Effect of pneumococcal conjugate vaccine on pneumococcal meningitis

How common is otogenic meningitis? A retrospective study in southern Sweden over 18 years

BACKGROUND

Bacterial meningitis is a rare, but life-threatening disease, which sometimes occurs as a complication to acute otitis media (AOM). The proportion of meningitis cases originating from AOM is not clear.

PURPOSE

The aim of this study was to investigate the proportion of meningitis cases caused by AOM, to compare risk factors, bacteriology and outcome between otogenic and non-otogenic meningitis, and to analyse the incidence of bacterial meningitis after the introduction of conjugate pneumococcal vaccines (PCV).

METHODS

The medical charts of all patients admitted to hospitals in southern Sweden with bacterial meningitis between 2000 and 2017 were retrieved. Based on otoscopy and/or imaging, the proportion of otogenic meningitis cases was calculated, as were annual incidences.

RESULTS

A total of 216 patients were identified, 25 of whom died. The proportion of otogenic meningitis was 31% but varied from 6% among teenagers to 40% among adults. Before PCV, 23% of all meningitis cases were children < 2 years, compared to 1% post-PCV. The average incidence in the adult population, on the other hand, increased post-PCV, though there were large annual variations. S. pneumoniae was the most commonly identified pathogen in everyone but teenagers, in whom N. meningitidis was predominant.

CONCLUSION

AOM is an important cause of meningitis in children and adults. Though bacterial meningitis almost disappeared in children < 2 years after the introduction of PCV, the incidence of pneumococcal meningitis in adults seems to have increased.

Meningitis in Children: Still a Can't-Miss Diagnosis

Although vaccination and antimicrobial treatment have significantly impacted the frequency and outcomes of meningitis in children, meningitis remains a critical can't-miss diagnosis for children, where early recognition and appropriate treatment can improve survival and neurologic outcomes. Signs and symptoms may be nonspecific, particularly in infants, and require a high index of suspicion to recognize potential meningitis and obtain the cerebrospinal fluid studies necessary for diagnosis. Understanding the pathogens associated with each age group and specific risk factors informs optimal empirical antimicrobial therapy. Early treatment and developmental support can significantly improve the survival rates and lifelong neurodevelopment of children with central nervous system infections.

Distinguishing community-acquired bacterial and viral meningitis: Microbes and biomarkers

Diagnostic tools to differentiate between community-acquired bacterial and viral meningitis are essential to target the potentially lifesaving antibiotic treatment to those at greatest risk and concurrently spare patients with viral meningitis from the disadvantages of antibiotics. In addition, excluding bacterial meningitis and thus decreasing antibiotic consumption would be important to help reduce antimicrobial resistance and healthcare expenses. The available diagnostic laboratory tests for differentiating bacterial and viral meningitis can be divided microbiological pathogen-focussed methods and biomarkers of the host response. Bacterial culture-independent microbiological methods, such as highly multiplexed nucleic acid amplification tests, are rapidly making their way into the clinical practice. At the same time, more conventional host protein biomarkers, such as procalcitonin and C-reactive protein, are supplemented by newer proteomic and transcriptomic signatures. This review aims to summarise the current state and the recent advances in diagnostic methods to differentiate bacterial from viral meningitis.

Specific inhibition on PAI-1 reduces the dose of Alteplase for ischemic stroke treatment

Administration of recombinant tPA (rtPA, or trade name Alteplase®) is an FDA-approved therapy for acute ischemic stroke (AIS), but poses the risk of hemorrhagic complications. Recombinant tPA can be rapidly inactivated by the endogenous inhibitor, plasminogen activator inhibitor 1 (PAI-1). In this work, we study a novel treatment approach that combines a PAI-1 inhibitor, PAItrap4, with a reduced dose of rtPA to address the hemorrhagic concern of rtPA. PAItrap4 is a highly specific and very potent protein-based inhibitor of PAI-1, comprising of a variant of uPA serine protease domain, human serum albumin, and a cyclic RGD peptide. PAItrap4 efficiently targets and inhibits PAI-1 on activated platelets, and also possesses a long half-life in vivo. Our results demonstrate that PAItrap4 effectively counteracts the inhibitory effects of PAI-1 on rtPA, preserving rtPA activity based on amidolytic and clot lysis assays. In an in vivo murine stroke model, PAItrap4, together with low-dose rtPA, enhances the blood perfusion in the stroke-affected areas, reduces infarct size, and promotes neurological recovery in mice. Importantly, such treatment does not increase the amount of cerebral hemorrhage, thus reducing the risk of cerebral hemorrhage. In addition, PAItrap4 does not compromise the normal blood coagulation function in mice, demonstrating its safety as a therapeutic agent. These findings highlight this combination therapy as a promising alternative for the treatment of ischemic stroke, offering improved safety and efficacy.

Robust Immune Response and Protection against Lethal Pneumococcal Challenge with a Recombinant BCG-PspA-PdT Prime/Boost Scheme Administered to Neonatal Mice

Pneumococcal diseases are an important public health problem, with high mortality rates in young children. Although conjugated pneumococcal vaccines offer high protection against invasive pneumococcal diseases, this is restricted to vaccine serotypes, leading to serotype replacement. Furthermore, the current vaccines do not protect neonates. Therefore, several protein-based pneumococcal vaccines have been studied over the last few decades. Our group established a recombinant BCG expressing rPspA-PdT as a prime/rPspA-PdT boost strategy, which protected adult mice against lethal intranasal pneumococcal challenge. Here, we immunized groups of neonate C57/Bl6 mice (6-10) (at 5 days) with rBCG PspA-PdT and a boost with rPspA-PdT (at 12 days). Controls were saline or each antigen alone. The prime/boost strategy promoted an IgG1 to IgG2c isotype shift compared to protein alone. Furthermore, there was an increase in specific memory cells (T and B lymphocytes) and higher cytokine production (IFN-γ, IL-17, TNF-α, IL-10, and IL-6). Immunization with rBCG PspA-PdT/rPspA-PdT showed 100% protection against pulmonary challenge with the WU2 pneumococcal strain; two doses of rPspA-PdT showed non-significant protection in the neonates. These results demonstrate that a prime/boost strategy using rBCG PspA-PdT/rPspA-PdT is effective in protecting neonates against lethal pneumococcal infection via the induction of strong antibody and cytokine responses.

