65 research outputs found
Draft genome sequences of 64 type strains of 50 species and 25 subspecies of the genus Staphylococcus Rosenbach 1884
Members of the genus Staphylococcus have been isolated from humans, animals, and the environment. Accurate identification with whole-genome sequencing requires access to data derived from type strains. We provide sequence data for type strains of 64 taxa in the genus that at the time of this writing have standing in the nomenclatur
Biofilm formation and cellulose expression by <i>Bordetella avium</i> 197N, the causative agent of bordetellosis in birds and an opportunistic respiratory pathogen in humans
Although bacterial cellulose synthase (bcs) operons are widespread within the Proteobacteria phylum, subunits required for the partial-acetylation of the polymer appear to be restricted to a few γ-group soil, plant-associated and phytopathogenic pseudomonads, including Pseudomonas fluorescens SBW25 and several Pseudomonas syringae pathovars. However, a bcs operon with acetylation subunits has also been annotated in the unrelated β-group respiratory pathogen, Bordetella avium 197N. Our comparison of subunit protein sequences and GC content analyses confirms the close similarity between the B. avium 197N and pseudomonad operons and suggests that, in both cases, the cellulose synthase and acetylation subunits were acquired as a single unit. Using static liquid microcosms, we can confirm that B. avium 197N expresses low levels of cellulose in air–liquid interface biofilms and that biofilm strength and attachment levels could be increased by elevating c-di-GMP levels like the pseudomonads, but cellulose was not required for biofilm formation itself. The finding that B. avium 197N is capable of producing cellulose from a highly-conserved, but relatively uncommon bcs operon raises the question of what functional role this modified polymer plays during the infection of the upper respiratory tract or survival between hosts, and what environmental signals control its production
Genomic diversity affects the accuracy of bacterial single-nucleotide polymorphism-calling pipelines
Background: Accurately identifying SNPs from bacterial sequencing data is an essential requirement for using genomics to track transmission and predict important phenotypes such as antimicrobial resistance. However, most previous performance evaluations of SNP calling have been restricted to eukaryotic (human) data. Additionally, bacterial SNP calling requires choosing an appropriate reference genome to align reads to, which, together with the bioinformatic pipeline, affects the accuracy and completeness of a set of SNP calls obtained. This study evaluates the performance of 209 SNP calling pipelines using a combination of simulated data from 254 strains of 10 clinically common bacteria and real data from environmentally-sourced and genomically diverse isolates within the genera Citrobacter, Enterobacter, Escherichia and Klebsiella.
Results: We evaluated the performance of 209 SNP calling pipelines, aligning reads to genomes of the same or a divergent strain. Irrespective of pipeline, a principal determinant of reliable SNP calling was reference genome selection. Across multiple taxa, there was a strong inverse relationship between pipeline sensitivity and precision, and the Mash distance (a proxy for average nucleotide divergence) between reads and reference genome. The effect was especially pronounced for diverse, recombinogenic, bacteria such as Escherichia coli, but less dominant for clonal species such as Mycobacterium tuberculosis.
