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Antimicrobial Agents and Chemotherapy Nov 2011Streptococcus pneumoniae is a major cause of invasive diseases worldwide. It spreads through an interindividual transmission, followed by usually harmless colonization...
Streptococcus pneumoniae is a major cause of invasive diseases worldwide. It spreads through an interindividual transmission, followed by usually harmless colonization of the host. Possible transmission differences reflecting intrinsic strain features (e.g., serotype and antibiotic susceptibility) have been little studied so far. In this study, we used epidemiological data from an interventional trial of S. pneumoniae carriage among kindergartners and developed a mathematical model to estimate the transmission parameters of the different strains isolated during that study. We found small but significant transmissibility differences between the observed serotypes: serotypes 3, 6A, and 19A were found to be the most epidemic, while serotypes 23F, 9V, and 14 were the least epidemic. Further analysis indicated that, within a serotype, susceptible and resistant strains had different abilities to be transmitted. Susceptible-to-resistant transmission rate ratios were computed for five serotypes; susceptible strains were significantly more epidemic than resistant strains for serotypes 6A (mean, 1.02) and 19F (1.05). Serotype 19A resistant strains were not outcompeted by susceptible strains (0.97). Nonsignificant trends were observed for serotypes 6B (1.01) and 15A (0.98). Our results support the existence of heterogeneous abilities of the different serotypes for host-to-host transmission. They also suggest that antibiotic susceptibility within a serotype affects this transmissibility. We conclude that pneumococcal strains should not be considered equally at-risk in terms of transmission. Further quantification of strain-specific epidemic potential is needed, especially in a context of extensive use of conjugate vaccines with the aim of preventing pneumococcal infections.
Topics: Anti-Bacterial Agents; Child; Child, Preschool; Female; Humans; Male; Microbial Sensitivity Tests; Models, Theoretical; Pneumococcal Infections; Serotyping; Streptococcus pneumoniae
PubMed: 21788454
DOI: 10.1128/AAC.00249-11 -
Applied and Environmental Microbiology May 2020The -acetylglucosaminidase LytB of is involved in nasopharyngeal colonization and is responsible for cell separation at the end of cell division; thus, Δ mutants form...
The -acetylglucosaminidase LytB of is involved in nasopharyngeal colonization and is responsible for cell separation at the end of cell division; thus, Δ mutants form long chains of cells. This paper reports the construction and properties of a defective pneumococcal mutant producing an inactive LytB protein (LytB). It is shown that an enzymatically active LytB is required for biofilm formation, as mutants (either Δ or producing the inactive LytB) are incapable of forming substantial biofilms, despite that extracellular DNA is present in the biofilm matrix. Adding small amounts (0.5 to 2.0 μg/ml) of exogenous LytB or some LytB constructs restored the biofilm-forming capacity of mutants to wild-type levels. The LytB mutant formed biofilm more rapidly than Δ mutants in the presence of LytB. This suggests that the mutant protein acted in a structural role, likely through the formation of complexes with extracellular DNA. The chain-dispersing capacity of LytB allowed the separation of daughter cells, presumably facilitating the formation of microcolonies and, finally, of biofilms. A role for the possible involvement of LytB in the synthesis of the extracellular polysaccharide component of the biofilm matrix is also discussed. It has been previously accepted that biofilm formation in must be a multigenic trait because the mutation of a single gene has led to only to partial inhibition of biofilm production. In the present study, however, evidence that the -acetylglucosaminidase LytB is crucial in biofilm formation is provided. Despite the presence of extracellular DNA, strains either deficient in LytB or producing a defective LytB enzyme formed only shallow biofilms.
Topics: Acetylglucosaminidase; Biofilms; N-Acetylmuramoyl-L-alanine Amidase; Streptococcus pneumoniae
PubMed: 32198170
DOI: 10.1128/AEM.00280-20 -
Journal of Clinical Microbiology Jun 2006To describe the serotype-specific epidemiology of colonizing and invasive Streptococcus pneumoniae isolates, which is important for vaccination strategies, we analyzed a...
