scholarly journals Unbiased profiling of CRISPR RNA-guided transposition products by long-read sequencing

Mobile DNA ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Phuc Leo H. Vo ◽  
Christopher Acree ◽  
Melissa L. Smith ◽  
Samuel H. Sternberg
Keyword(s):  
Mobile Element ◽  
Population Based ◽  
Dna Integration ◽  
E Coli ◽  
Vector Backbone ◽  
Long Read ◽  
Copy And Paste ◽  
Novel Strategy ◽  
Molecular Components ◽  
Donor Source

AbstractBacterial transposons propagate through either non-replicative (cut-and-paste) or replicative (copy-and-paste) pathways, depending on how the mobile element is excised from its donor source. In the well-characterized E. coli transposon Tn7, a heteromeric TnsA-TnsB transposase directs cut-and-paste transposition by cleaving both strands at each transposon end during the excision step. Whether a similar pathway is involved for RNA-guided transposons, in which CRISPR-Cas systems confer DNA target specificity, has not been determined. Here, we apply long-read, population-based whole-genome sequencing (WGS) to unambiguously resolve transposition products for two evolutionarily distinct transposon types that employ either Cascade or Cas12k for RNA-guided DNA integration. Our results show that RNA-guided transposon systems lacking functional TnsA primarily undergo copy-and-paste transposition, generating cointegrate products that comprise duplicated transposon copies and genomic insertion of the vector backbone. Finally, we report natural and engineered transposon variants encoding a TnsAB fusion protein, revealing a novel strategy for achieving RNA-guided transposition with fewer molecular components.

scholarly journals Unbiased profiling of CRISPR RNA-guided transposition products by long-read sequencing

2021 ◽  
Author(s):  
Phuc Leo Hong Vo ◽  
Christopher Acree ◽  
Melissa L. Smith ◽  
Samuel Henry Sternberg
Keyword(s):  
Mobile Element ◽  
Population Based ◽  
Dna Integration ◽  
E Coli ◽  
Vector Backbone ◽  
Long Read ◽  
Copy And Paste ◽  
Novel Strategy ◽  
Molecular Components ◽  
Donor Source

Bacterial transposons propagate through either non-replicative (cut-and-paste) or replicative (copy-and-paste) pathways, depending on how the mobile element is excised from its donor source. In the well-characterized E. coli transposon Tn7, a heteromeric TnsA-TnsB transposase directs cut-and-paste transposition by cleaving both strands at each transposon end during the excision step. Whether a similar pathway is involved for RNA-guided transposons, in which CRISPR-Cas systems confer DNA target specificity, has not been determined. Here, we apply long-read, population-based whole-genome sequencing (WGS) to unambiguously resolve transposition products for two evolutionarily distinct transposon types that employ either Cascade or Cas12k for RNA-guided DNA integration. Our results show that RNA-guided transposon systems lacking functional TnsA primarily undergo copy-and-paste transposition, generating cointegrate products that comprise duplicated transposon copies and insertion of the vector backbone. Finally, we report natural and engineered transposon variants encoding a TnsAB fusion protein, revealing a novel strategy for achieving RNA-guided transposition with fewer molecular components.

scholarly journals Comparison of long-read sequencing technologies in interrogating bacteria and fly genomes

2021 ◽  
Author(s):  
Eric S Tvedte ◽  
Mark Gasser ◽  
Benjamin C Sparklin ◽  
Jane Michalski ◽  
Carl E Hjelmen ◽  
...  
Keyword(s):  
Bacterial Genome ◽  
Hybrid Approach ◽  
Cost Effective ◽  
Fruit Fly ◽  
Drosophila Ananassae ◽  
Whole Genome Sequencing Data ◽  
Sequencing Data ◽  
E Coli ◽  
Hybrid Approaches ◽  
Long Read

