scholarly journals Chromosomal Rearrangements in Salmonella enterica Serovar Typhi Strains Isolated from Asymptomatic Human Carriers

mBio ◽  
2011 ◽  
Vol 2 (3) ◽  
Author(s):  
T. David Matthews ◽  
Wolfgang Rabsch ◽  
Stanley Maloy
Keyword(s):  
Salmonella Enterica ◽  
Large Scale ◽  
Chromosomal Rearrangements ◽  
Growth Conditions ◽  
Genetic Changes ◽  
Content Type ◽  
Long Term Storage ◽  
Bacterial Chromosomes ◽  
Over Time

ABSTRACTHost-specific serovars ofSalmonella entericaoften have large-scale chromosomal rearrangements that occur by recombination betweenrrnoperons. Two hypotheses have been proposed to explain these rearrangements: (i) replichore imbalance from horizontal gene transfer drives the rearrangements to restore balance, or (ii) the rearrangements are a consequence of the host-specific lifestyle. Although recent evidence has refuted the replichore balance hypothesis, there has been no direct evidence for the lifestyle hypothesis. To test this hypothesis, we determined therrnarrangement type for 20Salmonella entericaserovar Typhi strains obtained from human carriers at periodic intervals over multiple years. These strains were also phage typed and analyzed for rearrangements that occurred over long-term storage versus routine culturing. Strains isolated from the same carrier at different time points often exhibited different arrangement types. Furthermore, colonies isolated directly from the Dorset egg slants used to store the strains also had different arrangement types. In contrast, colonies that were repeatedly cultured always had the same arrangement type. Estimated replichore balance of isolated strains did not improve over time, and some of the rearrangements resulted in decreased replicore balance. Our results support the hypothesis that the restricted lifestyle of host-specificSalmonellais responsible for the frequent chromosomal rearrangements in these serovars.IMPORTANCEAlthough it was previously thought that bacterial chromosomes were stable, comparative genomics has demonstrated that bacterial chromosomes are dynamic, undergoing rearrangements that change the order and expression of genes. While mostSalmonellastrains have a conserved chromosomal arrangement type, rearrangements are very common in host-specificSalmonellastrains. This study suggests that chromosome rearrangements in the host-specificSalmonella entericaserovar Typhi, the causal agent of typhoid fever, occur within the human host over time. The results also indicate that rearrangements can occur during long-term maintenance on laboratory medium. Although these genetic changes do not limit survival under slow-growth conditions, they may limit the survival ofSalmonellaTyphi in other environments, as predicted for the role of pseudogenes and genome reduction in niche-restricted bacteria.

scholarly journals Highly Resistant Salmonella enterica Serovar Typhi with a NovelgyrAMutation Raises Questions about the Long-Term Efficacy of Older Fluoroquinolones for Treating Typhoid Fever

2012 ◽  
Vol 56 (5) ◽  
pp. 2761-2762 ◽  
Author(s):  
Kanika Deshpande Koirala ◽  
Duy Pham Thanh ◽  
Sudeep Dhoj Thapa ◽  
Amit Arjyal ◽  
Abhilasha Karkey ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Typhoid Fever ◽  
Treatment Failure ◽  
Salmonella Enterica ◽  
Systemic Infection ◽  
Resistant Isolate ◽  
Content Type ◽  
Salmonella Enterica Serovar Typhi ◽  
Term Efficacy

ABSTRACTAs a consequence of multidrug resistance, clinicians are highly dependent on fluoroquinolones for treating the serious systemic infection typhoid fever. While reduced susceptibility to fluoroquinolones, which lessens clinical efficacy, is becoming ubiquitous, comprehensive resistance is exceptional. Here we report ofloxacin treatment failure in typhoidal patient infected with a novel, highly fluoroquinolone-resistant isolate ofSalmonella entericaserovar Typhi. The isolation of this organism has serious implications for the long-term efficacy of ciprofloxacin and ofloxacin for typhoid treatment.

scholarly journals Lost in migration: document quality for batch conversion to PDF/A