Conclusions: The accuracy of SNP calling for a given species is compromised by increasing intra-species diversity. When reads were aligned to the same genome from which they were sequenced, among the highest performing pipelines was Novoalign/GATK. By contrast, when reads were aligned to particularly divergent genomes, the highest-performing pipelines often employed the aligners NextGenMap or SMALT, and/or the variant callers LoFreq, mpileup or Strelka
Telmisartan to reduce insulin resistance in HIV-positive individuals on combination antiretroviral therapy: the TAILoR dose-ranging Phase II RCT
BackgroundCombination antiretroviral therapy (cART) is the standard for human immunodeficiency virus (HIV) infection treatment but can result in metabolic abnormalities, such as insulin resistance, dyslipidaemia and lipodystrophy, which can increase the risk of cardiovascular disease.ObjectiveThe objective of the trial was to evaluate whether or not telmisartan, an angiotensin II receptor antagonist and a peroxisome proliferator-activated receptor-γ partial agonist, could reduce insulin resistance in HIV-positive individuals on cART, and affect blood and imaging biomarkers of cardiometabolic disease.DesignA Phase II, multicentre, randomised, open-labelled, dose-ranging trial of telmisartan over a period of 48 weeks with an adaptive design comprising two stages was used to identify the optimal dose of telmisartan. Participants were randomised to receive one of the three doses of telmisartan (20, 40 and 80 mg) or no intervention (control).SettingRecruitment was from 19 HIV specialist centres in the UK.ParticipantsA total of 377 patients infected with HIV who met the prespecified inclusion/exclusion criteria.Interventions20-, 40- and 80-mg tablets of telmisartan.Main outcome measuresThe primary outcome measure was reduction in the homeostatic model assessment of insulin resistance (HOMA-IR), a marker of insulin resistance, at 24 weeks. Secondary outcome measures were changes in plasma lipid profile; Quantitative Insulin Sensitivity Check Index (QUICKI) and revised QUICKI, alternative markers of insulin resistance, plasma adipokines (adiponectin, leptin, interleukin 8, tumour necrosis factor alpha, resistin); high-sensitivity C-reactive protein (hs-CRP); body fat redistribution, as measured by magnetic resonance imaging/proton magnetic resonance spectroscopy; changes in renal markers (albumin-to-creatinine ratio, neutrophil gelatinase-associated lipocalin); and tolerability to telmisartan.ResultsAt the interim analysis, 80 mg of telmisartan was taken forward into the second stage of the study. Baseline characteristics were balanced across treatment arms. There were no differences in HOMA-IR [0.007, standard error (SE) 0.106], QUICKI (0.001, SE 0.001) and revised QUICKI (0.002, SE 0.002) at 24 weeks between the telmisartan (80 mg; n = 106) and non-intervention (n = 105) arms. Longitudinal analysis over 48 weeks showed that there was no change in HOMA-IR, lipid or adipokine levels; however, but there were significant, but marginal, improvements in revised QUICKI [0.004, 95% confidence interval (CI) 0.000 to 0.008] and plasma hs-CRP (–0.222, 95% CI –0.433 to –0.011) over 48 weeks. Substudies also showed a significant reduction in the liver fat content at 24 weeks (1.714, 95% CI –2.787 to –0.642; p = 0.005) and urinary albumin excretion at 48 weeks (–0.665, 95% CI –1.31 to –0.019; p = 0.04). There were no differences in serious adverse events between the telmisartan and control arms.LimitationsThe patients had modest elevations of HOMA-IR at baseline, and our trial could have been under-powered to detect smaller improvements in insulin resistance over time.ConclusionsUsing a novel adaptive design, we demonstrated that there was no significant effect of telmisartan (80 mg) on the primary outcome measure of HOMA-IR and some secondary outcomes (plasma lipids and adipokines). Telmisartan did lead to favourable, and biologically plausible, changes of the secondary longitudinal outcome measures: revised QUICKI, hs-CRP, hepatic fat accumulation and urinary albumin excretion. Taken collectively, our findings showed that telmisartan did not reduce insulin resistance in patients infected with HIV on antiretrovirals.Future workThe mechanistic basis of adipocyte regulation will be studied to allow for development of biomarkers and interventions.Trial registrationCurrent Controlled Trials ISRCTN51069819.FundingThis project was funded by the Efficacy and Mechanism Evaluation (EME) programme, a Medical Research Council and National Institute for Health Research partnership
Accuracy of Different Bioinformatics Methods in Detecting Antibiotic Resistance and Virulence Factors from Staphylococcus aureus Whole-Genome Sequences.
