RESUMO
Topics associated with the chemical sciences form a significant part of the curriculum in science at the primary school level in the U.K. In this methodology paper, we demonstrate how a wide range of research articles associated with the chemical sciences can be disseminated to an elementary school audience and how children can carry out investigations associated with cutting-edge research in the classroom. We discuss how the Primary Science Teaching Trust's (PSTT's) "I bet you did not know" (IBYDK) articles and their accompanying Teacher Guides benefit children, primary (elementary) school teachers, and other stakeholders including the researchers themselves. We define three types of research articles; ones describing how children can reproduce the research themselves without much adaptation, others where children can mirror the research using similar methods, and some where an analogy can be used to explain the research. We provide exemplars of each type and some preliminary feedback on articles written.
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Climate change is of great concern to all age groups but in particular to children. "Simple" climate models have been in place for a long time and can be used effectively with post-16 students. For younger children, modifications are required, and we describe in this paper the development and use of two such models. The first (the Granny Model) is a pictorial version of the model that has been used extensively with primary and early secondary school aged children (14 and younger). The second is an online version of the simple climate model that can be used without recourse to the underpinning mathematics and science but allows children to experiment with changing variables and how these changes affect the average surface temperature of the Earth.
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All learners have a contribution to make to the development of the Chemical Sciences, be that in novel ways to teach, and their perspectives and contexts, but also in research, both in chemical education and the wider Chemical Sciences. Through four case studies, this paper explores interactions with diverse groups and how this has altered perspectives on both teaching and research. The case studies include work with visually impaired adults, a project bringing together First Peoples in Australia with academics to explore old ways (traditional science) and new ways (modern approaches), primary (elementary) school perspectives on teaching science, and a project in South Africa to connect university and township communities. Not only do these case studies demonstrate the immense value these diverse groups bring to our understanding about how to learn, but they also bring new perspectives on how to view and solve chemical problems.
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Legionella pneumophila is an environmental bacterium and the causative agent of Legionnaires' disease. Previous genomic studies have shown that recombination accounts for a high proportion (>96%) of diversity within several major disease-associated sequence types (STs) of L. pneumophila. This suggests that recombination represents a potentially important force shaping adaptation and virulence. Despite this, little is known about the biological effects of recombination in L. pneumophila, particularly with regards to homologous recombination (whereby genes are replaced with alternative allelic variants). Using newly available population genomic data, we have disentangled events arising from homologous and non-homologous recombination in six major disease-associated STs of L. pneumophila (subsp. pneumophila), and subsequently performed a detailed characterisation of the dynamics and impact of homologous recombination. We identified genomic "hotspots" of homologous recombination that include regions containing outer membrane proteins, the lipopolysaccharide (LPS) region and Dot/Icm effectors, which provide interesting clues to the selection pressures faced by L. pneumophila. Inference of the origin of the recombined regions showed that isolates have most frequently imported DNA from isolates belonging to their own clade, but also occasionally from other major clades of the same subspecies. This supports the hypothesis that the possibility for horizontal exchange of new adaptations between major clades of the subspecies may have been a critical factor in the recent emergence of several clinically important STs from diverse genomic backgrounds. However, acquisition of recombined regions from another subspecies, L. pneumophila subsp. fraseri, was rarely observed, suggesting the existence of a recombination barrier and/or the possibility of ongoing speciation between the two subspecies. Finally, we suggest that multi-fragment recombination may occur in L. pneumophila, whereby multiple non-contiguous segments that originate from the same molecule of donor DNA are imported into a recipient genome during a single episode of recombination.
Assuntos
Evolução Molecular , Recombinação Homóloga/genética , Legionella pneumophila/genética , Doença dos Legionários/genética , Proteínas da Membrana Bacteriana Externa/genética , Genoma Bacteriano , Doença dos Legionários/microbiologia , Lipopolissacarídeos/biossíntese , Lipopolissacarídeos/genética , Filogenia , Proteínas Recombinantes/genéticaRESUMO
[This corrects the article DOI: 10.1371/journal.pgen.1006855.].