2018 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Roland Erwin Suri ◽  
Mohamed El-Saad
Keyword(s):  
Large Scale ◽  
Software Tool ◽  
Batch Processing ◽  
Digital Archives ◽  
Adobe Acrobat ◽  
Content Type ◽  
Text Document ◽  
File Formats ◽  
Long Term Preservation

PurposeChanges in file format specifications challenge long-term preservation of digital documents. Digital archives thus often focus on specific file formats that are well suited for long-term preservation, such as the PDF/A format. Since only few customers submit PDF/A files, digital archives may consider converting submitted files to the PDF/A format. The paper aims to discuss these issues.Design/methodology/approachThe authors evaluated three software tools for batch conversion of common file formats to PDF/A-1b: LuraTech PDF Compressor, Adobe Acrobat XI Pro and 3-HeightsTMDocument Converter by PDF Tools. The test set consisted of 80 files, with 10 files each of the eight file types JPEG, MS PowerPoint, PDF, PNG, MS Word, MS Excel, MSG and “web page.”FindingsBatch processing was sometimes hindered by stops that required manual interference. Depending on the software tool, three to four of these stops occurred during batch processing of the 80 test files. Furthermore, the conversion tools sometimes failed to produce output files even for supported file formats: three (Adobe Pro) up to seven (LuraTech and 3-HeightsTM) PDF/A-1b files were not produced. Since Adobe Pro does not convert e-mails, a total of 213 PDF/A-1b files were produced. The faithfulness of each conversion was investigated by comparing the visual appearance of the input document with that of the produced PDF/A-1b document on a computer screen. Meticulous visual inspection revealed that the conversion to PDF/A-1b impaired the information content in 24 of the converted 213 files (11 percent). These reproducibility errors included loss of links, loss of other document content (unreadable characters, missing text, document part missing), updated fields (reflecting time and folder of conversion), vector graphics issues and spelling errors.Originality/valueThese results indicate that large-scale batch conversions of heterogeneous files to PDF/A-1b cause complex issues that need to be addressed for each individual file. Even with considerable efforts, some information loss seems unavoidable if large numbers of files from heterogeneous sources are migrated to the PDF/A-1b format.

scholarly journals Rediscovering Zygorhizidium affluens Canter: Molecular Taxonomy, Infectious Cycle, and Cryopreservation of a Chytrid Infecting the Bloom-Forming Diatom Asterionella formosa

2018 ◽  
Vol 84 (23) ◽  
Author(s):  
Cecilia Rad-Menéndez ◽  
Mélanie Gerphagnon ◽  
Andrea Garvetto ◽  
Paola Arce ◽  
Yacine Badis ◽  
...  
Keyword(s):  
Molecular Taxonomy ◽  
Cost Effective ◽  
Trophic Levels ◽  
Content Type ◽  
Long Term Storage ◽  
Asterionella Formosa ◽  
Infectious Cycle ◽  
Cryopreservation Method ◽  
Term Storage

ABSTRACT Parasitic Chytridiomycota (chytrids) are ecologically significant in various aquatic ecosystems, notably through their roles in controlling bloom-forming phytoplankton populations and in facilitating the transfer of nutrients from inedible algae to higher trophic levels. The diversity and study of these obligate parasites, while critical to understand the interactions between pathogens and their hosts in the environment, have been hindered by challenges inherent to their isolation and stable long-term maintenance under laboratory conditions. Here, we isolated an obligate chytrid parasite (CCAP 4086/1) on the freshwater bloom-forming diatom Asterionella formosa and characterized its infectious cycle under controlled conditions. Phylogenetic analyses based on 18S, 5.8S, and 28S ribosomal DNAs (rDNAs) revealed that this strain belongs to the recently described clade SW-I within the Lobulomycetales. All morphological features observed agree with the description of the known Asterionella parasite Zygorhizidium affluens Canter. We thus provide a phylogenetic placement for this chytrid and present a robust and simple assay that assesses both the infection success and the viability of the host. We also validate a cryopreservation method for stable and cost-effective long-term storage and demonstrate its recovery after thawing. All the above-mentioned tools establish a new gold standard for the isolation and long-term preservation of parasitic aquatic chytrids, thus opening new perspectives to investigate the diversity of these organisms and their physiology in a controlled laboratory environment. IMPORTANCE Despite their ecological relevance, parasitic aquatic chytrids are understudied, especially due to the challenges associated with their isolation and maintenance in culture. Here we isolated and established a culture of a chytrid parasite infecting the bloom-forming freshwater diatom Asterionella formosa. The chytrid morphology suggests that it corresponds to the Asterionella parasite known as Zygorhizidium affluens. The phylogenetic reconstruction in the present study supports the hypothesis that our Z. affluens isolate belongs to the order Lobulomycetales and clusters within the novel clade SW-I. We also validate a cryopreservation method for stable and cost-effective long-term storage of parasitic chytrids of phytoplankton. The establishment of a monoclonal pathosystem in culture and its successful cryopreservation opens the way to further investigate this ecologically relevant parasitic interaction.

