Use of mathematical modelling to assess the impact of vaccines on antibiotic resistance

Why prescribe antibiotics? A systematic review of knowledge, tension, and motivation among clinicians in low-, middle- and high-income countries

Medical professionals such as physicians and veterinarians are responsible for appropriate antimicrobial prescription (AMP) and use. Although seemingly straightforward, the factors influencing antibiotic prescription, a category of antimicrobials, are complex. Many studies have been conducted in the past two decades on this subject. As a result, there is a plethora of empirical evidence regarding the factors influencing clinicians' AMP practices.

AIM

A systematic review of AMR studies on AMP was conducted, condensing findings according to a combination of the Knowledge, Attitude, and Practice (KAP) and Capacity, Opportunity, Motivation-Behavior (COM-B) models. Review findings were then synthesized and analyzed for policy implementation according to the Consolidated Framework for Implementation Research (CFIR).

DESIGN AND METHODOLOGY

A systematic literature review was conducted according to PRISMA guidelines to identify peer-reviewed papers indexed in pre-determined medical science, social sciences, and humanities databases that apply the KAP model in their investigations. Antimicrobial prescription factors were compared and contrasted among low- and middle-income countries (LMICs) and high-income countries (HICs).

FINDINGS

The KAP model is a heuristic and structured framework for identifying and classifying respondents' knowledge. However, other than medical knowledge, factors that influence prescription decision-making can be expanded to include attitudes, perception, personal affinities, professional circumstances, relational pressure, and social norms.

Longitudinal Study of Antibiotic Resistance of Staphylococci from Cases of Subclinical Mastitis in Sheep in Greece: Incidence and Risk Factors

The present paper extends a previous publication on a field study of subclinical mastitis in sheep and focuses on the following laboratory characteristics of the staphylococcal isolates: antibiotic resistance and association with biofilm formation. The specific objectives of the present study were (a) to describe the incidence of isolation of antibiotic-resistant staphylococci from cases of mastitis throughout the milking period in dairy sheep flocks and (b) to identify relevant risk factors, which would contribute to the sustainable control of the infection. Staphylococcal isolates from subclinical mastitis were evaluated for antibiotic resistance to 18 antibiotics. Antibiotic resistance was detected in 57 of the 179 staphylococcal isolates from subclinical mastitis (31.8%). Resistance was recorded against 11 antibiotics, most often against ampicillin (63.2% of resistant isolates), penicillin (63.2%) and tetracycline (47.4%). Isolates resistant to ampicillin and penicillin were recovered in all 12 farms. Twenty-one multidrug-resistant isolates (11.7%) were also recovered. The incidence risk of isolation of staphylococci resistant to at least one (any) antibiotic throughout the study period was 23.8%. The incidence risk of isolation of staphylococci resistant to oxacillin was 5.0%; that of isolation of multidrug-resistant staphylococci was 8.8%. With regard to increased incidence risk of isolation of staphylococci resistant to at least one (any) antibiotic and increased incidence risk of isolation of staphylococci resistant to oxacillin, the omission of anti-staphylococcal mastitis vaccination of ewes emerged as a risk factor. With regard to increased incidence risk of isolation of multidrug-resistant staphylococci, the following variables emerged as risk factors: (a) higher number of antibiotics used on the farm for the treatment of mastitis and (b) younger age of lambs taken away from their dam. Most biofilm-forming antibiotic-resistant staphylococci were recovered from farms where anti-staphylococcal mastitis vaccination was not applied (55.9% versus 44.1% from farms where anti-staphylococcal mastitis vaccination was applied).

Association between seasonal influenza vaccination and antimicrobial use in Japan from the 2015-16 to 2020-21 seasons: from the VENUS study

BACKGROUND

Seasonal influenza vaccination might be considered an antimicrobial resistance (AMR) countermeasure because it can reduce unnecessary antimicrobial use for acute respiratory infection by mitigating the burden of such diseases.

OBJECTIVES

To examine the association between seasonal influenza vaccination and antimicrobial use (AMU) in Japan at the community level and to examine the impact of influenza vaccination on the frequency of unnecessary antimicrobial prescription for upper respiratory infection.

METHODS

For patients who visited any healthcare facility in one of the 23 wards of Tokyo, Japan, due to upper respiratory infection and who were aged 65 years or older, we extracted data from the Vaccine Effectiveness, Networking, and Universal Safety (VENUS) study database, which includes all claims data and vaccination records from the 2015-16 to 2020-21 seasons. We used the average treatment effect (ATE) with 1:1 propensity score matching to examine the association of vaccination status with frequency of antibiotic prescription, frequency of healthcare facility consultation, risk of admission and risk of death in the follow-up period of the same season (from 1 January to 31 March).

RESULTS

In total, 244 642 people were enrolled. Matched data included 101 734 people in each of the unvaccinated and vaccinated groups. The ATE of vaccination was -0.004 (95% CI -0.006 to -0.002) for the frequency of antibiotic prescription, -0.005 (-0.007 to -0.004) for the frequency of healthcare facility consultation, -0.001 (-0.002 to -0.001) for the risk of admission and 0.00 (0.00 to 0.00) for the risk of death.

CONCLUSIONS

Our results suggest that seasonal influenza vaccination is associated with lower frequencies of unnecessary antibiotic prescription and of healthcare facility consultation.

Potential business model for a European vaccine R&D infrastructure and its estimated socio-economic impact

Background

Research infrastructures are facilities or resources that have proven fundamental for supporting scientific research and innovation. However, they are also known to be very expensive in their establishment, operation and maintenance. As by far the biggest share of these costs is always borne by public funders, there is a strong interest and indeed a necessity to develop alternative business models for such infrastructures that allow them to function in a more sustainable manner that is less dependent on public financing.

