Development and evaluation of a novel, semiautomated Clostridium difficile typing platform

We describe a novel, semiautomated Clostridium difficile typing platform that is based on PCR-ribotyping in conjunction with a semiautomated molecular typing system. The platform is reproducible with minimal intra- or interassay variability. This method exhibited a discriminatory index of 0.954 and is therefore comparable to more arduous typing systems, such as pulsed-field gel electrophoresis

Whole-genome analysis of Exserohilum rostratum from an outbreak of fungal meningitis and other infections

Exserohilum rostratum was the cause of most cases of fungal meningitis and other infections associated with the injection of contaminated methylprednisolone acetate produced by the New England Compounding Center (NECC). Until this outbreak, very few human cases of Exserohilum infection had been reported, and very little was known about this dematiaceous fungus, which usually infects plants. Here, we report using whole-genome sequencing (WGS) for the detection of single nucleotide polymorphisms (SNPs) and phylogenetic analysis to investigate the molecular origin of the outbreak using 22 isolates of E. rostratum retrieved from 19 case patients with meningitis or epidural/spinal abscesses, 6 isolates from contaminated NECC vials, and 7 isolates unrelated to the outbreak. Our analysis indicates that all 28 isolates associated with the outbreak had nearly identical genomes of 33.8 Mb. A total of 8 SNPs were detected among the outbreak genomes, with no more than 2 SNPs separating any 2 of the 28 genomes. The outbreak genomes were separated from the next most closely related control strain by ∼136,000 SNPs. We also observed significant genomic variability among strains unrelated to the outbreak, which may suggest the possibility of cryptic speciation in E. rostratum

Tourism and toponymy: Commodifying and Consuming Place Names

Academic geographers have a long history of studying both tourism and place names, but have rarely made linkages between the two. Within critical toponymic studies there is increasing debate about the commodification of place names, but to date the role of tourism in this process has been almost completely overlooked. In some circumstances, toponyms can become tourist sights based on their extraordinary properties, their broader associations within popular culture, or their role as metanyms for some other aspect of a place. Place names may be sights in their own right or ‘markers’ of a sight and, in some cases, the marker may be more significant than the sight to which it refers. The appropriation of place names through tourism also includes the production and consumption of a broad range of souvenirs based on reproductions or replicas of the material signage that denote place names. Place names as attractions are also associated with a range of performances by tourists, and in some cases visiting a place name can be a significant expression of fandom. In some circumstances, place names can be embraced and promoted by tourism marketing strategies and are, in turn, drawn into broader circuits of the production and consumption of tourist space

Future-proofing and maximizing the utility of metadata: The PHA4GE SARS-CoV-2 contextual data specification package

Background The Public Health Alliance for Genomic Epidemiology (PHA4GE) (https://pha4ge.org) is a global coalition that is actively working to establish consensus standards, document and share best practices, improve the availability of critical bioinformatics tools and resources, and advocate for greater openness, interoperability, accessibility, and reproducibility in public health microbial bioinformatics. In the face of the current pandemic, PHA4GE has identified a need for a fit-for-purpose, open-source SARS-CoV-2 contextual data standard. Results As such, we have developed a SARS-CoV-2 contextual data specification package based on harmonizable, publicly available community standards. The specification can be implemented via a collection template, as well as an array of protocols and tools to support both the harmonization and submission of sequence data and contextual information to public biorepositories. Conclusions Well-structured, rich contextual data add value, promote reuse, and enable aggregation and integration of disparate datasets. Adoption of the proposed standard and practices will better enable interoperability between datasets and systems, improve the consistency and utility of generated data, and ultimately facilitate novel insights and discoveries in SARS-CoV-2 and COVID-19. The package is now supported by the NCBI’s BioSample database

Development and Validation of an Internationally-Standardized, High-Resolution Capillary Gel-Based Electrophoresis PCR-Ribotyping Protocol for Clostridium difficile

