Pneumococcal vaccines: do they prevent infection and how?

Research and predictive analysis of the disease burden of bloodstream infectious diseases in China

BACKGROUND

Bloodstream Infection(BSI) are one of the leading causes of infection-related mortality worldwide. However, epidemiological data related to BSI in China remain very limited.

METHODS

Based on the Global Burden of Disease(GBD) database, a systematic analysis was conducted on the epidemic trends, pathogen spectrum, and the current status of Antimicrobial Resistance(AMR) related to BSI in China for the year 2021. Additionally, an Autoregressive Integrated Moving Average(ARIMA) time series model was constructed to predict the trend of the disease burden associated with BSI in China from 2022 to 2035.

RESULTS

In terms of pathogens, the top five pathogens causing deaths due to BSI in China are as follows: Staphylococcus aureus, Escherichia coli, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii. There are significant differences in the pathogens causing BSI across different age groups. The disease burden is heaviest in the elderly population aged 70 and above. Among children under five years old, Staphylococcus aureus, Streptococcus pneumoniae, and Candida species are predominant. From 1990 to 2021, although there has been a gradual decline in mortality rates due to BSI across different age groups (with an approximately 52.4% reduction in age-standardized rates), the disease burden of BSI increases with age. This is especially evident in the population aged 70 and above, where the burden of disease is significantly higher than in other age groups. For instance, in 2021, the mortality rate for individuals aged 70-74 was 149.29 (per 100 K), while for those aged 95 and older, the mortality rate reached as high as 896.71 (per 100 K). On a global scale, the disease burden caused by BSI in China is at a moderate level. According to time series model projections, the mortality burden of BSI in China shows a complex trend toward 2035: the crude mortality rate across all age groups is expected to increase by approximately 14.26%, whereas the age-standardized mortality rate and Disability-Adjusted Life Years(DALYs) are projected to decrease significantly. Notably, the mortality burden is expected to decline most prominently in the 70 + and under 5 age groups, while the 25-44 age group is projected to see minimal change. Conversely, the mortality rates for the 5-49 age group are anticipated to increase slightly.

CONCLUSION

Staphylococcus aureus and Escherichia coli are key pathogens contributing to the high mortality burden of BSI. Additionally, the heavy burden associated with AMR poses significant challenges to clinical treatment. From 1990 to 2021, the age-standardized mortality rate mortality of BSI patients is gradually decreasing, and the change in BSI mortality will be mainly affected by the changes in population size and age structure. The forecast analysis for 2022-2035 finds that the death burden of the elderly will be the heaviest, and the mortality of people aged 5-49 years will increase slightly. BSI and its related health problems are still major challenges and need continuous attention.

CLINICAL TRIAL

Inapplicability.

Pediatric recurrent respiratory tract infections: when and how to explore the immune system? (About 53 cases)

Recurrent respiratory tract infections are one of the most frequent reasons for pediatric visits and hospitalization. Causes of this pathology are multiple ranging from congenital to acquired and local to general. Immune deficiencies are considered as underlying conditions predisposing to this pathology. Our work is about to determine when and how to explore the immune system when facing recurrent respiratory infections. This was based on the records of 53 children hospitalized at the pediatrics unit of Hassan II University Hospital, Fez Morocco. Thirty boys and 23 girls with age ranging from 5 months to 12 years with an average age of 2 years were involved in this study. Bronchial foreign body was the main etiology in children of 3 to 6 year old. Gastro-esophageal reflux, which in some cases is a consequence of chronic cough, as well as asthma were most frequent in infants (17 and 15% respectively). Immune deficiency was described in 7.5% of patients and the only death we deplored in our series belongs to this group. Recurrent respiratory tract infections have multiple causes. In our series they are dominated by foreign body inhalation and gastroesophageal reflux, which in some cases is a consequence of a chronic cough. Immune deficiency is not frequent but could influence the prognosis. Therefore immune explorations should be well codified.

Effectiveness of 7-valent pneumococcal conjugate vaccine: A meta-analysis of post-marketing studies

AIM: To investigate the 7-valent pneumococcal conjugate vaccine (PCV7) effectiveness.