Methods

In this article, we describe a feasibility study we have undertaken to develop a potentially sustainable business model for a vaccine research and development (R&D) infrastructure. The model we have developed integrates two different types of business models that would provide the infrastructure with two different types of revenue streams which would facilitate its establishment and would be a measure of risk reduction. For the business model we are proposing, we have undertaken an ex ante impact assessment that estimates the expected impact for a vaccine R&D infrastructure based on the proposed models along three different dimensions: health, society and economy.

Results

Our impact assessment demonstrates that such a vaccine R&D infrastructure could achieve a very significant socio-economic impact, and so its establishment is therefore considered worthwhile pursuing.

Conclusions

The business model we have developed, the impact assessment and the overall process we have followed might also be of interest to other research infrastructure initiatives in the biomedical field.

Total Synthesis of the Repeating Units of Proteus penneri 26 and Proteus vulgaris TG155 via a Common Disaccharide

Herein, we report the first total synthesis of the trisaccharide and tetrasaccharide repeating units of P. penneri 26 and P. vulgaris TG155, respectively, having a common disaccharide unit, 3-α-l-QuipNAc-(1 → 3)-α-d-GlcpNAc-(1 →. Striking features of the targets are the presence of rare sugar units, l-quinovosamine and l-rhamnosamine, all joined through α-glycosidic linkages. Major challenges in the formation of 1,2-cis glycosidic linkages in the case of d-glucosamine, l-quinovosamine, and d-galactosamine have been addressed.

The role of bacterial vaccines in the fight against antimicrobial resistance: an analysis of the preclinical and clinical development pipeline

Vaccines can be highly effective tools in combating antimicrobial resistance as they reduce infections caused by antibiotic-resistant bacteria and antibiotic consumption associated with disease. This Review looks at vaccine candidates that are in development against pathogens on the 2017 WHO bacterial priority pathogen list, in addition to Clostridioides difficile and Mycobacterium tuberculosis. There were 94 active preclinical vaccine candidates and 61 active development vaccine candidates. We classified the included pathogens into the following four groups: Group A consists of pathogens for which vaccines already exist-ie, Salmonella enterica serotype Typhi, Streptococcus pneumoniae, Haemophilus influenzae type b, and M tuberculosis. Group B consists of pathogens with vaccines in advanced clinical development-ie, extra-intestinal pathogenic Escherichia coli, Salmonella enterica serotype Paratyphi A, Neisseria gonorrhoeae, and C difficile. Group C consists of pathogens with vaccines in early phases of clinical development-ie, enterotoxigenic E coli, Klebsiella pneumoniae, non-typhoidal Salmonella, Shigella spp, and Campylobacter spp. Finally, group D includes pathogens with either no candidates in clinical development or low development feasibility-ie, Pseudomonas aeruginosa, Acinetobacter baumannii, Staphylococcus aureus, Helicobacter pylori, Enterococcus faecium, and Enterobacter spp. Vaccines are already important tools in reducing antimicrobial resistance and future development will provide further opportunities to optimise the use of vaccines against resistance.

Vaccination against Community-Acquired Pneumonia in Spanish Adults: Practical Recommendations by the NeumoExperts Prevention Group

In the adult population, community-acquired pneumonia (CAP) is a serious disease that is responsible for high morbidity and mortality rates, being frequently associated with multidrug resistant pathogens. The aim of this review is to update a practical immunization prevention guideline for CAP in Spain caused by prevalent respiratory pathogens, based on the available scientific evidence through extensive bibliographic review and expert opinion. The emergence of COVID-19 as an additional etiological cause of CAP, together with the rapid changes in the availability of vaccines and recommendations against SARS-CoV-2, justifies the need for an update. In addition, new conjugate vaccines of broader spectrum against pneumococcus, existing vaccines targeting influenza and pertussis or upcoming vaccines against respiratory syncytial virus (RSV) will be very useful prophylactic tools to diminish the burden of CAP and all of its derived complications. In this manuscript, we provide practical recommendations for adult vaccination against the pathogens mentioned above, including their contribution against antibiotic resistance. This guide is intended for the individual perspective of protection and not for vaccination policies, as we do not pretend to interfere with the official recommendations of any country. The use of vaccines is a realistic approach to fight these infections and ameliorate the impact of antimicrobial resistance. All of the recently available scientific evidence included in this review gives support to the indications established in this practical guide to reinforce the dissemination and implementation of these recommendations in routine clinical practice.

Factors affecting antimicrobial resistance in Streptococcus pneumoniae following vaccination introduction

Streptococcus pneumoniae is a major cause of pneumonia, meningitis, and septicaemia worldwide. Pneumococcal antimicrobial resistance (AMR) has been highlighted by the WHO as an important public health concern, with emerging serotypes showing resistance to multiple antibiotics. Indeed, although the introduction of pneumococcal conjugate vaccines (PCVs) has been associated with an overall decline in pneumococcal AMR, there have been increases in prevalence of potentially disease-causing AMR serotypes not targeted by vaccination. Here, we discuss a variety of evolutionary mechanisms at the host, pathogen, and environmental levels that may contribute to changes in the prevalence of pneumococcal AMR in the post-vaccination era. The relative importance of these factors may vary by population, pneumococcal lineage, geography, and time, leading to the complex relationship between vaccination, antibiotic use, and AMR.

The Opportunity of Point-of-Care Diagnostics in General Practice: Modelling the Effects on Antimicrobial Resistance

OBJECTIVES

Antimicrobial resistance (AMR) is a public health threat associated with antibiotic consumption. Community-acquired acute respiratory tract infections (CA-ARTIs) are a major driver of antibiotic consumption in primary care. We aimed to quantify the investments required for a large-scale rollout of point-of care (POC) diagnostic testing in Dutch primary care, and the impact on AMR due to reduced use of antibiotics.

