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Search Results: 1 - 10 of 214005 matches for " Lee D. Smythe "
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Development of a Multiple-Locus Variable number of tandem repeat Analysis (MLVA) for Leptospira interrogans and its application to Leptospira interrogans serovar Australis isolates from Far North Queensland, Australia
Andrew T Slack, Michael F Dohnt, Meegan L Symonds, Lee D Smythe
Annals of Clinical Microbiology and Antimicrobials , 2005, DOI: 10.1186/1476-0711-4-10
Abstract: In this study we have searched the available genomic sequence of L. interrogans serovar Copenhageni strain Fiocruz L1-130 for the presence of tandem repeats [1]. These repeats were evaluated against reference strains for diversity. Six loci were selected to create a Multiple Locus Variable Number of Tandem Repeats (VNTR) Analysis (MLVA) to explore the genetic diversity within L. interrogans serovar Australis clinical isolates from Far North Queensland.The 39 reference strains used for the development of the method displayed 39 distinct patterns. Diversity Indexes for the loci varied between 0.80 and 0.93 and the number of repeat units at each locus varied between less than one to 52 repeats. When the MLVA was applied to serovar Australis isolates three large clusters were distinguishable, each comprising various hosts including Rattus species, human and canines.The MLVA described in this report, was easy to perform, analyse and was reproducible. The loci selected had high diversity allowing discrimination between serovars and also between strains within a serovar. This method provides a starting point on which improvements to the method and comparisons to other techniques can be made.Leptospirosis, is the zoonotic disease caused by the spirochete Leptospira. Leptospirosis is characterised either as a febrile illness with sudden onset, or a 'flu like' illness. Patients present with chills, headaches, myalgia, and abdominal pain. In addition, patients may present with renal and pulmonary complications. It is considered an emerging infectious disease with large documented outbreaks occurring world-wide [2]. The majority of isolates detected in Queensland, Australia belong to the genomospecies, L. interrogans, with the dominant serovars being Zanoni or Australis. Typically Leptospirosis infections in Queensland are a result of occupational exposure with the majority of cases occurring in farming or animal based industries [3].The genus Leptospira contains 17 genomospeci
Emergence of new leptospiral serovars in American Samoa - ascertainment or ecological change?
Colleen L Lau, Chris Skelly, Lee D Smythe, Scott B Craig, Philip Weinstein
BMC Infectious Diseases , 2012, DOI: 10.1186/1471-2334-12-19
Abstract: Serovar epidemiology from our leptospirosis seroprevalence study in 2010 was compared to findings from a study in 2004. The variation in geographic distribution of the three most common serovars was explored by mapping sero-positive participants to their place of residence using geographic information systems. The relationship between serovar distribution and ecological zones was examined using geo-referenced data on vegetation type and population distribution.Human leptospirosis seroprevalence in American Samoa was 15.5% in 2010, with serological evidence that infection was caused by three predominant serovars (Hebdomadis, LT 751, and LT 1163). These serovars differed from those identified in an earlier study in 2004, and were not previously known to occur in American Samoa. In 2010, serovars also differed in geographic distribution, with variations in seroprevalence between islands and different ecological zones within the main island.Our findings might indicate artefactual emergence (where serovars were long established but previously undetected), but we believe the evidence is more in favour of true emergence (a result of ecological change). Possibilities include changes in interactions between humans and the environment; introduction of serovars through transport of animals; evolution in distribution and/or abundance of animal reservoirs; and environmental changes that favour transmission of particular serovars.Future research should explore the impact of ecological change on leptospirosis transmission dynamics and serovar emergence, and investigate how such new knowledge might better target environmental monitoring for disease control at a public health level.Leptospirosis is the most common bacterial zoonosis in the world, cause by bacteria belonging to the phylum Spirochaetes and genus Leptospira [1,2]. Mammals serve as reservoir hosts for leptospires and maintain enzootic transmission cycles within and between animal species. Leptospires have been isolated
Identification of pathogenic Leptospira species by conventional or real-time PCR and sequencing of the DNA gyrase subunit B encoding gene
Andrew T Slack, Meegan L Symonds, Michael F Dohnt, Lee D Smythe
BMC Microbiology , 2006, DOI: 10.1186/1471-2180-6-95