RESUMO
Legionella pneumophila is an environmental bacterium and the leading cause of Legionnaires' disease. Just five sequence types (ST), from more than 2000 currently described, cause nearly half of disease cases in northwest Europe. Here, we report the sequence and analyses of 364 L. pneumophila genomes, including 337 from the five disease-associated STs and 27 representative of the species diversity. Phylogenetic analyses revealed that the five STs have independent origins within a highly diverse species. The number of de novo mutations is extremely low with maximum pairwise single-nucleotide polymorphisms (SNPs) ranging from 19 (ST47) to 127 (ST1), which suggests emergences within the last century. Isolates sampled geographically far apart differ by only a few SNPs, demonstrating rapid dissemination. These five STs have been recombining recently, leading to a shared pool of allelic variants potentially contributing to their increased disease propensity. The oldest clone, ST1, has spread globally; between 1940 and 2000, four new clones have emerged in Europe, which show long-distance, rapid dispersal. That a large proportion of clinical cases is caused by recently emerged and internationally dispersed clones, linked by convergent evolution, is surprising for an environmental bacterium traditionally considered to be an opportunistic pathogen. To simultaneously explain recent emergence, rapid spread and increased disease association, we hypothesize that these STs have adapted to new man-made environmental niches, which may be linked by human infection and transmission.
Assuntos
Evolução Molecular , Legionella pneumophila/genética , Doença dos Legionários/microbiologia , Humanos , Legionella pneumophila/classificação , Legionella pneumophila/isolamento & purificação , Legionella pneumophila/patogenicidade , Mutação , Filogenia , Polimorfismo de Nucleotídeo Único , Seleção Genética , Virulência/genéticaRESUMO
Background: Legionnaires' disease is an important cause of hospital-acquired pneumonia and is caused by infection with the bacterium Legionella. Because current typing methods often fail to resolve the infection source in possible nosocomial cases, we aimed to determine whether whole-genome sequencing (WGS) could be used to support or refute suspected links between cases and hospitals. We focused on cases involving a major nosocomial-associated strain, L. pneumophila sequence type (ST) 1. Methods: WGS data from 229 L. pneumophila ST1 isolates were analyzed, including 99 isolates from the water systems of 17 hospitals and 42 clinical isolates from patients with confirmed or suspected hospital-acquired infections, as well as isolates obtained from or associated with community-acquired sources of Legionnaires' disease. Results: Phylogenetic analysis demonstrated that all hospitals from which multiple isolates were obtained have been colonized by 1 or more distinct ST1 populations. However, deep sampling of 1 hospital also revealed the existence of substantial diversity and ward-specific microevolution within the population. Across all hospitals, suspected links with cases were supported with WGS, although the degree of support was dependent on the depth of environmental sampling and available contextual information. Finally, phylogeographic analysis revealed that hospitals have been seeded with L. pneumophila via both local and international spread of ST1. Conclusions: WGS can be used to support or refute suspected links between hospitals and Legionnaires' disease cases. However, deep hospital sampling is frequently required due to the potential coexistence of multiple populations, existence of substantial diversity, and similarity of hospital isolates to local populations.