PCR-ribotyping has been adopted in many laboratories as the method of choice for C. difficile typing and surveillance. However, issues with the conventional agarose gel-based technique, including inter-laboratory variation and interpretation of banding patterns have impeded progress. The method has recently been adapted to incorporate high-resolution capillary gel-based electrophoresis (CE-ribotyping), so improving discrimination, accuracy and reproducibility. However, reports to date have all represented single-centre studies and inter-laboratory variability has not been formally measured or assessed. Here, we achieved in a multi-centre setting a high level of reproducibility, accuracy and portability associated with a consensus CE-ribotyping protocol. Local databases were built at four participating laboratories using a distributed set of 70 known PCR-ribotypes. A panel of 50 isolates and 60 electronic profiles (blinded and randomized) were distributed to each testing centre for PCR-ribotype identification based on local databases generated using the standard set of 70 PCR-ribotypes, and the performance of the consensus protocol assessed. A maximum standard deviation of only ±3.8bp was recorded in individual fragment sizes, and PCR-ribotypes from 98.2% of anonymised strains were successfully discriminated across four ribotyping centres spanning Europe and North America (98.8% after analysing discrepancies). Consensus CE-ribotyping increases comparability of typing data between centres and thereby facilitates the rapid and accurate transfer of standardized typing data to support future national and international C. difficile surveillance programs

Strengthening the Reporting of Molecular Epidemiology for Infectious Diseases (STROME-ID): an extension of the STROBE statement

Molecular data are now widely used in epidemiological studies to investigate the transmission, distribution, biology, and diversity of pathogens. Our objective was to establish recommendations to support good scientific reporting of molecular epidemiological studies to encourage authors to consider specific threats to valid inference. The statement Strengthening the Reporting of Molecular Epidemiology for Infectious Diseases (STROME-ID) builds upon the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) initiative. The STROME-ID statement was developed by a working group of epidemiologists, statisticians, bioinformaticians, virologists, and microbiologists with expertise in control of infection and communicable diseases. The statement focuses on issues relating to the reporting of epidemiological studies of infectious diseases using molecular data that were not addressed by STROBE. STROME-ID addresses terminology, measures of genetic diversity within pathogen populations, laboratory methods, sample collection, use of molecular markers, molecular clocks, timeframe, multiple-strain infections, non-independence of infectious-disease data, missing data, ascertainment bias, consistency between molecular and epidemiological data, and ethical considerations with respect to infectious-disease research. In total, 20 items were added to the 22 item STROBE checklist. When used, the STROME-ID recommendations should advance the quality and transparency of scientific reporting, with clear benefits for evidence reviews and health-policy decision making

Canonical Single Nucleotide Polymorphisms (SNPs) for High-Resolution Subtyping of Shiga-Toxin Producing <i>Escherichia coli</i> (STEC) O157:H7

<div><p>The objective of this study was to develop a canonical, parsimoniously-informative SNP panel for subtyping Shiga-toxin producing <i>Escherichia coli</i> (STEC) O157:H7 that would be consistent with epidemiological, PFGE, and MLVA clustering of human specimens. Our group had previously identified 906 putative discriminatory SNPs, which were pared down to 391 SNPs based on their prevalence in a test set. The 391 SNPs were screened using a high-throughput form of TaqMan PCR against a set of clinical isolates that represent the most diverse collection of O157:H7 isolates from outbreaks and sporadic cases examined to date. Another 30 SNPs identified by others were also screened using the same method. Two additional targets were tested using standard TaqMan PCR endpoint analysis. These 423 SNPs were reduced to a 32 SNP panel with the almost the same discriminatory value. While the panel partitioned our diverse set of isolates in a manner that was consistent with epidemiological data and PFGE and MLVA phylogenies, it resulted in fewer subtypes than either existing method and insufficient epidemiological resolution in 10 of 47 clusters. Therefore, another round of SNP discovery was undertaken using comparative genomic resequencing of pooled DNA from the 10 clusters with insufficient resolution. This process identified 4,040 potential SNPs and suggested one of the ten clusters was incorrectly grouped. After its removal, there were 2,878 SNPs, of which only 63 were previously identified and 438 occurred across multiple clusters. Among highly clonal bacteria like STEC O157:H7, linkage disequilibrium greatly limits the number of parsimoniously informative SNPs. Therefore, it is perhaps unsurprising that our panel accounted for the potential discriminatory value of numerous other SNPs reported in the literature. We concluded published O157:H7 SNPs are insufficient for effective epidemiological subtyping. However, the 438 multi-cluster SNPs we identified may provide the additional information required.</p></div

Phylogeny of isolate set using 32 discriminatory SNPs.

<p>This is a phylogeny of all isolates used in the study with the exception of a few positive controls shared by other authors using the panel of 32 discriminatory SNPs. The 10 clusters with insufficient epidemiological resolution have been labeled. These clusters are completely different from the three mentioned by Leopold, <i>et al</i>. AM series isolates were considered epidemiologically sporadic and should have therefore had additional reticulation in this figure. Some grouping of S-series isolates was expected because some outbreaks were represented by multiple isolates.</p