Abstract The newest generation of DNA sequencing technology is highlighted by the ability to generate sequence reads hundreds of kilobases in length. Pacific Biosciences (PacBio) and Oxford Nanopore Technologies (ONT) have pioneered competitive long read platforms, with more recent work focused on improving sequencing throughput and per-base accuracy. We used whole-genome sequencing data produced by three PacBio protocols (Sequel II CLR, Sequel II HiFi, RS II) and two ONT protocols (Rapid Sequencing and Ligation Sequencing) to compare assemblies of the bacteria Escherichia coli and the fruit fly Drosophila ananassae. In both organisms tested, Sequel II assemblies had the highest consensus accuracy, even after accounting for differences in sequencing throughput. ONT and PacBio CLR had the longest reads sequenced compared to PacBio RS II and HiFi, and genome contiguity was highest when assembling these datasets. ONT Rapid Sequencing libraries had the fewest chimeric reads in addition to superior quantification of E. coli plasmids versus ligation-based libraries. The quality of assemblies can be enhanced by adopting hybrid approaches using Illumina libraries for bacterial genome assembly or polishing eukaryotic genome assemblies, and an ONT-Illumina hybrid approach would be more cost-effective for many users. Genome-wide DNA methylation could be detected using both technologies, however ONT libraries enabled the identification of a broader range of known E. coli methyltransferase recognition motifs in addition to undocumented D. ananassae motifs. The ideal choice of long read technology may depend on several factors including the question or hypothesis under examination. No single technology outperformed others in all metrics examined.

scholarly journals Mortality in Escherichia coli bloodstream infections: a multinational population-based cohort study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Melissa C. MacKinnon ◽  
Scott A. McEwen ◽  
David L. Pearl ◽  
Outi Lyytikäinen ◽  
Gunnar Jacobsson ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Mortality Rate ◽  
Case Fatality ◽  
Population Based ◽  
Day Case ◽  
Fatality Risk ◽  
E Coli ◽  
Factors Associated ◽  
Case Fatality Risk ◽  
Age And Sex

Abstract Background Escherichia coli is the most common cause of bloodstream infections (BSIs) and mortality is an important aspect of burden of disease. Using a multinational population-based cohort of E. coli BSIs, our objectives were to evaluate 30-day case fatality risk and mortality rate, and determine factors associated with each. Methods During 2014–2018, we identified 30-day deaths from all incident E. coli BSIs from surveillance nationally in Finland, and regionally in Sweden (Skaraborg) and Canada (Calgary, Sherbrooke, western interior). We used a multivariable logistic regression model to estimate factors associated with 30-day case fatality risk. The explanatory variables considered for inclusion were year (2014–2018), region (five areas), age (< 70-years-old, ≥70-years-old), sex (female, male), third-generation cephalosporin (3GC) resistance (susceptible, resistant), and location of onset (community-onset, hospital-onset). The European Union 28-country 2018 population was used to directly age and sex standardize mortality rates. We used a multivariable Poisson model to estimate factors associated with mortality rate, and year, region, age and sex were considered for inclusion. Results From 38.7 million person-years of surveillance, we identified 2961 30-day deaths in 30,923 incident E. coli BSIs. The overall 30-day case fatality risk was 9.6% (2961/30923). Calgary, Skaraborg, and western interior had significantly increased odds of 30-day mortality compared to Finland. Hospital-onset and 3GC-resistant E. coli BSIs had significantly increased odds of mortality compared to community-onset and 3GC-susceptible. The significant association between age and odds of mortality varied with sex, and contrasts were used to interpret this interaction relationship. The overall standardized 30-day mortality rate was 8.5 deaths/100,000 person-years. Sherbrooke had a significantly lower 30-day mortality rate compared to Finland. Patients that were either ≥70-years-old or male both experienced significantly higher mortality rates than those < 70-years-old or female. Conclusions In our study populations, region, age, and sex were significantly associated with both 30-day case fatality risk and mortality rate. Additionally, 3GC resistance and location of onset were significantly associated with 30-day case fatality risk. Escherichia coli BSIs caused a considerable burden of disease from 30-day mortality. When analyzing population-based mortality data, it is important to explore mortality through two lenses, mortality rate and case fatality risk.

scholarly journals An Assessment of the Viability of Lytic Phages and Their Potency against Multidrug Resistant Escherichia coli O177 Strains under Simulated Rumen Fermentation Conditions