METHODS: A systematic literature review of studies which evaluated the effectiveness of PCV7 vaccine was performed searching the keyword “heptavalent pneumococcal conjugate vaccine” in PubMed and Scopus until March 16, 2013. The selection of potential eligible articles was done by two researchers independently on the basis of abstract and title and only post-marketing studies were included in the systematic review. Data extraction was carried out by two researchers with respect to invasive pneumococcal diseases due to both all and vaccine serotypes in pre-vaccine and post-vaccine periods in children less than 5 years. Results of studies which were considered suitable for meta-analysis were combined by means of relative risk (RR) with 95%CI. Vaccine effectiveness was calculated as (1-RR) × 100. Heterogeneity was assessed by I² and a random effects model was used to combine data in the case of heterogeneity. RevMan 5 was used to pool data.

RESULTS: On the whole, 757 eligible papers were identified from the literature search in PubMed and Scopus. Of them, 62 were finally considered in the systematic review and 38 were included in the meta-analysis. In all post-marketing studies included in the systematic review the incidence of invasive pneumococcal diseases due to vaccine serotypes declined significantly with the exception of few studies showing stability or a slight, but not significant, increase. Furthermore most of studies highlighted also a reduction in the incidence of invasive pneumococcal diseases due to all serotypes. With regards to meta-analysis, a random effects model was used to combine data because of the high heterogeneity. Data combination showed that the effectiveness of PCV7 in reducing invasive pneumococcal diseases due to vaccine serotypes and to all serotypes was 84% (95%CI: 74%-90%) and 53% (95%CI: 46%-59%) respectively. These results are confirmatory with respect to the efficacy of PCV7 against invasive pneumococcal diseases due to vaccine serotypes.

CONCLUSION: PCV7 implementation determines a significant decrease of invasive pneumococcal diseases.

Etiology and antimicrobial susceptibility of middle ear fluid pathogens in Costa Rican children with otitis media before and after the introduction of the 7-valent pneumococcal conjugate vaccine in the National Immunization Program: acute otitis media microbiology in Costa Rican children

Acute otitis media (AOM) microbiology was evaluated in children after 7-valent pneumococcal conjugate vaccine (PCV7) introduction in Costa Rica (private sector, 2004; National Immunization Program, 2009). This was a combined prospective and retrospective study conducted in a routine clinical setting in San José, Costa Rica. In the prospective part of the study, which was conducted post-PCV7 introduction (2010-2012), standard bacteriological procedures were used to evaluate the etiology and serotype distribution of middle ear fluid samples collected by tympanocentesis or otorrhea from children aged 3-59 months diagnosed with AOM. E-tests were used to evaluate antimicrobial susceptibility in culture-positive samples. Retrospective data recorded between 1999 and 2004 were used for comparison of bacterial etiology and serotype distribution before and after PCV7 introduction. Statistical significance was evaluated in bivariate analyses at the P-value < 0.05 level (without multiplicity correction). Post-PCV7 introduction, Haemophilus influenzae was detected in 118/456 and Streptococcus pneumoniae in 87/456 AOM episodes. Most H. influenzae isolates (113/118) were non-typeable. H. influenzae was more (27.4% vs 20.8%) and S. pneumoniae less (17.1% vs 25.5%) frequently observed in vaccinated (≥ 2 PCV7 doses or ≥ 1 PCV7 dose at >1 year of age) versus unvaccinated children. S. pneumoniae non-susceptibility rates were 1.1%, 34.5%, 31.7%, and 50.6% for penicillin, erythromycin, azithromycin, and trimethoprim/sulfamethoxazole (TMP-SMX), respectively. H. influenzae non-susceptibility rate was 66.9% for TMP-SMX. Between pre- and post-PCV7 introduction, H. influenzae became more (20.5% vs 25.9%; P-value < 0.001) and S. pneumoniae less (27.7% vs 19.1%; P-value = 0.002) prevalent, and PCV7 serotype proportions decreased among pneumococcal isolates (65.8% vs 43.7%; P-value = 0.0005). Frequently identified pneumococcal serotypes were 19F (34.2%), 3 (9.7%), 6B (9.7%), and 14 (9.7%) pre-PCV7 introduction, and 19F (27.6%), 14 (8.0%), and 35B (8.0%) post-PCV7 introduction. Following PCV7 introduction, a change in the distribution of AOM episodes caused by H. influenzae and pneumococcal serotypes included in PCV7 was observed in Costa Rican children. Pneumococcal vaccines impact should be further evaluated following broader vaccination coverage.

