Antibiotic resistance - why is the problem so difficult to solve?

Encouraging the Development of New Antibiotics: Are Financial Incentives the Right Way Forward? A Systematic Review and Case Study

Antibiotic resistance is an urgent public health threat that has received substantial attention from the world's leading health agencies and national governmental bodies alike. However, despite increasing rates of antibiotic resistance, pharmaceutical companies are reluctant to develop new antibiotics due to scientific, regulatory, and financial barriers. Nonetheless, only a handful of countries have addressed this by implementing or proposing financial incentive models to promote antibiotic innovation. This study is comprised of a systematic review that aimed to understand which antibiotic incentive strategies are most recommended within the literature and subsequently analyzed these incentives to determine which are most likely to sustainably revitalize the antibiotic pipeline. Through a case study of Canada, we apply our incentive analysis to the Canadian landscape to provide decision-makers with a possible path forward. Based on our findings, we propose that Canada support the ongoing efforts of other countries by implementing a fully delinked subscription-based market entry reward. This paper seeks to spark action in Canada by shifting the national paradigm to one where antibiotic research and development is prioritized as a key element to addressing antibiotic resistance.

Extended-Spectrum Beta-Lactamase-Producing Klebsiella pneumoniae Isolated from Healthy and Sick Dogs in Portugal

Extended-spectrum beta-lactamase (ESBL)- and carbapenemase (CP)-producing Klebsiella pneumoniae isolates are a public health concern at clinical level, mainly in Southern European countries. However, there are scarce data on the role of companion animals in the emergence of resistance to clinically relevant antibiotics. Therefore, our study aimed to determine the presence of K. pneumoniae with relevant beta-lactamases in fecal samples from healthy dogs (kennel and house dogs) and sick dogs in seven different hospitals in Portugal. Fecal samples from 125 healthy dogs and 231 sick dogs (one per animal) were collected during April-August 2017. Samples were screened on MacConkey agar supplemented with meropenem, and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) was used for K. pneumoniae identification. Genotypic detection of ESBLs or CPs was carried out by PCR/sequencing. Moreover, the presence of other antimicrobial resistance genes and multilocus sequence typing was tested by PCR/sequencing. K. pneumoniae isolates were obtained from 16 tested samples (4.4%), and 3 of them were ertapenem and/or meropenem intermediate/resistant (all of them imipenem susceptible and negative for CP genes). Fifteen K. pneumoniae isolates were ESBL producers, and they carried the following beta-lactamase genes: bla_CTX-M-15+bla_SHV-28 (four isolates, in three cases associated with bla_TEM-1), bla_CTX-M-15+bla_SHV-1 (five isolates, associated with TEM-1 in three cases), and bla_SHV-28+bla_TEM-1 (six isolates). Three ESBL-producing K. pneumoniae isolates of different origins and beta-lactamase genotypes (CTX-M-15+SHV-28, CTX-M-15+SHV-28+TEM-1, or SHV-28+TEM-1) belonged to the lineage ST307, and one isolate was identified as ST15 (CTX-M-15+SHV-1). These findings highlight that dogs are frequent carriers of ESBL-producing K. pneumonia isolates, harboring mostly genes encoding CTX-M-15 or SHV-28, associated in some cases with the high-risk clones ST307 and ST15.

Reversal of carbapenem-resistance in Shewanella algae by CRISPR/Cas9 genome editing

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Emergence of carbapenem-resistant S. algae is a severe problem.

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Re-sensitization of S. algae to carbapenem by CRISPR/Cas9 genome editing.

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The bla_OXA-55-like gene is essential for carbapenem resistance in S. algae.

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One-plasmid genome editing system for CRISPR/Cas9 genome editing in S. algae.

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CRISPR/Cas9 genome editing is a promising approach to validate the gene function.