Assuntos
Infecção Hospitalar/epidemiologia , Genômica/métodos , Legionella pneumophila/classificação , Legionella pneumophila/genética , Doença dos Legionários/epidemiologia , Epidemiologia Molecular/métodos , Tipagem Molecular/métodos , Biologia Computacional/métodos , Infecção Hospitalar/microbiologia , Genótipo , Hospitais , Humanos , Legionella pneumophila/isolamento & purificação , Doença dos Legionários/microbiologia , Filogenia , Análise de Sequência de DNA/métodos , Microbiologia da ÁguaRESUMO
Sequence-based typing (SBT), analogous to multilocus sequence typing (MLST), is the current "gold standard" typing method for investigation of legionellosis outbreaks caused by Legionella pneumophila However, as common sequence types (STs) cause many infections, some investigations remain unresolved. In this study, various whole-genome sequencing (WGS)-based methods were evaluated according to published guidelines, including (i) a single nucleotide polymorphism (SNP)-based method, (ii) extended MLST using different numbers of genes, (iii) determination of gene presence or absence, and (iv) a kmer-based method. L. pneumophila serogroup 1 isolates (n = 106) from the standard "typing panel," previously used by the European Society for Clinical Microbiology Study Group on Legionella Infections (ESGLI), were tested together with another 229 isolates. Over 98% of isolates were considered typeable using the SNP- and kmer-based methods. Percentages of isolates with complete extended MLST profiles ranged from 99.1% (50 genes) to 86.8% (1,455 genes), while only 41.5% produced a full profile with the gene presence/absence scheme. Replicates demonstrated that all methods offer 100% reproducibility. Indices of discrimination range from 0.972 (ribosomal MLST) to 0.999 (SNP based), and all values were higher than that achieved with SBT (0.940). Epidemiological concordance is generally inversely related to discriminatory power. We propose that an extended MLST scheme with â¼50 genes provides optimal epidemiological concordance while substantially improving the discrimination offered by SBT and can be used as part of a hierarchical typing scheme that should maintain backwards compatibility and increase discrimination where necessary. This analysis will be useful for the ESGLI to design a scheme that has the potential to become the new gold standard typing method for L. pneumophila.
Assuntos
Genoma Bacteriano , Legionella pneumophila/classificação , Epidemiologia Molecular/métodos , Tipagem Molecular/métodos , Análise de Sequência de DNA , Humanos , Legionella pneumophila/genética , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
Existing pertussis surveillance systems tend to underidentify less severe cases among older children and adults. For routine follow-up of notified, nonconfirmed, clinically diagnosed pertussis cases, use of an oral fluid test was pilot tested in England and Wales during June 2007-August 2009. During that period, 1,852 cases of pertussis were confirmed by established laboratory methods and another 591 by oral fluid testing only. Although introduction of serologic testing in 2002 led to the greatest increase in ascertainment of pertussis, oral fluid testing increased laboratory ascertainment by 32% overall; maximal increase (124%) occurred among children 5-9 years of age. Patients whose pertussis was confirmed by oral fluid testing were least likely to be hospitalized, suggesting that milder community cases were being confirmed by this method. Oral fluid testing is an easily administered, noninvasive surveillance tool that could further our understanding of pertussis epidemiology and thereby contribute to decisions on vaccination strategies.
Assuntos
Bordetella pertussis/isolamento & purificação , Vigilância da População , Saliva/microbiologia , Coqueluche/diagnóstico , Adolescente , Bordetella pertussis/imunologia , Criança , Pré-Escolar , Inglaterra/epidemiologia , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Incidência , Lactente , Vacina contra Coqueluche/administração & dosagem , Reação em Cadeia da Polimerase , Vacinação , País de Gales/epidemiologia , Coqueluche/epidemiologia , Coqueluche/imunologia , Coqueluche/prevenção & controleRESUMO
BACKGROUND: To date, all descriptions of legionellosis in neonates have emerged from a small number of isolated case reports in newborns with unusually severe pneumonia. In December 2008, a large outbreak of Legionella infection occurred in term neonates in Cyprus, providing new information on the epidemiological and clinical features of Legionellosis in this age group. METHODS: An environmental investigation was performed at a small private hospital where the infected neonates were delivered. The medical records of the infected neonates were retrospectively reviewed to obtain clinical data on presentation, complications, and course of disease. RESULTS: Nine of the 32 (28%) newborns who were exposed to the contaminated source at the private nursery were infected with Legionella. Six subjects had pulmonary infiltrates, but in 3 cases there were no abnormal radiological findings and clinical presentation was mild. In 4 neonates, pulmonary infiltrates at presentation were bilateral and extensive and 3 died, conferring a mortality rate of 50% in subjects with pulmonary infiltrates and an overall mortality of 33.3%. Legionella pneumophila serogroup 3 was recovered in neonatal biological samples, although in some patients there was implication of a second strain, serogroup 1. It was determined that the neonates were infected while in the nursery at the private hospital by aerosol produced by a recently installed cold-mist humidifier that was filled with contaminated water. CONCLUSIONS: Use of humidifiers in nursery units must be avoided as the risk of disseminating Legionella in neonates is very high. In neonates legionellosis should be suspected when signs of infection first appear and take an unusual course, even when no pulmonary infiltrates appear.