Abstract: A conventional and real-time PCR methodology was developed and optimised for the amplification of the gyrB from pathogenic Leptospira species. Non pathogenic and opportunistic Leptospira species such as L. fainei and L. broomi were not amplified. The gyrB gene shows greater nucleotide divergence (3.5% to 16.1%) than the 16s rRNA gene (0.1% to 1.4%). Minimum evolution analysis reveals that the gyrB has a different evolution topology for L. kirschneri and L. interrogans. When the two genes were compared for the identification of the 50 unknown isolates there was 100% agreement in the results.This research has successfully developed a methodology for the identification of pathogenic Leptospira using an alternate gene to 16s rRNA. The gyrB encoding gene shows higher nucleotide/evolutionary divergence allowing for superior identification and also the potential for the development of DNA probe based identification.Leptospirosis is the zoonotic disease caused by members of the genus, Leptospira. They are motile helical spirochaetes that metabolise long chain fatty acids as their carbon source. There are 17 species of Leptospira as determined by DNA-DNA hybridisation [1-4]. These species can be further divided into pathogenic, non-pathogenic and opportunistic/possibly pathogenic Leptospira with pathogenic species. The pathogenic Leptospira include; L. interrogans, L. kirschneri, L. santarosai, L. weilii, L. alexanderi, L. borgpetersenii, L. genomospecies 1 and L. noguchii. The non pathogenic Leptospira include: L. biflexa, L. meyeri, L. wolbachii, L. genomospecies 3, L. genomospecies 4, L. genomospecies 5 and opportunistic/intermediate pathogens Leptospira include L. broomi, L. fainei and L. inadai [3]. The grouping of the last three species as opportunistic or possible pathogens is due to the lack of information on the pathogenicity of the species, different phenotypic characteristics compared to the pathogenic Leptospira and also the limited number of reports of these spe
Simulation and Millennials—The Perfect Storm  [PDF]
Gwen D. Erlam, Liz Smythe, Valerie Wright
Open Journal of Nursing (OJN) , 2016, DOI: 10.4236/ojn.2016.69071
Abstract: Simulation in its various forms has developed extensively over the past 15 - 20 years for use in undergraduate nursing programs. The widespread integration of technology-based educational tools into nursing curricula is raising concerns that technology rather than sound philosophically-based pedagogy is informing nursing education. Some believe that educational soundness has been overtaken by a focus on technological prowess. The manikins used in this immersive classroom often breathe, blink, and even speak in response to lecturer-controlled commands. This research explores how Millennials as a generational cohort (18 - 30 years of age) interface with the teaching/learning platform of simulation. This action research study is unfolded in three distinct action cycles involving 161 undergraduate nursing students. Millennial characteristics of confidence, high achievement, team orientation, technology focus, feedback-saturated, and trophy-seeking traits make them especially adept in immersive simulation environment. If supported by appropriate philosophical underpinnings, simulation as a teaching/learning platform has the potential to become the preferred classroom for Millennial nursing students.
Leptospirosis in American Samoa – Estimating and Mapping Risk Using Environmental Data
Colleen L. Lau ,Archie C. A. Clements,Chris Skelly,Annette J. Dobson,Lee D. Smythe,Philip Weinstein
PLOS Neglected Tropical Diseases , 2012, DOI: 10.1371/journal.pntd.0001669
Abstract: Background The recent emergence of leptospirosis has been linked to many environmental drivers of disease transmission. Accurate epidemiological data are lacking because of under-diagnosis, poor laboratory capacity, and inadequate surveillance. Predictive risk maps have been produced for many diseases to identify high-risk areas for infection and guide allocation of public health resources, and are particularly useful where disease surveillance is poor. To date, no predictive risk maps have been produced for leptospirosis. The objectives of this study were to estimate leptospirosis seroprevalence at geographic locations based on environmental factors, produce a predictive disease risk map for American Samoa, and assess the accuracy of the maps in predicting infection risk. Methodology and Principal Findings Data on seroprevalence and risk factors were obtained from a recent study of leptospirosis in American Samoa. Data on environmental variables were obtained from local sources, and included rainfall, altitude, vegetation, soil type, and location of backyard piggeries. Multivariable logistic regression was performed to investigate associations between seropositivity and risk factors. Using the multivariable models, seroprevalence at geographic locations was predicted based on environmental variables. Goodness of fit of models was measured using area under the curve of the receiver operating characteristic, and the percentage of cases correctly classified as seropositive. Environmental predictors of seroprevalence included living below median altitude of a village, in agricultural areas, on clay soil, and higher density of piggeries above the house. Models had acceptable goodness of fit, and correctly classified ~84% of cases. Conclusions and Significance Environmental variables could be used to identify high-risk areas for leptospirosis. Environmental monitoring could potentially be a valuable strategy for leptospirosis control, and allow us to move from disease surveillance to environmental health hazard surveillance as a more cost-effective tool for directing public health interventions.