In principle, whole-genome sequencing (WGS) can predict phenotypic resistance directly from a genotype, replacing laboratory-based tests. However, the contribution of different bioinformatics methods to genotype-phenotype discrepancies has not been systematically explored to date. We compared three WGS-based bioinformatics methods (Genefinder [read based], Mykrobe [de Bruijn graph based], and Typewriter [BLAST based]) for predicting the presence/absence of 83 different resistance determinants and virulence genes and overall antimicrobial susceptibility in 1,379 Staphylococcus aureus isolates previously characterized by standard laboratory methods (disc diffusion, broth and/or agar dilution, and PCR). In total, 99.5% (113,830/114,457) of individual resistance-determinant/virulence gene predictions were identical between all three methods, with only 627 (0.5%) discordant predictions, demonstrating high overall agreement (Fleiss' kappa = 0.98, P < 0.0001). Discrepancies when identified were in only one of the three methods for all genes except the cassette recombinase, ccrC(b). The genotypic antimicrobial susceptibility prediction matched the laboratory phenotype in 98.3% (14,224/14,464) of cases (2,720 [18.8%] resistant, 11,504 [79.5%] susceptible). There was greater disagreement between the laboratory phenotypes and the combined genotypic predictions (97 [0.7%] phenotypically susceptible, but all bioinformatic methods reported resistance; 89 [0.6%] phenotypically resistant, but all bioinformatics methods reported susceptible) than within the three bioinformatics methods (54 [0.4%] cases, 16 phenotypically resistant, 38 phenotypically susceptible). However, in 36/54 (67%) cases, the consensus genotype matched the laboratory phenotype. In this study, the choice between these three specific bioinformatic methods to identify resistance determinants or other genes in S. aureus did not prove critical, with all demonstrating high concordance with each other and phenotypic/molecular methods. However, each has some limitations; therefore, consensus methods provide some assurance.This research was supported by the National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Healthcare Associated Infections and Antimicrobial Resistance at Oxford University in partnership with Public Health England ([PHE] grant HPRU-2012-10041) and the NIHR Oxford Biomedical Research Centre; D.C. and T.P. are NIHR senior investigators
Enhanced Determination of Streptococcus pneumoniae Serotypes Associated with Invasive Disease in Laos by Using a Real-Time Polymerase Chain Reaction Serotyping Assay with Cerebrospinal Fluid
A prospective hospital-based study was undertaken to define the incidence of invasive pneumococcal disease (IPD) and circulating serotypes in Laos. Of 10,799 patients with hemocultures and 353 patients with cerebrospinal fluid samples, 0.21% and 5.4%, respectively, were positive for Streptococcus pneumoniae, giving a total of 35 IPD patients. We developed a real-time polymerase chain reaction to detect serotypes represented in the 13-valent pneumococcal vaccine. A blinded evaluation comparing serotype as defined by the Quellung reaction versus the polymerase chain reaction demonstrated 100% concordance. The most frequent serotype (n = 33 patients) was 1 (n = 6), followed by serotypes 5, 6A/B/C, 14, and 23F. Serotypes represented in the 7-valent polysaccharide-protein conjugate vaccine (PCV-7) infected 39% of patients, with 73% coverage for the PCV-10 and PCV-13 vaccines. Although the sample size is small, these data suggest that the PCV-7 vaccine may have relatively low efficacy in Laos. Further studies are urgently needed to guide pneumococcal vaccine policy in Laos
Live Art on Camera : Performance and Photography
"The exhibition Live Art on Camera has evolved from a series of discussions on the subject of performance documentation. These conversations have taken place in artists', photographers' and filmmakers' studios and archives. The impetus was to learn more about the ways in which our reading of seminal performances, through performance documentation, has potentially been influenced through the intentions, ideas, and esthetics of those who recorded the events" -- p. 1
Height and timing of growth spurt during puberty in young people living with vertically acquired HIV in Europe and Thailand.