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Infecção Hospitalar/epidemiologia , Surtos de Doenças , Legionella pneumophila/isolamento & purificação , Doença dos Legionários/epidemiologia , Poluição do Ar em Ambientes Fechados , Chipre/epidemiologia , Feminino , Hospitais , Humanos , Recém-Nascido , Masculino , UltrassomRESUMO
BACKGROUND: Legionella pneumophila is an opportunistic pathogen of humans where the source of infection is usually from contaminated man-made water systems. When an outbreak of Legionnaires' disease caused by L. pneumophila occurs, it is necessary to discover the source of infection. A seven allele sequence-based typing scheme (SBT) has been very successful in providing the means to attribute outbreaks of L. pneumophila to a particular source or sources. Particular sequence types described by this scheme are known to exhibit specific phenotypes. For instance some types are seen often in clinical cases but are rarely isolated from the environment and vice versa. Of those causing human disease some types are thought to be more likely to cause more severe disease. It is possible that the genetic basis for these differences are vertically inherited and associated with particular genetic lineages within the population. In order to provide a framework within which to test this hypothesis and others relating to the population biology of L. pneumophila, a set of genomes covering the known diversity of the organism is required. RESULTS: Firstly, this study describes a means to group L. pneumophila strains into pragmatic clusters, using a methodology that takes into consideration the genetic forces operating on the population. These clusters can be used as a standardised nomenclature, so those wishing to describe a group of strains can do so. Secondly, the clusters generated from the first part of the study were used to select strains rationally for whole genome sequencing (WGS). The data generated was used to compare phylogenies derived from SBT and WGS. In general the SBT sequence type (ST) accurately reflects the whole genome-based genotype. Where there are exceptions and recombination has resulted in the ST no longer reflecting the genetic lineage described by the whole genome sequence, the clustering technique employed detects these sequence types as being admixed, indicating their mixed inheritance. CONCLUSIONS: We conclude that SBT is usually a good proxy for the genetic lineage described by the whole genome, and therefore utility of SBT is still suitable until the technology and economics of high throughput sequencing reach the point where routine WGS of L. pneumophila isolates for outbreak investigation is feasible.
Assuntos
Variação Genética , Legionella pneumophila/classificação , Legionella pneumophila/genética , Tipagem Molecular , Análise de Sequência de DNA , DNA Bacteriano/química , DNA Bacteriano/genética , Genoma Bacteriano , Humanos , Epidemiologia Molecular/métodos , Dados de Sequência MolecularRESUMO
Results of an accelerated pertussis vaccination schedule for infants introduced in 1990 in England and Wales were examined. Earlier scheduling and sustained high vaccine coverage resulted in fewer reported cases of pertussis among infants, reinforcing the World Health Organization drive for on-time completion of the infant vaccination schedule. As determined by using the screening method, the first dose of vaccine was 61.7% effective in infants <6 months of age, and effectiveness increased with subsequent doses. Three doses of a good whole-cell pertussis vaccine were 83.7% effective in children 10-16 years of age; a preschool booster vaccination further reduced pertussis incidence in children <10 years of age. As in other industrialized countries, surveillance data during 1998-2009 showed that pertussis in England and Wales mainly persists in young infants (i.e., <3 months of age), teenagers, and adults. Future vaccine program changes may be beneficial, but additional detail is required to inform such decisions.
