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Microbiology Spectrum Mar 2019The polysaccharide capsule of is the dominant surface structure of the organism and plays a critical role in virulence, principally by interfering with host... (Review)
Review
The polysaccharide capsule of is the dominant surface structure of the organism and plays a critical role in virulence, principally by interfering with host opsonophagocytic clearance mechanisms. The capsule is the target of current pneumococcal vaccines, but there are 98 currently recognised polysaccharide serotypes and protection is strictly serotype-specific. Widespread use of these vaccines is driving changes in serotype prevalence in both carriage and disease. This chapter summarises current knowledge on the role of the capsule and its regulation in pathogenesis, the mechanisms of capsule synthesis, the genetic basis for serotype differences, and provides insights into how so many structurally distinct capsular serotypes have evolved. Such knowledge will inform ongoing refinement of pneumococcal vaccination strategies.
Topics: Animals; Bacterial Capsules; Humans; Pneumococcal Vaccines; Polysaccharides, Bacterial; Streptococcus pneumoniae
PubMed: 30977464
DOI: 10.1128/microbiolspec.GPP3-0019-2018 -
Clinical Microbiology and Infection :... May 2010Streptococcus pneumoniae is a major pathogen of humans, causing diseases such as pneumonia and meningitis. The organism produces several virulence factors that are... (Review)
Review
Streptococcus pneumoniae is a major pathogen of humans, causing diseases such as pneumonia and meningitis. The organism produces several virulence factors that are involved in the disease process. The molecular basis of the action of some of these virulence factors is being elucidated. The advent of whole genome sequencing combined with biological studies has demonstrated that genome variation is important in the ability of pneumococci to interact with the host. This review discusses the biological activity of several pneumococcal virulence factors, and describes how genome variation may impact on the ability of pneumococci to cause disease.
Topics: Genetic Variation; Humans; Pneumococcal Infections; Streptococcus pneumoniae; Virulence Factors
PubMed: 20132250
DOI: 10.1111/j.1469-0691.2010.03183.x -
Frontiers in Cellular and Infection... 2017
Topics: Acetylglucosamine; Biofilms; Drug Resistance, Multiple, Bacterial; Humans; Pneumococcal Infections; Streptococcus pneumoniae
PubMed: 28744450
DOI: 10.3389/fcimb.2017.00310 -
Frontiers in Cellular and Infection... 2014Streptococcus pneumoniae (the pneumococcus) is a common colonizer of the human nasopharynx. Despite a low rate of invasive disease, the high prevalence of colonization... (Review)
Review
Streptococcus pneumoniae (the pneumococcus) is a common colonizer of the human nasopharynx. Despite a low rate of invasive disease, the high prevalence of colonization results in millions of infections and over one million deaths per year, mostly in individuals under the age of 5 and the elderly. Colonizing pneumococci form well-organized biofilm communities in the nasopharyngeal environment, but the specific role of biofilms and their interaction with the host during colonization and disease is not yet clear. Pneumococci in biofilms are highly resistant to antimicrobial agents and this phenotype can be recapitulated when pneumococci are grown on respiratory epithelial cells under conditions found in the nasopharyngeal environment. Pneumococcal biofilms display lower levels of virulence in vivo and provide an optimal environment for increased genetic exchange both in vitro and in vivo, with increased natural transformation seen during co-colonization with multiple strains. Biofilms have also been detected on mucosal surfaces during pneumonia and middle ear infection, although the role of these biofilms in the disease process is debated. Recent studies have shown that changes in the nasopharyngeal environment caused by concomitant virus infection, changes in the microflora, inflammation, or other host assaults trigger active release of pneumococci from biofilms. These dispersed bacteria have distinct phenotypic properties and transcriptional profiles different from both biofilm and broth-grown, planktonic bacteria, resulting in a significantly increased virulence in vivo. In this review we discuss the properties of pneumococcal biofilms, the role of biofilm formation during pneumococcal colonization, including their propensity for increased ability to exchange genetic material, as well as mechanisms involved in transition from asymptomatic biofilm colonization to dissemination and disease of otherwise sterile sites. Greater understanding of pneumococcal biofilm formation and dispersion will elucidate novel avenues to interfere with the spread of antibiotic resistance and vaccine escape, as well as novel strategies to target the mechanisms involved in induction of pneumococcal disease.
