Pneumococcal vaccines for children: a global public health priority

A broad-spectrum pneumococcal vaccine induces mucosal immunity and protects against lethal Streptococcus pneumoniae challenge

Pneumococcal disease is a major threat to public health globally, impacting individuals across all age groups, particularly infants and elderly individuals. The use of current vaccines has led to unintended consequences, including serotype replacement, leading to a need for a new approach to combat pneumococcal disease. A promising solution is the development of a broad-spectrum pneumococcal vaccine. In this study, we present the development of a broad-spectrum protein-based pneumococcal vaccine that contains three pneumococcal virulence factors: rlipo-PsaA (lipidated form), rPspAΔC (truncated form), and rPspCΔC (truncated form). Intranasal immunization with rlipo-PsaA, rPspAΔC, and rPspCΔC (LAAC) resulted in significantly higher IgG titres than those induced by administration of nonlipidated rPsaA, rPspAΔC, and rPspCΔC (AAC). Furthermore, LAAC immunization induced the production of higher IgA titres in vaginal washes, feces, and sera in mice, indicating that LAAC can induce systemic mucosal immunity. In addition, administration of LAAC also induced Th1/Th17-biased immune responses and promoted opsonic phagocytosis of Streptococcus pneumoniae strains of various serotypes, implying that the immunogenicity of LAAC immunization provides a protective effect against pneumococcal infection. Importantly, challenge data showed that the LAAC-immunized mice had a reduced bacterial load not only for several serotypes of the 13-valent conjugate pneumococcal vaccine (PCV13) but also for selected non-PCV13 serotypes. Consistently, LAAC immunization increased the survival rate of mice after bacterial challenge with both PCV13 and non-PCV13 serotypes. In conclusion, our protein-based pneumococcal vaccine provides protective effects against a broad spectrum of Streptococcus pneumoniae serotypes.

Changing Parental Attitudes Towards Rotavirus Vaccine

BACKGROUND

 Rotavirus is known to be one of the most common infections, usually associated with severe diarrhea. Despite the existence of two licensed vaccines, many countries, including Turkey, have not included rotavirus vaccination in their nationally funded vaccination program. This article explores what factors influence parents' decisions about whether to have their children vaccinated against rotavirus and which factors changed from 2010 through 2016.

MATERIALS AND METHODS

 Data were collected over two periods via questionnaires. The first period was from January 2009 through March 2010, and data were gathered from a semi-private pediatric outpatient clinic in Kocaeli, Turkey. The second period was from August 2015 through May 2016, and data were collected from parents during their pediatric outpatient clinic visits. Two questionnaires were designed to find out the rotavirus vaccination status of the children, socio-demographic factors, and reasons for excluding/accepting the rotavirus vaccine. The level of knowledge about the rotavirus vaccine was investigated. Parents indicated their level of agreement with each statement using a five-point Likert scale.

RESULTS

 While only 3.8% of the parents accepted the rotavirus in 2009-2010, it increased to 69.5% in 2015-2016. Significant factors influencing parents' decision to vaccinate their children for rotavirus were advice from a pediatrician, a lack of correct and timely rotavirus information, and the cost of the vaccine.

CONCLUSIONS

 The acceptance of the rotavirus vaccine depends on parental perceptions, which may be influenced by accurate and timely information, the advice of their healthcare provider, and inclusion in the nationally funded vaccination program. In contrast to other studies reported, the education level of the mothers and fathers and their job types appear to be important. It was also found that parents' attitudes and perceptions changed over time.

Surveillance of adverse events following immunization of 13-valent pneumococcal conjugate vaccine among infants, in Zhejiang province, China

OBJECTIVES

To evaluate the safety of 13-valent pneumococcal conjugate vaccine (PCV13) after its licensure.

METHODS

Review and describe the AEFI reported to national adverse event following immunization surveillance system (NAEFISS) in Zhejiang province from 2017 to 2020. Reporting rates of AEFI were calculated by age, city, severity of AEFI, categories of AEFI, and reaction categories. The data mining algorithm used in this study was reporting odds ratio (ROR). A value of ROR-1.96SE >1 (standard error [SE]) was considered as the positive signal.

RESULTS

NAEFISS received 3332 AEFI cases following PCV13, with a reporting rate of 17.58/10000 doses. Of the reported AEFI, 652 were serious AEFI cases and the reporting rate was 3.44 for serious AEFI. The reporting rate of fever was the highest among all the clinical diagnosis (7.39/10000 doses). The positive signals were obtained for injection site reaction (ROR-1.96SE: 1.55), hypotonic hyporesponsive episode (HHE) (ROR-1.96SE: 1.62) and febrile seizure (ROR-1.96SE: 1.52).

CONCLUSION

The present results supported previous observations that the PCV13 administered as the four-dose schedule was generally well tolerated in Chinese infants as we did not identify any new/unexpected safety concern from the NAEFISS during a four-year time period.

Indoor bacterial and fungal aerosols as predictors of lower respiratory tract infections among under-five children in Ibadan, Nigeria

BACKGROUND

This study aimed to investigate the association between exposure to diverse indoor microbial aerosols and lower respiratory tract infections (LRTI) among children aged 1 to 59 months in Ibadan, Nigeria.

METHODS

One hundred and seventy-eight (178) hospital-based LRTI cases among under-five children were matched for age (± 3 months), sex and geographical location with 180 community-based controls (under-five children without LRTI). Following consent from caregivers of eligible participants, a child's health questionnaire, clinical proforma and standardized home-walkthrough checklist were used to collect data. Participant homes were visited and sampled for indoor microbial exposures using active sampling approach by Anderson sampler. Indoor microbial count (IMC), total bacterial count (TBC), and total fungal count (TFC) were estimated and dichotomized into high (> median) and low (≤ median) exposures. Alpha diversity measures including richness (R), Shannon (H) and Simpson (D) indices were also estimated. Conditional logistic regression models were used to test association between exposure to indoor microbial aerosols and LRTI risk among under-five children.

RESULTS

Significantly higher bacterial and fungal diversities were found in homes of cases (R = 3.00; H = 1.04; D = 2.67 and R = 2.56; H = 0.82; D = 2.33) than homes of controls (R = 2.00; H = 0.64; D = 1.80 and R = 1.89; H = 0.55; D = 1.88) p < 0.001, respectively. In the multivariate models, higher categories of exposure to IMC (aOR = 2.67, 95% CI 1.44-4.97), TBC (aOR = 2.51, 95% CI 1.36-4.65), TFC (aOR = 2.75, 95% CI 1.54-4.89), bacterial diversity (aOR = 1.87, 95% CI 1.08-3.24) and fungal diversity (aOR = 3.00, 95% CI 1.55-5.79) were independently associated with LRTI risk among under-five children.

CONCLUSIONS

This study suggests an increased risk of LRTI when children under the age of five years are exposed to high levels of indoor microbial aerosols.

COVID-19 Vaccination in Pediatric Population: A Necessity or Obstruction to the Protection of the Right to Health? Biojuridical Perspective

One of the most recently debated topics worldwide is the mass vaccination of children against coronavirus disease 2019 (COVID-19). Next, the risk/benefit ratio of COVID-19 vaccination and infection in children are compared. Nonetheless, the real question in this debate is as follows: Does the vaccine represent a necessary tool or is it an obstacle in protecting the right to health? From a public health point of view, the Supreme Court of Nova Scotia, in Canada, recommends COVID-19 vaccination in the pediatric population. Based on Article 25 of the Draft Articles on State responsibility, vaccination can be considered a social act necessary for protecting the individual's right to health. The 1989 New York Convention on the Rights of the Child and the European Regulation number 219/1111 state that the opinion of a minor aged >12 years is considerable. However, this validity of opinion is related to age and degree of discernment. The onset of adverse events following the administration of the COVID-19 vaccine may lead to compensation in the near future. Recent studies have identified a new COVID-19-related pediatric pathology, known as multisystem inflammatory syndrome. Other studies have demonstrated that myocarditis in the pediatric population might occur following COVID-19 vaccine administration. In June 2021 in the USA, the Center for Control and Prevention of Infectious Diseases Advisory Committee on Immunization Practices declared that the benefits of vaccination against COVID-19 in the pediatric population outweighed the risks. In the meantime, whereas the bioethical debate remains open, monitoring the real risk/benefit ratio of vaccination in the pediatric population is crucial.

