, which further reduces its treatment by antibiotics and the risk of its poor outcomes. It is possible to reduce the microbial population upon vaccination, which will theoretically reduce the chances for exchange of genetic elements responsible for resistance. The international collaborations among health workers and researchers are required to build surveillance and control strategy to combat antibiotic resistance. Priorities should be given towards the development of rapid diagnostics and characterization of resistant bacterial strains by basic and applied research.