Improved influenza and pneumococcal vaccination in rheumatology patients taking immunosuppressants using an electronic health record best practice alert

OBJECTIVE

To examine whether an electronic health record (EHR) best practice alert (BPA), a clinical reminder to help guideline adherence, improved vaccination rates in rheumatology patients receiving immunosuppressants. Guidelines recommend yearly influenza and pneumococcal vaccination with revaccination for patients age >65 years who are taking immunosuppressive medications.

METHODS

A vaccination BPA was developed based on immunosuppressant treatment, age, and prior vaccinations. At site 1, a hospital-based academic practice, physicians ordered vaccinations. At site 2, a community-based practice, physicians signed orders placed by nurses. Demographics, vaccination rates, and documentation (vaccination or no administration) were obtained. Chi-square and Fisher's exact test analysis compared vaccination and documentation rates for October 1 through December 31, 2006 (preBPA), and October 1 through December 31, 2007 (postBPA). Breslow-Day statistics tested the odds ratio of improvement across the years between the sites.

RESULTS

PostBPA influenza vaccination rates significantly increased (47% to 65%; P < 0.001), with significant improvement at both sites. PostBPA pneumococcal vaccination rates likewise significantly increased (19% to 41%; P < 0.001). PostBPA documentation rates for influenza and pneumococcal vaccinations also increased significantly. Site 2 (nurse-driven) had significantly higher preBPA vaccination rates for influenza (69% versus 43%; P < 0.001) than pneumococcal (47% versus 15%; P < 0.001).

CONCLUSION

The use of a BPA significantly increased influenza and pneumococcal vaccination and documentation rates in rheumatology patients taking immunosuppressants. A nurse-driven process offered higher efficacy. An EHR programmed to alert providers is an effective tool for improving quality of care for patients receiving immunosuppressants.

Transmission-dynamic model to capture the indirect effects of infant vaccination with Prevnar (7-valent pneumococcal conjugate vaccine (PCV7)) in older populations

We developed an age-structured, transmission-dynamic, mathematical model to quantify the direct and indirect benefits of infant PCV7 vaccination. The model simulates the acquisition of asymptomatic carriage of Streptococcus pneumoniae and the development of fatal and non-fatal invasive pneumococcal disease (IPD) among vaccinated and unvaccinated individuals aged <2, 2-4, 5-17, 18-49, 50-64, and >or=65 years old. The model was parameterized using published US surveillance data, supplemented with data from published literature. The model predicts the observed incidence of IPD with good agreement and may be used to predict the impact of various vaccination strategies in the US or other populations yet to introduce PCV7.

Rational design of novel antibacterial vaccines with an emphasis on tuberculosis

Vaccines are available for some, but not all, bacterial pathogens. Accordingly, bacterial pathogens still cause major health problems. Novel insights into the basic immunological mechanisms involved in protection against bacteria will provide guidelines for the design of novel vaccines. In particular, these include broad-acting vaccines composed of protein antigens shared by all members of a given pathogen group but absent in the human host and vaccines which operate via T-cells.

[Is the incidence of parapneumonic pleural effusion increasing?]

INTRODUCTION

Streptococcus pneumoniae is the microorganism most frequently associated with complicated pleural effusion. After the introduction of the heptavalent pneumococcal vaccine, there was a decline in the incidence of invasive pneumococcal disease and, to a lesser extent, in that of pneumonia. However, the incidence of empyema apparently increased. The antipneumococcal heptavalent vaccine was introduced in Spain in 2001.

OBJECTIVES

To determine whether the incidence of pleural effusion secondary to pneumonia has increased in hospitalized patients and to examine the possible influence of the antipneumococcal heptavalent vaccine on the incidence rate of parapneumonic effusions.

PATIENTS AND METHODS

Patients aged less than 16 years old admitted to our hospital with a diagnosis of pneumonia between 1999 and 2005 were retrospectively reviewed. We calculated the annual incidence rate of pleural effusion with respect to the total number of patients admitted with pneumonia and with respect to patients considered to have probable bacterial pneumonia, based on previously established criteria.