Challenges in Establishing Vaccine Induced Herd Immunity through Age Specific Community Vaccinations

Presently, the second wave of COVID-19 pandemic is driving the world towards a devastating total failure of the healthcare system. The purpose of the review is to search for the studies reporting on the implication of herd immunity into a naïve population through age specific mass vaccination. This review is based on selected publications on the effect herd immunity to COVID 19 in communities. We searched published scientific articles, review articles, reports, published in 2020 as well as read some basic, cult publications related to establishment of indirect immunity to a population. We have focused on use of application of vaccine induced herd immunity into community to confer indirect immunity against COVID-19 and searched on electronic databases, including PubMed (http://www.pubmed.com), Scopus (http://www.scopus.com), Google Scholar (http://www.scholar.google.com), Web of Science (www.webofscience.com) and Science Direct by using key words such as Herd immunity, indirect or passive immunization, Coronavirus disease 2019 (COVID-19), severe acute respiratory syndrome, coronavirus 2 (SARS-CoV-2), and immune-technique. This review proposes the implication of mass vaccination-induced herd immunity in a population to curb the infection, and to every individual in a given population irrespective of their age.

Promising Expectations for Pneumococcal Vaccination during COVID-19

The emergence of new viral infections has increased over the decades. The novel virus is one such pathogen liable for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, popularly known as coronavirus disease 2019 (COVID-19). Most fatalities during the past century's influenza pandemics have cooperated with bacterial co/secondary infections. Unfortunately, many reports have claimed that bacterial co-infection is also predominant in COVID-19 patients (COVID-19 associated co/secondary infection prevalence is up to 45.0%). In the COVID-19 pandemic, Streptococcus pneumoniae is the most common coinfecting pathogen. Half of the COVID-19 mortality cases showed co-infection, and pneumonia-related COVID-19 mortality in patients >65 years was 23%. The weakening of immune function caused by COVID-19 remains a high-risk factor for pneumococcal disease. Pneumococcal disease and COVID-19 also have similar risk factors. For example, underlying medical conditions on COVID-19 and pneumococcal diseases increase the risk for severe illness at any age; COVID-19 is now considered a primary risk factor for pneumococcal pneumonia and invasive pneumococcal disease. Thus, pneumococcal vaccination during the COVID-19 pandemic has become more critical than ever. This review presents positive studies of pneumococcal vaccination in patients with COVID-19 and other medical conditions and the correlational effects of pneumococcal disease with COVID-19 to prevent morbidity and mortality from co/secondary infections and superinfections. It also reports the importance and role of pneumococcal vaccination during the current COVID-19 pandemic era to strengthen the global health system.

An ethical analysis of vaccinating children against COVID-19: benefits, risks, and issues of global health equity

COVID-19 vaccination of children has begun in various high-income countries with regulatory approval and general public support, but largely without careful ethical consideration. This trend is expected to extend to other COVID-19 vaccines and lower ages as clinical trials progress. This paper provides an ethical analysis of COVID-19 vaccination of healthy children. Specifically, we argue that it is currently unclear whether routine COVID-19 vaccination of healthy children is ethically justified in most contexts, given the minimal direct benefit that COVID-19 vaccination provides to children, the potential for rare risks to outweigh these benefits and undermine vaccine confidence, and substantial evidence that COVID-19 vaccination confers adequate protection to risk groups, such as older adults, without the need to vaccinate healthy children. We conclude that child COVID-19 vaccination in wealthy communities before adults in poor communities worldwide is ethically unacceptable and consider how policy deliberations might evolve in light of future developments.

An ethical analysis of vaccinating children against COVID-19: benefits, risks, and issues of global health equity

COVID-19 vaccination of children over 12 has begun in various high-income countries with regulatory approval and general public support, but largely without careful ethical consideration. This trend is expected to extend to other COVID-19 vaccines and lower ages as clinical trials progress. This paper provides an ethical analysis of COVID-19 vaccination of healthy children. Specifically, we argue that it is currently unclear whether routine COVID-19 vaccination of healthy children is ethically justified in most contexts, given the minimal direct benefit that COVID-19 vaccination provides to children, the potential for rare risks to outweigh these benefits and undermine vaccine confidence, and substantial evidence that COVID-19 vaccination confers adequate protection to risk groups, such as older adults, without the need to vaccinate children. We conclude that child COVID-19 vaccination in wealthy communities before adults in poor communities worldwide is ethically unacceptable and consider how policy deliberations might evolve in light of future developments.

Incidence and Mortality Trends of Acute Gastroenteritis and Pneumococcal Disease in Children Following Universal Rotavirus and Pneumococcal Conjugate Vaccination in Ecuador

INTRODUCTION

Ecuador introduced routine infant rotavirus (RV) vaccination in 2008 and pneumococcal conjugate vaccination (PCV) in 2011 to manage disease and mortality in children caused by gastroenteritis (GE) and by pneumonia (PNE) and invasive pneumococcal disease (IPD), respectively.

METHODS

This retrospective ecological database study described vaccination coverage as well as the trends in incidence and mortality in the pre- versus post-vaccination periods and used time-trend analysis models to assess the impact of vaccination.

RESULTS

RV vaccination coverage of the second dose was between 79-97% from 2008 to 2016. GE incidence and mortality showed a declining trend before vaccination which continued in the post-vaccination period. The model estimated a statistically significant decrease of 72.4% for GE mortality and 51.2% for GE incidence in the post-vaccination period. PCV vaccination coverage remained above 80% (second dose) and 40% (third dose) after 2011. PNE mortality showed a declining trend before vaccination and a continued decline after vaccination, while PNE incidence was more variable (sharp increase from 2005-2009 then decrease and eventual stabilisation). The model estimated a statistically significant decline of 41.1% for PNE mortality and a stable PNE incidence in the post- versus pre-vaccination period. IPD incidence and mortality yearly data showed large variability by year and low numbers, making it difficult to discern a trend. The model estimated a statistically significant reduction of 51.1% for IPD mortality and 31.5% for IPD incidence in the post- versus pre-vaccination period.

CONCLUSION

After the first 9 years of routine RV vaccination and 6 years of routine PCV vaccination in Ecuador, significant decreases in incidence and mortality in children < 5 years of age due to GE and pneumococcal disease have been observed.

Approaching In Vivo Models of Pneumococcus-Host Interaction: Insights into Surface Proteins, Capsule Production, and Extracellular Vesicles

Infections caused by the Gram-positive bacterium Streptococcus pneumoniae have become a major health problem worldwide because of their high morbidity and mortality rates, especially in developing countries. This microorganism colonizes the human upper respiratory tract and becomes pathogenic under certain circumstances, which are not well known. In the interaction with the host, bacterial surface structures and proteins play major roles. To gain knowledge into gradual changes and adaptive mechanisms that this pathogen undergoes from when it enters the host, we mimicked several in vivo situations representing interaction with epithelial and macrophage cells, as well as a condition of presence in blood. Then, we analyzed, in four pneumococcal strains, two major surface structures, the capsule and extracellular vesicles produced by the pneumococci, as well as surface proteins by proteomics, using the “shaving” approach, followed by LC-MS/MS. We found important differences in both surface ultrastructures and proteins among the culture conditions and strains used. Thus, this work provides insights into physiological adaptations of the pneumococcus when it interacts with the host, which may be useful for the design of strategies to combat infections caused by this pathogen.

