3,057 research outputs found
Carriage of serogroup C meningococci 1 year after meningococcal C conjugate polysaccharide vaccination
No full textThe UK was the first place to Introduce meningococcal serogroup C conjugate (MCC) vaccines. From November, 1999, all people younger than 18 years, about 14 million individuals, were offered MCC immunisation. The uptake rate was more than 70% by November, 2000. We compared the carriage of meningococci in isolates we obtained from 14 064 students aged 15–17 years during vaccination in 1999, with those from 16 583 students of the same age surveyed 1 year later. Carriage of serogroup C meningococci was reduced by 66% (p=0·004). Our results show that MCC vaccines protect against carriage of meningococci that express serogroup C polysaccharide capsules
Diarrhoeagenic Escherichia coli—an emerging problem?
No full textDiarrhea remains one of the main sources of morbidity and morbidity in today's world and a large proportion is caused by diarrheagenic Escherichia coli. They are a particular problem in developed countries although traveler's diarrhea and hemorrhagic colitis are also a problem in developed countries. There are seven classes of diarrheagenic E. coli, namely enteropathogenic E. coli (EPEC), enterohaemorrhagic E. coli (EHEC), enteroinvasive E. coli (EIEC), enterotoxigenic E. coli (ETEC), enteroaggregative E. coli (EAggEC), diarrhea-associated hemolytic E. coli (DHEC) and cytolethal distending toxin (CDT)- producing E. coli. Many of their virulence determinants have been determined and some classes of diarrheagenic E. coli produce toxins. The virulence factors of some diarrhogenic E. coli have yet to be full determined and in the meantime they remain a large and emerging problem without the availability of effective vaccines.</p
Nucleotide sequence‐based typing of bacteria and the impact of automation
No full textDNA-based typing methods are increasingly important for the characterisation of bacteria. They are used to monitor the epidemiology of pathogens with public health significance and also to help understand the evolution and population biology of bacteria. However, these methods require accuracy and reproducibility and are often of a high-throughput nature. Laboratory automation is therefore the key to the successful implementation of such methods. This review describes the impact of automation on DNA-based typing methods, particularly multi-locus sequence typing (MLST), and the method components that can be automated.</p
Increased genetic diversity of Neisseria meningitidis isolates after the introduction of meningococcal serogroup C polysaccharide conjugate vaccines
No full textDuring the 1990s, the incidence of meningococcal disease was high in the United Kingdom. This was due primarily to an increase in serogroup C disease, particularly that within the ET-37/ST-11 genetic lineage. Serogroup C meningococcal polysaccharide conjugate vaccines were introduced in the United Kingdom in 1999, but the sequence types of meningococci causing disease since that time have not yet been reported. We have used serogrouping and multilocus sequence typing to characterize meningococci from patients with invasive disease over a 4-year period and show that there is a significant increase in genetic diversity but no genetic evidence of capsule switching.</p
Control of pneumococcal disease in the United Kingdom – the start of a new era
No full textIn 2000, a multi-valent pneumococcal conjugate vaccine, known as Prevnar, was licensed for use ininfants and young children in the USA. The subsequent introduction of the vaccine into thechildhood immunization schedule in that country led to a significant decrease in pneumococcaldisease. The vaccine is effective against invasive and non-invasive pneumococcal infection, can beused in young children as well as adults and, like all conjugate vaccines, provides long-lastingimmunity. Moreover, it reduces the incidence of antibiotic resistance because a number ofresistant serotypes are targeted by the vaccine. Prevnar, also known as Prevenar, has since beenlicensed in numerous countries, including the UK.On 8 February 2006, the Departments of Health inEngland, Scotland and Wales announced the inclusion of Prevenar in the childhood immunizationschedule. This announcement has important implications for pneumococcal infection, diseasesurveillance and immunization policy in the UK
Pyrosequencing: nucleotide sequencing technology with bacterial genotyping applications
No full textPyrosequencing is a relatively new method for real-time nucleotide sequencing. It has rapidly found applications in DNA sequencing, genotyping, single nucleotide polymorphism analysis, allele quantification and whole-genome sequencing within the areas of microbiology, clinical genetics and pharmacogenetics. It is fast becoming a real alternative to the traditional Sanger sequencing method although, at present, read lengths are normally limited to approximately 70 nucleotides. The pyrosequencing method involves four main stages: first, target DNA is amplified using PCR; second, double-stranded DNA is converted to single-stranded DNA templates; third, oligonucleotide primers are hybridized to a complementary sequence of interest; and, finally, the pyrosequencing reaction itself, in which a reaction mixture of enzymes and substrates catalyses the synthesis of complementary nucleotides. Data are shown as a collection of signal peaks in a pyrogram. Pyrosequencing is increasingly used for bacterial detection, identification and typing, and, recently, a commercial system became available for the identification of bacterial isolates. Pyrosequencing can also be partially or fully automated, thus enabling the high-throughput analysis of samples. Wider use of pyrosequencing may occur in the future if longer nucleotide reads are made possible, which will enable its expansion into larger nucleotide sequencing such as multilocus sequence typing and whole-genome sequencing.</p