Early impact of Covid-19 on private sector employees finance homeownership in Kingdom of Saudia Arabia

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Raed Khamis Alharbi
Keyword(s):  
Private Sector ◽  
Large Scale ◽  
Housing Finance ◽  
Policy Framework ◽  
Content Type ◽  
Financial Uncertainty ◽  
Key Stakeholders ◽  
Negative Impacts ◽  
Future Policy

Purpose For almost two years, the economic shocks and financial uncertainty created by the Covid-19 pandemic have affected all sectors. The private sector employees may be the worst hit. This is because of the lockdown across many countries, including the Kingdom of Saudi Arabia (KSA), leading to income irregularities. Studies exploring private-sector employees concerning housing finance for the houses purchased and how the lockdown has affected their sources of income for repayment plans are scarce. Therefore, this study aims to investigate the possible early negative impacts of Covid-19 on private sector employees’ housing finance homeownership in KSA. Design/methodology/approach A phenomenology type of qualitative research was used. Data were sourced from three cities (Riyadh, Al-Qassim and Medina) and three mortgage banks across KSA. Virtual interviews via Zoom and WhatsApp video calls were conducted with engaged participants (bankers, government agencies and private sector employees). Thematic analysis was adopted, and the analysed data was presented in themes. Findings Findings show that the partial and full lockdown resulted in income irregularities in many private businesses. Also, findings identified downsizing, leading to large-scale unemployment, half-monthly income for employees, loss of profit, human resources wastage, etc. Findings reveal that because of the economic shock, many homeowners have not been able to meet up with their monthly mortgage repayment obligation. Also, the absence of financial support in form of socioeconomic needs has not helped the matter. Research limitations/implications The paper is limited to the early negative impacts of Covid-19 on private sector employees’ housing finance homeownership in KSA and data collected via Zoom and WhatsApp video calls across the three main cities. The recommendations that will emerge from this study may be adopted by other Gulf and Islamic countries with similar homeownership repayment challenges. Practical implications This study would stir key stakeholders, especially the policymakers and mortgage institutions to consider future policy principles that focus on who is at the highest risk for housing-related hardships because of the Covid-19 or future pandemic. The outcome can be used to develop an equitable housing policy framework to foster long-term economic mobility and be validated in the future by scholars. Originality/value Similar research in this area is limited, which makes this study one of the pioneering attempts to investigate the early negative impacts of Covid-19 on private sector employees’ housing finance homeownership in KSA. The paper sheds light on the emerged early negative impacts and proffer feasible possible solutions to promote homeownership amongst Saudi citizens.

Activity networks and the temporality of urban space: the case of a cul-de-sac square

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ahlam Ammar Sharif
Keyword(s):  
Urban Space ◽  
Actor Network Theory ◽  
Ethnographic Study ◽  
Urban Change ◽  
Content Type ◽  
Activity Networks ◽  
Nuanced Understanding ◽  
The Stability ◽  
Over Time

