Publications by authors named "Kathryn Holt"

Unlabelled: Sequencing DNA directly from patient samples enables faster pathogen characterization compared to traditional culture-based approaches, but often yields insufficient sequence data for effective downstream analysis. CRISPR-Cas9 enrichment is designed to improve the yield of low abundance sequences but has not been thoroughly explored with Oxford Nanopore Technologies (ONT) for use in clinical bacterial epidemiology. We designed CRISPR-Cas9 guide RNAs to enrich the human pathogen , by targeting multi-locus sequence type (MLST) and transfer RNA (tRNA) genes, as well as common antimicrobial resistance (AMR) genes and the resistance-associated integron gene .

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Shigella sonnei is a major cause of diarrhoea globally and is increasing in prevalence relative to other Shigella because of multiple demographic and environmental influences. This single-serotype species has traditionally received less attention in comparison to Shigella flexneri and Shigella dysenteriae, which were more common in low-income countries and more tractable in the laboratory. In recent years, we have learned that Shigella are highly complex and highly susceptible to environmental change, as exemplified by epidemiological trends and increasing relevance of S.

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Bacteria are typically isolated on rich media to maximise isolation success, removing them from their native evolutionary context. This eliminates selection pressures, enabling otherwise deleterious genomic events to accumulate. Here, we present a cautionary tale of these 'quiet mutations' which can persist unnoticed in bacterial culture lines.

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Article Synopsis
  • EnteroBase is a web-based platform that offers curated databases of genome sequences from over 1.1 million bacterial isolates, including notable pathogens like Streptococcus and Mycobacterium tuberculosis.
  • The platform now features tools for detecting antimicrobial resistance and a new bubble plot tool for visualizing bacterial genomic structures.
  • Enhanced access and functionalities are provided through a user-friendly interface and a RESTful API, with ongoing development by an international consortium to improve and maintain the system.
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Interpreting the phenotypes of alleles in genomes is complex. Whilst all strains are expected to carry a chromosomal copy conferring resistance to ampicillin, they may also carry mutations in chromosomal alleles or additional plasmid-borne alleles that have extended-spectrum β-lactamase (ESBL) activity and/or β-lactamase inhibitor (BLI) resistance activity. In addition, the role of individual mutations/a changes is not completely documented or understood.

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Article Synopsis
  • Enteric fever, caused by Salmonella enterica serovars Typhi and Paratyphi A, poses a significant public health issue due to rising antimicrobial resistance, complicating treatment options and worsening health outcomes.
  • *The study sequenced bacteria samples from blood cultures of febrile patients in urban sites of Dhaka (Bangladesh), Kathmandu (Nepal), and Blantyre (Malawi) to analyze their genetic characteristics and resistance mechanisms.
  • *Findings revealed that different genotypes of S. Typhi were present across the sites, with high rates of multidrug resistance in Blantyre and Dhaka but not in Kathmandu, highlighting diverse transmission dynamics and resistance patterns.
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Precision public health (PPH) considers the interplay between genetics, lifestyle and the environment to improve disease prevention, diagnosis and treatment on a population level-thereby delivering the right interventions to the right populations at the right time. In this Review, we explore the concept of PPH as the next generation of public health. We discuss the historical context of using individual-level data in public health interventions and examine recent advancements in how data from human and pathogen genomics and social, behavioral and environmental research, as well as artificial intelligence, have transformed public health.

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Non-carbapenemase-producing carbapenem-resistant (non-CP CRE) may be associated with a grave outcome. The common underlying mechanism is beta-lactamases and mutations in outer membrane porins. We report a case of a deep-seated infection caused by ST395 not amenable to source control, involving recurrent bloodstream infection, resulting in selection of carbapenem resistance under therapy.

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As public health laboratories expand their genomic sequencing and bioinformatics capacity for the surveillance of different pathogens, labs must carry out robust validation, training, and optimization of wet- and dry-lab procedures. Achieving these goals for algorithms, pipelines and instruments often requires that lower quality datasets be made available for analysis and comparison alongside those of higher quality. This range of data quality in reference sets can complicate the sharing of sub-optimal datasets that are vital for the community and for the reproducibility of assays.

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Article Synopsis
  • * Researchers utilized advanced genomic techniques to identify 44 different strains, notably finding that ST133 was the most prevalent, while many isolates also contained resistance genes against multiple antibiotic classes, including significant resistance to carbapenems.
  • * The results highlight a diverse and complex landscape of K. pneumoniae in the region, emphasizing the urgent need for continuous genomic surveillance to tackle the challenge of rising antimicrobial resistance.
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Klebsiella pneumoniae causes community- and healthcare-associated infections in children and adults. Globally in 2019, an estimated 1.27 million (95% Uncertainty Interval [UI]: 0.

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Article Synopsis
  • - Shigella is a major pathogen causing significant global diarrheal diseases, with rising antimicrobial resistance and no effective vaccine, emphasizing the need for new treatment and prevention strategies.
  • - The review highlights innovative research methods including the organ-on-chip model, zebrafish infection model, an oral mouse model, and controlled human infection models, each providing unique insights into Shigella infection mechanisms.
  • - These models are crucial for understanding Shigella's biology and immune responses, and they are paving the way for future research aimed at developing effective therapies and vaccines against shigellosis.
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Background: Ciprofloxacin is the first-line drug for treating typhoid fever in many countries in Africa with a high disease burden, but the emergence of non-susceptibility poses a challenge to public health programmes. Through enhanced surveillance as part of vaccine evaluation, we investigated the occurrence and potential determinants of ciprofloxacin non-susceptibility in Blantyre, Malawi.