Simulation Is Not a Pedagogy  [PDF]
Gwen D. Erlam, Liz Smythe, Valerie Wright-St Clair
Open Journal of Nursing (OJN) , 2017, DOI: 10.4236/ojn.2017.77059
Abstract: Simulation as a teaching/learning tool has evolved at an unprecedented pace which some believe has occurred despite a lack of research into pedagogies appropriate to guide this technology-based learning tool. There seems to be some confusion as to what simulation actually is. Some have called simulation a pedagogy, which is incorrect. Simulation is not a pedagogy, but an immersive teaching/learning platform which is a representation of a functioning system or process. Simulation has been used in undergraduate nursing education in a focused manner for nearly 20 years. Its effectiveness in improving clinical reasoning and critical thinking is not certain if overall instructional design principles do not reflect suitable philosophical paradigms. Simulation as a teaching/learning platform is maximized when instructional design includes the inspiration of behaviorism, cognitivism, and constructivism. Behaviorist design principles include rote learning, repetition, modular learning, stimulus-response, and conditioning. Cognitivist design principles include observational techniques, bootstrapping, and equilibration in the form of assimilation and accommodation. Constructivist design principles include new habit formation through experience and interaction with a “mature social medium” in the form of a simulation facilitator. All of these philosophical underpinnings have the potential to maximize simulation when used as underpinnings in the overall design.
Diagnostic Accuracy of Real-Time PCR Assays Targeting 16S rRNA and lipl32 Genes for Human Leptospirosis in Thailand: A Case-Control Study
Janjira Thaipadunpanit,Wirongrong Chierakul,Vanaporn Wuthiekanun,Direk Limmathurotsakul,Premjit Amornchai,Siriphan Boonslip,Lee D. Smythe,Roongrueng Limpaiboon,Alex R. Hoffmaster,Nicholas P. J. Day,Sharon J. Peacock
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0016236
Abstract: Rapid PCR-based tests for the diagnosis of leptospirosis can provide information that contributes towards early patient management, but these have not been adopted in Thailand. Here, we compare the diagnostic sensitivity and specificity of two real-time PCR assays targeting rrs or lipL32 for the diagnosis of leptospirosis in northeast Thailand.
A quantitative PCR (TaqMan) assay for pathogenic Leptospira spp
Lee D Smythe, Ina L Smith, Greg A Smith, Michael F Dohnt, Meegan L Symonds, Leonie J Barnett, David B McKay
BMC Infectious Diseases , 2002, DOI: 10.1186/1471-2334-2-13
Abstract: The polymerase chain reaction (PCR) has been used to detect a large number of microorganisms, including those of clinical significance. The sensitivity of PCR often precludes the need for isolation and culture, thus making it ideal for the rapid detection of organisms involved in acute infections. We employed real-time (quantitative) PCR using TaqMan chemistry to detect leptospires in clinical and environmental samples.The PCR assay can be applied to either blood or urine samples and does not rely on the isolation and culture of the organism. Capability exists for automation and high throughput testing in a clinical laboratory. It is specific for Leptospira and may discriminate pathogenic and non-pathogenic species. The limit of detection is as low as two cells.Leptospirosis is an emerging infectious disease [1]. Leptospira spp. are endemic to feral and domestic animals that may serve as reservoirs, with rats and rodents recognised as the most important sources [2,3]. Human infections result from contact with contaminated soil, vegetation or water, or with the body fluids of infected animals. The genus Leptospira comprises both pathogenic and non-pathogenic species: L. interrogans, L. borgpetersenii, L. weilii, L. noguchii, L. meyeri, L. fainei, L. alexanderi, L. santarosai, L. kirschneri, L. inadai; L. biflexa, and L. wolbachii[1]. There is some controversy about the classification or pathogenicity of some members within species such as L. meyeri and L. inadai[2,4,5].The differential diagnosis of leptospirosis is difficult due to the varied and often "flu like" symptoms which may result in a missed or delayed diagnosis [6]. For example, patients presenting with severe fever and haemorrhage have symptoms which are difficult to distinguish from viral haemorrhagic fever [7].There are over 230 known serovars in the genus Leptospira[2]. Confirmatory serological diagnosis of leptospirosis is usually made using the microscopic agglutination test (MAT) which is able to det