Detection of Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae in blood and cerebrospinal fluid using fluorescence-based PCR
No full textThe polymerase chain reaction (PCR) is a fundamental part of modern molecular biology. Fluorescence-based PCR methods also are now available, which enable rapid, specific, and sensitive assays for the amplification and analysis of deoxyribonucleic acid (DNA). These methods are performed in closed-tube format, thereby reducing the risk of contamination between stages. In addition, post-PCR processing, such as clean-up steps and gel electrophoresis, are eliminated as the results are read via an integrated fluorimeter. An example of this methodology is fluorescence-based PCR using dual-labeled probes, termed dual-labeled end-point fluorescence PCR. This method uses oligonucleotide probes that are dual-labeled with a reporter dye and quencher dye. The method has the advantage that DNA extraction, liquid handling, PCR, and analysis also can be fully automated. In this chapter, the simultaneous detection of Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae from clinical samples is described
The impact of meningococcal serogroup C conjugate vaccine in Scotland
No full textThe increasing number of cases of serogroup C meningococcal disease in Scotland in the late 1990s coincided with the availability of a new meningococcal conjugate serogroup C (MCC) vaccine that, from 1999 onwards, was offered to all individuals aged <20 years. Annual incidence rates between 1994 and 2003 were calculated in 3 age groups (<5 years old; 5-19 years old; and 20 years old), and Poisson regression models were used to verify disease trends over time. Dramatic reductions ( ) in the incidence of serogroup C meningococcal disease were seen in target age groups: from 15.8 incidents per 100,000 subjects in 1999 (95% confidence interval [CI], 11.3-20.3) to 0.7 incidents per 100,000 subjects in 2001 (95% CI, −0.3 to 1.6), for subjects <5 years old, and from 6.7 incidents per 100,000 subjects in 1999 (95% CI, 5.1-8.3) to 1.5 incidents per 100,000 subjects in 2001 (95% CI, 0.7-2.3), for subjects 5-19 years old. An increasing incidence of serogroup B meningococcal disease in individuals 5-19 years old was clearly established before the campaign began. A 30% decrease in the case‐fatality rate for individuals <20 years old was not significant ( ). The MCC vaccine program has been highly effective in Scotland, leading to substantial reductions in serogroup C meningococcal disease and meningococcal mortality, with no adverse effects on other groups
Genotypic characterization of Neisseria meningitidis using Pyrosequencing
No full textPyrosequencing involves the synthesis of single-stranded deoxyribonucleic acid leading to rapid and accurate analysis of nucleotide sequences. This article describes the development of typing assays for the characterization of Neisseria meningitidis using Pyrosequencing. This involved developing methods for the nucleotide sequence analysis of important variable regions contained on a major capsule gene and on outer membrane protein genes that are used for grouping, typing, and subtyping meningococci. To achieve this, primers were designed for amplification of three genes, siaD, porB, and porA from the four main serogroups B, C, Y, and W135. To facilitate throughput and reproducibility, the method was also automated. Data from 717 isolates have shown that Pyrosequencing can be used for the single nucleotide polymorphism and sequence-analysis characterization of meningococci.</p
The nasopharyngeal microbiome
No full textHuman microbiomes have received increasing attention over the last 10 years, leading to a pervasiveness of hypotheses relating dysbiosis to health and disease. The respiratory tract has received much less attention in this respect than that of, for example, the human gut. Nevertheless, progress has been made in elucidating the immunological, ecological and environmental drivers that govern these microbial consortia and the potential consequences of aberrant microbiomes. In this review, we consider the microbiome of the nasopharynx, a specific niche of the upper respiratory tract. The nasopharynx is an important site, anatomically with respect to its gateway position between upper and lower airways, and for pathogenic bacterial colonisation. The dynamics of the latter are important for long-term respiratory morbidity, acute infections of both invasive and non-invasive disease and associations with chronic airway disease exacerbations. Here, we review the development of the nasopharyngeal (NP) microbiome over the life course, examining it from the early establishment of resilient profiles in neonates through to perturbations associated with pneumonia risk in the elderly. We focus specifically on the commensal, opportunistically pathogenic members of the NP microbiome that includes Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae and Moraxella catarrhalis. In addition, we consider the role of relatively harmless genera such as Dolosigranulum and Corynebacterium. Understanding that the NP microbiome plays such a key, beneficial role in maintaining equilibrium of commensal species, prevention of pathogen outgrowth and host immunity enables future research to be directed appropriately
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