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Controle de Doenças Transmissíveis/métodos , Vacina contra Coqueluche/imunologia , Coqueluche/epidemiologia , Coqueluche/prevenção & controle , Adolescente , Criança , Pré-Escolar , Controle de Doenças Transmissíveis/história , Inglaterra/epidemiologia , História do Século XX , História do Século XXI , Humanos , Esquemas de Imunização , Imunização Secundária , Lactente , Vacina contra Coqueluche/administração & dosagem , Vigilância da População , Fatores de Tempo , País de Gales/epidemiologia , Coqueluche/mortalidadeRESUMO
Bartonella henselae is one of the most common zoonotic agents acquired from companion animals (cats) in industrialized countries. Nonetheless, although the prevalence of infections in cats is high, the number of human cases reported is relatively low. One hypothesis for this discrepancy is that B. henselae strains vary in their zoonotic potential. To test this hypothesis, we employed structured sampling to explore the population structure of B. henselae in the United Kingdom and to determine the distribution of strains associated with zoonotic disease within this structure. A total of 118 B. henselae strains were delineated into 12 sequence types (STs) using multilocus sequence typing. We observed that most (85%) of the zoonosis-associated strains belonged to only three genotypes, i.e., ST2, ST5, and ST8. Conversely, most (74%) of the feline isolates belonged to ST4, ST6, and ST7. The difference in host association of ST2, ST5, and ST8 (zoonosis associated) and ST6 (feline) was statistically significant (P < 0.05), indicating that a few, uncommon STs were responsible for the majority of symptomatic human infections.
Assuntos
Técnicas de Tipagem Bacteriana , Bartonella henselae/classificação , Bartonella henselae/genética , Doença da Arranhadura de Gato/epidemiologia , Doença da Arranhadura de Gato/microbiologia , Zoonoses/epidemiologia , Zoonoses/microbiologia , Animais , Bartonella henselae/isolamento & purificação , Gatos , Análise por Conglomerados , Genótipo , Humanos , Epidemiologia Molecular , Tipagem de Sequências Multilocus , Reino Unido/epidemiologiaRESUMO
Legionella pneumophila is a ubiquitous inhabitant of environmental water reservoirs. The bacteria infect a wide variety of protozoa and, after accidental inhalation, human alveolar macrophages, which can lead to severe pneumonia. The capability to thrive in phagocytic hosts is dependent on the Dot/Icm type IV secretion system (T4SS), which translocates multiple effector proteins into the host cell. In this study, we determined the draft genome sequence of L. pneumophila strain 130b (Wadsworth). We found that the 130b genome encodes a unique set of T4SSs, namely, the Dot/Icm T4SS, a Trb-1-like T4SS, and two Lvh T4SS gene clusters. Sequence analysis substantiated that a core set of 107 Dot/Icm T4SS effectors was conserved among the sequenced L. pneumophila strains Philadelphia-1, Lens, Paris, Corby, Alcoy, and 130b. We also identified new effector candidates and validated the translocation of 10 novel Dot/Icm T4SS effectors that are not present in L. pneumophila strain Philadelphia-1. We examined the prevalence of the new effector genes among 87 environmental and clinical L. pneumophila isolates. Five of the new effectors were identified in 34 to 62% of the isolates, while less than 15% of the strains tested positive for the other five genes. Collectively, our data show that the core set of conserved Dot/Icm T4SS effector proteins is supplemented by a variable repertoire of accessory effectors that may partly account for differences in the virulences and prevalences of particular L. pneumophila strains.