RESULTS

A total of 337 patients were analyzed, of which 213 (63.2%) met the criteria for a diagnosis of probable bacterial pneumonia. Pleural effusion was found in 34 patients (15.9%), and 13 of these effusions (38%) were complicated. No clear trend was detected in the annual incidence of probable bacterial pneumonia per 100 admitted patients, although the highest numbers were detected in the last two years of the study period. The percentage of complications (effusions) remained constant (mean: 16.28%). No differences were found in the effusion rate between vaccinated and unvaccinated patients (12.5% vs 18.6%).

CONCLUSIONS

The trend in the incidence of parapneumonic pleural effusions was parallel and proportional to that of probable bacterial pneumonia.

The contribution of immunology to the rational design of novel antibacterial vaccines

In most cases, a successful vaccine must induce an immune response that is better than the response invoked by natural infection. Vaccines are still unavailable for several bacterial infections and vaccines to prevent such infections will be best developed on the basis of our increasing insights into the immune response. Knowledge of the signals that determine the best possible acquired immune response against a given pathogen - comprising a profound T- and B-cell memory response as well as long-lived plasma cells - will provide the scientific framework for the rational design of novel antibacterial vaccines.

Vaccines in the era of genomics: the pneumococcal challenge

In this review we aim to provide the reader with an understanding of the capsular-based complexity of Streptococcus pneumoniae, one of the main limitations to current vaccine development. We then discuss the need for a new vaccine strategy based on proteic antigen candidates discovered in silico. Describing specifically how reverse vaccinology coupled to conventional vaccinology has led to a new paradigm of vaccine development. Finally, we conclude with the importance of defining the pan-genome of the pneumococcus, that is, the sequencing and analysis of multiple genomes from the same species. A critical factor in determining conserved proteins in a group of epidemiologically relevant circulating S. pneumoniae strains, in order to achieve the greatest coverage. Ultimately, the identification of immunogenic surface antigens and assessment of their efficacy will be imperative in the development of a vaccine with the ability to protect against invasive disease independent of serotype.

A conjugate vaccine composed of a heat shock protein 60 T-cell epitope peptide (p458) and Neisseria meningitidis type B capsular polysaccharide

Neisseria meningitidis type B is a major world-health problem. The Meningococcus type B capsular polysaccharide (MnB) is very poorly immunogenic and no vaccine to the antigen exists. Here, we conjugated the MnB to a T-cell carrier peptide (p458) derived from the self-60kDa heat shock protein molecule. The conjugate vaccine was effective in inducing long-lasting IgG antibodies to the MnB antigen in mice. The vaccine was also immunogenic when injected in PBS. Thus, the p458 carrier peptide can induce T-cell help for the switch to IgG Ab to the MnB antigen.

Variation in the presence of neuraminidase genes among Streptococcus pneumoniae isolates with identical sequence types

Streptococcus pneumoniae frequently colonizes the upper respiratory tract of young children and is an important cause of otitis media and invasive disease. Carriage is more common than disease, yet the genetic factors that predispose a given clone for disease are not known. The relationship between capsule type, genetic background, and virulence is complex, and important questions remain regarding how pneumococcal clones differ in their ability to cause disease. Pneumococcal neuraminidase cleaves sialic acid-containing substrates and is thought to be important for pneumococcal virulence. We describe the distribution of multilocus sequence types (ST), capsule type, and neuraminidase genes among 342 carriage, middle ear, blood, and cerebrospinal fluid (CSF) pneumococcal strains from young children. We found 149 STs among our S. pneumoniae isolates. nanA was present in all strains, while nanB and nanC were present in 96% and 51% of isolates, respectively. The distribution of nanC varied among the strain collections from different tissue sources (P = 0.03). The prevalence of nanC was 1.41 (95% confidence interval, 1.11, 1.79) times higher among CSF isolates than among carriage isolates. We identified isolates of the same ST that differed in the presence of nanB and nanC. These studies demonstrate that virulence determinants, other than capsule loci, vary among strains of identical ST. Our studies suggest that the presence of nanC may be important for tissue-specific virulence. Studies that both incorporate MLST and take into account additional virulence determinants will provide a greater understanding of the pneumococcal virulence potential.