To describe the serotype-specific epidemiology of colonizing and invasive Streptococcus pneumoniae isolates, which is important for vaccination strategies, we analyzed a total of 2,388 invasive and 1,540 colonizing S. pneumoniae isolates collected between January 2001 and December 2004 within two nationwide surveillance programs. We found that the relative rank orders of the most frequent serotypes (serotypes 1, 3, 4, 6B, 7F, 14, 19F, and 23F) differed among invasive and colonizing isolates. Serotypes 1, 4, 5, 7F, 8, 9V, and 14 had increased invasive potential, and serotypes/serogroups 3, 6A, 7, 10, 11, 19F, and 23F were associated with colonization. The proportion of pediatric serotypes was higher among children < 5 years old (48.5%) and persons > 64 years old (34.1%) than among other age groups (29.1%); it was also higher in West Switzerland (40.2%) than in other geographic regions (34.7%). Likewise, serotype-specific proportions of penicillin-resistant isolates for types 6B, 9V, 14, and 19F were significantly higher in West Switzerland. The relative frequency of pediatric serotypes corresponded with antibiotic consumption patterns. We conclude that the epidemiology of invasive and colonizing S. pneumoniae isolates is influenced by the serotype-specific potential for invasiveness, and therefore, surveillance programs should include colonizing and invasive S. pneumoniae isolates. Antibiotic selection pressure determines the serotype distribution in different age groups and geographic regions and therefore the expected direct and indirect effects of the 7-valent conjugate vaccine.
Topics: Adolescent; Adult; Anti-Bacterial Agents; Child; Child, Preschool; Drug Resistance, Bacterial; Female; Humans; Male; Microbial Sensitivity Tests; Middle Aged; Nasopharynx; Pneumococcal Infections; Selection, Genetic; Serotyping; Streptococcus pneumoniae; Switzerland
PubMed: 16757594
DOI: 10.1128/JCM.00275-06 -
PloS One 2013We aimed to obtain insights on the nature of a collection of isolates presumptively identified as atypical Streptococcus pneumoniae recovered from invasive and...
We aimed to obtain insights on the nature of a collection of isolates presumptively identified as atypical Streptococcus pneumoniae recovered from invasive and non-invasive infections in Spain. One-hundred and thirty-two isolates were characterized by: optochin susceptibility in ambient and CO(2)-enriched atmosphere; bile solubility; PCR-based assays targeting pneumococcal genes lytA, ply, pspA, cpsA, Spn9802, aliB-like ORF2, and a specific 16S rRNA region; multilocus sequence analysis; and antimicrobial susceptibility. By multilocus sequence analysis, 61 isolates were S. pseudopneumoniae, 34 were pneumococci, 13 were S. mitis, and 24 remained unclassified as non-pneumococci. Among S. pseudopneumoniae isolates, 51 (83.6%) were collected from respiratory tract samples; eight isolates were obtained from sterile sources. High frequency of non-susceptibility to penicillin (60.7%) and erythromycin (42.6%) was found. Only 50.8% of the S. pseudopneumoniae isolates displayed the typical optochin phenotype originally described for this species. None harbored the cpsA gene or the pneumococcal typical lytA restriction fragment length polymorphism. The Spn9802 and the specific 16S rRNA regions were detected among the majority of the S. pseudopneumoniae isolates (n = 59 and n = 49, respectively). The ply and pspA genes were rarely found. A high genetic diversity was found and 59 profiles were identified. Among the S. pneumoniae, 23 were capsulated and 11 were non-typeable. Three non-typeable isolates, associated to international non-capsulated lineages, were recovered from invasive disease sources. In conclusion, half of the atypical pneumococcal clinical isolates were, in fact, S. pseudopneumoniae and one-fourth were other streptococci. We identified S. pseudopneumoniae and non-typeable pneumococci as cause of disease in Spain including invasive disease.
Topics: Female; Genotype; Humans; Male; Microbial Sensitivity Tests; Multilocus Sequence Typing; Phenotype; Phylogeny; Spain; Streptococcal Infections; Streptococcus; Streptococcus pneumoniae
PubMed: 23437306
DOI: 10.1371/journal.pone.0057047 -
PloS One 2015Pneumococcal disease, a major cause of morbidity and mortality globally, has higher incidence among young children, the elderly and the immunocompromised of all ages. In...
BACKGROUND
Pneumococcal disease, a major cause of morbidity and mortality globally, has higher incidence among young children, the elderly and the immunocompromised of all ages. In Tunisia, pneumococcal conjugate vaccines (PCVs) are not included in the national immunization program. Also, few studies have described the epidemiology of S. pneumoniae in this country and, in particular, no molecular typing studies have been performed. The aim of this study was to evaluate serotype distribution, antimicrobial resistance and clonality of Streptococcus pneumoniae isolated from neutropenic patients in Tunisia.