METHODS

We developed an individual-based model that simulates consultations for CA-ARTI at GP practices in the Netherlands and compared a scenario where GPs test all CA-ARTI patients with a hypothetical diagnostic strategy to continuing the current standard-of-care for the years 2020-2030. We estimated differences in costs and future AMR rates caused by testing all patients consulting for CA-ARTI with a hypothetical diagnostic strategy, compared to the current standard-of-care in GP practices.

RESULTS

Compared to the current standard-of-care, the diagnostic algorithm increases the total costs of GP consultations for CA-ARTI by 9% and 19%, when priced at €5 and €10, respectively. The forecast increase in Streptococcus pneumoniae resistance against penicillins can be partly restrained by the hypothetical diagnostic strategy from 3.8 to 3.5% in 2030, albeit with considerable uncertainty.

CONCLUSIONS

Our results show that implementing a hypothetical diagnostic strategy for all CA-ARTI patients in primary care raises the costs of consultations, while lowering antibiotic consumption and AMR. Novel health-economic methods to assess and communicate the potential benefits related to AMR may be required for interventions with limited gains for individual patients, but considerable potential related to antibiotic consumption and AMR.

A national longitudinal study evaluating the activity of cefditoren and other antibiotics against non-susceptible Streptococcus pneumoniae strains during the period 2004-20 in Spain

BACKGROUND

Surveillance studies including antibiotic resistance and evolution of pneumococcal serotypes are critical to evaluate the susceptibility of commonly used antibiotics and the contribution of conjugate vaccines against resistant strains.

OBJECTIVES

To determine the susceptibility of clinical isolates of Streptococcus pneumoniae with reduced susceptibility to penicillin to a panel of antibiotics during the period 2004-20 and characterize the impact of pneumococcal conjugate vaccines in the evolution of resistant serotypes.

METHODS

We selected 3017 clinical isolates in order to determine the minimal inhibitory concentration to penicillin, amoxicillin, cefotaxime, erythromycin, levofloxacin and oral cephalosporins, including cefditoren, cefixime and cefpodoxime.

RESULTS

The antibiotics with the lowest proportion of resistant strains from 2004 to 2020 were cefditoren (<0.4%), followed by cefotaxime (<5%), penicillin (<6.5%) and levofloxacin (<7%). Among oral cephalosporins, cefixime was the cephalosporin with the highest MIC90 (32 mg/L) and MIC50 (8-16 mg/L) throughout the study, followed by cefpodoxime with highest values of MIC90 (4 mg/L) and MIC50 (2 mg/L) for the majority of the study period. In contrast, cefditoren was the cephalosporin with the lowest MIC90 (1 mg/L) and MIC50 (0.25-0.5 mg/L).

CONCLUSIONS

Cefditoren was the antibiotic with the highest proportion of susceptible strains. Hence, more than 80% of the clinical strains were susceptible to cefditoren throughout the period 2004-20. The proportion of resistant isolates to cefditoren and cefotaxime was scarce, being less than 0.4% for cefditoren and lower than 5% for cefotaxime, despite the increased rates of serotypes not covered by the 13-valent pneumococcal conjugate vaccine.

Modeling the effect of vaccination on selection for antibiotic resistance in Streptococcus pneumonia e

Vaccines against bacterial pathogens can protect recipients from becoming infected with potentially antibiotic-resistant pathogens. However, by altering the selective balance between antibiotic-sensitive and antibiotic-resistant bacterial strains, vaccines may also suppress-or spread-antibiotic resistance among unvaccinated individuals. Predicting the outcome of vaccination requires knowing what drives selection for drug-resistant bacterial pathogens and what maintains the circulation of both antibiotic-sensitive and antibiotic-resistant strains of bacteria. To address this question, we used mathematical modeling and data from 2007 on penicillin consumption and penicillin nonsusceptibility in Streptococcus pneumoniae (pneumococcus) invasive isolates from 27 European countries. We show that the frequency of penicillin resistance in S. pneumoniae can be explained by between-host diversity in antibiotic use, heritable diversity in pneumococcal carriage duration, or frequency-dependent selection brought about by within-host competition between antibiotic-resistant and antibiotic-sensitive S. pneumoniae strains. We used our calibrated models to predict the impact of non-serotype-specific pneumococcal vaccination upon the prevalence of S. pneumoniae carriage, incidence of disease, and frequency of S. pneumoniae antibiotic resistance. We found that the relative strength and directionality of competition between drug-resistant and drug-sensitive pneumococcal strains was the most important determinant of whether vaccination would promote, inhibit, or have little effect upon the evolution of antibiotic resistance. Last, we show that country-specific differences in pathogen transmission substantially altered the predicted impact of vaccination, highlighting that policies for managing antibiotic resistance with vaccines must be tailored to a specific pathogen and setting.

Enterotoxigenic Escherichia coli (ETEC) vaccines: Priority activities to enable product development, licensure, and global access