Streptococcus Pneumoniae-Associated Hemolytic Uremic Syndrome in the Era of Pneumococcal Vaccine

Streptococcus pneumoniae-associated hemolytic uremic syndrome (Sp-HUS) is a serious complication of invasive pneumococcal disease that is associated with increased mortality in the acute phase and morbidity in the long term. Recently, Sp-HUS definition has undergone revision and cases are categorized as definite, probable, and possible, based on less invasive serological investigations that evaluate Thomsen-Friedenreich crypt antigen (T-antigen) activation. In comparison to the pre-vaccine era, Sp-HUS incidence seems to be decreasing after the introduction of 7-serotype valence and 13-serotype valence pneumococcal vaccines in 2000 and 2010, respectively. However, Sp-HUS cases continue to occur secondary to vaccine failure and emergence of non-vaccine/replacement serotypes. No single hypothesis elucidates the molecular basis for Sp-HUS occurrence, although pneumococcal neuraminidase production and formation of T-antigen antibody complexes on susceptible endothelial and red blood cells continues to remain the most acceptable explanation. Management of Sp-HUS patients remains supportive in nature and better outcomes are being reported secondary to earlier recognition, better diagnostic tools and improved medical care. Recently, the addition of eculizumab therapy in the management of Sp-HUS for control of dysregulated complement activity has demonstrated good outcomes, although randomized clinical trials are awaited. A sustained pneumococcal vaccination program and vigilance for replacement serotypes will be the key for persistent reduction in Sp-HUS cases worldwide.

High prevalence of antimicrobial resistance in non-vaccine serotypes of non-invasive/colonization isolates of Streptococcus pneumoniae: A cross-sectional study eight years after the licensure of conjugate vaccine in Japan

BACKGROUND

Multidrug resistance (MDR) in non-vaccine serotypes (NVTs)-Streptococcus pneumoniae is a global public health concern after the widespread use of pneumococcal conjugate vaccines (PCVs). The present study aimed to analyze the prevalence of serotypes and antimicrobial susceptibilities of non-invasive/colonization isolates of S. pneumoniae eight years after the introduction of PCV in Japan.

METHODS

A total of 545 non-invasive pneumococcal isolates (460 children, 85 adults) obtained from July 2018 to January 2019 were studied. All isolates were tested for susceptibility to ten antimicrobials and were characterized for serotypes, penicillin binding protein (PBP) genotypes, and macrolide resistance genes.

RESULTS

Among children, 95.0% of isolates belonged to non-13-valent pneumococcal conjugate vaccine (PCV13) serotypes (NVTs), with 15A (15.0%) being dominant, followed by 35B (12.2%), 23A (11.1%), 15B (9.8%), and 15C (9.6%). In contrast, serotype 3 (18.8%) was the most prevalent in adults, while 15A, 10A, and 23A were also common. Serotypes covered by PCV13 and 23-valent pneumococcal polysaccharide vaccine (PPSV23) in all the adult isolates were 25.9% and 48.2%, respectively. High resistance rates were observed against erythromycin, tetracycline, and clindamycin (≥62.4% children, ≥58.8% adults). Penicillin-resistant and penicillin-intermediate isolates represented 2.2% and 33.8% of all isolates, respectively. Most isolates of the three dominant NVTs 15A, 35B, and 23A were non-susceptible to penicillin. Overall, multiple drug resistance (MDR) was detected in 69.0% of all isolates, including dominant NVTs 15A, 35B, 23A, 15B, and 15C. Among all the isolates, 81.8% harbored at least one altered PBP genes, and erm(B), mef(A/E) and both these genes were found in 68.2%, 23.3%, and 6.8%, respectively. High prevalence (>90%) of erm(B) was observed in serogroup 15, and serotypes 23A, 33F, and 12F.

CONCLUSION

The present study revealed the high prevalence of NVTs 15 and 23A, and 35B showing MDR, suggesting their spread after introduction of routine PCV immunization.

Missed vaccinations and critical care admission: all you may wish to know or rediscover-a narrative review

Most vaccines are so effective that they could lead to the control/elimination of the diseases they target and directly impact on intensive care admissions or complications. This is best illustrated by the use of vaccines against Haemophilus influenzae type b, Streptococcus pneumoniae, zoster, yellow fever, Ebola virus, influenza or measles-but also by third party strategies such as maternal, toddler and care-giver immunization. However, each of these vaccine-induced protection is threatened by insufficient vaccine uptake. Here, we briefly discuss how vaccine hesitancy has led to the resurgence of diseases that were considered as controlled and explore the effect of vaccine-hesitant healthcare workers on nosocomial infections. As intensive care physicians are in charge of polymorbid patients, we briefly summarize the current recommendations for vaccinations in high-risk patients. We finally give some perspective on ongoing research, and discuss how institutional policies and intensive care physicians could play a role in increasing the impact of vaccination, overall and in intensive care units.

HEMOLYTIC UREMIC SYNDROME ASSOCIATED WITH STREPTOCOCCUS PNEUMONIAE IN PEDIATRICS: A CASE SERIES

Objective:

To describe a case series of four (4) patients with hemolytic uremic syndrome due to Streptococcus pneumoniae in a level four complexity institution in the city of Bogotá, D.C., Colombia.

Cases description:

We describe cases of four patients who presented respiratory symptoms and fever. All four patients were in regular conditions on hospital admission, after which they required intensive care and ventilatory support. Upon admission, three cases showed evidence of pleuropulmonary complication. Penicillin-sensitive Streptococcus pneumoniae was isolated in all cases. All patients presented anemia, severe thrombocytopenia, schistocytes on peripheral blood smear, and hyperazotemia. They required blood transfusion and renal replacement therapy during their hospitalization. The patients were diagnosed with hemolytic uremic syndrome due to S. pneumoniae. Three of the four patients had a progressive recovery of the renal function and were discharged after an average of 36 days of hospital stay. The remaining patient had two amputations in the extremities due to thrombotic vascular complications and was discharged after 99 days of hospital stay, requiring hemodialysis every other day.

Comments:

Hemolytic uremic syndrome due to Streptococcus pneumoniae is a rare but severe complication of invasive pneumococcal disease. Complicated pneumonia is the main condition associated with this entity. It is noteworthy the short period in which these cases were presented, considering the low annual incidence of the disease.

High Immunogenicity of the Pneumococcal Conjugated Vaccine in Immunocompromised Adults With Inflammatory Bowel Disease

INTRODUCTION

Patients with inflammatory bowel disease (IBD) are predisposed to pneumococcal infections due to their underlying disease and iatrogenic immunosuppression. Vaccination with the 13-valent pneumococcal conjugated vaccine (PCV13) is recommended, but with poor take-up and few data available. We performed an open-label, phase IV, multicenter study to evaluate the safety and immunogenicity of PCV13 in adults with IBD and to analyze the influence of immunomodulating treatments on anti-pneumococcal seroresponses.

METHODS

We enrolled 306 patients with IBD from March 2014 through February 2016, with the following exclusion criteria: current IBD flare, pregnancy, pneumococcal immunization in the previous 5 years, and influenza immunization in the previous 4 weeks. PCV13 was administered intramuscularly. Serotype-specific vaccine responses were evaluated using an opsonophagocytic assay. Adverse events were monitored by diary cards and standardized phone interviews.