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 265
Author(s):  
Peter Kotsoana Montso ◽  
Caven Mguvane Mnisi ◽  
Collins Njie Ateba ◽  
Victor Mlambo
Keyword(s):  
Escherichia Coli ◽  
Rumen Fluid ◽  
Multidrug Resistant ◽  
Rumen Fermentation ◽  
Ruminal Fermentation ◽  
Fermentation Conditions ◽  
E Coli ◽  
Cell Counts ◽  
Milk Contamination ◽  
Novel Strategy

Preslaughter starvation and subacute ruminal acidosis in cattle are known to promote ruminal proliferation of atypical enteropathogenic Escherichia coli strains, thereby increasing the risk of meat and milk contamination. Using bacteriophages (henceforth called phages) to control these strains in the rumen is a potentially novel strategy. Therefore, this study evaluated the viability of phages and their efficacy in reducing E. coli O177 cells in a simulated ruminal fermentation system. Fourteen phage treatments were allocated to anaerobic serum bottles containing a grass hay substrate, buffered (pH 6.6–6.8) bovine rumen fluid, and E. coli O177 cells. The serum bottles were then incubated at 39 °C for 48 h. Phage titres quadratically increased with incubation time. Phage-induced reduction of E. coli O177 cell counts reached maximum values of 61.02–62.74% and 62.35–66.92% for single phages and phage cocktails, respectively. The highest E. coli O177 cell count reduction occurred in samples treated with vB_EcoM_366B (62.31%), vB_EcoM_3A1 (62.74%), vB_EcoMC3 (66.67%), vB_EcoMC4 (66.92%), and vB_EcoMC6 (66.42%) phages. In conclusion, lytic phages effectively reduced E. coli O177 cells under artificial rumen fermentation conditions, thus could be used as a biocontrol strategy in live cattle to reduce meat and milk contamination in abattoirs and milking parlours, respectively.

scholarly journals Temporal Trend of ST131 Clone among Urinary Escherichia coli Isolates in the Community: A Taiwan National Surveillance from 2002 to 2016

2021 ◽  
Vol 9 (5) ◽  
pp. 963
Author(s):  
Jiun-Ling Wang ◽  
Wen-Chien Ko ◽  
Chih-Hsin Hung ◽  
Ming-Fang Cheng ◽  
Hui-Ying Wang ◽  
...  
Keyword(s):  
Temporal Trend ◽  
Multidrug Resistant ◽  
Population Based ◽  
Pulsed Field Gel Electrophoresis ◽  
Sequence Type ◽  
E Coli ◽  
Factors Associated ◽  
Resistant Group ◽  
Ciprofloxacin Resistance ◽  
Susceptible Group

Sequence type (ST) 131 is a multidrug-resistant pandemic lineage of E. coli responsible for extraintestinal infections. Few surveillance data of ST131 included all antimicrobial-susceptible and -resistant isolates or focused on community-acquired urinary tract infection (UTI). From a population-based surveillance pool of 2997 outpatient urine E. coli isolates, 542 were selected for detection of ST131 based on ciprofloxacin and/or cefotaxime resistance. Pulsed-field gel electrophoresis (PFGE) was performed on all ST131 isolates to further determine their relatedness. The estimated overall ST131 prevalence in this community UTI cohort increased from 11.2% (in 2002–2004), 12.2% (in 2006–2008), 13.6% (in 2010–2012), to 17.4% in 2014–2016 (p < 0.01). In the ciprofloxacin-resistant/cefotaxime-resistant group, ST131 increased from 33.3% in 2002–2004 to 72.1% in 2014–2016 (p < 0.01). In the ciprofloxacin-resistant/cefotaxime-susceptible group, ST131 was found in 24.3% overall without significant increase in its prevalence over time. PFGE showed emergence of a cluster of ciprofloxacin-resistant/cefotaxime-resistant ST131 carrying Gr. 1 CTX-M ESBL in 2014–2016, especially 2016. Multivariate analysis revealed that age (≥65 y.o) and ciprofloxacin resistance were independent factors associated with ST131. This longitudinal surveillance showed that ciprofloxacin-resistant/cefotaxime-susceptible ST131 has been circulating in the community since 2002 but ciprofloxacin-resistant/cefotaxime-resistant ST131 increased rapidly in the later years.

scholarly journals Multidrug Resistance Dissemination in Escherichia coli Isolated from Wild Animals: Bacterial Clones and Plasmid Complicity