Diarrhoeal disease attributable to enterotoxigenic Escherichia coli (ETEC) causes substantial morbidity and mortality predominantly in paediatric populations in low- and middle-income countries. In addition to acute illness, there is an increasing appreciation of the long-term consequences of enteric infections, including ETEC, on childhood growth and development. Provision of potable water and sanitation and appropriate clinical care for acute illness are critical to reduce the ETEC burden. However, these interventions are not always practical and may not achieve equitable and sustainable coverage. Vaccination may be the most cost-effective and equitable means of primary prevention; however, additional data are needed to accelerate the investment and guide the decision-making process for ETEC vaccines. First, to understand and quantify the ETEC disease burden, additional data are needed on the association between ETEC infection and physical and cognitive stunting as well as delayed educational attainment. Furthermore, the role of inappropriate or inadequate antibiotic treatment of ETEC-attributable diarrhoea may contribute to the development of antimicrobial resistance (AMR) and needs further elucidation. An ETEC vaccine that mitigates acute diarrhoeal illness and minimizes the longer-term disease manifestations could have significant public health impact and be a cost-effective countermeasure. Herein we review the ETEC vaccine pipeline, led by candidates compatible with the general parameters of the Preferred Product Characteristics (PPC) recently developed by the World Health Organization. Additionally, we have developed an ETEC Vaccine Development Strategy to provide a framework to underpin priority activities for researchers, funders and vaccine manufacturers, with the goal of addressing globally unmet data needs in the areas of research, product development, and policy, as well as commercialization and delivery. The strategy also aims to guide prioritization and co-ordination of the priority activities needed to minimize the timeline to licensure and use of ETEC vaccines, especially in in low- and middle-income countries, where they are most urgently needed.

Mathematical assessment of the impact of cohort vaccination on pneumococcal carriage and serotype replacement

Although pneumococcal vaccines are quite effective in reducing disease burden, factors such as imperfect vaccine efficacy and serotype replacement present an important challenge against realizing direct and herd protection benefits of the vaccines. In this study, a novel mathematical model is designed and used to describe the dynamics of two Streptococcus pneumoniae (SP) serotypes, in response to the introduction of a cohort vaccination program which targets one of the two serotypes. The model is fitted to a pediatric SP carriage prevalence data from Atlanta, GA. The model, which is rigorously analysed to investigate the existence and asymptotic stability properties of the associated equilibria (in addition to exploring conditions for competitive exclusion), is simulated to assess the impact of vaccination under different levels of serotype-specific competition and illustrate the phenomenon of serotype replacement. The calibrated model is used to forecast the carriage prevalence in the pediatric cohort over 30 years.

Lung Cancer Radiotherapy: Simulation and Analysis Based on a Multicomponent Mathematical Model

Background

Lung cancer has been one of the most deadly illnesses all over the world, and radiotherapy can be an effective approach for treating lung cancer. Now, mathematical model has been extended to many biomedical fields to give a hand for analysis, evaluation, prediction, and optimization.

Methods

In this paper, we propose a multicomponent mathematical model for simulating the lung cancer growth as well as radiotherapy treatment for lung cancer. The model is digitalized and coded for computer simulation, and the model parameters are fitted with many research and clinical data to provide accordant results along with the growth of lung cancer cells in vitro.

Results

Some typical radiotherapy plans such as stereotactic body radiotherapy, conventional fractional radiotherapy, and accelerated hypofractionated radiotherapy are simulated, analyzed, and discussed. The results show that our mathematical model can perform the basic work for analysis and evaluation of the radiotherapy plan.

Conclusion

It will be expected that in the near future, mathematical model will be a valuable tool for optimization in personalized medical treatment.

Associations between private vaccine and antimicrobial consumption across Indian states, 2009-2017

Vaccines can reduce antibiotic use and, consequently, antimicrobial resistance by averting vaccine-preventable and secondary infections. We estimated the associations between private vaccine and antibiotic consumption across Indian states during 2009-2017 using monthly and annual consumption data from IQVIA and employed fixed-effects regression and the Arellano-Bond Generalized Method of Moments (GMM) model for panel data regression, which controlled for income and public sector vaccine use indicators obtained from other sources. In the annual data fixed-effects model, a 1% increase in private vaccine consumption per 1000 under-5 children was associated with a 0.22% increase in antibiotic consumption per 1000 people (P < 0.001). In the annual data GMM model, a 1% increase in private vaccine consumption per 1000 under-5 children was associated with a 0.2% increase in private antibiotic consumption (P < 0.001). In the monthly data GMM model, private vaccine consumption was negatively associated with antibiotic consumption when 32, 34, 35, and 44-47 months had elapsed after vaccine consumption, with a positive association with lags of fewer than 18 months. These results indicate vaccine-induced longer-term reductions in antibiotic use in India, similar to findings of studies from other low- and middle-income countries.

Economic Evaluation of Vaccines: Belgian Reflections on the Need for a Broader Perspective

OBJECTIVES

The standard framework of economic evaluation of health programs, which is increasingly used for policy funding decisions, is insufficiently equipped to reflect the full range of health and economic benefits conferred by vaccines and thus undervalues vaccination.

METHODS

In 2019, a group of Belgian health economic and clinical experts, supported by 2 senior international vaccination experts (1 American, 1 Belgian), convened 4 roundtable meetings to highlight which particular value elements of vaccination remain neglected in economic evaluations.

RESULTS

They concluded that the standard economic evaluation framework fails to reflect the full value of vaccination with respect to prevention of complications linked to some vaccine-preventable diseases, health gains for caregivers, herd effects, changes in exposure to and distribution of serotypes, the effect on antimicrobial resistance, productivity gains for caregivers and patients, and the distributive implications of vaccination programs.

CONCLUSIONS

Here, suggestions are made regarding how these shortcomings can be addressed in future economic evaluations of vaccines and how a more level playing field between vaccines and other health programs can be created.

To give or not to give antibiotics is not the only question

In a 1945 Nobel Lecture, Sir Alexander Fleming warned against the overuse of antibiotics, particularly in response to public pressure. In the subsequent decades, evidence has shown that bacteria can become resistant to almost any available molecule. One key question is how the emergence and dissemination of resistant bacteria or resistance genes can be delayed. Although some clinicians remain sceptical, in this Personal View, we argue that the prescription of fewer antibiotics and shorter treatment duration is just as effective as longer regimens that remain the current guideline. Additionally, we discuss the fact that shorter antibiotic treatments exert less selective pressure on microorganisms, preventing the development of resistance. By contrast, longer treatments associated with a strong selective pressure favour the emergence of resistant clones within commensal organisms. We also emphasise that more studies are needed to identify the optimal duration of antibiotic therapy for common infections, which is important for making changes to the current guidelines, and to identify clinical biomarkers to guide antibiotic treatment in both hospital and ambulatory settings.