PurposeThis study draws on recent actor-network theory (ANT) literature to provide a nuanced understanding of the effect of time on activity networks in urban spaces. It investigates the role of time in multiplying these networks and producing urban change, which is limited in similar ANT-related research.Design/methodology/approachThis ethnographic study of a cul-de-sac square within a housing project in the suburb of Dahiyat Al-Hussein in Amman, Jordan, documents the changes in its activity networks when comparing the 1990s with 2019. Data were collected through interviews and site observations covering the two time periods to investigate the different activities that occurred constantly over time, which reflect the temporal network stabilisation within the square.FindingsThe findings demonstrate the profound effect time has on the stability of activity networks related to playing, observing, walking, vending and their interrelations. Their overlaps and conflicts with each other and with other networks in the space were observed. Unpacking the stability of activity networks and their interrelations demonstrates the change in their actor relations and temporalities over time. This is significant in understanding urban change.Originality/valueThe study investigates the importance of time in recognising and extending the multiplicity of urban activities, which suggests new ways of understanding urban change. This exploration highlights new possibilities for creating more adaptable spaces according to residents' long-term needs.

scholarly journals O7C.2 Developing a measuring strategy for monitoring and evaluation of a national occupational health intervention programme in great britain (GB)

2019 ◽  
Vol 76 (Suppl 1) ◽  
pp. A64.3-A65
Author(s):  
Yiqun Chen ◽  
Andrew Curran
Keyword(s):  
Occupational Health ◽  
Large Scale ◽  
National Level ◽  
Health And Safety ◽  
Monitoring And Evaluation ◽  
Work Related ◽  
Measurement Framework ◽  
Wide Range ◽  
Over Time

The Health and Safety Executive (HSE) is the GB regulator for health and safety at work. The HSE Health and Work (H&W) program designs and carries out a wide range of interventions; including inspection, enforcement and other regulatory activities as well as prevention; targeting priority health conditions in high-risk sectors. It is anticipated that long-term, sustainable and coordinated actions developed as part of the program will over time improve awareness, behaviors, control of exposures, and, as a result, prevent work-related ill health in GB workforce.An HSE Measuring Strategy, together with measurement framework and principles, has been developed. The measurement framework draws together data systems, covering Attitudes (A), Behaviors (B), Control of exposures (C), and Disease and work-related ill health reduction (D), based on a simple model to provide evidence required for evaluating the short, medium and long term impacts of the large scale and complex H&W program on the GB health and safety system. The Strategy gives a new focus on measuring behavioral changes and risk reductions; and emphasizes longitudinal measurement designs to assess progress over time.For developing the Strategy, workshops were organized to bring stakeholders across HSE to review existing systems for conducting population surveys, collecting exposure intelligence and occupational health surveillance, which have contributed to forming a long-term vision of fit-for-purpose measurement systems.We will present the development of the Strategy and the plans to implement it with the H&W program, which requires close collaborations between epidemiologists and social researchers, policy makers, and other multidisciplinary regulatory specialists. The lessons learnt will help HSE towards building the right evidence base for monitoring and evaluation of a range of national level intervention programs for work-related ill health prevention.©British Crown copyright (2019)

scholarly journals Maintaining business relationships: resilience through institutional work

2019 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ilkka Tapani Ojansivu ◽  
Jan Hermes
Keyword(s):  
Relationship Maintenance ◽  
Historical Case Study ◽  
Business Relationships ◽  
Business Relationship ◽  
Historical Case ◽  
Content Type ◽  
Codes Of Practice ◽  
The Relationship ◽  
Over Time

Purpose Business relationships are considered long-term and stable. Furthermore, over time, business relationships are expected to become and remain “institutionalized”. The undertone is that this process is deterministic and inevitable. While the authors do not question the long-term nature of business relationships, they argue that the process of “institutionalization” requires more construct clarity. Consequently, they ask the following: What is the source of resilience in business relationships, and how are these relationships maintained over time? Design/methodology/approach To unravel these questions, the authors conducted an historical case study of a business relationship between a government buyer and a software seller extending over two decades. Findings The authors found that while the network around the business relationship is crumbling and all odds are in favor of relationship dissolution, the active maintenance work of key individuals in the relationship prevented detrimental effects and resulted in not only its continuation but also an increased degree of institutionalization. Research limitations/implications The authors contribute to the Industrial Network approach (INA) by providing a non-deterministic approach to the typically taken-for-granted end phase of business relationships. Practical implications The findings illustrate that the process of institutionalization is manageable but requires hard work, highlighting managers as the principle vehicle of relationship maintenance. Originality/value The authors provide construct clarity around the process of “institutionalization”. In fact, they regard the process as reverse compared to the early interpretation in the INA literature in which a business relationship is assumed to start as a “clean slate” and then begins to represent the industry codes of practice over time. They found that “institutionalization” implies that a business relationship is no longer compared with nor is comparable to the institutional prescriptions; in contrast, the relationship has established its own rules and norms, which have been taken for granted by the buyer and seller organization.