OBJECTIVE: The aim of this study was to describe growth during puberty in young people with vertically acquired HIV. DESIGN: Pooled data from 12 paediatric HIV cohorts in Europe and Thailand. METHODS: One thousand and ninety-four children initiating a nonnucleoside reverse transcriptase inhibitor or boosted protease inhibitor based regimen aged 1-10 years were included. Super Imposition by Translation And Rotation (SITAR) models described growth from age 8 years using three parameters (average height, timing and shape of the growth spurt), dependent on age and height-for-age z-score (HAZ) (WHO references) at antiretroviral therapy (ART) initiation. Multivariate regression explored characteristics associated with these three parameters. RESULTS: At ART initiation, median age and HAZ was 6.4 [interquartile range (IQR): 2.8, 9.0] years and -1.2 (IQR: -2.3 to -0.2), respectively. Median follow-up was 9.1 (IQR: 6.9, 11.4) years. In girls, older age and lower HAZ at ART initiation were independently associated with a growth spurt which occurred 0.41 (95% confidence interval 0.20-0.62) years later in children starting ART age 6 to 10 years compared with 1 to 2 years and 1.50 (1.21-1.78) years later in those starting with HAZ less than -3 compared with HAZ at least -1. Later growth spurts in girls resulted in continued height growth into later adolescence. In boys starting ART with HAZ less than -1, growth spurts were later in children starting ART in the oldest age group, but for HAZ at least -1, there was no association with age. Girls and boys who initiated ART with HAZ at least -1 maintained a similar height to the WHO reference mean. CONCLUSION: Stunting at ART initiation was associated with later growth spurts in girls. Children with HAZ at least -1 at ART initiation grew in height at the level expected in HIV negative children of a comparable age
Streptococcus pneumoniae Serotype-2 Childhood Meningitis in Bangladesh: A Newly Recognized Pneumococcal Infection Threat
BACKGROUND: Streptococcus pneumoniae is a leading cause of meningitis in countries where pneumococcal conjugate vaccines (PCV) targeting commonly occurring serotypes are not routinely used. However, effectiveness of PCV would be jeopardized by emergence of invasive pneumococcal diseases (IPD) caused by serotypes which are not included in PCV. Systematic hospital based surveillance in Bangladesh was established and progressively improved to determine the pathogens causing childhood sepsis and meningitis. This also provided the foundation for determining the spectrum of serotypes causing IPD. This article reports an unprecedented upsurge of serotype 2, an uncommon pneumococcal serotype, without any known intervention. METHODS AND FINDINGS: Cases with suspected IPD had blood or cerebrospinal fluid (CSF) collected from the beginning of 2001 till 2009. Pneumococcal serotypes were determined by capsular swelling of isolates or PCR of culture-negative CSF specimens. Multicenter national surveillance, expanded from 2004, identified 45,437 patients with suspected bacteremia who were blood cultured and 10,618 suspected meningitis cases who had a lumber puncture. Pneumococcus accounted for 230 culture positive cases of meningitis in children <5 years. Serotype-2 was the leading cause of pneumococcal meningitis, accounting for 20.4% (45/221; 95% CI 15%-26%) of cases. Ninety eight percent (45/46) of these serotype-2 strains were isolated from meningitis cases, yielding the highest serotype-specific odds ratio for meningitis (29.6; 95% CI 3.4-256.3). The serotype-2 strains had three closely related pulsed field gel electrophoresis types. CONCLUSIONS: S. pneumoniae serotype-2 was found to possess an unusually high potential for causing meningitis and was the leading serotype-specific cause of childhood meningitis in Bangladesh over the past decade. Persisting disease occurrence or progressive spread would represent a major potential infection threat since serotype-2 is not included in PCVs currently licensed or under development
Identification of Serotype in Culture Negative Pneumococcal Meningitis Using Sequential Multiplex PCR: Implication for Surveillance and Vaccine Design
BACKGROUND: PCR-based serotyping of Streptococcus pneumoniae has been proposed as a simpler approach than conventional methods, but has not been applied to strains in Asia where serotypes are diverse and different from other part of the world. Furthermore, PCR has not been used to determine serotype distribution in culture-negative meningitis cases. METHODOLOGY: Thirty six serotype-specific primers, 7 newly designed and 29 previously published, were arranged in 7 multiplex PCR sets, each in new hierarchies designed for overall serotype distribution in Bangladesh, and specifically for meningitis and non-meningitis isolates. Culture-negative CSF specimens were then tested directly for serotype-specific sequences using the meningitis-specific set of primers. PCR-based serotyping of 367 strains of 56 known serotypes showed 100% concordance with quellung reaction test. The first 7 multiplex reactions revealed the serotype of 40% of all, and 31% and 48% non-meningitis and meningitis isolates, respectively. By redesigning the multiplex scheme specifically for non-meningitis or meningitis, the quellung reaction of 43% and 48% of respective isolates could be identified. Direct examination of 127 culture-negative CSF specimens, using the meningitis-specific set of primers, yielded serotype for 51 additional cases. CONCLUSIONS: This PCR approach, could improve ascertainment of pneumococcal serotype distributions, especially for meningitis in settings with high prior use of antibiotics
- …