Topics: Animals; Bacterial Proteins; Biofilms; Humans; Pneumococcal Infections; Streptococcus pneumoniae
PubMed: 25629011
DOI: 10.3389/fcimb.2014.00194 -
International Microbiology : the... Jun 2009Over 60% of bacterial infections (and up to 80% of chronic infections) are currently considered to involve microbial growth in biofilms. This peculiar form of life poses... (Review)
Review
Over 60% of bacterial infections (and up to 80% of chronic infections) are currently considered to involve microbial growth in biofilms. This peculiar form of life poses an array of problems in human clinical practice, from infections associated with the implant of prosthetic devices and dental plaque formation to diseases such as cystic fibrosis, otitis media, and endocarditis. Biofilms are also at the basis of a variety of problems in industry. This report describes the biofilms produced by Streptococcus pneumoniae. This bacterium often colonizes the upper airways in humans as a normal commensal, yet it may spread to other areas of the body, causing otitis media, pneumonia, or invasive diseases such as bacteremia and meningitis. The capacity of S. pneumoniae to form biofilms had not been explored until recently. Several newly developed in vitro systems have allowed to test the capacity of S. pneumoniae to form biofilms, and to analyze the influence of several factors, including DNA and proteins-which play a role in the virulence of this "supergerm" in the formation and development of biofilms. In this brief review, we update the knowledge available on pneumococcal biofilm formation and the unusual features of this structure.
Topics: Bacterial Proteins; Biofilms; DNA, Bacterial; Models, Biological; Streptococcus pneumoniae
PubMed: 19784927
DOI: No ID Found -
Microbiology Spectrum Feb 2023The short generation time of many bacterial pathogens allows the accumulation of mutations during routine culture procedures used for the preparation and propagation of...
The short generation time of many bacterial pathogens allows the accumulation of mutations during routine culture procedures used for the preparation and propagation of bacterial stocks. Taking the major human pathogen Streptococcus pneumoniae as an example, we sought to determine the influence of standard laboratory handling of microbes on within-strain genetic diversity and explore how these changes influence virulence characteristics and experimental outcomes. A single culture of S. pneumoniae D39 grown overnight resulted in the enrichment of previously rare genotypes present in bacterial freezer stocks and the introduction of new variation to the bacterial population through the acquisition of mutations. A comparison of D39 stocks from different laboratories demonstrated how changes in bacterial population structure taking place during individual culture events can cumulatively lead to fixed, divergent change that profoundly alters virulence characteristics. The passage of D39 through mouse models of infection, a process used to standardize virulence, resulted in the enrichment of high-fitness genotypes that were originally rare (<2% frequency) in D39 culture collection stocks and the loss of previously dominant genotypes. In the most striking example, the selection of a <2%-frequency genotype carrying a mutation in , a gene thought to be essential for the establishment of lung infection, was associated with enhanced systemic virulence. Three separately passaged D39 cultures originating from the same frozen stocks showed considerable genetic divergence despite comparable virulence. Laboratory bacteriology involves the use of high-density cultures that we often assume to be clonal but that in reality are populations consisting of multiple genotypes at various abundances. We have demonstrated that the genetic structure of a single population of a widely used Streptococcus pneumoniae strain can be substantially altered by even short-term laboratory handling and culture and that, over time, this can lead to changes in virulence characteristics. Our findings suggest that caution should be applied when comparing data generated in different laboratories using the same strain but also when comparing data within laboratories over time. Given the dramatic reductions in the cost of next-generation sequencing technology in recent years, we advocate for the frequent sampling and sequencing of bacterial isolate collections.
Topics: Animals; Mice; Bacterial Proteins; Mutation; Streptococcus pneumoniae; Virulence
PubMed: 36507681
DOI: 10.1128/spectrum.03103-22 -
European Journal of Clinical... Nov 2013Streptococcus infections are still one of the important problems facing contemporary medicine. As the World Health Organization (WHO) warns, Streptococcus pneumoniae is... (Review)
Review
Streptococcus infections are still one of the important problems facing contemporary medicine. As the World Health Organization (WHO) warns, Streptococcus pneumoniae is responsible for the highest number of pneumonia cases all over the world. Despite an increasing number of pneumococcal vaccinations, incidences of disease connected to this pathogen's infection stay at the same level, which is related to a constantly increasing number of infections caused by nonvaccinal serotypes. Unfortunately, the pathogenicity of bacteria of the Streptococcus genus is also connected to species considered to be physiological flora in humans or animals and, additionally, new species exhibiting pathogenic potential have been discovered. This paper presents an opinion concerning the epidemiology of streptococci infections based on case studies and other publications devoted to this problem. It also sheds new light based on recent reports on the prevention of protective vaccinations application in the case of streptococci infections.