RESULTS

The median seroprotection rate increased significantly from 43.9% (95% confidence interval [CI], 42.3-45.5) at inclusion to 90.4% (95% CI, 89.5-91.3%; P < 0.001) after vaccination. Patients receiving anti-tumor necrosis factor agents achieved a slightly lower seroprotection rate (from 44.5% [95% CI, 42.3%-46.8%] to 86.6% [95% CI, 84.9%-88.1%]) than patients treated with other types of immunosuppressive regimens (thiopurine, methotrexate, oral corticosteroids; from 44.7% [95% CI, 41.7%-47.7%] to 93.8% [95% CI, 92.1%-95.2%]) or nonimmunosuppressive treatment (5-aminosalicylate, topical corticosteroids, vedolizumab; from 41.3% [95% CI, 37.9%-44.8%] to 95.2% [95% CI, 93.4%-96.6%]). There were no safety issues.

DISCUSSION

Overall, the administration of PCV13 was highly immunogenic and well tolerated, irrespective of the baseline treatment, and should be encouraged in all adults with IBD.

Predictors of uptake of newly introduced vaccines in Malawi - monovalent human rotavirus and pneumococcal conjugate vaccines: Evidence from the 2015-16 Malawi demographic and health survey

OBJECTIVES

The purpose of this study was to examine the uptake and predictors of monovalent human rotavirus and pneumococcal conjugate vaccines among children of age 12-35 months in Malawi.

METHODS

This study used cross-sectional data obtained from the 2015-16 Malawi Demographic and Health Survey. Multivariate logistic regression was used to identify the factors related to uptake of pneumococcal and rotavirus vaccination.

RESULTS

The uptake of rotavirus and pneumococcal vaccines was 90.96% and 88.84%, respectively. The multivariate logistic results showed that children whose mothers had no formal education, who did not attend postnatal care for the baby within 2 months and had no vaccination card or had lost it were less likely to achieve vaccination uptake. Furthermore, children from northern region had increased odds of achieving vaccination uptake.

CONCLUSIONS

Strategies aimed at increasing further uptake of rotavirus and pneumococcal vaccines should target uneducation women to improve health knowledge on vaccination.

Bacterial Aetiologies of Lower Respiratory Tract Infections among Adults in Yaoundé, Cameroon

Lower respiratory tract infections (LRTIs) remain a challenge in African healthcare settings and only few data are available on their aetiology in Cameroon. The purpose of this study was to access the bacterial cause of LRTIs in patients in Cameroon by two methods. Methods. Participants with LRTIs were enrolled in the referral centre for respiratory diseases in Yaoundé city and its surroundings. To detect bacteria, specimens were tested by conventional bacterial culture and a commercial reverse-transcriptase real-time polymerase chain reaction (RT-PCR) assay. One hundred forty-one adult patients with LRTIs were enrolled in the study. Among the participants, 46.8% were positive for at least one bacterium. Streptococcus pneumoniae and Haemophilus influenzae were the most detected bacteria with 14.2% (20/141) followed by Klebsiella pneumoniae, 9.2% (13/141), Staphylococcus aureus, 7.1% (10/141), and Moraxella catarrhalis, 4.3% (6/141). Bacterial coinfection accounted for 23% (14/61) with Haemophilus influenzae being implicated in 19.7% (12/61). The diagnostic performance of RT-PCR for bacteria detection (43.3%) was significantly different from that of culture (17.7%) (p< 0.001). Only Streptococcus pneumoniae detection was associated with empyema by RT-PCR (p<0.001). These findings enhance understanding of bacterial aetiologies in order to improve respiratory infection management and treatment. It also highlights the need to implement molecular tools as part of the diagnosis of LRTIs.

Comparison of early effects of pneumococcal conjugate vaccines: PCV7, PCV10 and PCV13 on Streptococcus pneumoniae nasopharyngeal carriage in a population based study; The Palestinian-Israeli Collaborative Research (PICR)

Background

Pneumococcal conjugate vaccines (PCVs), PCV10 and PCV13, are currently used in different countries. We have previously reported the effectiveness of PCV7, following its introduction in Israel and before PCVs were introduced in Palestine. Here, we extended the study and compared the initial impact of PCV10 to that of PCV7/13.

Methods

Four cross-sectional surveys of S. pneumoniae carriage among children <5y through 2009–2014 were preformed among two proximate populations, living under two distinct health authorities, with different vaccination policies. In East-Jerusalem (EJ), PCV7 was implemented in 2009 and replaced by PCV13 in late 2010, while in Palestine (PA), PCV10 was implemented in 2011.

Results

A total of 1267 and 2414 children from EJ and PA were screened. In 2014, S. pneumoniae was detected in 30.7% and 28.6% of the children in EJ and PA respectively Implementation of both PCV7 (in EJ) and PCV10 (in PA) did not affect overall S. pneumoniae carriage, but resulted in a significant decrease in the prevalence of vaccine-type strains. In the pre-vaccine era, VT7/VT13 strains consisted 47.0%/62.0% and 41.2%/54.8% of pneumococci in EJ and PA, respectively. A 48.6% and 53.9% decrease in VT7 strains was observed within 3 years of PCV7 implementation in EJ (p = 0.001) and PCV10 in PA (p<0.0001), respectively. These vaccination policies also resulted in ~50% reduction in VT13-added serotypes especially 6A (from 11.0% to 0.0% (EJ) and 9.5% to 4.9% (PA)). Three years after PCV13 implementation in EJ, an additional 67% decrease in VT13 strains was observed, yet an increase in serotype 3 was observed (0.0% to 3.4%, p = 0.056). While the prevalence of VT13 strains decreased significantly during the study period, the overall carriage rate didn’t change significantly due to replacement with non-VT13 strains which comprised 89.8% and 70.7% of all pneumococci, in EJ and in PA respectively in the last study year.

Conclusions

Within the first three years following PCV implementation, we observed similar reductions in carriage of VT10 and VT13 strains with either vaccination policies, with no effect on overall carriage. Further follow-up is needed to compare the long-term effects.

Environmental and genetic modulation of the phenotypic expression of antibiotic resistance

Antibiotic resistance can be acquired by mutation or horizontal transfer of a resistance gene, and generally an acquired mechanism results in a predictable increase in phenotypic resistance. However, recent findings suggest that the environment and/or the genetic context can modify the phenotypic expression of specific resistance genes/mutations. An important implication from these findings is that a given genotype does not always result in the expected phenotype. This dissociation of genotype and phenotype has important consequences for clinical bacteriology and for our ability to predict resistance phenotypes from genetics and DNA sequences. A related problem concerns the degree to which the genes/mutations currently identified in vitro can fully explain the in vivo resistance phenotype, or whether there is a significant additional amount of presently unknown mutations/genes (genetic ‘dark matter’) that could contribute to resistance in clinical isolates. Finally, a very important question is whether/how we can identify the genetic features that contribute to making a successful pathogen, and predict why some resistant clones are very successful and spread globally? In this review, we describe different environmental and genetic factors that influence phenotypic expression of antibiotic resistance genes/mutations and how this information is needed to understand why particular resistant clones spread worldwide and to what extent we can use DNA sequences to predict evolutionary success.