Methods: We conducted systematic surveillance of typhoid fever cases and antibiotic prescription in two health centres in Blantyre, Malawi, between Oct 1, 2016, and Oct 31, 2019, as part of the STRATAA and TyVAC studies.

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Article Synopsis
  • KpSC is a significant cause of hospital infections worldwide, showing high antimicrobial resistance, driving research into its virulence and metabolic processes for new treatments.
  • Researchers created KpSC pan v2, an advanced metabolic model using data from 507 KpSC isolates, which includes 3550 reactions and can simulate growth on 360 substrates, showing improved accuracy over previous models.
  • This model is available for free online, providing a valuable resource for researchers to study metabolism and develop targeted therapies.
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Typhoid fever is an invasive bacterial disease associated with bloodstream infection that causes a high burden of disease in Africa and Asia. Typhoid primarily affects individuals ranging from infants through to young adults. The causative organism, Salmonella enterica subsp.

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Nitrofurantoin is a commonly used chemotherapeutic agent in the treatment of uncomplicated urinary tract infections caused by the problematic multidrug resistant Gram-negative pathogen . The present study aims to elucidate the mechanism of nitrofurantoin action and high-level resistance in using whole-genome sequencing (WGS), qPCR analysis, mutation structural modeling and untargeted metabolomic analysis. WGS profiling of evolved highly resistant mutants (nitrofurantoin minimum inhibitory concentrations > 256 mg/L) revealed modified expression of several genes related to membrane transport (porin and efflux pump regulator ) and nitroreductase activity ( and , involved in nitrofurantoin reduction).

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Nearly a century after the beginning of the antibiotic era, which has been associated with unparalleled improvements in human health and reductions in mortality associated with infection, the dwindling pipeline for new antibiotic classes coupled with the inevitable spread of antimicrobial resistance (AMR) poses a major global challenge. Historically, surveillance of bacteria with AMR typically relied on phenotypic analysis of isolates taken from infected individuals, which provides only a low-resolution view of the epidemiology behind an individual infection or wider outbreak. Recent years have seen increasing adoption of powerful new genomic technologies with the potential to revolutionise AMR surveillance by providing a high-resolution picture of the AMR profile of the bacteria causing infections and providing real-time actionable information for treating and preventing infection.

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Historically, epidemiological investigation and surveillance for bacterial antimicrobial resistance (AMR) has relied on low-resolution isolate-based phenotypic analyses undertaken at local and national reference laboratories. Genomic sequencing has the potential to provide a far more high-resolution picture of AMR evolution and transmission, and is already beginning to revolutionise how public health surveillance networks monitor and tackle bacterial AMR. However, the routine integration of genomics in surveillance pipelines still has considerable barriers to overcome.

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Integration of genomic technologies into routine antimicrobial resistance (AMR) surveillance in health-care facilities has the potential to generate rapid, actionable information for patient management and inform infection prevention and control measures in near real time. However, substantial challenges limit the implementation of genomics for AMR surveillance in clinical settings. Through a workshop series and online consultation, international experts from across the AMR and pathogen genomics fields convened to review the evidence base underpinning the use of genomics for AMR surveillance in a range of settings.

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Drug-resistant tuberculosis (TB) infection is a growing and potent concern, and combating it will be necessary to achieve the WHO's goal of a 95% reduction in TB deaths by 2035. While prior studies have explored the evolution and spread of drug resistance, we still lack a clear understanding of the fitness costs (if any) imposed by resistance-conferring mutations and the role that genetic lineage plays in determining the likelihood of resistance evolution. This study offers insight into these questions by assessing the dynamics of resistance evolution in a high-burden Southeast Asian setting with a diverse lineage composition.

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Metabolic capacity can vary substantially within a bacterial species, leading to ecological niche separation, as well as differences in virulence and antimicrobial susceptibility. Genome-scale metabolic models are useful tools for studying the metabolic potential of individuals, and with the rapid expansion of genomic sequencing there is a wealth of data that can be leveraged for comparative analysis. However, there exist few tools to construct strain-specific metabolic models at scale.

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Background: The Global Typhoid Genomics Consortium was established to bring together the typhoid research community to aggregate and analyse serovar Typhi (Typhi) genomic data to inform public health action. This analysis, which marks 22 years since the publication of the first Typhi genome, represents the largest Typhi genome sequence collection to date (n=13,000).

Methods: This is a meta-analysis of global genotype and antimicrobial resistance (AMR) determinants extracted from previously sequenced genome data and analysed using consistent methods implemented in open analysis platforms GenoTyphi and Pathogenwatch.

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Shigella represents a paraphyletic group of enteroinvasive Escherichia coli. More than 40 Shigella serotypes have been reported. However, most cases within the men who have sex with men (MSM) community are attributed to 3 serotypes: Shigella sonnei unique serotype and Shigella flexneri 2a and 3a serotypes.

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RNAseq data can be used to infer genetic variants, yet its use for estimating genetic population structure remains underexplored. Here, we construct a freely available computational tool (RGStraP) to estimate RNAseq-based genetic principal components (RG-PCs) and assess whether RG-PCs can be used to control for population structure in gene expression analyses. Using whole blood samples from understudied Nepalese populations and the Geuvadis study, we show that RG-PCs had comparable results to paired array-based genotypes, with high genotype concordance and high correlations of genetic principal components, capturing subpopulations within the dataset.

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