METHODS
Fifty-nine S. pneumoniae were isolated from infection (n = 31) and colonization (n = 28) sites of patients (children and adults) attending the National Centre of Bone Marrow Transplantation in Tunis between 2005-2011. All isolates were characterized by serotype, antimicrobial resistance pattern and multilocus sequence typing (MLST).
RESULTS
The majority (66.1%) of the isolates belonged to five serotypes all included in PCVs: 6B, 9V, 14, 19F and 23F. The potential coverage of the 10-valent and 13-valent PCV was of 71.2% and 76.3% respectively. Resistance rates were very high and 69.5% of the isolates were multidrug resistant: non-susceptibility rates to penicillin, amoxicillin and cefotaxime were 66.1%, 40.7% and 27.1%, respectively; resistance rates to erythromycin, clindamycin, tetracycline, chloramphenicol and trimethoprim-sulfamethoxazole, were 69.5%, 61.0%, 37.3%, 22.0% and 67.8%, respectively. The most frequent serotypes had STs characteristic of multidrug resistant international clones known to be highly successful and important causes of pneumococcal infection: Spain 23F-ST81, France 9V/14-ST156, Spain 6B-ST90, 19F-ST320, and Portugal 19F-ST177.
CONCLUSIONS
The majority of S. pneumoniae strains recovered from immunocompromised patients in Tunisia are representatives of multidrug resistant pandemic clones that express serotypes targeted by PCVs. To contain the burden of pneumococcal disease and improve treatment choices among Tunisian immunocompromised patients PCVs should be offered to all of them.
Topics: Adolescent; Adult; Aged; Anti-Infective Agents; Child; Child, Preschool; Clone Cells; Drug Resistance, Microbial; Female; Humans; Immunocompromised Host; Infant; Infant, Newborn; Male; Microbial Sensitivity Tests; Middle Aged; Multilocus Sequence Typing; Serogroup; Streptococcus pneumoniae; Tunisia; Young Adult
PubMed: 26461259
DOI: 10.1371/journal.pone.0140390 -
Cell Cycle (Georgetown, Tex.) 2015
Topics: Bacterial Proteins; Cytokinesis; Cytoskeletal Proteins; Streptococcus pneumoniae
PubMed: 25803432
DOI: 10.1080/15384101.2015.1010978 -
Protein Science : a Publication of the... Oct 2019Many bacterial pathogens express small G5 domains that exist in the context of various membrane-anchored proteins and these G5 domains have been associated with...
Many bacterial pathogens express small G5 domains that exist in the context of various membrane-anchored proteins and these G5 domains have been associated with colonization, cellular adhesion, and biofilm formation. However, despite over a decade since the computational prediction of these G5 domains, many remain uncharacterized, particularly those from Streptococcus pneumoniae. Of five previously predicted G5 domains we found that four of these, all derived from S. pneumoniae, are independently folded modules. As one of these exhibits extreme line broadening due to self-association, we were able to use NMR solution studies to probe the potential ligand interactions of the remaining three G5 domains. None of these G5 domains engage N-acetylglucosamine (NAG) as previously predicted but do interact with other small molecules that may modulate adherence to both bacteria and host cells. Specifically, while all G5 domains tested engage Zn, only one of these G5 domains engage heparin. NMR solution structural studies of the IgA1 Protease G5 (IgA1P-G5) and endo-beta-N-acetylglucosaminidase-D G5 (ENDD-G5) also facilitated identification of the ligand binding sites and confirm the typical G5 fold that comprises two connected β-sheets with no canonical core. NMR relaxation experiments indicate flexibility on both ends and within the connecting regions between the β-sheets. Our studies thus establish a basis for future biological experiments to test whether the ligands presented here are involved in bacterial adherence, either to bacteria or to host cells.
Topics: Bacterial Adhesion; Bacterial Proteins; Ligands; Models, Molecular; Nuclear Magnetic Resonance, Biomolecular; Streptococcus pneumoniae
PubMed: 31390088
DOI: 10.1002/pro.3693 -
Molecular Microbiology Jan 2000Genetic plasticity plays a central role in the biology of the human pathogen Streptococcus pneumoniae. This is illustrated by the existence of at least 90 different... (Review)
Review
Genetic plasticity plays a central role in the biology of the human pathogen Streptococcus pneumoniae. This is illustrated by the existence of at least 90 different capsular types (the polysaccharide capsule has an essential antiphagocytic function) as well as by the rapid emergence of penicillin-resistant (PenR) pneumococcal isolates. Natural genetic transformation is believed to be essential for this genetic plasticity; capsular types can be switched by intraspecies transformation, whereas interspecies transformation is responsible for the appearance, in the PenR isolates, of mosaic pbp genes, which encode proteins with reduced affinity for penicillin. Data on the regulation of competence for transformation in S. pneumoniae, on the control of intra- and interspecies genetic exchange and on the shuffling and capture of exogenous sequences during transformation are reviewed. Possible links between transformation and changes in environmental conditions are discussed, and the adaptive 'strategy' deduced for S. pneumoniae is compared with that of Escherichia coli.