Antibodies to PcpA and PhtD protect mice against Streptococcus pneumoniae by a macrophage- and complement-dependent mechanism

Currently marketed Streptococcus pneumoniae (Spn) vaccines, which contain polysaccharide capsular antigens from the most common Spn serotypes, have substantially reduced pneumococcal disease rates but have limited coverage. A trivalent pneumococcal protein vaccine containing pneumococcal choline-binding protein A (PcpA), pneumococcal histidine triad protein D (PhtD), and detoxified pneumolysin is being developed to provide broader, cross-serotype protection. Antibodies against detoxified pneumolysin protect against bacterial pneumonia by neutralizing Spn-produced pneumolysin, but how anti-PhtD and anti-PcpA antibodies protect against Spn has not been established. Here, we used a murine passive protection sepsis model to investigate the mechanism of protection by anti-PhtD and anti-PcpA antibodies. Depleting complement using cobra venom factor eliminated protection by anti-PhtD and anti-PcpA monoclonal antibodies (mAbs). Consistent with a requirement for complement, complement C3 deposition on Spn in vitro was enhanced by anti-PhtD and anti-PcpA mAbs and by sera from PhtD- and PcpA-immunized rabbits and humans. Moreover, in the presence of complement, anti-PhtD and anti-PcpA mAbs increased uptake of Spn by human granulocytes. Depleting neutrophils using anti-Ly6G mAbs, splenectomy, or a combination of both did not affect passive protection against Spn, whereas depleting macrophages using clodronate liposomes eliminated protection. These results suggest anti-PhtD and anti-PcpA antibodies induced by pneumococcal protein vaccines protect against Spn by a complement- and macrophage-dependent opsonophagocytosis.

A bivalent pneumococcal histidine triad protein D-choline-binding protein A vaccine elicits functional antibodies that passively protect mice from Streptococcus pneumoniae challenge

Vaccines based on conserved pneumococcal proteins are being investigated because serotype coverage by pneumococcal polysaccharide and polysaccharide conjugate vaccines is incomplete and may eventually decrease due to serotype replacement. Here, we examined the functionality of human antibodies induced by a candidate bivalent choline-binding protein A- pneumococcal histidine triad protein D (PcpA-PhtD) vaccine. Pre- and post-immune sera from subjects who had been vaccinated with the PcpA-PhtD candidate vaccine were tested in an established passive protection model in which mice were challenged by intravenous injection with Streptococcus pneumoniae serotype 3 strain A66.1. Serum antibody concentrations were determined by enzyme-linked immunosorbent assay (ELISA). Bacterial surface binding by serum antibodies was determined by a flow cytometry-based assay. Sera from 20 subjects were selected based on low activity of pre-immune samples in the passive protection model. Bacterial surface binding correlated more strongly with anti-PcpA (0.87; p < 0.0001) than with anti-PhtD (0.71; p < 0.0001). The odds ratio for predicting survival in the passive protection assay was higher for the anti-PcpA concentration (470 [95% confidence interval (CI), 46.8 to >999.9]) than for the anti-PhtD concentration (3.4 [95% CI, 1.9 to 5.6]) or bacterial surface binding (9.4 [95% CI, 3.6 to 24.3]). Pooled post-immune serum also protected mice against a challenge with S. pneumoniae serotype 3 strain WU2. Both anti-PcpA and anti-PhtD antibodies induced by the bivalent candidate vaccine mediate protection against S. pneumoniae. The results also showed that the ELISA titer might be useful as a surrogate for estimating the functional activity of antibodies induced by pneumococcal protein vaccines.

Pneumococcal vaccination and efficacy in patients with heterotaxy syndrome

BackgroundPneumococcal vaccines, including pneumococcal polysaccharide vaccine (PPV) and pneumococcal conjugated vaccine (PCV), are crucial in preventing invasive pneumococcal diseases. We analyzed the pneumococcal vaccination rate, efficacy, and durability in patients with heterotaxy.MethodsAll patients with heterotaxy and CCHD who were followed up at our institution between 2010 and 2015 were included. Pneumococcal vaccine status and geometric mean concentration (GMC) of serotypes 6B, 14, 19F, and 23F were analyzed. Splenic function was considered abnormal when the percentage of IgM memory B cell was less than 1%.ResultsThe GMCs of the four serotypes did not differ significantly between patients with heterotaxy and those with CCHD; the GMCs were also not affected by abnormal splenic function. Most patients had GMCs >0.35 μg/ml (protection level) 4-5 years after either PPV or PCV injection; however, it may decay gradually in some serotypes. In addition, 21.4% of 42 patients with heterotaxy did not receive pneumococcal vaccine, and none completely adhered to the vaccine guidelines.ConclusionsVaccine efficacy was acceptable, even in patients with abnormal splenic function. In some patients, the durability of PPV and PCV decreased with time, highlighting the importance of booster doses. Vaccination rate in patients with heterotaxy is unsatisfactory.

Secondary Bacterial Infections Associated with Influenza Pandemics

Lower and upper respiratory infections are the fourth highest cause of global mortality (Lozano et al., 2012). Epidemic and pandemic outbreaks of respiratory infection are a major medical concern, often causing considerable disease and a high death toll, typically over a relatively short period of time. Influenza is a major cause of epidemic and pandemic infection. Bacterial co/secondary infection further increases morbidity and mortality of influenza infection, with Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus reported as the most common causes. With increased antibiotic resistance and vaccine evasion it is important to monitor the epidemiology of pathogens in circulation to inform clinical treatment and development, particularly in the setting of an influenza epidemic/pandemic.

Impact of Pneumococcal Conjugate Vaccines on Selected Head and Neck Infections in Hospitalized Israeli Children

BACKGROUND

Streptococcus pneumoniae is a major pathogen of pediatric head and neck infections (HNIs), for example, acute otitis media (AOM), acute mastoiditis, acute bacterial sinusitis and meningitis. The aim of this study was to characterize the epidemiology of pneumococcal HNIs (pHNIs) before, during and after the introduction of pneumococcal conjugate vaccines (PCVs).

METHODS

Children 0-16 years of age, who were hospitalized with HNIs in the pediatrics department in a general hospital between January 1, 2007, and December 31, 2014, were retrospectively identified. Study years were categorized according to the PCV introduction timeline: 2007-2008: "pre-PCV years"; 2009-2011: "transition years" and 2012-2014: "post-PCV years." pHNIs episodes were defined if pneumococcal culture or urine antigen was positive. Children who received ≥2 doses of PCV7/PCV13 were considered as immunized. All other children were considered as unimmunized.

RESULTS

HNIs accounted for 2.5%-4.7% of the total admissions; 3%-17% of them were pHNIs. Eighty-seven pHNI episodes were identified: AOM (n = 42), acute mastoiditis (n = 28) and meningitis (n = 17). There was a downward trend in the overall incidence of HNIs, and particularly of pHNIs, in the post-PCV years. The average age and hospitalization duration of children with HNIs/pHNIs remained stable during the study years. In 2009-2010, pHNIs incidence sharply decreased, from 7 to 1.74/1000 hospitalized children/year, due to ~55% reduction of pneumococcal AOM episodes. An additional decrease was observed in the post-PCV years (1.62/1000 hospitalized children/year). Immunized children were less likely to present with pHNIs (P = 0.001) but were more likely to undergo surgery (P = 0.042).

CONCLUSION

We observed a reduction in pHNIs incidence after PCV program implementation.

Optimizing seroprotection against pneumococcus in children with nephrotic syndrome using the 13-valent pneumococcal conjugate vaccine

BACKGROUND

Infections are among the main life-threatening complications in patients with nephrotic syndrome (NS), in particular with Streptococcus pneumoniae, the first cause of bacterial peritonitis and sepsis in these patients. This study aims to evaluate the baseline seroprotection of NS patients against S. pneumoniae, and immunize them with the 13-valent pneumococcal conjugate vaccine (PCV13) regardless of disease activity and previous immunization history, in order to evaluate the immunogenicity, safety profile, and effect of NS treatment on vaccine responses.

METHODS

This multicentre prospective interventional study enrolled 42 children with NS at disease onset or during a regular follow-up appointment. PCV13 was administered at inclusion. Serotype-specific S. pneumoniae IgG titer were assessed at baseline, after immunization, and at 1year follow-up. Vaccine safety was evaluated clinically and by urinary tests.

