Streptococcus pneumoniae (pneumococcus) is a major cause of worldwide mortality and morbidity, and to a large extent is vaccine-preventable. Nasopharyngeal carriage of pneumococcus precedes disease ...and is the source of pneumococcal spread between people. The use of vaccine effect on carriage as part of the vaccine licensure and post-vaccine introduction evaluation could facilitate and expand the licensure of new, life-saving pneumococcal vaccines and enable a comprehensive estimate of population effects after vaccine introduction. The authors provide a review of the evidence supporting pneumococcal carriage at the individual level as an immediate and necessary precursor to pneumococcal disease. Based on such a causal link between carriage and disease, the authors emphasize the role of information on pneumococcal carriage in vaccine trials and in public health decision-making.
The polysaccharide capsule of Streptococcus pneumoniae inhibits phagocytic killing by innate immune mechanisms. Certain serotypes are associated with invasive disease while others with a ...nasopharyngeal carriage. The invasiveness of serotypes may partly be explained by ability to resist deposition of complement (C3) on the bacterial surface and consequent opsonophagocytic killing. In our previous studies, we observed that clinical isolates of serotypes 1 and 5, which are rarely detected in asymptomatic carriage, were resistant to complement deposition and opsonophagocytosis, whereas serotypes 6B and 23F, both common in carriage, were more sensitive to deposition of C3 and opsonophagocytic killing. However, presence of significant variation in C3 deposition between isolates of the same serotype indicated that factors other than the capsule also affect complement resistance. To distinguish the relative effect of the capsular serotype and other virulence factors on C3 deposition, we compared capsule-switched mutants prepared in genetic backgrounds of pneumococcal strains TIGR4, 603, and 618. Clinical isolates which had the same multilocus sequence type but expressed different serotypes were also compared. We found that the serotype had a significant impact on complement resistance and that the more resistant the strain was to complement, the higher was the concentration of polysaccharide-specific antibodies required for opsonophagocytic killing. Comparison of strains expressing the same capsular polysaccharides in the different genetic backgrounds and various capsular mutants of the same strain suggests that while the genotype affects complement resistance, the serotype is the most important determinant. Differences between serotypes were more significant than the differences between strains.
We evaluated the effect of aging on the functional activity of naturally acquired anti-pneumococcal antibodies, the function of neutrophils in phagocytic killing of opsonized pneumococci, and the ...complement activity. Opsonic activities of antibodies to all tested pneumococcal serotypes were significantly lower and phagocytic killing of pneumococci by neutrophils was significantly impaired among the elderly, whereas the complement activity was slightly higher in the elderly than in the young adults. The reduced functional activity of serotype-specific antibodies and the compromised function of neutrophils in the opsonophagocytosis of pneumococci are likely to contribute to the increased susceptibility of the elderly to pneumococcal diseases.
We explored the influence of coadministration on safety and immunogenicity of the most common travellers' vaccine hepatitis A (HepA) and the pneumococcal conjugate vaccine (PCV) increasingly used ...both at home and before travel.
Volunteers aged ≥18 years (n = 305) were randomly assigned 1:1:1 into three groups receiving: 13-valent PCV (PCV13) + HepA, PCV13, or HepA. Anti-pneumococcal IgG concentrations, opsonophagocytic activity (OPA) titres, and total hepatitis A antibody (anti-HAV) concentrations were measured before and 28 ± 3 days after vaccination. Adverse events (AEs) were recorded over 4 weeks.
After vaccination, the anti-HAV geometric mean concentration was significantly lower in the PCV13+HepA than the HepA group: 34.47 mIU/mL (95% CI: 26.42–44.97 mIU/mL) versus 72.94 mIU/mL (95% CI: 55.01–96.72 mIU/mL), p < 0.001. Anti-HAV ≥10 mIU/mL considered protective was reached by 71 of 85 (83.5%) in the PCV13+HepA group versus 76 of 79 (96.2%) in the HepA group, p 0.008. The increases in anti-pneumococcal IgG and OPA levels were comparable in the PCV13+HepA and PCV13 groups, apart from a bigger rise in the PCV13+HepA group for serotype 3 (one-way ANOVA: serotype 3 IgG p 0.010, OPA p 0.002). AEs proved more frequent among those receiving PCV13 than HepA, but simultaneous administration did not increase the rates: ≥one AE was reported by 45 of 56 (80.4%) PCV13, 43 of 54 (79.6%) PCV13+HepA, and 25 of 53 (47.2%) HepA recipients providing structured AE data.
