Vaccines as remedy for antimicrobial resistance and emerging infections

Targeting plasmid-encoded proteins that contain immunoglobulin-like domains to combat antimicrobial resistance

Antimicrobial resistance (AMR) poses a significant threat to human health. Although vaccines have been developed to combat AMR, it has proven challenging to associate specific vaccine antigens with AMR. Bacterial plasmids play a crucial role in the transmission of AMR. Our recent research has identified a group of bacterial plasmids (specifically, IncHI plasmids) that encode large molecular mass proteins containing bacterial immunoglobulin-like domains. These proteins are found on the external surface of the bacterial cells, such as in the flagella or conjugative pili. In this study, we show that these proteins are antigenic and can protect mice from infection caused by an AMR Salmonella strain harboring one of these plasmids. Furthermore, we successfully generated nanobodies targeting these proteins, that were shown to interfere with the conjugative transfer of IncHI plasmids. Considering that these proteins are also encoded in other groups of plasmids, such as IncA/C and IncP2, targeting them could be a valuable strategy in combating AMR infections caused by bacteria harboring different groups of AMR plasmids. Since the selected antigens are directly linked to AMR itself, the protective effect extends beyond specific microorganisms to include all those carrying the corresponding resistance plasmids.

Community pharmacists as antimicrobial resistance stewards: a narrative review on their contributions and challenges in low- and middle-income countries

Antimicrobial resistance (AMR) is a global public health crisis that impedes the therapeutic effectiveness of available antimicrobial agents. Due to the high burden of infectious diseases and limited resources, especially trained healthcare professionals, low- and middle-income countries (LMICs) are particularly susceptible to the detrimental effects of AMR. Sometimes, as the first and last point of contact for patients seeking treatment for infections, community pharmacists can play a pivotal role in the stewardship required for AMR. This review aims to highlight the contributions made by community pharmacists in LMICs as AMR stewards. The review considers the challenges from the perspectives of limited resources, inadequate training, a lack of policies and regulations, and issues related to patient behavior. Community pharmacists in LMICs could optimize their advocacy contributions by focusing on One Health AMR stewardship. Transformational and actionable patient and population-centric antimicrobial stewardship (AMS) is feasible with the synergy of policymakers and other healthcare providers in the implementation of AMS policies and programs that support community pharmacists in their efforts to promote rational antimicrobial use.

Recent Advancements and Novel Approaches Contributing to the Present Arsenal of Prophylaxis and Treatment Strategies Against Category A Bacterial Biothreat Agents

Bacterial pathogens have always been a part of the ecosystem in which we thrive. Some pathogens have caused deadly outbreaks in the past and have been exploited as an agent of threat. Natural hotspots for these biological pathogens are widely distributed throughout the world and hence they remain clinically important. Technological advancement and change in general lifestyle has driven the evolution of these pathogens into more virulent and resistant variants. There has been a growing concern over the development of multidrug-resistant bacterial strains that could be used as bioweapons. This rapid change in pathogens also propels the field of science to develop and innovate new strategies and methodologies which are superior and safer to the existing ones. Some bacterial agents like-Bacillus anthracis, Yersinia pestis, Francisella tularensis and toxins produced by strains of Clostridium botulinum, have been segregated as Category A substances as they pose imminent threat to public health with a history of life threatening and catastrophic disease. This review highlights some encouraging developments and value additions in the current plan of action for protection against these select biothreat bacterial pathogens.