Exhibition destination attractiveness – organizers' and visitors’ perspectives

2016 ◽  
Vol 28 (12) ◽  
pp. 2795-2819 ◽  
Author(s):  
Xin Jin ◽  
Karin Weber
Keyword(s):  
Large Scale ◽  
Holistic View ◽  
Content Type ◽  
Key Stakeholders ◽  
Destination Attractiveness ◽  
Practical Guidelines ◽  
Second Tier ◽  
Business Events ◽  
Business To Business

Purpose The purpose of this study was to provide a holistic view of exhibition destination attractiveness by examining perceptions of two of the three key stakeholders (exhibition organizers and visitors) and contrasting them with those of exhibitors. Design/methodology/approach This research used a mixed method approach, collecting 535 responses from visitors attending nine business-to-business exhibitions in four major cities in China via structured surveys. In addition, eight in-depth interviews with CEOs/owners of leading global and Chinese exhibition companies were conducted. Findings The findings revealed that exhibitors may go almost anywhere where there is potential for successful business. In contrast, visitors prefer exhibition destinations with good accessibility to minimize travel time and an attractive leisure environment that offers a degree of enjoyment in addition to taking care of business. A destination’s “economic environment” and “cluster effects” were comparatively less important to them. Organizers were cognizant of these differences, contributing to their reluctance in taking large-scale, branded exhibitions to second-tier destinations, despite considerable efforts by these cities to improve their infrastructure. Practical implications This study offers practical guidelines for destination administrators and exhibition organizers with regard to evaluating destination resources for long-term exhibition development. Originality/value In contrast to prior studies, this research identifies significant differences in perceptions of exhibition destination attractiveness among all three key industry stakeholders. It also presents a persuasive case for the need to clearly differentiate between the attractiveness of a destination for attracting/hosting exhibitions versus conventions, rather than approaching the subject from a more generic meetings, incentives, conferences, and exhibitions (MICE) segment/business events perspective.

scholarly journals Population Dynamics of Salmonella enterica within Beef Cattle Cohorts Followed from Single-Dose Metaphylactic Antibiotic Treatment until Slaughter

2019 ◽  
Vol 85 (23) ◽  
Author(s):  
Gizem Levent ◽  
Ashlynn Schlochtermeier ◽  
Samuel E. Ives ◽  
Keri N. Norman ◽  
Sara D. Lawhon ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Single Dose ◽  
Lymph Node ◽  
Beef Cattle ◽  
Salmonella Enterica ◽  
Antibiotic Use ◽  
Feeding Period ◽  
Long Term Effects ◽  
Content Type