RESULTS

PCV13 induced high serotype-specific IgG titers that were maintained at high levels one year after vaccination, even in children previously immunized. No serious adverse event occurred and relapse frequency was unchanged.

CONCLUSION

Given that high IgG titers were achieved and maintained after PCV13 vaccination, and considering the high morbidity related to S. pneumoniae, we propose PCV13 (re-)vaccination for all NS patients, irrespective of their previous immunization history, treatment and disease activity.

A longitudinal study of natural antibody development to pneumococcal surface protein A families 1 and 2 in Papua New Guinean Highland children: a cohort study

BACKGROUND

Pneumococcal surface protein A (PspA), a conserved virulence factor essential for Streptococcus pneumoniae attachment to upper respiratory tract (URT) epithelia, is a potential vaccine candidate for preventing colonisation.

METHODS

This cohort study was conducted in the Asaro Valley in the Eastern Highlands Province of Papua New Guinea, of which Goroka town is the provincial capital. The children included in the analysis were participants in a neonatal pneumococcal conjugate vaccine trial (ClinicalTrials.gov NCT00219401) that was conducted between 2005 and 2009. We investigated the development of anti-PspA antibodies in the first 18 months of life relative to URT pneumococcal carriage in Papua New Guinean infants who experience one of the earliest and highest colonisation rates in the world. Blood samples and nasopharyngeal swabs were collected from a cohort of 88 children at ages 3, 9, and 18 months to quantify immunoglobulin G (IgG) levels to PspA families 1 and 2 using an enzyme-linked immunosorbent assay and to determine URT carriage.

RESULTS

Seventy-three per cent (64/88) of infants carried S. pneumoniae at age 3 months; 85 % (75/88) at 9 months, and 83 % (73/88) at 18 months. PspA-IgG levels declined between ages 3 and 9 months (p < 0.001), then increased between 9 and 18 months (p < 0.001). At age 3 months, pneumococcal carriers showed lower PspA1-IgG levels (geometric mean concentration [GMC] 602 arbitrary units [AU]/ml, 95 % confidence interval [CI] 497-728) than non-carriers (GMC 1058 AU/ml [95 % CI 732-1530]; p = 0.008), while at 9 months, PspA1- and PspA2-IgG levels were significantly higher in carriers (PspA1: 186 AU/ml, 95 % CI 136-256; PspA2: 284 AU/ml, 95 % CI 192-421) than in non-carriers (PspA1 87 AU/ml, 95 % CI 45-169; PspA2 74 AU/ml, 95 % CI 34-159) (PspA1: p = 0.037, PspA2: p = 0.003).

CONCLUSION

Our findings confirm that PspA is immunogenic and indicate that natural anti-PspA immune responses are acquired through exposure and develop with age. PspA may be a useful candidate in an infant pneumococcal vaccine to prevent early URT colonisation.

Passive protection of mice against Streptococcus pneumoniae challenge by naturally occurring and vaccine-induced human anti-PhtD antibodies

Currently marketed Streptococcus pneumoniae vaccines are based on polysaccharide capsular antigens from the most common strains. Pneumococcal histidine triad protein D (PhtD) is a conserved surface protein that is being evaluated as a candidate for a vaccine with improved serotype coverage. Here, we measured the functional activity of human anti-PhtD antibodies in a passive protection model wherein mice were challenged with a lethal dose of S. pneumoniae by intravenous injection. This functional activity was compared with anti-PhtD antibody concentrations measured by enzyme-linked immunosorbent assay (ELISA) to estimate the 50% protective dose (ED50). Anti-PhtD antibodies affinity purified from pooled normal human sera passively protected mice with an ED50 of 1679 ELISA units/ml (95% confidence interval, 1420–1946). Sera from subjects injected with aluminum-adjuvanted PhtD in a phase I trial had similar activity per unit of antibody (ED50 = 1331 ELISA units/ml [95% confidence interval, 762–2038]). Vaccine-induced activity in the passive protection model was blocked by pre-incubation with recombinant PhtD but not by a control S. pneumoniae antigen (LytB). These results show that human anti-PhtD antibodies, whether naturally acquired or induced by the PhtD candidate vaccine, are functional. This supports the development of the PhtD candidate as part of a broadly protective pneumococcal vaccine.

Biomarkers of Host Response Predict Primary End-Point Radiological Pneumonia in Tanzanian Children with Clinical Pneumonia: A Prospective Cohort Study

Background

Diagnosing pediatric pneumonia is challenging in low-resource settings. The World Health Organization (WHO) has defined primary end-point radiological pneumonia for use in epidemiological and vaccine studies. However, radiography requires expertise and is often inaccessible. We hypothesized that plasma biomarkers of inflammation and endothelial activation may be useful surrogates for end-point pneumonia, and may provide insight into its biological significance.

Methods

We studied children with WHO-defined clinical pneumonia (n = 155) within a prospective cohort of 1,005 consecutive febrile children presenting to Tanzanian outpatient clinics. Based on x-ray findings, participants were categorized as primary end-point pneumonia (n = 30), other infiltrates (n = 31), or normal chest x-ray (n = 94). Plasma levels of 7 host response biomarkers at presentation were measured by ELISA. Associations between biomarker levels and radiological findings were assessed by Kruskal-Wallis test and multivariable logistic regression. Biomarker ability to predict radiological findings was evaluated using receiver operating characteristic curve analysis and Classification and Regression Tree analysis.

Results

Compared to children with normal x-ray, children with end-point pneumonia had significantly higher C-reactive protein, procalcitonin and Chitinase 3-like-1, while those with other infiltrates had elevated procalcitonin and von Willebrand Factor and decreased soluble Tie-2 and endoglin. Clinical variables were not predictive of radiological findings. Classification and Regression Tree analysis generated multi-marker models with improved performance over single markers for discriminating between groups. A model based on C-reactive protein and Chitinase 3-like-1 discriminated between end-point pneumonia and non-end-point pneumonia with 93.3% sensitivity (95% confidence interval 76.5–98.8), 80.8% specificity (72.6–87.1), positive likelihood ratio 4.9 (3.4–7.1), negative likelihood ratio 0.083 (0.022–0.32), and misclassification rate 0.20 (standard error 0.038).

Conclusions

In Tanzanian children with WHO-defined clinical pneumonia, combinations of host biomarkers distinguished between end-point pneumonia, other infiltrates, and normal chest x-ray, whereas clinical variables did not. These findings generate pathophysiological hypotheses and may have potential research and clinical utility.

A Pneumococcal Protein Array as a Platform to Discover Serodiagnostic Antigens Against Infection

Pneumonia is one of the most common and severe diseases associated with Streptococcus pneumoniae infections in children and adults. Etiological diagnosis of pneumococcal pneumonia in children is generally challenging because of limitations of diagnostic tests and interference with nasopharyngeal colonizing strains. Serological assays have recently gained interest to overcome some problems found with current diagnostic tests in pediatric pneumococcal pneumonia. To provide insight into this field, we have developed a protein array to screen the antibody response to many antigens simultaneously. Proteins were selected by experimental identification from a collection of 24 highly prevalent pediatric clinical isolates in Spain, using a proteomics approach consisting of "shaving" the cell surface with proteases and further LC/MS/MS analysis. Ninety-five proteins were recombinantly produced and printed on an array. We probed it with a collection of sera from children with pneumococcal pneumonia. From the set of the most seroprevalent antigens, we obtained a clear discriminant response for a group of three proteins (PblB, PulA, and PrtA) in children under 4 years old. We validated the results by ELISA and an immunostrip assay showed the translation to easy-to-use, affordable tests. Thus, the protein array here developed presents a tool for broad use in serodiagnostics.

