Publications by authors named "Ashlee M Earl"

Motivation: Partial order alignment is a widely used method for computing multiple sequence alignments, with applications in genome assembly and pangenomics, among many others. Current algorithms to compute the optimal, gap-affine partial order alignment do not scale well to larger graphs and sequences. While heuristic approaches exist, they do not guarantee optimal alignment and sacrifice alignment accuracy.

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Background: Klebsiella pneumoniae (Kpn), a WHO priority pathogen with high rates of antimicrobial resistance (AMR), has emerged as a leading cause of hospital acquired pneumonia and neonatal sepsis.

Objective: We aimed to define the clinical characteristics of a cohort of patients with Kpn infection in Dhaka, Bangladesh and to perform phenotypic and genetic characterization of the associated isolates.

Methods: We retrospectively extracted clinical data about patients at Dhaka Medical College Hospital from whom Klebsiella spp was isolated from a clinical specimen collected between February and September 2022.

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Background: The effects of antibiotic use on children's gut microbiomes and resistomes are not well characterized in middle-income countries, where pediatric antibiotic consumption is exceptionally common. We characterized the effects of antibiotics commonly used by Peruvian children (i.e.

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Article Synopsis
  • The study assessed the prevalence of Klebsiella pneumoniae (Kp) in healthy adults and children living in Dhaka, Bangladesh, revealing higher rates in adults (81%) compared to children (61%).
  • Kp was found in household water (64%) and standing water (85%), but there was no strong correlation between Kp levels in water and stool samples from the same households.
  • Notable levels of antimicrobial resistance were observed, with some stool and water isolates showing multidrug resistance and significant rates of carbapenem resistance, indicating a public health concern.
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Low-abundance members of microbial communities are difficult to study in their native habitats, including Escherichia coli, a minor but common inhabitant of the gastrointestinal tract, and key opportunistic pathogen of the urinary tract. While multi-omic analyses have detailed interactions between uropathogenic Escherichia coli (UPEC) and the bladder mediating urinary tract infection (UTI), little is known about UPEC in its pre-infection reservoir, the gastrointestinal tract, partly due to its low relative abundance (<1%). To sensitively explore the genomes and transcriptomes of diverse gut E.

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Avibactam (AVI) is a diazabicyclooctane (DBO) β-lactamase inhibitor used clinically in combination with ceftazidime. At concentrations higher than those typically achieved , it also has broad-spectrum direct antibacterial activity against strains, including metallo-β-lactamase-producing isolates, mediated by inhibition of penicillin-binding protein 2 (PBP2). This activity is mechanistically similar to that of more potent novel DBOs (zidebactam, nacubactam) in late clinical development.

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Traditionally, surveillance programs for food products and food processing environments have focused on targeted pathogens and resistance genes. Recent advances in high throughput sequencing allow for more comprehensive and untargeted monitoring. This study assessed the microbiome and resistome in a poultry burger processing line using culturing techniques and whole metagenomic sequencing (WMS).

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Identifying bacterial transmission pathways is crucial to inform strategies aimed at curbing the spread of pathogenic and antibiotic-resistant bacteria, especially in rapidly urbanizing low- and middle-income countries. In this study, we assessed bacterial strain-sharing and dissemination of antibiotic resistance across humans, domesticated poultry, canines, household soil, and drinking water in urban informal settlements in Nairobi, Kenya. We collected 321 samples from 50 households and performed Pooling Isolated Colonies-seq (PIC-seq) by sequencing pools of up to five colonies per sample to capture strain diversity, strain-sharing patterns, and overlap of antibiotic-resistant genes (ARGs).

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Article Synopsis
  • Current methods for predicting bacterial gene functions are limited due to a lack of database matches for novel proteins, necessitating improved prediction techniques.
  • A new tool called SAFPred has been developed, utilizing protein embeddings from advanced language models to enhance gene function prediction in bacteria while incorporating their unique operon structures.
  • SAFPred demonstrated superior performance over traditional methods and identified 11 potential novel toxins in enterococci, which could have important health implications.
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Low-abundance members of microbial communities are difficult to study in their native habitats. This includes , a minor, but common inhabitant of the gastrointestinal tract and opportunistic pathogen, including of the urinary tract, where it is the primary pathogen. While multi-omic analyses have detailed critical interactions between uropathogenic (UPEC) and the bladder that mediate UTI outcome, comparatively little is known about UPEC in its pre-infection reservoir, partly due to its low abundance there (<1% relative abundance).

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Article Synopsis
  • Enterococci are gut microbes found in many land animals and have evolved over hundreds of millions of years, leading to over 60 known species, some of which are harmful, especially in hospitals due to antibiotic resistance.
  • Researchers have identified 18 new species of enterococci from various hosts and environments, indicating a significant increase in known diversity.
  • The study enhances our understanding of enterococcal evolution and highlights potential health threats, as well as identifies key traits and genes connected to host specialization and survival.
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Several bacterial pathogens, including Salmonella enterica, can cause persistent infections in humans by mechanisms that are poorly understood. By comparing genomes of isolates longitudinally collected from 256 prolonged salmonellosis patients, we identified repeated mutations in global regulators, including the barA/sirA two-component regulatory system, across multiple patients and Salmonella serovars. Comparative RNA-seq analysis revealed that distinct mutations in barA/sirA led to diminished expression of Salmonella pathogenicity islands 1 and 4 genes, which are required for Salmonella invasion and enteritis.