Tobramycin Nanoantibiotics and Their Advantages: A Minireview

Nowadays, antimicrobial resistance (AMR) represents a challenge for antibiotic therapy, mostly involving Gram-negative bacteria. Among the strategies activated to overcome AMR, the repurposing of already available antimicrobial molecules by encapsulating them in drug delivery systems, such as nanoparticles (NPs) and also engineered NPs, seems to be promising. Tobramycin is a powerful and effective aminoglycoside, approved for complicated infections and reinfections and indicated mainly against Gram-negative bacteria, such as Pseudomonas aeruginosa, Escherichia coli, Proteus, Klebsiella, Enterobacter, Serratia, Providencia, and Citrobacter species. However, the drug presents several side effects, mostly due to dose frequency, and for this reason, it is a good candidate for nanomedicine formulation. This review paper is focused on what has been conducted in the last 20 years for the development of Tobramycin nanosized delivery systems (nanoantibiotics), with critical discussion and comparison. Tobramycin was selected as the antimicrobial drug because it is a wide-spectrum antibiotic that is effective against both Gram-positive and Gram-negative aerobic bacteria, and it is characterized by a fast bactericidal effect, even against multidrug-resistant microorganisms (MDR).

Coronavirus Disease 2019 (COVID-19) Pandemic across Africa: Current Status of Vaccinations and Implications for the Future

The introduction of effective vaccines in December 2020 marked a significant step forward in the global response to COVID-19. Given concerns with access, acceptability, and hesitancy across Africa, there is a need to describe the current status of vaccine uptake in the continent. An exploratory study was undertaken to investigate these aspects, current challenges, and lessons learnt across Africa to provide future direction. Senior personnel across 14 African countries completed a self-administered questionnaire, with a descriptive analysis of the data. Vaccine roll-out commenced in March 2021 in most countries. COVID-19 vaccination coverage varied from low in Cameroon and Tanzania and up to 39.85% full coverage in Botswana at the end of 2021; that is, all doses advocated by initial protocols versus the total population, with rates increasing to 58.4% in Botswana by the end of June 2022. The greatest increase in people being fully vaccinated was observed in Uganda (20.4% increase), Botswana (18.5% increase), and Zambia (17.9% increase). Most vaccines were obtained through WHO-COVAX agreements. Initially, vaccination was prioritised for healthcare workers (HCWs), the elderly, adults with co-morbidities, and other at-risk groups, with countries now commencing vaccination among children and administering booster doses. Challenges included irregular supply and considerable hesitancy arising from misinformation fuelled by social media activities. Overall, there was fair to reasonable access to vaccination across countries, enhanced by government initiatives. Vaccine hesitancy must be addressed with context-specific interventions, including proactive programmes among HCWs, medical journalists, and the public.

Promising advances in nanobiotic-based formulations for drug specific targeting against multidrug-resistant microbes and biofilm-associated infections

Antimicrobial agents and alternative strategies to combat bacterial infections have become urgent due to the rapid development of multidrug-resistant bacteria caused by the misuse and overuse of antibiotics, as well as the ineffectiveness of antibiotics against difficult-to-treat infectious diseases. Nanobiotics is one of the strategies being explored to counter the increase in antibiotic-resistant bacteria. Nanobiotics are antibiotic molecules encapsulated in nanoparticles or artificially engineered pure antibiotics that are ≤ 100 nm in size in at least one dimension. Formulation scientists recognize nanobiotic delivery systems as an effective strategy to overcome the limitations associated with conventional antibiotic therapy. This review highlights the general mechanisms by which nanobiotics can be used to target resistant microbes and biofilm-associated infections. We focus on the design elements, properties, characterization, and toxicity assessment of organic nanoparticles, inorganic nanoparticle and molecularly imprinted polymer-based nano-formulations that can be designed to improve the efficacy of nanobiotic formulation.

Tackling antimicrobial resistance across sub-Saharan Africa: current challenges and implications for the future

INTRODUCTION

Antimicrobial resistance (AMR) is a concern as this increases morbidity, mortality, and costs, with sub-Saharan Africa having the highest rates globally. Concerns with rising AMR have resulted in international, Pan-African, and country activities including the development of national action plans (NAPs). However, there is variable implementation across Africa with key challenges persisting.

AREAS COVERED

Consequently, there is an urgent need to document current NAP activities and challenges across sub-Saharan Africa to provide future guidance. This builds on a narrative review of the literature.