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DNA Bacteriano/química , Genoma Bacteriano , Legionella pneumophila/genética , Proteínas de Membrana Transportadoras/genética , Fatores de Virulência/genética , Sequência Conservada , DNA Bacteriano/genética , Microbiologia Ambiental , Humanos , Legionella pneumophila/isolamento & purificação , Legionella pneumophila/metabolismo , Legionella pneumophila/patogenicidade , Doença dos Legionários/microbiologia , Proteínas de Membrana Transportadoras/metabolismo , Dados de Sequência Molecular , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Fatores de Virulência/metabolismoRESUMO
The diagnosis of severe Streptococcus pneumoniae infection relies heavily on insensitive culture techniques. To improve the usefulness of PCR assays, we developed a dual-PCR protocol (targeted at pneumolysin and autolysin) for EDTA blood samples. This was compared to the Binax NOW S. pneumoniae urine antigen test in patients with bacteremic pneumococcal infections. Patients with nonbacteremic community-acquired pneumonia also were tested by these methods to determine what proportion could be confirmed as pneumococcal infections. A direct comparison was made in a group of patients who each had both tests performed. The Binax NOW S. pneumoniae urine antigen test was positive in 51 of 58 bacteremic pneumococcal cases (sensitivity, 88%; 95% confidence interval [CI], 77 to 95%), whereas the dual PCR was positive in 31 cases (sensitivity, 53.5%; 95% CI, 40 to 67%; P < 0.0001), and all of these had detectable urinary antigens. Both tests gave positive results in 2 of 51 control patients (referred to as other-organism septicemia), giving a specificity of 96% (95% CI, 86.5 to 99.5%). In 77 patients with nonbacteremic community-acquired pneumonia, urinary antigen was detected significantly more often (in 21 patients [27%]) than a positive result by the dual-PCR protocol (6 [8%]) (P = 0.002). The development of a dual-PCR protocol enhanced the sensitivity compared to that of the individual assays, but it is still significantly less sensitive than the Binax NOW urine antigen test, as well as being more time-consuming and expensive. Urinary antigen detection is the nonculture diagnostic method of choice for patients with possible severe pneumococcal infection.
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Antígenos de Bactérias/urina , Bacteriemia/diagnóstico , Infecções Comunitárias Adquiridas/microbiologia , Infecções Pneumocócicas/diagnóstico , Pneumonia Pneumocócica/diagnóstico , Reação em Cadeia da Polimerase/métodos , Streptococcus pneumoniae/isolamento & purificação , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Bacteriemia/microbiologia , Humanos , Pessoa de Meia-Idade , Pneumonia Pneumocócica/microbiologia , Sensibilidade e Especificidade , Adulto JovemRESUMO
As part of an enhanced surveillance programme for pertussis in England and Wales, a real-time PCR service for the detection of Bordetella pertussis was introduced for infants aged Assuntos
Reação em Cadeia da Polimerase
, Coqueluche/diagnóstico
, Coqueluche/epidemiologia
, Adolescente
, Adulto
, Idoso
, Bordetella/isolamento & purificação
, Criança
, Pré-Escolar
, Inglaterra/epidemiologia
, Humanos
, Lactente
, Pessoa de Meia-Idade
, Sensibilidade e Especificidade
, Fatores de Tempo
, País de Gales/epidemiologia
, Adulto Jovem
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The objective of the study was to determine the prevalence of detectable antipertussis antibodies (anti-PT) and recent pertussis infection in a representative sample (n=508) of pregnant women in Catalonia (Spain). Antipertussis (PT) antibodies were determined in cord blood samples using an in-house enzyme-linked immunosorbent assay test. The prevalence of detectable anti-PT levels was 72.8% and the prevalence of recent pertussis infection in mothers (cord blood anti-PT level of > or = 195 EU/mL was 1.8%. The (P<0.05) and the prevalence of recent pertussis infection decreased with maternal age (P< 0.01). Results obtained in this study show that it might be necessary to develop a pertussis vaccination program using acellular pertussis vaccines aimed at pregnant women to reduce the risk of pertussis infection during pregnancy and in neonates.