Evolution of antimicrobial resistance and serotype distribution of Streptococcus pneumoniae isolated from children with invasive and noninvasive pneumococcal diseases in Algeria from 2005 to 2012

Pneumococcal infections are a major cause of morbidity and mortality in developing countries. The introduction of pneumococcal conjugate vaccines (PCVs) has dramatically reduced the incidence of pneumococcal diseases. PCVs are not currently being used in Algeria. We conducted a prospective study from 2005 to 2012 in Algeria to determine antimicrobial drug resistance and serotype distribution of Streptococcus pneumoniae from children with pneumococcal disease. Among 270 isolated strains from children, 97 (36%) were invasive disease; of these, 48% were not susceptible to penicillin and 53% not susceptible to erythromycin. A high rate of antimicrobial nonsusceptibility was observed in strains isolated from children with meningitis. The serotype distribution from pneumococci isolated from children with invasive infections was (by order of prevalence): 14, 1, 19F, 19A, 6B, 5, 3, 6A and 23F. Multidrug resistance was observed in serotypes 14, 19F, 19A and 6B. The vaccine coverage of serotypes isolated from children aged <5 years was 55.3% for PCV7, 71.1% for PCV10 and 86.8% for PCV13. Our results highlight the burden of pneumococcal disease in Algeria and the increasing S. pneumoniae antibiotic resistance. The current pneumococcal vaccines cover a high percentage of the circulating strains. Therefore, vaccination would reduce the incidence of pneumococcal disease in Algeria.

Proteomics-driven design of a multiplex bead-based platform to assess natural IgG antibodies to pneumococcal protein antigens in children

Pneumococcal surface proteins are potential candidates for the development of protein-based vaccines and serological assays. The objective of the study was to develop a multiple bead-based immunoassay using Luminex xMAP® technology for the quantitation of natural antibodies against Streptococcus pneumoniae proteins and the characterization of the acute serum response following pneumococcal pneumonia in children. Sixty-four recombinantly produced pneumococcal proteins, which were selected based on their proteomic experimental identification by "shaving" live cells with trypsin followed by LC/MS/MS analysis, were coupled to fluorescent SeroMAP® beads and anti-pneumococcal specific IgG levels were determined in sera. Multiplex assay was validated through comparison of IgG levels to 14 randomly chosen pneumococcal antigens by using multiplex and singleplex assays. Acute serum IgG levels against RrgB were significantly lower in children ≤ 4 years old with pneumococcal pneumonia than those in controls. In addition, there was a small trend toward slightly lower antibody levels for PrsA, RrgC and RrgB in pneumonia patients of the all age group.

Streptococcus pneumoniae Enhances Human Respiratory Syncytial Virus Infection In Vitro and In Vivo

Human respiratory syncytial virus (HRSV) and Streptococcus pneumoniae are important causative agents of respiratory tract infections. Both pathogens are associated with seasonal disease outbreaks in the pediatric population, and can often be detected simultaneously in infants hospitalized with bronchiolitis or pneumonia. It has been described that respiratory virus infections may predispose for bacterial superinfections, resulting in severe disease. However, studies on the influence of bacterial colonization of the upper respiratory tract on the pathogenesis of subsequent respiratory virus infections are scarce. Here, we have investigated whether pneumococcal colonization enhances subsequent HRSV infection. We used a newly generated recombinant subgroup B HRSV strain that expresses enhanced green fluorescent protein and pneumococcal isolates obtained from healthy children in disease-relevant in vitro and in vivo model systems. Three pneumococcal strains specifically enhanced in vitro HRSV infection of primary well-differentiated normal human bronchial epithelial cells grown at air-liquid interface, whereas two other strains did not. Since previous studies reported that bacterial neuraminidase enhanced HRSV infection in vitro, we measured pneumococcal neuraminidase activity in these cultures but found no correlation with the observed infection enhancement in our model. Subsequently, a selection of pneumococcal strains was used to induce nasal colonization of cotton rats, the best available small animal model for HRSV. Intranasal HRSV infection three days later resulted in strain-specific enhancement of HRSV replication in vivo. One S. pneumoniae strain enhanced HRSV both in vitro and in vivo, and was also associated with enhanced syncytium formation in vivo. However, neither pneumococci nor HRSV were found to spread from the upper to the lower respiratory tract, and neither pathogen was transmitted to naive cage mates by direct contact. These results demonstrate that pneumococcal colonization can enhance subsequent HRSV infection, and provide tools for additional mechanistic and intervention studies.

Early trends in invasive pneumococcal disease in children following the introduction of 13-valent pneumococcal conjugate vaccine: results from eight years of active surveillance in a Mexican hospital

BACKGROUND

In May 2012, universal vaccination with the 13-valent pneumococcal conjugate vaccine (PCV-13) was introduced for all children in the Tijuana region of Mexico, with a coverage of 80%.

METHOD

Between October 2005 and September 2013 active surveillance was undertaken for all invasive pneumococcal diseases (IPDs) in children admitted to the Tijuana General Hospital.

RESULTS

Following PCV-13 implementation, there was a 75% reduction in overall IPD, and no cases of serotype 19A, pneumococcal meningitis, and pneumococcal-associated deaths.

CONCLUSIONS

These results are the first to show the effectiveness of PCV-13 in Mexico.

A pilot study showing differences in glycosylation patterns of IgG subclasses induced by pneumococcal, meningococcal, and two types of influenza vaccines

The presence of a carbohydrate moiety on asparagine 297 in the Fc part of an IgG molecule is essential for its effector functions and thus influences its vaccine protective effect. Detailed structural carbohydrate analysis of vaccine induced IgGs is therefore of interest as this knowledge can prove valuable in vaccine research and design and when optimizing vaccine schedules. In order to better understand and exploit the protective potential of IgG antibodies, we carried out a pilot study; collecting serum or plasma from volunteers receiving different vaccines and determining the IgG subclass glycosylation patterns against specific vaccine antigens at different time points using LC-ESI-MS analysis. The four vaccines included a pneumococcal capsule polysaccharide vaccine, a meningococcal outer membrane vesicle vaccine, a seasonal influenza vaccine, and a pandemic influenza vaccine. The number of volunteers was limited, but the results following immunization indicated that the IgG subclass which dominated the response showed increased galactose and the level of sialic acid increased with time for most vaccinees. Fucose levels increased for some vaccinees but in general stayed relatively unaltered. The total background IgG glycosylation analyzed in parallel varied little with time and hence the changes seen were likely to be caused by vaccination. The presence of an adjuvant in the pandemic influenza vaccine seemed to produce simpler and less varied glycoforms compared to the adjuvant-free seasonal influenza vaccine. This pilot study demonstrates that detailed IgG glycosylation pattern analysis might be a necessary step in addition to biological testing for optimizing vaccine development and strategies.

Bacterial vaccines and antibiotic resistance

Spread of antibiotic resistance is mediated by clonal lineages of bacteria that besides being resistant also possess other properties promoting their success. Some vaccines already in use, such as the pneumococcal conjugate vaccines, have had an effect on these successful clones, but at the same time have allowed for the expansion and resistance evolution of previously minor clones not covered by the vaccine. Since resistance frequently is horizontally transferred it will be difficult to generate a vaccine that covers all possible genetic lineages prone to develop resistance unless the vaccine target(s) is absolutely necessary for spread and/or disease development. Targeting the resistance mechanism itself by a vaccine is an interesting but hitherto unexplored approach.