A Dominant Clone of Leptospira interrogans Associated with an Outbreak of Human Leptospirosis in Thailand
Janjira Thaipadungpanit,Vanaporn Wuthiekanun,Wirongrong Chierakul,Lee D. Smythe,Wimol Petkanchanapong,Roongrueng Limpaiboon,Apichat Apiwatanaporn,Andrew T. Slack,Yupin Suputtamongkol,Nicholas J. White,Edward J. Feil,Nicholas P. J. Day,Sharon J. Peacock
PLOS Neglected Tropical Diseases , 2007, DOI: 10.1371/journal.pntd.0000056
Abstract: Background A sustained outbreak of leptospirosis occurred in northeast Thailand between 1999 and 2003, the basis for which was unknown. Methods and Findings A prospective study was conducted between 2000 and 2005 to identify patients with leptospirosis presenting to Udon Thani Hospital in northeast Thailand, and to isolate the causative organisms from blood. A multilocus sequence typing scheme was developed to genotype these pathogenic Leptospira. Additional typing was performed for Leptospira isolated from human cases in other Thai provinces over the same period, and from rodents captured in the northeast during 2004. Sequence types (STs) were compared with those of Leptospira drawn from a reference collection. Twelve STs were identified among 101 isolates from patients in Udon Thani. One of these (ST34) accounted for 77 (76%) of isolates. ST34 was Leptospira interrogans, serovar Autumnalis. 86% of human Leptospira isolates from Udon Thani corresponded to ST34 in 2000/2001, but this figure fell to 56% by 2005 as the outbreak waned (p = 0.01). ST34 represented 17/24 (71%) of human isolates from other Thai provinces, and 7/8 (88%) rodent isolates. By contrast, 59 STs were found among 76 reference strains, indicating a much more diverse population genetic structure; ST34 was not identified in this collection. Conclusions Development of an MLST scheme for Leptospira interrogans revealed that a single ecologically successful pathogenic clone of L. interrogans predominated in the rodent population, and was associated with a sustained outbreak of human leptospirosis in Thailand.
Comparison of Two Multilocus Sequence Based Genotyping Schemes for Leptospira Species
Ahmed Ahmed equal contributor ,Janjira Thaipadungpanit equal contributor,Siriphan Boonsilp,Vanaporn Wuthiekanun,Kishore Nalam,Brian G. Spratt,David M. Aanensen,Lee D. Smythe,Niyaz Ahmed,Edward J. Feil,Rudy A. Hartskeerl,Sharon J. Peacock
PLOS Neglected Tropical Diseases , 2011, DOI: 10.1371/journal.pntd.0001374
Abstract: Background Several sequence based genotyping schemes have been developed for Leptospira spp. The objective of this study was to genotype a collection of clinical and reference isolates using the two most commonly used schemes and compare and contrast the results. Methods and Findings A total of 48 isolates consisting of L. interrogans (n = 40) and L. kirschneri (n = 8) were typed by the 7 locus MLST scheme described by Thaipadungpanit et al., and the 6 locus genotyping scheme described by Ahmed et al., (termed 7L and 6L, respectively). Two L. interrogans isolates were not typed using 6L because of a deletion of three nucleotides in lipL32. The remaining 46 isolates were resolved into 21 sequence types (STs) by 7L, and 30 genotypes by 6L. Overall nucleotide diversity (based on concatenated sequence) was 3.6% and 2.3% for 7L and 6L, respectively. The D value (discriminatory ability) of 7L and 6L were comparable, i.e. 92.0 (95% CI 87.5–96.5) vs. 93.5 (95% CI 88.6–98.4). The dN/dS ratios calculated for each locus indicated that none were under positive selection. Neighbor joining trees were reconstructed based on the concatenated sequences for each scheme. Both trees showed two distinct groups corresponding to L. interrogans and L. kirschneri, and both identified two clones containing 10 and 7 clinical isolates, respectively. There were six instances in which 6L split single STs as defined by 7L into closely related clusters. We noted two discrepancies between the trees in which the genetic relatedness between two pairs of strains were more closely related by 7L than by 6L. Conclusions This genetic analysis indicates that the two schemes are comparable. We discuss their practical advantages and disadvantages.
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