Assessment of the Potential of Vaccination to Combat Antibiotic Resistance in Gonorrhea: A Modeling Analysis to Determine Preferred Product Characteristics

BACKGROUND

Gonorrhea incidence is increasing rapidly in many countries, while antibiotic resistance is making treatment more difficult. Combined with evidence that two meningococcal vaccines are likely partially protective against gonorrhea, this has renewed interest in a gonococcal vaccine, and several candidates are in development. Key questions are how protective and long-lasting a vaccine needs to be, and how to target it. We assessed vaccination's potential impact and the feasibility of achieving the World Health Organization's (WHO) target of reducing gonorrhea incidence by 90% during 2018-2030, by comparing realistic vaccination strategies under a range of scenarios of vaccine efficacy and duration of protection, and emergence of extensively-resistant gonorrhea.

METHODS

We developed a stochastic transmission-dynamic model, incorporating asymptomatic and symptomatic infection and heterogeneous sexual behavior in men who have sex with men (MSM). We used data from England, which has a comprehensive, consistent nationwide surveillance system. Using particle Markov chain Monte Carlo methods, we fitted to gonorrhea incidence in 2008-2017, then used Bayesian forecasting to examine an extensive range of scenarios.

RESULTS

Even in the worst-case scenario of untreatable infection emerging, the WHO target is achievable if all MSM attending sexual health clinics receive a vaccine offering ≥ 52% protection for ≥ 6 years. A vaccine conferring 31% protection (as estimated for MeNZB) for 2-4 years could reduce incidence in 2030 by 45% in the worst-case scenario, and by 75% if > 70% of resistant gonorrhea remains treatable.

CONCLUSIONS

Even a partially-protective vaccine, delivered through a realistic targeting strategy, could substantially reduce gonorrhea incidence, despite antibiotic resistance.

Clinical Relevance and Molecular Pathogenesis of the Emerging Serotypes 22F and 33F of Streptococcus pneumoniae in Spain

Streptococcus pneumoniae is the main bacterial cause of respiratory infections in children and the elderly worldwide. Serotype replacement is a frequent phenomenon after the introduction of conjugated vaccines, with emerging serotypes 22F and 33F as frequent non-PCV13 serotypes in children and adults in North America and other countries. Characterization of mechanisms involved in evasion of the host immune response by these serotypes is of great importance in public health because they are included in the future conjugated vaccines PCV15 and PCV20. One of the main strategies of S. pneumoniae to persistently colonize and causes infection is biofilm formation. In this study, we have evaluated the influence of capsule polysaccharide in biofilm formation and immune evasion by using clinical isolates from different sources and isogenic strains with capsules from prevalent serotypes. Since the introduction of PCV13 in Spain in the year 2010, isolates of serotypes 22F and 33F are rising among risk populations. The predominant circulating genotypes are ST433^22F and ST717^33F, being CC433 in 22F and CC717 in 33F the main clonal complexes in Spain. The use of clinical isolates of different origin, demonstrated that pediatric isolates of serotypes 22F and 33F formed better biofilms than adult isolates and this was statistically significant. This phenotype was greater in clinical isolates from blood origin compared to those from cerebrospinal fluid, pleural fluid and otitis. Opsonophagocytosis assays showed that serotype 22F and 33F were recognized by the PSGL-1 receptor on leukocytes, although serotype 22F, was more resistant than serotype 33F to phagocytosis killing and more lethal in a mouse sepsis model. Overall, the emergence of additional PCV15 serotypes, especially 22F, could be associated to an enhanced ability to divert the host immune response that markedly increased in a biofilm state. Our findings demonstrate that pediatric isolates of 22F and 33F, that form better biofilm than isolates from adults, could have an advantage to colonize the nasopharynx of children and therefore, be important in carriage and subsequent dissemination to the elderly. The increased ability of serotype 22F to avoid the host immune response, might explain the emergence of this serotype in the last years.

Effect of Pediatric Influenza Vaccination on Antibiotic Resistance, England and Wales

Vaccines against viral infections have been proposed to reduce prescribing of antibiotics and thereby help control resistant bacterial infections. However, by combining published data sources, we predict that pediatric live attenuated influenza vaccination in England and Wales will not substantially reduce antibiotic consumption or adverse health outcomes associated with antibiotic resistance.

Antimicrobial Resistance in the Asia Pacific region: a meeting report

The Asia Pacific region, home to two-thirds of the world's population and ten of the least developed countries, is considered a regional hot-spot for the emergence and spread of antimicrobial resistance (AMR). Despite this, there is a dearth of high-quality regional data on the extent of AMR. Recognising the urgency to close this gap, Singapore organised a meeting to discuss the problems in the region and frame a call for action. Representatives from across the region and beyond attended the meeting on the "Antimicrobial Resistance in the Asia Pacific & its impact on Singapore" held in November 2018. This meeting report is a summary of the discussions on the challenges and progress in surveillance, drivers and levers of AMR emergence, and the promising innovations and technologies that could be used to combat the increasing threat of AMR in the region. Enhanced surveillance and research to provide improved evidence-based strategies and policies are needed. The major themes that emerged for an action plan are working towards a tailored solution for the region by harnessing the One Health approach, enhancing inter-country collaborations, and collaboratively leverage upon new emerging technologies. A regionally coordinated effort that is target-driven, sustainable and builds on a framework facilitating communication and governance will strengthen the fight against AMR in the Asia Pacific region.