Towards New Broader Spectrum Pneumococcal Vaccines: The Future of Pneumococcal Disease Prevention

Seven-valent pneumococcal conjugate vaccine (PCV7) introduction and routine pediatric use has substantially reduced the burden of Streptococcus pneumoniae disease worldwide. However, a significant amount of disease burden, due to serotypes not contained in PCV7, still exists globally. A newly recognized serotype, 6C, was until recently, identified and reported as serotype 6A. This review summarizes the serotype epidemiology of pneumococcal disease pre- and post-introduction of PCV7, available post-marketing surveillance data following the introduction of higher valency pneumococcal vaccines (PCV10, PCV13) and future prospects for the development of new pneumococcal vaccines.

Development of Streptococcus pneumoniae Vaccines Using Live Vectors

Streptococcus pneumoniae still causes severe morbidity and mortality worldwide, especially in young children and the elderly. Much effort has been dedicated to developing protein-based universal vaccines to conquer the current shortcomings of capsular vaccines and capsular conjugate vaccines, such as serotype replacement, limited coverage and high costs. A recombinant live vector vaccine delivering protective antigens is a promising way to achieve this goal. In this review, we discuss the researches using live recombinant vaccines, mainly live attenuated Salmonella and lactic acid bacteria, to deliver pneumococcal antigens. We also discuss both the limitations and the future of these vaccines.

13-valent pneumococcal conjugate vaccine: a review of its use in infants, children, and adolescents

The 13-valent pneumococcal conjugate vaccine (Prevenar 13(®); Prevnar 13(®)) [PCV13] includes 13 serotype-specific polysaccharides of Streptococcus pneumoniae conjugated individually to non-toxic diphtheria CRM197 protein, thus providing wider coverage of pneumococcal serotypes than its 7-valent predecessor (PCV7). For pediatric populations, PCV13 was initially approved for use in infants and children up to 5 years of age, but recently received approval for expanded use (ages 6 weeks to 17 years) in the EU and the USA. This change in labeling was made primarily on the basis of results of Study 3011, which demonstrated the serotype-specific immunogenicity of a single dose of PCV13 in children ≥5 to <10 years of age who had previously received PCV7. Study 3011 also demonstrated functional immune responses after a single dose of PCV13 in a cohort ≥10 to <18 years of age who had not previously received PCV7. Importantly, prior to Study 3011, several randomized studies comparing PCV13 and PCV7 in infants and younger children demonstrated noninferiority of immune responses to the seven serotypes common to both vaccines after a two- or three-dose primary infant series and after the toddler booster dose; immunogenicity and functional immune responses were also demonstrated for the six additional serotypes. The safety and reactogenicity of PCV13 was generally similar to that of PCV7, and PCV13 did not interfere with the immune responses to coadministered routine pediatric vaccines. PCV13 is expected to substantially reduce the incidence of invasive pneumococcal diseases in a manner similar to that which occurred after PCV7 was introduced, and evidence of the protective effectiveness of PCV13 against pneumococcal diseases is emerging.

Improving the lethal effect of cpl-7, a pneumococcal phage lysozyme with broad bactericidal activity, by inverting the net charge of its cell wall-binding module

Phage endolysins are murein hydrolases that break the bacterial cell wall to provoke lysis and release of phage progeny. Recently, these enzymes have also been recognized as powerful and specific antibacterial agents when added exogenously. In the pneumococcal system, most cell wall associated murein hydrolases reported so far depend on choline for activity, and Cpl-7 lysozyme constitutes a remarkable exception. Here, we report the improvement of the killing activity of the Cpl-7 endolysin by inversion of the sign of the charge of the cell wall-binding module (from -14.93 to +3.0 at neutral pH). The engineered variant, Cpl-7S, has 15 amino acid substitutions and an improved lytic activity against Streptococcus pneumoniae (including multiresistant strains), Streptococcus pyogenes, and other pathogens. Moreover, we have demonstrated that a single 25-μg dose of Cpl-7S significantly increased the survival rate of zebrafish embryos infected with S. pneumoniae or S. pyogenes, confirming the killing effect of Cpl-7S in vivo. Interestingly, Cpl-7S, in combination with 0.01% carvacrol (an essential oil), was also found to efficiently kill Gram-negative bacteria such as Escherichia coli and Pseudomonas putida, an effect not described previously. Our findings provide a strategy to improve the lytic activity of phage endolysins based on facilitating their pass through the negatively charged bacterial envelope, and thereby their interaction with the cell wall target, by modulating the net charge of the cell wall-binding modules.

Identification of potential new protein vaccine candidates through pan-surfomic analysis of pneumococcal clinical isolates from adults

Purified polysaccharide and conjugate vaccines are widely used for preventing infections in adults and in children against the Gram-positive bacterium Streptococcus pneumoniae, a pathogen responsible for high morbidity and mortality rates, especially in developing countries. However, these polysaccharide-based vaccines have some important limitations, such as being serotype-dependent, being subjected to losing efficacy because of serotype replacement and high manufacturing complexity and cost. It is expected that protein-based vaccines will overcome these issues by conferring a broad coverage independent of serotype and lowering production costs. In this study, we have applied the “shaving” proteomic approach, consisting of the LC/MS/MS analysis of peptides generated by protease treatment of live cells, to a collection of 16 pneumococcal clinical isolates from adults, representing the most prevalent strains circulating in Spain during the last years. The set of unique proteins identified in all the isolates, called “pan-surfome”, consisted of 254 proteins, which included most of the protective protein antigens reported so far. In search of new candidates with vaccine potential, we identified 32 that were present in at least 50% of the clinical isolates analyzed. We selected four of them (Spr0012, Spr0328, Spr0561 and SP670_2141), whose protection capacity has not yet been tested, for assaying immunogenicity in human sera. All of them induced the production of IgM antibodies in infected patients, thus indicating that they could enter the pipeline for vaccine studies. The pan-surfomic approach shows its utility in the discovery of new proteins that can elicit protection against infectious microorganisms.

Burden of acute otitis media in primary care pediatrics in Italy: a secondary data analysis from the Pedianet database

BACKGROUND

The incidence of acute otitis media (AOM) vary from country to country. Geographical variations together with differences in study designs, reporting and settings play a role. We assessed the incidence of AOM in Italian children seen by primary care paediatricians (PCPs), and described the methods used to diagnose the disease.

METHODS

This secondary data analysis from the Pedianet database considered children aged 0-6 years between 01/2003 and 12/2007. The AOM episodes were identified and validated by means of patient diaries. Incidence rates/100 person-years (PY) were calculated for total AOM and for single or recurrent AOM.

RESULTS

The 92,373 children (52.1% males) were followed up for a total of 227,361 PY: 23,039 (24.9%) presented 38,241 episodes of AOM (94.6% single episodes and 5.4% recurrent episodes). The total incidence rate of AOM in the 5-year period was 16.8 episodes per 100 PY (95% CI: 16.7-16.9), including single AOM (15.9 episodes per 100 PY; 95% CI: 15.7-16.1) and recurrent AOM (0.9 episodes per 100 PY; 95% CI: 0.9-0.9). There was a slight and continuously negative trend decrease over time (annual percent change -4.6%; 95%CI: -5.3, -3.9%). The AOM incidence rate varied with age, peaking in children aged 3 to 4 years (22.2 episodes per 100 PY; 95% CI 21.8-22.7). The vast majority of the AOM episodes (36,842/38,241, 96.3%) were diagnosed using a static otoscope; a pneumatic otoscope was used in only 3.7%.

CONCLUSIONS

Our data fill a gap in our knowledge of the incidence of AOM in Italy, and indicate that AOM represents a considerable burden for the Italian PCP system. Educational programmes concerning the diagnosis of AOM are needed, as are further studies to monitor the incidence in relation to the introduction of wider pneumococcal conjugate vaccines.