Intranasal vaccination of neonatal mice with polysaccharide conjugate vaccine for protection against pneumococcal otitis media

Streptococcus pneumoniae is the leading bacterial cause of acute otitis media (OM) in young children, and can often produce invasive disease. Typical intramuscular routes of vaccination are poorly protective against development of OM. In the present study, we intranasally (i.n.) inoculated neonatal 1-week-old mice with pneumococcal polysaccharide conjugate vaccine using IL-12 as a mucosal adjuvant. The protective efficacy of this treatment was tested by challenging immunized infant (3-week-old) mice with bacteria to induce OM and invasive disease. i.n. vaccination was found to enhance levels of specific antibodies in middle ear (ME) washes and sera from wild-type (but not IFN-gamma(-/-)) mice. Immunization in the presence of IL-12 resulted in enhanced clearance of S. pneumoniae from the ME. Opsonization of bacteria with ME wash fluids or sera from immunized mice caused increased bacterial clearance from the ME of naïve mice. In addition, immunized mice demonstrated 89% survival after OM-induced invasive pneumococcal infection, compared to 22% survival in unvaccinated mice. These results indicate that i.n. vaccination of neonatal mice in the presence of IL-12 is able to enhance IFN-gamma dependent ME mucosal and systemic immune responses to pneumococci and efficiently protect against both OM and invasive infection.

Cochlear Preservation After Meningitis: An Animal Model Confirmation of Adjunctive Steroid Therapy

OBJECTIVE/HYPOTHESIS

The objective of the present study was to determine whether treating pneumococcal meningitis with a combined antibiotic and steroid regime will prevent cochlear damage, a common pneumococcal meningitis side effect.

STUDY DESIGN

This was a prospective animal study.

METHODS

Gerbils were randomly assigned to three experimental groups. Animals in group 1, the control animals, received intrathecal saline injections. Animals in groups 2 and 3 received intrathecal injections of Streptococcus pneumoniae to induce meningitis. Although group 2 solely was treated for 7 days with intraperitoneal penicillin injections (48,0000 units), group 3 received, in addition to the antibiotic for 4 days, 0.5 mg/kg intraperitoneal dexamethasone injections. Three months after the meningitis was induced, the animals' cochlear function was determined using auditory brainstem responses (ABRs). Fifteen frequencies were tested, five octaves at three steps per octave between 2 and 50 kHz.

RESULTS

ABR thresholds were significantly elevated only in group 2. When compared with group 1, ABR thresholds were 19 dB higher (P<.05). Frequencies at the low-frequency end of the hearing range were affected more than the midfrequencies. Animals that received dexamethasone had 2-dB higher thresholds than the control group (P>.05).

CONCLUSIONS

Dexamethasone therapy in conjunction with antibiotic therapy preserves cochlear function in cases of S. pneumoniae meningitis in the Mongolian gerbil model.

Rationale and design of the prevention of respiratory infections and management in children (PRIMAKid) study: a randomized controlled trial on the effectiveness and costs of combined influenza and pneumococcal vaccination in pre-school children with recurrent respiratory tract infections

Health and economic burden of recurrent respiratory tract infections (RTIs) in early childhood is considerable. A systematic review of licensed influenza and pneumococcal vaccines showed substantial efficacy in children, but the health-economic impact of such vaccines among pre-school children with recurrent RTIs is unknown. We therefore, designed a double-blind randomized controlled trial to determine the effectiveness and costs of a combined influenza and pneumococcal vaccination program among a primary care based cohort of children with recurrent episodes of RTI aged between 18 and 72 months. We will enroll 690 children over three consecutive years (2003--2005) who will be randomly allocated to receive vaccinations against influenza and pneumococcal disease, influenza alone or hepatitis B in a similar schedule. Follow up by parental diaries, tympanic temperature measurements, questionnaires and interviews is planned until May 2006. Primary outcome is number of febrile RTIs. Other outcomes include duration and severity of RTI episodes, medical consumption, safety and costs.

Community-acquired pneumonia in children

PURPOSE OF REVIEW

This review highlights recent developments in the diagnosis, etiology, therapy, and prevention of community-acquired pneumonia in children.