Antibiotic resistance in pathogens is a growing threat to human health. Of particular concern is resistance to carbapenem, which is an antimicrobial agent listed as critically important by the World Health Organization. With the global spread of carbapenem-resistant organisms, there is an urgent need for new treatment options. Shewanella algae is an emerging pathogen found in marine environments throughout the world that has increasing resistance to carbapenem. The organism is also a possible antibiotic resistance reservoir in humans and in its natural habitat. The development of CRISPR/Cas9-based methods has enabled precise genetic manipulation. A number of attempts have been made to knock out resistance genes in various organisms. The study used a single plasmid containing CRISPR/Cas9 and recE/recT recombinase to reverse an antibiotic-resistant phenotype in S. algae and showed bla_OXA-55-like gene is essential for the carbapenem resistance. This result demonstrates a potential validation strategy for functional genome annotation in S. algae.

Towards a global definition of responsible antibiotic use: results of an international multidisciplinary consensus procedure

Background

Conducted as part of the Driving Reinvestment in Research and Development and Responsible Antibiotic Use (DRIVE-AB) project, this study aimed to identify key elements for a global definition of responsible antibiotic use based on diverse stakeholder input.

Methods

A three-step RAND-modified Delphi method was applied. First, a systematic review of antibiotic stewardship literature and relevant organization web sites identified definitions and synonyms of responsible use. Identified elements of definitions were presented by questionnaire to a multidisciplinary international stakeholder panel for appraisal of their relevance. Finally, questionnaire results were discussed in a consensus meeting.

Results

The systematic review and the web site search identified 17 synonyms (e.g. appropriate, correct) and 22 potential elements to include in a definition of responsible use. Elements were grouped into patient-level (e.g. Indication, Documentation) or societal-level elements (e.g. Education, Future Effectiveness). Forty-eight stakeholders with diverse backgrounds [medical community, public health, patients, antibiotic research and development (R&D), regulators, governments] from 18 countries across all continents participated in the questionnaire. Based on relevance scores, 21 elements were retained, 9 were rephrased and 1 was added. Together, the 22 elements and associated best-practice descriptions comprise an exhaustive list of elements to be considered when defining responsible use.

Conclusions

Combination of concepts from the literature and stakeholder opinion led to an international multidisciplinary consensus on a global definition of responsible antibiotic use. The widely diverging perspectives of stakeholders providing input should ensure the comprehensiveness and relevance of the definition for both individual patients and society. An aspirational goal would be to address all elements.

Screening and Optimizing Antimicrobial Peptides by Using SPOT-Synthesis

Peptide arrays on cellulose are a powerful tool to investigate peptide interactions with a number of different molecules, for examples antibodies, receptors or enzymes. Such peptide arrays can also be used to study interactions with whole cells. In this review, we focus on the interaction of small antimicrobial peptides with bacteria. Antimicrobial peptides (AMPs) can kill multidrug-resistant (MDR) human pathogenic bacteria and therefore could be next generation antibiotics targeting MDR bacteria. We describe the screen and the result of different optimization strategies of peptides cleaved from the membrane. In addition, screening of antibacterial activity of peptides that are tethered to the surface is discussed. Surface-active peptides can be used to protect surfaces from bacterial infections, for example implants.

Bloodstream infections in intensive care unit patients: distribution and antibiotic resistance of bacteria

Bloodstream infections (BSIs) are among the leading infections in critically ill patients. The case-fatality rate associated with BSIs in patients admitted to intensive care units (ICUs) reaches 35%–50%. The emergence and diffusion of bacteria with resistance to antibiotics is a global health problem. Multidrug-resistant bacteria were detected in 50.7% of patients with BSIs in a recently published international observational study, with methicillin resistance detected in 48% of Staphylococcus aureus strains, carbapenem resistance detected in 69% of Acinetobacter spp., in 38% of Klebsiella pneumoniae, and in 37% of Pseudomonas spp. Prior hospitalization and antibiotic exposure have been identified as risk factors for infections caused by resistant bacteria in different studies. Patients with BSIs caused by resistant strains showed an increased risk of mortality, which may be explained by a higher incidence of inappropriate empirical therapy in different studies. The molecular genetic characterization of resistant bacteria allows the understanding of the most common mechanisms underlying their resistance and the adoption of surveillance measures. Knowledge of epidemiology, risk factors, mechanisms of resistance, and outcomes of BSIs caused by resistant bacteria may have a major influence on global management of ICU patients. The aim of this review is to provide the clinician an update on BSIs caused by resistant bacteria in ICU patients.