Topics: Adaptation, Physiological; Animals; Genetic Variation; Genome, Bacterial; Humans; Recombination, Genetic; Streptococcus pneumoniae; Transformation, Bacterial
PubMed: 10652087
DOI: 10.1046/j.1365-2958.2000.01718.x -
Microbial Biotechnology Jul 2012Biofilm-grown bacteria are refractory to antimicrobial agents and show an increased capacity to evade the host immune system. In recent years, studies have begun on... (Review)
Review
Biofilm-grown bacteria are refractory to antimicrobial agents and show an increased capacity to evade the host immune system. In recent years, studies have begun on biofilm formation by Streptococcus pneumoniae, an important human pathogen, using a variety of in vitro model systems. The bacterial cells in these biofilms are held together by an extracellular matrix composed of DNA, proteins and, possibly, polysaccharide(s). Although neither the precise nature of these proteins nor the composition of the putative polysaccharide(s) is clear, it is known that choline-binding proteins are required for successful biofilm formation. Further, many genes appear to be involved, although the role of each appears to vary when biofilms are produced in batch or continuous culture. Prophylactic and therapeutic measures need to be developed to fight S. pneumoniae biofilm formation. However, much care needs to be taken when choosing strains for such studies because different S. pneumoniae isolates can show remarkable genomic differences. Multispecies and in vivo biofilm models must also be developed to provide a more complete understanding of biofilm formation and maintenance.
Topics: Bacterial Proteins; Biofilms; DNA, Bacterial; Gene Expression Regulation, Bacterial; Genes, Bacterial; Polysaccharides, Bacterial; Streptococcus pneumoniae
PubMed: 21906265
DOI: 10.1111/j.1751-7915.2011.00294.x -
Carbohydrate Research Oct 2017Streptococcus pneumoniae is a globally important encapsulated human pathogen with approximately 100 different serotypes recognized. Serogroup 23 consists of serotype... (Comparative Study)
Comparative Study
Streptococcus pneumoniae is a globally important encapsulated human pathogen with approximately 100 different serotypes recognized. Serogroup 23 consists of serotype 23F, present in licensed vaccines, and emerging serotypes 23A and 23B. Here, we report the previously unknown structures of the pneumococcal capsular polysaccharides serotype 23A and 23B determined using genetic analysis, NMR spectroscopy, composition and linkage analysis and Smith degradation (of polysaccharide 23A). The structure of the serotype 23A capsular polysaccharide is: →4)-β-D-Glcp-(1→3)-[[α-L-Rhap-(1→2)]-[Gro-(2→P→3)]-β-D-Galp-(1→4)]-β-L-Rhap-(1→. This structure differs from polysaccharide 23F as it features a disaccharide backbone and the di-substituted β-Gal is linked to β-Rha as a side chain. This is due to the different polymerization position catalysed by the unusually divergent repeat unit polymerase Wzy in the 23A cps biosynthesis locus. Steric crowding in 23A, confirmed by molecular models, causes the NMR signal for H-1 of the di-substituted 2,3-β-Gal to resonate in the α-anomeric region. The structure of the serotype 23B capsular polysaccharide is the same as 23F, but without the terminal α-Rha: →4)-β-D-Glcp-(1→4)-[Gro-(2→P→3)]-β-D-Galp-(1→4)-β-L-Rhap-(1→. The immunodominant terminal α-Rha of 23F is more sterically crowded in 23A and absent in 23B. This may explain the reported typing cross reactions for serotype 23F: slight with 23A and none with 23B.
Topics: Bacterial Capsules; Carbohydrate Sequence; Polysaccharides, Bacterial; Repetitive Sequences, Nucleic Acid; Species Specificity; Streptococcus pneumoniae
PubMed: 28837839
DOI: 10.1016/j.carres.2017.08.006