ABSTRACT Antibiotic use in cattle can select for multidrug-resistant Salmonella enterica, which is considered a serious threat by the U.S. Centers for Disease Control and Prevention. A randomized controlled longitudinal field trial was designed to determine the long-term effects of a single dose of ceftiofur or tulathromycin on Salmonella population characteristics in cattle feces and peripheral lymph nodes and on hides. A total of 134 beef cattle from two sources were divided among 12 pens, with cattle in each of the 3-pen blocks receiving a single dose of either ceftiofur or tulathromycin or neither (control) on day 0. Fecal samples were collected before treatment (day 0) and repeatedly following treatment until slaughter (day 99+). Hide and lymph node samples were collected at slaughter age. Salmonella prevalence, phenotypic antimicrobial resistance, serotype, and phylogenetic relationships were examined. Multilevel mixed logistic regression models indicated no significant effects (P ≥ 0.218) of metaphylactic antibiotics on the prevalence of Salmonella across sample types. However, there was a significant time effect observed, with prevalence increasing from spring through the midsummer months (P < 0.0001) in feces. The majority of Salmonella isolates were pansusceptible to a panel of 14 antibiotics both before and after treatment. Highly prevalent Salmonella serotypes were Salmonella enterica serovar Montevideo, Salmonella enterica serovar Anatum, Salmonella enterica serovar Cerro, and Salmonella enterica serovar Lubbock across all sample types. Strong pen and cattle source serotype clustering effects were observed among Salmonella isolates originating from fecal, lymph node, and hide samples; however, the potential role of Salmonella isolates from the pen environment prior to animal placement was not assessed in this study. IMPORTANCE Salmonella is a leading bacterial foodborne pathogen, causing a significant number of human infections and deaths every year in the United States. Macrolides and 3rd-generation cephalosporins play critical roles in the treatment of human salmonellosis. Use of these antibiotics in beef cattle can select for resistant bacteria that may enter the food chain or spread from the farm via manure. There is a lack of longitudinal research concerning the long-term effects of metaphylactic antibiotic administration. Here, we assessed Salmonella population dynamics during the feeding period until slaughter following single-dose antibiotic treatment. We found no long-term effects of antibiotic use early in the cattle-feeding period on Salmonella prevalence and antimicrobial resistance at slaughter. We identified the pens in which cattle were housed as the factor that contributed most to Salmonella serotypes being shared; importantly, the dominant strain in each pen changed repeatedly over the entire feeding period.

scholarly journals SlyA and HilD Counteract H-NS-Mediated Repression on the ssrAB Virulence Operon of Salmonella enterica Serovar Typhimurium and Thus Promote Its Activation by OmpR

2019 ◽  
Vol 201 (8) ◽  
Author(s):  
María M. Banda ◽  
Crispín Zavala-Alvarado ◽  
Deyanira Pérez-Morales ◽  
Víctor H. Bustamante
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Growth Conditions ◽  
The Other ◽  
Regulatory Mechanisms ◽  
Two Component System ◽  
Content Type ◽  
Additive Action ◽  
Serovar Typhimurium ◽  
Bacterial Fitness

ABSTRACT H-NS-mediated repression of acquired genes and the subsequent adaptation of regulatory mechanisms that counteract this repression have played a central role in the Salmonella pathogenicity evolution. The Salmonella pathogenicity island 2 (SPI-2) is an acquired chromosomal region containing genes necessary for Salmonella enterica to colonize and replicate in different niches of hosts. The ssrAB operon, located in SPI-2, encodes the two-component system SsrA-SsrB, which positively controls the expression of the SPI-2 genes but also other many genes located outside SPI-2. Several regulators have been involved in the expression of ssrAB, such as the ancestral regulators SlyA and OmpR, and the acquired regulator HilD. In this study, we show how SlyA, HilD, and OmpR coordinate to induce the expression of ssrAB under different growth conditions. We found that when Salmonella enterica serovar Typhimurium is grown in nutrient-rich lysogeny broth (LB), SlyA and HilD additively counteract H-NS-mediated repression on ssrAB, whereas in N-minimal medium (N-MM), SlyA antagonizes H-NS-mediated repression on ssrAB independently of HilD. Interestingly, our results indicate that OmpR is required for the expression of ssrAB independently of the growth conditions, even in the absence of repression by H-NS. Therefore, our data support two mechanisms adapted for the expression of ssrAB under different growth conditions. One involves the additive action of SlyA and HilD, whereas the other involves SlyA, but not HilD, to counteract H-NS-mediated repression on ssrAB, thus favoring in both cases the activation of ssrAB by OmpR. IMPORTANCE The global regulator H-NS represses the expression of acquired genes and thus avoids possible detrimental effects on bacterial fitness. Regulatory mechanisms are adapted to induce expression of the acquired genes in particular niches to obtain a benefit from the information encoded in the foreign DNA, as for pathogenesis. Here, we show two mechanisms that were integrated for the expression of virulence genes in Salmonella Typhimurium. One involves the additive action of the regulators SlyA and HilD, whereas the other involves SlyA, but not HilD, to counteract H-NS-mediated repression on the ssrAB operon, thus favoring its activation by the OmpR regulator. To our knowledge, this is the first report involving the coordinated action of two regulators to counteract H-NS-mediated repression.

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