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The discovery of novel structural classes of antibiotics is urgently needed to address the ongoing antibiotic resistance crisis. Deep learning approaches have aided in exploring chemical spaces; these typically use black box models and do not provide chemical insights. Here we reasoned that the chemical substructures associated with antibiotic activity learned by neural network models can be identified and used to predict structural classes of antibiotics.

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We explored the utility of brief Mycobacterium tuberculosis whole-genome sequencing (WGS) "snapshots" at a sentinel site within Lima, Peru, for evaluating local transmission dynamics over time. Within a 17-km2 area, 15 of 70 (21%) isolates with WGS collected during 2011-2012 and 22 of 81 (27%) collected during 2020-2021 were clustered (P = .414), and additional isolates clustered with those from outside the area.

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Background: Culture-based studies have shown that acquisition of extended-spectrum β-lactamase-producing Enterobacterales is common during international travel; however, little is known about the role of the gut microbiome before and during travel, nor about acquisition of other antimicrobial-resistant organisms. We aimed to identify (1) whether the gut microbiome provided colonisation resistance against antimicrobial-resistant organism acquisition, (2) the effect of travel and travel behaviours on the gut microbiome, and (3) the scale and global heterogeneity of antimicrobial-resistant organism acquisition.

Methods: In this metagenomic analysis, participants were recruited at three US travel clinics (Boston, MA; New York, NY; and Salt Lake City, UT) before international travel.

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Background: The clinical and microbial factors associated with Klebsiella pneumoniae bloodstream infections (BSIs) are not well characterized. Prior studies have focused on highly resistant or hypervirulent isolates, limiting our understanding of K. pneumoniae strains that commonly cause BSI.

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Article Synopsis
  • Urinary tract infections (UTIs) in children are primarily caused by uropathogenic Escherichia coli (UPEC), yet there is limited understanding of their genetic makeup and antibiotic resistance.
  • Researchers analyzed whole-genome sequences from 96 UPEC isolates, focusing on those from children with pyelonephritis and multidrug-resistant ST131 strains.
  • The study revealed similar UPEC population structures in children and adults, identified genetic markers linked to antibiotic resistance, and highlighted unexpected genetic associations within different UPEC subclades.
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Background: Antibiotic resistance is a leading cause of death, with the highest burden occurring in low-resource settings. There is little evidence on the potential for water, sanitation, and hygiene (WASH) access to reduce antibiotic resistance in humans. We aimed to determine the relationship between the burden of antibiotic resistance in humans and community access to drinking water and sanitation.

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Many universally and conditionally important genes are genomically aggregated within clusters. Here, we introduce fai and zol, which together enable large-scale comparative analysis of different types of gene clusters and mobile-genetic elements (MGEs), such as biosynthetic gene clusters (BGCs) or viruses. Fundamentally, they overcome a current bottleneck to reliably perform comprehensive orthology inference at large scale across broad taxonomic contexts and thousands of genomes.

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Enterococci are commensal gut microbes of most land animals. They diversified over hundreds of millions of years adapting to evolving hosts and host diets. Of over 60 known enterococcal species, and uniquely emerged in the antibiotic era among leading causes of multidrug resistant hospital-associated infection.

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Article Synopsis
  • Carbapenem-resistant Enterobacteriaceae (CRE) can develop resistance through various methods, which affects how they are monitored and treated in healthcare settings.
  • The study found that different resistance mechanisms significantly influence the carbapenem inoculum effect (IE), where the size of bacteria samples can change the perceived effectiveness of the antibiotics being tested.
  • Results showed that all carbapenemase-producing CRE had a strong IE, leading to concerns that many isolates could appear more susceptible to antibiotics than they truly are, complicating treatment decisions.
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Motivation: Today, we know the function of only a small fraction of the protein sequences predicted from genomic data. This problem is even more salient for bacteria, which represent some of the most phylogenetically and metabolically diverse taxa on Earth. This low rate of bacterial gene annotation is compounded by the fact that most function prediction algorithms have focused on eukaryotes, and conventional annotation approaches rely on the presence of similar sequences in existing databases.

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Uropathogenic Escherichia coli (UPEC) is extremely diverse genotypically and phenotypically. Individual strains can variably carry diverse virulence factors, making it challenging to define a molecular signature for this pathotype. For many bacterial pathogens, mobile genetic elements (MGEs) constitute a major mechanism of virulence factor acquisition.

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A bacterial species is considered to be intrinsically resistant to an antimicrobial when nearly all of the wild-type isolates (i.e., those without acquired resistance) exhibit minimum inhibitory concentration (MIC) values that are sufficiently high such that susceptibility testing is unnecessary, and that the antimicrobial should not be considered for therapy.

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Background: Extended spectrum beta-lactamase producing Enterobacterales (ESBL-PE) present a risk to public health by limiting the efficacy of multiple classes of beta-lactam antibiotics against infection. International travellers may acquire these organisms and identifying individuals at high risk of acquisition could help inform clinical treatment or prevention strategies.

Methods: We used data collected from a cohort of 528 international travellers enrolled in a multicentre US-based study to derive a clinical prediction rule (CPR) to identify travellers who developed ESBL-PE colonization, defined as those with new ESBL positivity in stool upon return to the United States.

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