Mathematical modelling for antibiotic resistance control policy: do we know enough?

BACKGROUND

Antibiotics remain the cornerstone of modern medicine. Yet there exists an inherent dilemma in their use: we are able to prevent harm by administering antibiotic treatment as necessary to both humans and animals, but we must be mindful of limiting the spread of resistance and safeguarding the efficacy of antibiotics for current and future generations. Policies that strike the right balance must be informed by a transparent rationale that relies on a robust evidence base.

MAIN TEXT

One way to generate the evidence base needed to inform policies for managing antibiotic resistance is by using mathematical models. These models can distil the key drivers of the dynamics of resistance transmission from complex infection and evolutionary processes, as well as predict likely responses to policy change in silico. Here, we ask whether we know enough about antibiotic resistance for mathematical modelling to robustly and effectively inform policy. We consider in turn the challenges associated with capturing antibiotic resistance evolution using mathematical models, and with translating mathematical modelling evidence into policy.

CONCLUSIONS

We suggest that in spite of promising advances, we lack a complete understanding of key principles. From this we advocate for priority areas of future empirical and theoretical research.

Potential impact of influenza vaccine roll-out on antibiotic use in Africa

Background

Influenza infections result in both inappropriate and appropriate antibiotic prescribing. There is a huge burden of both influenza and infections caused by antimicrobial-resistant pathogens in Africa. Influenza vaccines have the potential to reduce appropriate antibiotic use, through reduction of secondary bacterial infections, as well as to reduce levels of influenza misdiagnosed and treated as a bacterial infection (inappropriate).

Objectives

To estimate potential reductions in antibiotic use that are achievable by introducing an influenza vaccine into various African settings.

Methods

Influenza incidence was combined with population size, vaccine and health system characteristics.

Results

We estimated that the direct impact of vaccination could avert more than 390 prescriptions per 100 000 population per year if a 50% efficacious influenza vaccine at 30% coverage was introduced to adults >65 years old in South Africa or children 2–5 years old in Senegal. Across Africa, purely through reducing the number of severe acute respiratory infections, the same vaccine characteristics could avert at least 24 000 antibiotic prescriptions per year if given to children <5 years old.

Conclusions

The introduction of an influenza vaccine into multiple African settings could have a dramatic indirect impact on antibiotic usage. Our values are limited underestimates, capturing only the direct impact of vaccination in a few settings and risk groups. This is owing to the huge lack of epidemiological information on antibiotic use and influenza in Africa. However, it is likely that influenza vaccination in Africa could substantially impact antibiotic usage in addition to influenza-related mortality and morbidity.

Vaccine impact on antimicrobial resistance to inform Gavi, the Vaccine Alliance's 2018 Vaccine Investment Strategy: report from an expert survey

Background: While the rise of antimicrobial resistance (AMR) has been recognised as a major public health problem, the value of vaccines to control AMR is poorly defined. This expert survey was launched with the aim of informing the 2018 Vaccine Investment Strategy through which Gavi, the Vaccine Alliance prioritises future vaccine funding. This exercise focused on both vaccines currently supported by Gavi and under consideration for future funding. Methods: The relative importance of pre-defined criteria as drivers of overall value of vaccines as a tool/ intervention to control AMR was assessed by 18 experts: prevention of mortality and morbidity due to resistant pathogens, antibiotic use prevented, societal impact, ethical importance and sense of urgency. For each vaccine, experts attributed scores reflecting the estimated value for each criterion, and overall value relative to AMR was derived from the value assigned to each criterion and their relative importance for each vaccine. Results: Mortality, morbidity due to targeted resistant pathogens, and antibiotic use prevented were considered the most important determinants of overall value. Pneumococcal, typhoid and malaria vaccines were assigned highest value relative to antimicrobial resistance. Intermediate value was estimated for specific rotavirus, cholera, respiratory syncytial virus (RSV), influenza, dengue, measles, meningitis and Haemophilus influenza type b- (Hib-) containing pentavalent vaccines. Lowest value relative to AMR was estimated for Japanese encephalitis, hepatitis A, yellow fever, rabies and human papilloma virus vaccine. Conclusions: In the future, more evidence-based, data-driven, robust methodologies should be developed to guide coordinated, rational decision making on priority actions aimed at strengthening the use of vaccines against AMR.

Impact of Antimicrobial Treatment for Acute Otitis Media on Carriage Dynamics of Penicillin-Susceptible and Penicillin-Nonsusceptible Streptococcus pneumoniae

Background

Despite concerns that antimicrobial treatment of prevalent infections may select for drug-resistant bacteria, the effects of antimicrobial treatment on colonization dynamics have not been well quantified.

Methods

We measured impacts of antimicrobial treatment on nasopharyngeal carriage of penicillin-susceptible Streptococcus pneumoniae (PSSP) and penicillin-nonsusceptible (PNSP) lineages at the end of treatment and 15, 30, and 60 days after treatment in a previously conducted randomized, double-blinded, placebo-controlled trial of amoxicillin-clavulanate for stringently defined acute otitis media.

Results

In intention-to-treat analyses, immediate treatment with amoxicillin-clavulanate reduced PSSP carriage prevalence by 88% (95% confidence interval [CI], 76%-96%) at the end of treatment and by 27% (-3%-49%) after 60 days but did not alter PNSP carriage prevalence. By the end of treatment, 7% of children who carried PSSP at enrollment remained colonized in the amoxicillin-clavulanate arm, compared with 61% of PSSP carriers who received placebo; impacts of amoxicillin-clavulanate persisted at least 60 days after treatment among children who carried PSSP at enrollment. Amoxicillin-clavulanate therapy reduced PSSP acquisition by >80% over 15 days. Among children who carried PNSP at enrollment, no impacts on carriage prevalence of S. pneumoniae, PSSP, or PNSP were evident at follow-up visits.