2021 ◽  
Vol 12 (1) ◽  
pp. 123-137
Author(s):  
Carolina Sabença ◽  
Gilberto Igrejas ◽  
Patrícia Poeta ◽  
Frédéric Robin ◽  
Richard Bonnet ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Epidemiological Data ◽  
Generation Cephalosporin ◽  
Wild Animals ◽  
Variable Regions ◽  
E Coli ◽  
Wild Fauna ◽  
Long Read ◽  
Sequence Types ◽  
Animal Isolates

Objectives. Epidemiological data concerning third-generation cephalosporin (3GC) resistance in wild fauna are scarce. The aim of this study was to characterize the resistance genes, their genetic context, and clonal relatedness in 17 Escherichia coli resistant to 3GC isolated from wild animals. Methods. The isolates were characterized by short-read whole genome sequencing, and long-read sequencing was used for the hybrid assembly of plasmid sequences. Results. The 3GC resistance gene most identified in the isolates was the extended-spectrum β-lactamases (ESBL)-encoding gene blaCTX-M-1 (82.3%), followed by blaCTX-M-32 (5.9%), blaCTX-M-14 (5.9%), and blaSHV-12 (5.9%). E. coli isolates mainly belonged to the sequence types (STs) rarely reported from humans. The single nucleotide polymorphism (SNP)-based typing showed that most E. coli genomes from wild animals (wild boars, birds of prey, and buzzards) formed clonal clusters (<5 SNPs), showing a clonal dissemination crossing species boundaries. blaCTX-M-1-harboring IncI1-ST3 plasmid was the predominant ESBL-encoding plasmid (76.4%) in wild animal isolates. Plasmid comparison revealed a 110-kb self-transferable plasmid consisting of a conserved backbone and two variable regions involved in antimicrobial resistance and in interaction with recipient cells during conjugation. Conclusion. Our results highlighted the unexpected clonal dissemination of blaCTX-M-1-encoding clones and the complicity of IncI1-ST3 plasmid in the spread of blaCTX-M-1 within wild fauna.

scholarly journals First Report of a Foodborne Salmonella enterica Serovar Gloucester (4:i:l,w) ST34 Strain Harboring blaCTX–M–55 and qnrS Genes Located in IS26-Mediated Composite Transposon

2021 ◽  
Vol 12 ◽  
Author(s):  
Lili Li ◽  
Rikke Heidemann Olsen ◽  
Anhua Song ◽  
Jian Xiao ◽  
Chong Wang ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Structural Unit ◽  
Bacterial Species ◽  
Meat Products ◽  
Sequence Type ◽  
E Coli ◽  
Serovar Typhimurium ◽  
Long Read ◽  
Phenotypic And Genotypic Characterization

Extended-spectrum β-lactamases (ESBLs) production and (fluoro)quinolone (FQ) resistance among Salmonella pose a public health threat. The objective of this study was the phenotypic and genotypic characterization of an ESBL-producing and nalidixic acid-resistant Salmonella enterica serovar Gloucester isolate (serotype 4:i:l,w) of sequence type 34 (ST34) from ready-to-eat (RTE) meat products in China. Whole-genome short and long read sequencing (HiSeq and MinION) results showed that it contained blaCTX–M–55, qnrS1, and tetB genes, with blaCTX–M–55 and qnrS1 located in chromosomal IS26-mediated composite transposon (IS26–qnrS1–IS3–Tn3–orf–blaCTX–M–55–ISEcp1–IS26). The same genetic structure was found in the chromosome of S. enterica subsp. enterica serovar Typhimurium strain and in several plasmids of Escherichia coli, indicating that the IS26-mediated composite transposon in the chromosome of S. Gloucester may originate from plasmids of E. coli and possess the ability to disseminate to Salmonella and other bacterial species. Besides, the structural unit qnrS1–IS3–Tn3–orf–blaCTX–M–55 was also observed to be linked with ISKpn19 in both the chromosomes and plasmids of various bacteria species, highlighting the contribution of the insertion sequences (IS26 and ISKpn19) to the co-dissemination of blaCTX–M–55 and qnrS1. To our knowledge, this is the first description of chromosomal blaCTX–M–55 and qnrS in S. Gloucester from RTE meat products. Our work expands the host range and provides additional evidence of the co-transfer of blaCTX–M–55 and qnrS1 among different species of Salmonella through the food chain.