Topics: Global Health; Humans; Prevalence; Streptococcal Infections; Streptococcus pneumoniae; Virulence
PubMed: 24141975
DOI: 10.1007/s10096-013-1914-9 -
Genes Oct 2019Despite its inclusion in pneumococcal conjugate vaccine 13 (PCV13), serotype 3 remains a major cause of invasive pneumococcal disease in England and Wales. Previous...
Despite its inclusion in pneumococcal conjugate vaccine 13 (PCV13), serotype 3 remains a major cause of invasive pneumococcal disease in England and Wales. Previous studies have indicated that there are distinct lineages within serotype 3 clonal complex 180 and the clade distributions have shifted in recent years with the emergence of clade II. We undertook whole genome sequencing and genomic analysis of 616 serotype 3 isolates from England and Wales between 2003 and 2018, including invasive and carriage isolates. Our investigations showed that clade II has expanded since 2014 and now represents 50% of serotype 3 invasive pneumococcal disease (IPD) isolates in England and Wales. Genomic analysis of antibiotic resistance and protein antigen genes showed that distinct profiles are present within the clades which could account for the recent emergence of this clade. This investigation highlights the importance and utility of routine whole genome sequencing and its ability to identify new and emerging variation at the single nucleotide level which informs surveillance and will impact future vaccine development.
Topics: Antigens, Bacterial; England; Evolution, Molecular; Genome, Bacterial; Humans; Immunologic Deficiency Syndromes; Pneumococcal Infections; Serogroup; Streptococcus pneumoniae; Wales
PubMed: 31731573
DOI: 10.3390/genes10110845 -
Clinical Microbiology and Infection :... May 2010Over the past three decades, antimicrobial resistance in Streptococcus pneumoniae has dramatically increased worldwide. Non-susceptibility to penicillin in S. pneumoniae... (Review)
Review
Over the past three decades, antimicrobial resistance in Streptococcus pneumoniae has dramatically increased worldwide. Non-susceptibility to penicillin in S. pneumoniae was first described in Australia in 1967, and later in New Guinea (1974), South Africa (1977), and Spain (1979). Most of these strains showed resistance to multiple antibiotics and belonged to serotypes 6A, 6B, 19A, 19F, and 23F. By the late 1980s and 1990s, the emergence and rapid dissemination of antibiotic-resistant pneumococci was observed in southern and eastern Europe, North America, South America, Africa, and Asia. Great geographical variability, both in serotype distribution and in the prevalence of resistant pneumococci, has been reported. However, the highest rates of resistance to penicillin and erythromycin worldwide were found in serotypes 6B, 6A, 9V, 14, 15A, 19F, 19A, and 23F. The introduction of the seven-valent pneumococcal conjugate vaccine (PCV7) in the 2000s and a reduction in antimicrobial use were associated with a significant decline in the incidence of invasive pneumococcal infections and in rates of antibiotic resistance in the USA. However, an increase in the incidence of infections caused by non-PCV7 serotypes, especially multiresistant serotype 19A pneumococci, has been observed in many countries over the last 5 years. The dynamic character of serotypes and antibiotic resistance in S. pneumoniae should be controlled by a policy of prudent antibiotic use and by implementation of the new generation of conjugate vaccines.
Topics: Anti-Bacterial Agents; Drug Resistance, Bacterial; Humans; Microbial Sensitivity Tests; Pneumococcal Infections; Serotyping; Streptococcus pneumoniae
PubMed: 20132251
DOI: 10.1111/j.1469-0691.2010.03182.x -
International Microbiology : the... Sep 2004Infectious diseases currently kill more than 15 million people annually, and the WHO estimates that every year 1.6 million people die from pneumococcal diseases.... (Review)
Review
Infectious diseases currently kill more than 15 million people annually, and the WHO estimates that every year 1.6 million people die from pneumococcal diseases. Streptococcus pneumoniae (pneumococcus), a bacterium with a long biological pedigree, best illustrates the rapid evolution of antibiotic resistance, which has led to major public health concern. This article discusses the molecular basis of the two main virulence factors of pneumococcus, the capsule and cell-wall hydrolases, as well as new approaches to developing medicinal weapons for preventing pneumococcal infections. In addition, current knowledge regarding pneumococcal phages as potential contributors to virulence and the use of lytic enzymes encoded by these phages as therapeutic tools is reviewed.
Topics: Cell Wall; Streptococcus Phages; Streptococcus pneumoniae
PubMed: 15492930
DOI: No ID Found