Coadministration of HepA and PCV13 did not cause safety concerns, nor did it impact the patients' response to PCV13, apart from serotype 3. However, coadministered PCV13 significantly impaired antibody responses to HepA.
Acute otitis media in children accounts for 20 million office visits per year in the United States, and 18 percent of ambulatory care visits among preschool children.
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Impaired hearing and ...delayed speech development are the most frequent long-term effects of recurrent episodes of otitis.
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The economic effect of acute otitis media also indicates that prevention is needed. The estimated annual cost associated with otitis is $138 million in Finland (population, 5 million)
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and $2 billion to $5.3 billion in the United States.
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Streptococcus pneumoniae
is the most commonly reported bacterial cause of acute otitis media, accounting for . . .
The 23-valent pneumococcal polysaccharide vaccine (PPV23) given alone is ineffective in patients with chronic lymphocytic leukemia (CLL) and better antibody response is achieved with pneumococcal ...conjugate vaccines (PCVs). In this study, we determine whether CLL patients would achieve a significant antibody response and broaden their serotype coverage against invasive pneumococcal disease (IPD) with PPV23 given five years after the 7-valent conjugate vaccine (PCV7). A total of 24 patients with CLL and eight controls were vaccinated with PPV23 five years after PCV7. Blood samples for evaluation of antibody response to PCV7 serotypes and PPV23 serotypes 5 and 7 were taken before vaccination and one month after it. Post-vaccination samples were available from 20 patients. IgG antibodies were measured with ELISA. Antibody concentrations after PPV23 were significantly lower in CLL patients for six of the PCV7 serotypes and for both PPV23 serotypes. Only 10% to 15% of CLL patients achieved an antibody response suggested to be protective against IPD. Hence, PCV7 given five years before PPV23 did not improve antibody response in patients with CLL. Based on our results, PPV23 given after a PCV primer is not useful against IPD in CLL patients.
Objective To determine whether pneumococcal carriage at the time of 11-valent pneumococcal conjugate vaccine (PCV-11) administration interferes with immune response in infants. Study design A total ...of 1111 Filipino infants recruited into an immunogenicity and carriage study, nested in an efficacy trial, received PCV-11 or saline solution placebo at 6, 10, and 14 weeks of age. Antibody concentrations to the most frequently carried vaccine serotypes 6B, 19F, and 23F were measured by enzyme immunoassay from sera obtained at 18 weeks and 9 months of age. Serotype-specific antibody concentration was compared between groups of children among PCV-11 recipients stratified according to their carriage status at 6 weeks of age. Results Antibody concentrations to 6B, 19F, and 23F were significantly lower at 18 weeks and 9 months of age among children who were carriers of the specific serotype at 6 weeks of age than among non-carriers of the serotype. The hyporesponsiveness was specific to the carried serotype. The specific antibody concentrations induced by PCV-11 among carriers did not differ significantly from those in placebo recipients, whereas the differences were highly significant among noncarriers. Conclusions Pneumococcal carriage, prevalent in Filipino infants, interferes with serotype-specific immune response to primary series of PCV and has potential implications for immunization programs.
The polysaccharide capsule is a major virulence factor of Streptococcus pneumoniae; it affects complement resistance and shields the bacterium from phagocytes. Certain capsular serotypes appear to be ...better able to cause invasive disease than others. Serotypes 1 and 5 are common causes of invasive disease but are rarely isolated from healthy carriers, whereas serotypes 6B and 23F are more frequently isolated from carriage than invasive disease. We have recently shown that serotypes 6B and 19F differ in resistance to complement C3 deposition and opsonophagocytic killing. In this study we assessed the complement resistance and susceptibility to opsonophagocytosis of several other serotypes targeted by the pneumococcal conjugate vaccines. Clinical isolates of serotypes 1, 4, 5, 14, 18C, and 23F were tested along reference strains of corresponding capsular types. The concentration of anticapsular antibodies required for opsonophagocytic killing correlated inversely with C3 deposition on the serotype. Serotype 1 was the most resistant of the clinical isolates to C3 deposition and, along with serotypes 5 and 19F, required the highest concentration of capsule antibodies for opsonophagocytic killing, whereas serotype 23F was the most sensitive to opsonophagocytosis. Sensitivity to C3 deposition and opsonophagocytosis was associated with serotype-specific mortality of invasive pneumococcal disease, suggesting that the primary pathogens, such as serotypes 1 and 5, are more resistant to complement and require a higher concentration of capsule antibodies for opsonophagocytic killing than the opportunistic serotypes such as 6B and 23F, which are associated with a more severe disease outcome.
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