scholarly journals Programmable Microbial Ink for 3D Printing of Living Materials Produced from Genetically Engineered Protein Nanofibers

2021 ◽  
Author(s):  
Anna M Duraj-Thatte ◽  
Avinash Manjula Basavanna ◽  
Jarod Rutledge ◽  
Jing Xia ◽  
Shabir Hassan ◽  
...  
Keyword(s):  
3D Printing ◽  
Self Assembly ◽  
Genetically Engineered ◽  
Ambient Conditions ◽  
Chemical Induction ◽  
Genetic Circuits ◽  
3D Print ◽  
E Coli ◽  
Molecular Components ◽  
Living Materials

Living cells have the capability to synthesize molecular components and precisely assemble them from the nanoscale to build macroscopic living functional architectures under ambient conditions. The emerging field of living materials has leveraged microbial engineering to produce materials for various applications, but building 3D structures in arbitrary patterns and shapes has been a major challenge. We set out to develop a new bioink, termed as "microbial ink" that is produced entirely from genetically engineered microbial cells, programmed to perform a bottom-up, hierarchical self-assembly of protein monomers into nanofibers, and further into nanofiber networks that comprise extrudable hydrogels. We further demonstrate the 3D printing of functional living materials by embedding programmed Escherichia coli (E. coli) cells and nanofibers into microbial ink, which can sequester toxic moieties, release biologics and regulate its own cell growth through the chemical induction of rationally designed genetic circuits. This report showcases the advanced capabilities of nanobiotechnology and living materials technology to 3D-print functional living architectures.

scholarly journals Urinary tract infections in pregnancy in a rural population of Bangladesh: population-based prevalence, risk factors, etiology, and antibiotic resistance

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Anne CC Lee ◽  
Luke C. Mullany ◽  
Alain K. Koffi ◽  
Iftekhar Rafiqullah ◽  
Rasheda Khanam ◽  
...  
Keyword(s):  
Risk Factors ◽  
Antibiotic Resistance ◽  
Urinary Tract ◽  
Asymptomatic Bacteriuria ◽  
Population Based ◽  
E Coli ◽  
Maternal Undernutrition ◽  
Low Middle Income Countries ◽  
Tract Infections ◽  
In Pregnancy

Abstract Background Urinary tract infection (UTI) in pregnancy, including asymptomatic bacteriuria, is associated with maternal morbidity and adverse pregnancy outcomes, including preterm birth and low birthweight. In low-middle income countries (LMICs), the capacity for screening and treatment of UTIs is limited. The objective of this study was to describe the population-based prevalence, risk factors, etiology and antimicrobial resistance patterns of UTIs in pregnancy in Bangladesh. Methods In a community-based cohort in Sylhet district, Bangladesh, urine specimens were collected at the household level in 4242 pregnant women (< 20 weeks gestation) for culture and antibiotic susceptibility testing. Basic descriptive analysis was performed, as well as logistic regression to calculate adjusted odds ratios (aOR) for UTI risk factors. Results The prevalence of UTI was 8.9% (4.4% symptomatic UTI, 4.5% asymptomatic bacteriuria). Risk factors for UTI in this population included maternal undernutrition (mid-upper arm circumference <23 cm: aOR= 1.29, 95% CI: 1.03–1.61), primiparity (aOR= 1.45, 95% CI: 1.15–1.84), and low paternal education (no education: aOR= 1.56, 95% CI: 1.09–2.22). The predominant uro-pathogens were E. coli (38% of isolates), Klebsiella (12%), and staphyloccocal species (23%). Group B streptococcus accounted for 5.3% of uro-pathogens. Rates of antibiotic resistance were high, with only two-thirds of E. coli susceptible to 3rd generation cephalosporins. Conclusions In Sylhet, Bangladesh, one in 11 women had a UTI in pregnancy, and approximately half of cases were asymptomatic. There is a need for low-cost and accurate methods for UTI screening in pregnancy and efforts to address increasing rates of antibiotic resistance in LMIC.

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