Conclusions

Although the absolute risk of carrying PNSP was unaffected by treatment, antimicrobial therapy conferred a selective impact on colonizing pneumococci by accelerating clearance and delaying acquisition of PSSP.

Interaction With Nontypeable Haemophilus influenzae Alters Progression of Streptococcus pneumoniae From Colonization to Disease in a Site-Specific Manner

BACKGROUND

Pneumococci and nontypeable Haemophilus influenzae (NTHi) often cocolonize children. The impact of species interactions on disease risk across the upper respiratory mucosa is not known.

METHODS

We analyzed data from 4104 acute conjunctivitis (AC) cases, 11 767 otitis media (OM) cases, and 1587 nasopharyngeal specimens collected from Israeli children before pneumococcal conjugate vaccine introduction. We compared pneumococcal serotype distributions with NTHi present and absent, and compared single-species and mixed-species rates of serotype-specific progression from colonization to AC and OM.

RESULTS

Pneumococcal serotypes causing single-species OM (NTHi absent) were less diverse than colonizing serotypes and also less diverse than those causing mixed-species OM; colonizing and OM-causing pneumococcal serotype distributions were more similar to each other with NTHi present than with NTHi absent. In contrast, serotype diversity did not differ appreciably between colonizing and AC-causing pneumococci, regardless of NTHi co-occurrence. The similarity of colonizing and AC-causing pneumococcal serotype distributions was consistent in the presence and absence of NTHi. Differences in rates that pneumococcal serotypes progressed from colonization to disease were reduced in both AC and OM when NTHi was present.

CONCLUSIONS

Interactions with NTHi may alter progression of pneumococcal serotypes to diseases of the upper respiratory mucosa in a site-specific manner.

Host contact dynamics shapes richness and dominance of pathogen strains

The interaction among multiple microbial strains affects the spread of infectious diseases and the efficacy of interventions. Genomic tools have made it increasingly easy to observe pathogenic strains diversity, but the best interpretation of such diversity has remained difficult because of relationships with host and environmental factors. Here, we focus on host-to-host contact behavior and study how it changes populations of pathogens in a minimal model of multi-strain interaction. We simulated a population of identical strains competing by mutual exclusion and spreading on a dynamical network of hosts according to a stochastic susceptible-infectious-susceptible model. We computed ecological indicators of diversity and dominance in strain populations for a collection of networks illustrating various properties found in real-world examples. Heterogeneities in the number of contacts among hosts were found to reduce diversity and increase dominance by making the repartition of strains among infected hosts more uneven, while strong community structure among hosts increased strain diversity. We found that the introduction of strains associated with hosts entering and leaving the system led to the highest pathogenic richness at intermediate turnover levels. These results were finally illustrated using the spread of Staphylococcus aureus in a long-term health-care facility where close proximity interactions and strain carriage were collected simultaneously. We found that network structural and temporal properties could account for a large part of the variability observed in strain diversity. These results show how stochasticity and network structure affect the population ecology of pathogens and warn against interpreting observations as unambiguous evidence of epidemiological differences between strains.

Toward economic evaluation of the value of vaccines and other health technologies in addressing AMR

We discuss the need to make economic evaluations of vaccines antimicrobial resistance (AMR)-sensitive and ways to do so. Such AMR-sensitive evaluations can play a role in value-for-money comparisons of different vaccines within a national immunization program, or in comparisons of vaccine-centric and non-vaccine-centric technologies within an anti-AMR program. In general terms, incremental cost-effectiveness ratios and rates of return and their associated decision rules are unaltered by consideration of AMR-related value. The decision metrics need to have their various health, cost, and socioeconomic terms disaggregated into resistance-related subcategories, which in turn have to be measured carefully before they are reaggregated. The fundamental scientific challenges lie primarily in quantifying the causal impact of health technologies on resistance-related health outcomes, and secondarily in ascertaining the economic value of those outcomes. We emphasize the importance of evaluating vaccines in the context of other potentially complementary and substitutable nonvaccine technologies. Complementarity implies that optimal spending on each set of interventions is positive, and substitutability implies that the ratio of spending will depend on relative value for money. We exemplify this general point through a qualitative discussion of the complementarities and (especially the) substitutability between pneumococcal conjugate vaccines and antimicrobial stewardship and between research and development (R&D) of a gonorrhea vaccine versus R&D of a gonorrhea antibiotic. We propose a roadmap for future work, which includes quantifying the causal effects of vaccination and other health technologies on short-term and long-term resistance-related outcomes, measuring the health-sector costs and broader socioeconomic consequences of resistance-related mortality and morbidity, and evaluating vaccines in the context of nonvaccine complements and substitutes.

Estimating the proportion of bystander selection for antibiotic resistance among potentially pathogenic bacterial flora

Bystander selection-the selective pressure for resistance exerted by antibiotics on microbes that are not the target pathogen of treatment-is critical to understanding the total impact of broad-spectrum antibiotic use on pathogenic bacterial species that are often carried asymptomatically. However, to our knowledge, this effect has never been quantified. We quantify bystander selection for resistance for a range of clinically relevant antibiotic-species pairs as the proportion of all antibiotic exposures received by a species for conditions in which that species was not the causative pathogen ("proportion of bystander exposures"). Data sources include the 2010-2011 National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey, the Human Microbiome Project, and additional carriage and etiological data from existing literature. For outpatient prescribing in the United States, we find that this proportion over all included antibiotic classes is over 80% for eight of nine organisms of interest. Low proportions of bystander exposure are often associated with infrequent bacterial carriage or concentrated prescribing of a particular antibiotic for conditions caused by the species of interest. Applying our results, we roughly estimate that pneumococcal conjugate vaccination programs result in nearly the same proportional reduction in total antibiotic exposures of Streptococcus pneumoniae, Staphylococcus aureus, and Escherichia coli, despite the latter two organisms not being targeted by the vaccine. These results underscore the importance of considering antibiotic exposures of bystanders, in addition to the target pathogen, in measuring the impact of antibiotic resistance interventions.