Assuntos
Anticorpos Antibacterianos/sangue , Bordetella pertussis/imunologia , Sangue Fetal/imunologia , Complicações Infecciosas na Gravidez/epidemiologia , Coqueluche/epidemiologia , Adolescente , Adulto , Distribuição de Qui-Quadrado , Feminino , Humanos , Pessoa de Meia-Idade , Gravidez , Prevalência , Espanha/epidemiologiaRESUMO
Real-time PCR was employed to detect a region of the P1 cytadhesin gene of Mycoplasma pneumoniae in clinical samples. An internal processing control was included that could be co-amplified simultaneously in the same reaction tube. The assay could reproducibly detect 1 x 10(3) M. pneumoniae organisms ml(-1) in clinical samples. There was no amplification of DNA or signal production from 15 other species of human mycoplasmas and 19 other bacterial species. Using a panel of 175 respiratory samples taken from patients with pneumonia of proven aetiology, the sensitivity was found to be 60 % and the specificity of the assay 96.7 % when compared with serology. This assay is suitable for same-day diagnosis of M. pneumoniae infection and batch processing of respiratory samples for clinical screening.
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Mycoplasma pneumoniae/isolamento & purificação , Pneumonia por Mycoplasma/diagnóstico , Reação em Cadeia da Polimerase/métodos , Adesinas Bacterianas/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Primers do DNA , Genes Bacterianos/genética , Humanos , Pessoa de Meia-Idade , Mycoplasma pneumoniae/genética , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Escarro/microbiologiaRESUMO
Bordetella pertussis infection is being increasingly recognized as a cause of prolonged, distressing cough (without whooping symptoms) in children and young adults. Diagnosis of infection in this population is important for treatment and surveillance purposes, and may also prove useful in reducing transmission to unvaccinated babies, for whom disease can be fatal. Serum IgG titres against pertussis toxin (PT) are routinely used as a marker of recent or persisting B. pertussis infection. However, collection of serum from young children is difficult, and compliance amongst these subjects to give samples is low. To circumvent these problems, an IgG-capture ELISA capable of detecting anti-PT IgG in oral fluid was devised. The assay was evaluated by comparison to a serum ELISA, using 187 matched serum and oral fluid samples from children (aged 5-16 years) with a history of prolonged coughing, whose serum anti-PT titre had already been determined (69 seropositive, 118 seronegative). The results showed that, using a cutoff of 70 arbitrary units (AU), the oral fluid assay detected seropositive subjects with a sensitivity of 79.7% [95% confidence interval (CI) 68.3-88.4] and a specificity of 96.6% (95% CI 91.5-99.1). Thus, oral fluid titres of >or=70 AU would possess a positive predictive value of 76.2-93.2% for pertussis amongst children with chronic coughs when used as a surrogate for the serum ELISA (assuming disease prevalence of 12-37%). This oral fluid ELISA will greatly assist in the convenience of B. pertussis disease diagnosis and surveillance.
Assuntos
Anticorpos Antibacterianos/análise , Antitoxinas/análise , Ensaio de Imunoadsorção Enzimática/métodos , Imunoglobulina G/análise , Toxina Pertussis/imunologia , Saliva/imunologia , Coqueluche/diagnóstico , Adolescente , Anticorpos Antibacterianos/sangue , Bordetella pertussis/imunologia , Criança , Pré-Escolar , Humanos , Valor Preditivo dos Testes , Sensibilidade e EspecificidadeRESUMO
Legionella pneumophila is the leading cause of Legionnaires' disease, a severe pneumonia that can occur as sporadic cases or point-source outbreaks affecting multiple patients. The infection is acquired by inhalation of aerosols from contaminated water systems. In order to identify the probable source and prevent further cases, clinical and environmental isolates are compared using phenotypic and genotypic methods. Typically up to 10 days are required to isolate L. pneumophila prior to the application of standard typing protocols. A rapid protocol using a real-time PCR specific for L. pneumophila and serogroup 1, combined with nested direct molecular typing, was adopted by Public Health England in 2012 to reduce reporting time for preliminary typing results. This rapid protocol was first used to investigate an outbreak that occurred in July/August 2012 and due to the positive feedback from that investigation, it was subsequently applied to other incidents in England and Wales where faster typing results would have aided incident investigation. We present here results from seven incidents that occurred between July 2012 and June 2015 where the use of this rapid approach provided preliminary characterization of the infecting strain in an average 1.58 days (SD 1.01) after sample receipt in contrast to 9.53 days (SD 3.73) when standard protocols were applied.