EXPERT OPINION

All surveyed sub-Saharan African countries have developed their NAPs; however, there is variable implementation. Countries including Botswana and Namibia are yet to officially launch their NAPs with Eswatini only recently launching its NAP. Cameroon is further ahead with its NAP than these countries; though there are concerns with implementation. South Africa appears to have made the greatest strides with implementing its NAP including regular monitoring of activities and instigation of antimicrobial stewardship programs. Key challenges remain across Africa. These include available personnel, expertise, capacity, and resources to undertake agreed NAP activities including active surveillance, lack of focal points to drive NAPs, and competing demands and priorities including among donors. These challenges are being addressed, with further co-ordinated efforts needed to reduce AMR.

Nanoantibiotics to fight multidrug resistant infections by Gram-positive bacteria: hope or reality?

The spread of antimicrobial resistance in Gram-positive pathogens represents a threat to human health. To counteract the current lack of novel antibiotics, alternative antibacterial treatments have been increasingly investigated. This review covers the last decade's developments in using nanoparticles as carriers for the two classes of frontline antibiotics active on multidrug-resistant Gram-positive pathogens, i.e., glycopeptide antibiotics and daptomycin. Most of the reviewed papers deal with vancomycin nanoformulations, being teicoplanin- and daptomycin-carrying nanosystems much less investigated. Special attention is addressed to nanoantibiotics used for contrasting biofilm-associated infections. The status of the art related to nanoantibiotic toxicity is critically reviewed.

Breast cancer vaccines for treatment and prevention

Breast cancer is immunogenic and a variety of vaccines have been designed to boost immunity directed against the disease. The components of a breast cancer vaccine, the antigen, the delivery system, and the adjuvant, can have a significant impact on vaccine immunogenicity. There have been numerous immunogenic proteins identified in all subtypes of breast cancer. The majority of these antigens are weakly immunogenic nonmutated tumor-associated proteins. Mutated proteins and neoantigen epitopes are found only in a small minority of patients and are enriched in the triple negative subtype. Several vaccines have advanced to large randomized Phase II or Phase III clinical trials. None of these trials met their primary endpoint of either progression-free or overall survival. Despite these set-backs investigators have learned important lessons regarding the clinical application of breast cancer vaccines from the type of immune response needed for tumor eradication, Type I T-cell immunity, to the patient populations most likely to benefit from vaccination. Many therapeutic breast cancer vaccines are now being tested in combination with other forms of immune therapy or chemotherapy and radiation. Breast cancer vaccines as single agents are now studied in the context of the prevention of relapse or development of disease. Newer approaches are designing vaccines to prevent breast cancer by intercepting high-risk lesions such as ductal carcinoma in situ to limit the progression of these tumors to invasive cancer. There are also several efforts to develop vaccines for the primary prevention of breast cancer by targeting antigens expressed during breast cancer initiation.

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.

CRISPR-Cas Systems: Prospects for Use in Medicine

CRISPR-Cas systems, widespread in bacteria and archaea, are mainly responsible for adaptive cellular immunity against exogenous DNA (plasmid and phage). However, the latest research shows their involvement in other functions, such as gene expression regulation, DNA repair and virulence. In recent years, they have undergone intensive research as convenient tools for genomic editing, with Cas9 being the most commonly used nuclease. Gene editing may be of interest in biotechnology, medicine (treatment of inherited disorders, cancer, etc.), and in the development of model systems for various genetic diseases. The dCas9 system, based on a modified Cas9 devoid of nuclease activity, called CRISPRi, is widely used to control gene expression in bacteria for new drug biotargets validation and is also promising for therapy of genetic diseases. In addition to direct use for genomic editing in medicine, CRISPR-Cas can also be used in diagnostics, for microorganisms’ genotyping, controlling the spread of drug resistance, or even directly as “smart” antibiotics. This review focuses on the main applications of CRISPR-Cas in medicine, and challenges and perspectives of these approaches.