Within-host dynamics shape antibiotic resistance in commensal bacteria

The spread of antibiotic resistance, a major threat to human health, is poorly understood. Simple population-level models of disease transmission predict that above a certain rate of antibiotic consumption in a population, resistant bacteria should completely eliminate non-resistant strains, while below this threshold they should be unable to persist at all. This prediction stands at odds with empirical evidence showing that resistant and non-resistant strains coexist stably over a wide range of antibiotic consumption rates. Not knowing what drives this long-term coexistence is a barrier to developing evidence-based strategies for managing the spread of resistance. Here, we argue that competition between resistant and sensitive pathogens within individual hosts gives resistant pathogens a relative fitness benefit when they are rare, promoting coexistence between strains at the population level. To test this hypothesis, we embed mechanistically-explicit within-host dynamics in a structurally-neutral disease transmission model. Doing so allows us to reproduce patterns of resistance observed in the opportunistic pathogens Escherichia coli and Streptococcus pneumoniae across European countries, and to identify factors that may shape resistance evolution in bacteria by modulating the intensity and outcomes of within-host competition.

Combination of Antibodies and Antibiotics as a Promising Strategy Against Multidrug-Resistant Pathogens of the Respiratory Tract

The emergence of clinical isolates associated to multidrug resistance is a serious threat worldwide in terms of public health since complicates the success of the antibiotic treatment and the resolution of the infectious process. This is of great concern in pathogens affecting the lower respiratory tract as these infections are one of the major causes of mortality in children and adults. In most cases where the respiratory pathogen is associated to multidrug-resistance, antimicrobial concentrations both in serum and at the site of infection may be insufficient and the resolution of the infection depends on the interaction of the invading pathogen with the host immune response. The outcome of these infections largely depends on the susceptibility of the pathogen to the antibiotic treatment, although the humoral and cellular immune responses also play an important role in this process. Hence, prophylactic measures or even immunotherapy are alternatives against these multi-resistant pathogens. In this sense, specific antibodies and antibiotics may act concomitantly against the respiratory pathogen. Alteration of cell surface structures by antimicrobial drugs even at sub-inhibitory concentrations might result in greater exposure of microbial ligands that are normally hidden or hardly exposed. This alteration of the bacterial envelope may stimulate opsonization by natural and/or specific antibodies or even by host defense components, increasing the recognition of the microbial pathogen by circulating phagocytes. In this review we will explain the most relevant studies, where vaccination or the use of monoclonal antibodies in combination with antimicrobial treatment has demonstrated to be an alternative strategy to overcome the impact of multidrug resistance in respiratory pathogens.

Migrant and refugee populations: a public health and policy perspective on a continuing global crisis

The 2015-2017 global migratory crisis saw unprecedented numbers of people on the move and tremendous diversity in terms of age, gender and medical requirements. This article focuses on key emerging public health issues around migrant populations and their interactions with host populations. Basic needs and rights of migrants and refugees are not always respected in regard to article 25 of the Universal Declaration of Human Rights and article 23 of the Refugee Convention. These are populations with varying degrees of vulnerability and needs in terms of protection, security, rights, and access to healthcare. Their health status, initially conditioned by the situation at the point of origin, is often jeopardised by adverse conditions along migratory paths and in intermediate and final destination countries. Due to their condition, forcibly displaced migrants and refugees face a triple burden of non-communicable diseases, infectious diseases, and mental health issues. There are specific challenges regarding chronic infectious and neglected tropical diseases, for which awareness in host countries is imperative. Health risks in terms of susceptibility to, and dissemination of, infectious diseases are not unidirectional. The response, including the humanitarian effort, whose aim is to guarantee access to basic needs (food, water and sanitation, healthcare), is gripped with numerous challenges. Evaluation of current policy shows insufficiency regarding the provision of basic needs to migrant populations, even in the countries that do the most. Governments around the world need to rise to the occasion and adopt policies that guarantee universal health coverage, for migrants and refugees, as well as host populations, in accordance with the UN Sustainable Development Goals. An expert consultation was carried out in the form of a pre-conference workshop during the 4th International Conference on Prevention and Infection Control (ICPIC) in Geneva, Switzerland, on 20 June 2017, the United Nations World Refugee Day.

Maternal Vaccination as an Essential Component of Life-Course Immunization and Its Contribution to Preventive Neonatology

Maternal immunisation schedules are increasingly coming under the spotlight as part of the development of lifetime immunisation programmes for the role that they play in improving maternal, foetal, and neonatal health. Maternally-acquired antibodies are critical in protecting infants during the first months of their lives. Maternal immunisation was previously overlooked owing to concerns regarding vaccinations in this untested and high-risk population but is now acknowledged for its potential impact on the outcomes in many domains of foetal and neonatal health, aside from its maternal benefits. This article highlights the role that maternal immunisation may play in reducing infections in preterm and term infants. It explores the barriers to antenatal vaccinations and the optimisation of the immunisation uptake. This review also probes the part that maternal immunisation may hold in the reduction of perinatal antimicrobial resistance and the prevention of non-infectious diseases. Both healthcare providers and expectant mothers should continue to be educated on the importance and safety of the appropriate immunizations during pregnancy. Maternal vaccination merits its deserved priority in a life-course immunization approach and it is perhaps the only immunization whereby two generations benefit directly from a single input. We outline the current recommendations for antenatal vaccinations and highlight the potential advances in the field contributing to “preventive neonatology”.