A low-cost, hands-on module to characterize antimicrobial compounds using an interdisciplinary, biophysical approach

A cost-effective and resource-efficient hands-on educational module that uses an interdisciplinary approach to characterize antimicrobial compounds, combining microbiology experiments and a physics-based analytical model.

We have developed a hands-on experimental module that combines biology experiments with a physics-based analytical model in order to characterize antimicrobial compounds. To understand antibiotic resistance, participants perform a disc diffusion assay to test the antimicrobial activity of different compounds and then apply a diffusion-based analytical model to gain insights into the behavior of the active antimicrobial component. In our experience, this module was robust, reproducible, and cost-effective, suggesting that it could be implemented in diverse settings such as undergraduate research, STEM (science, technology, engineering, and math) camps, school programs, and laboratory training workshops. By providing valuable interdisciplinary research experience in science outreach and education initiatives, this module addresses the paucity of structured training or education programs that integrate diverse scientific fields. Its low-cost requirements make it especially suitable for use in resource-limited settings.

Antibiotic resistance is widespread in urban aquatic environments of Rio de Janeiro, Brazil

Bacterial resistance to antibiotics has become a public health issue. Over the years, pathogenic organisms with resistance traits have been studied due to the threat they pose to human well-being. However, several studies raised awareness to the often disregarded importance of environmental bacteria as sources of resistance mechanisms. In this work, we analyze the diversity of antibiotic-resistant bacteria occurring in aquatic environments of the state of Rio de Janeiro, Brazil, that are subjected to distinct degrees of anthropogenic impacts. We access the diversity of aquatic bacteria capable of growing in increasing ampicillin concentrations through 16S rRNA gene libraries. This analysis is complemented by the characterization of antibiotic resistance profiles of isolates obtained from urban aquatic environments. We detect communities capable of tolerating antibiotic concentrations up to 600 times higher than the clinical levels. Among the resistant organisms are included potentially pathogenic species, some of them classified as multiresistant. Our results extend the knowledge of the diversity of antibiotic resistance among environmental microorganisms and provide evidence that the diversity of drug-resistant bacteria in aquatic habitats can be influenced by pollution.

Celecoxib sensitizes Staphylococcus aureus to antibiotics in macrophages by modulating SIRT1

We have previously shown that celecoxib in combination with an antibiotic, increase the bacterial sensitivity to antibiotics. However, the underlying molecular mechanism remained elusive. Efficacy of the combinatorial treatment of celecoxib and ampicillin in vitro was evaluated on macrophage-phagocytosed S. aureus. To elucidate the mechanism, signaling pathway of infection and inflammation involving TLR2, JNK, SIRT1 and NF-κB was studied by FACS, Western blot, ELISA and activity assays. Combinatorial treatment of ampicillin and celecoxib reduced the bacterial load in the macrophages. Further studies clearly suggested the activation of the master regulator of oxidative stress and inflammation SIRT1, by celecoxib when used alone and/or in combination with ampicillin. Also, the results indicated that celecoxib inhibited JNK phosphorylation thereby stabilizing and activating SIRT1 protein that inhibited the COX-2 gene transcription with a significant decrease in the levels of protein inflammatory cytokines like IL-6, MIP-1α and IL-1β via inhibition of NF-κB. SIRT1 activation by celecoxib also resulted in increase of catalase and peroxidase activity with a decrease in Nitric oxide levels. In conclusion, we demonstrate a novel role of celecoxib in controlling inflammation as an enhancer of antibiotic activity against bacteria by modulating SIRT1.

Antibiotic resistance - why is the problem so difficult to solve?

Antibiotic resistance has been increasing along with antibiotic use. At the same time, the supply of new drugs to replace those rendered inefficient by the development has been dwindling, leading to concerns that we may soon lack efficient means to treat bacterial infections. Though the problem has received considerable interest, there are no indications that the situation is about to change. The present review maintains that this is because the two objectives - preserving the efficiency of existing drugs and increasing the supply of new ones - are partly opposing. Hence, creating an incentive structure compatible with both of them is not easy. Nevertheless, it is suggested that levying a fee on the use of antibiotics, and earmarking the proceeds from this fee for subsidizing development of new antibiotics, would be an important step towards increasing incentives for a better antibiotic stewardship while preserving incentives to develop new substances.