RECENT FINDINGS

Sensitive new diagnostic methods have increased the detection rate of the causative agent up to 94%. Streptococcus pneumoniae is the most prevalent bacterial pathogen in all ages. Polymerase chain reaction is a rapid and sensitive method for the detection of Chlamydia pneumoniae and Mycoplasma pneumoniae, which have gained greater importance in recent years. During the period covered by this review, two new agents causing pneumonia were extensively studied. Human metapneumonovirus detected in young children is a leading cause of respiratory disease during the first years of life. A novel coronavirus was identified as the causative agent of severe respiratory syndrome, a new respiratory illness that affects adults and children. One multicenter trial concluded that nonsevere pneumonia can be treated with a short course of oral amoxicillin and a multicenter international study showed that children with severe pneumonia have similar outcomes whether treated with oral amoxicillin or parenteral penicillin, but more data are needed to demonstrate the safety and efficacy of such regimens.

SUMMARY

The continued evolution of bacterial resistance highlights the need for appropriate use of antibacterials. Improved diagnostic techniques will aid the treatment of children with community-acquired pneumonia. Aggressive vaccination with the pneumococcal conjugate vaccine and other available vaccines as well as the development of new vaccines will aid the prevention of respiratory disease in children.

Assignment of weight-based immunoglobulin G1 (IgG1) and IgG2 units in antipneumococcal reference serum lot 89-S(F) for pneumococcal polysaccharide serotypes 1, 4, 5, 7F, 9V, and 18C

Weight-based assignments for immunoglobulin G1 (IgG1) and IgG2 subclass antibodies to Streptococcus pneumoniae capsular polysaccharides (PnPs) in antipneumococcal standard reference serum lot 89-S (lot 89-S), also known as lot 89-SF, have been determined for serotypes 1, 4, 5, 7F, 9V, and 18C. This extends the usefulness of lot 89-S beyond the IgG1 and IgG2 subclass assignments for serotypes 3, 6B, 14, 19F, and 23F made previously (A. Soininen, H. Kayhty, I. Seppala, and T. Wuorimaa, Clin. Diagn. Lab. Immunol. 5:561-566, 1998) to cover 11 major serotypes associated with the highest percentage of pneumococcal disease worldwide. A method of equivalence of absorbances in enzyme immunosorbent assays was used to determine the IgG1 and IgG2 antibody concentrations for the additional serotypes in lot 89-S, based on the subclass values previously assigned for PnPs serotypes 6B, 14, and 23F. This cross-standardization method assures consistency with previous antibody assignments in that reference serum. The newly assigned subclass values for serotype 9V, and previously assigned values for serotype 14, were used to quantitate PnPs antibodies in sera from adult and pediatric subjects immunized with a pneumococcal conjugate vaccine. There was a predominance of IgG1 anti-PnPs antibodies in pediatric sera and IgG2 anti-PnPs antibodies in the adult sera. The IgG1 and IgG2 subclass assignments for the 11 PnPs serotypes in antipneumococcal standard reference serum lot 89-S are useful for quantitating and characterizing immune responses to pneumococcal infection and vaccination regimens.

Office pediatrics: current issues in lower respiratory infections in children

PURPOSE OF REVIEW

Recent estimates indicate that 1.9 million children worldwide die each year from acute respiratory illnesses, many of which are lower respiratory infections (LRIs). Global threats from indoor and outdoor air pollution, urban crowding, biologic weapons, and worldwide rapid transportation complicate our efforts to reduce the impact of LRI disease in children. As new strategies are developed to limit the spread of LRI disease in children, existing pathogens become more complex to treat and newer pathogens emerge as causes of clinical disease. Most LRI disease is managed in outpatient settings and remains a challenge to those who care for children.

RECENT FINDINGS

Atypical pathogens (notably mycoplasma pneumoniae) are now known to cause a wide spectrum of disease, and with more extensive complications than previously recognized. Available data suggest a rapid increase in S. pneumoniae resistance to penicillin and macrolides in many cases of community acquired pneumonia, which has resulted in shifts in outpatient (and inpatient) antibiotic treatment regimens. Human metapneumovirus (HMPV) is now recognized to cause LRI illness similar to respiratory syncytial virus (RSV) in infants and children. General strategies for the prevention of influenza infection are expanded to include many infants and young children, and are projected to significantly reduce morbidity and mortality from this key LRI pathogen.

SUMMARY

The spectrum of LRI pathogens--and the clinical illnesses caused by them--continues to change. Innovations in immunotherapy and vaccines will be instrumental to reducing the burden of LRI morbidity in infants and children worldwide in the future.