The Risk of Meningitis After Cochlear Implantation: A Systematic Review and Meta-Analysis

OBJECTIVE

This study aims to estimate the rate of postoperative meningitis (both immediate and long-term) in patients following cochlear implants (CIs). It aims to do so through a systematic review and meta-analysis of published studies tracking complications after CIs.

DATA SOURCES

MEDLINE, Embase, and Cochrane Library.

REVIEW METHODS

This review was performed in line with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies tracking complications following CIs in patients were included. Exclusion criteria included non-English language studies and case series reporting <10 patients. Bias risk was evaluated using the Newcastle-Ottawa Scale. Meta-analysis was performed through DerSimonian and Laird random-effects models.

RESULTS

A total of 116/1931 studies met the inclusion criteria and were included in the meta-analysis. Overall, there were 112 cases of meningitis in 58,940 patients after CIs. Meta-analysis estimated an overall rate of postoperative meningitis of 0.07% (95% confidence interval [CIs], 0.03%-0.1%; I2  = 55%). Subgroup meta-analysis showed this rate had 95% CIs crossing 0% in implanted patients who received the pneumococcal vaccine, antibiotic prophylaxis, those with postoperative acute otitis media (AOM), and those implanted less than 5 years.

CONCLUSION

Meningitis is a rare complication following CIs. Our estimated rates of meningitis after CIs appear lower than prior estimates based on epidemiological studies in the early 2000s. However, the rate still appears higher than the baseline rate in the general population. The risk was very low in implanted patients who received the pneumococcal vaccine, antibiotic prophylaxis, received unilateral or bilateral implantations, developed AOM, those implanted with a round window or cochleostomy techniques, and those under 5 years.

Cost-effectiveness analysis of PCV20 to prevent pneumococcal disease in the Canadian pediatric population

This study assessed the cost-effectiveness of the 20-valent pneumococcal conjugate vaccine (PCV20) in Canadian infants aged <2 years versus the standard of care (SoC), a 13-valent pneumococcal conjugate vaccine (PCV13), or a potential 15-valent pneumococcal conjugate vaccine (PCV15). A decision-analytic Markov model was developed to compare PCV20 with PCV13 or PCV15 in a 2 + 1 schedule over 10 years. Vaccine effect estimates (direct and indirect) across all ages were informed by PCV13 clinical effectiveness and impact studies as well as PCV7 efficacy studies. Epidemiologic, clinical, health state utilities, utility decrements, cost per event, and list price data were from Canadian sources where available. Clinical and economic outcomes related to invasive pneumococcal disease (IPD), hospitalized and non-hospitalized pneumonia, and simple and complex otitis media (OM) were calculated for each strategy. Cost-effectiveness was evaluated from the publicly funded healthcare system perspective. Over 10 years, PCV20 versus PCV13 was estimated to avert over 11,000 IPD cases, 316,000 hospitalized and non-hospitalized pneumonia cases, 335,000 simple and complex OM cases, and 15,000 deaths, resulting in cost savings of over 3.2 billion Canadian dollars (CAD) and 47,000 more quality-adjusted life years (i.e. dominant strategy). Compared with PCV15, PCV20 was estimated to result in over 1.4 billion CAD in cost savings and 21,000 more QALYs (i.e. dominant strategy). PCV20 was dominant over both PCV13 and PCV15. Given broader serotype coverage, substantial incremental benefits and cost-savings, PCV20 should be considered as a replacement for the SoC in the publicly funded Canadian infant immunization program.

Pneumonia hospitalization after introduction of pneumococcal conjugate vaccine in Japan: Descriptive study using a nationwide claims database

BACKGROUND

The pneumococcal conjugate vaccine (PCV) was introduced to children in Japan in February 2010 for PCV7 and February 2013 for PCV13. This study aimed to investigate the changes in child pneumonia hospitalization in Japan, before and after the introduction of PCV.

METHODS

We utilized the JMDC Claims Database, an insurance claims database in Japan, with a cumulative population of approximately 10.6 million as of 2022. We extracted data of approximately 3.16 million children below 15 years of age from January 2006 to December 2019, and evaluated the number of pneumonia hospitalizations per 1,000 persons per year. The primary analysis was a comparison of three categories according to PCVs: before PCV7, before PCV13, and after PCV13 (2006-2009, 2010-2012, and 2013-2019). The secondary analysis was an interrupted time series (ITS) analysis, assessing the slope change in pneumonia hospitalizations per month, with PCV introduction as an intervening factor.

RESULTS

The cases of pneumonia hospitalizations during the study period was 19,920 (0.6 %); 25 % of these were 0-1 years, 48 % were 2-4 years, 18 % were 5-9 years, and 9 % were 10-14 years. Pneumonia hospitalizations per 1000 population was 6.10 before PCV7 and 4.03 after PCV13, representing a 34 % decrease (p < 0.001). The reduction by age group was -30.1 % in 0-1 years, -20.3 % in 2-4 years, -41.7 % in 5-9 years, and -52.9 % in 10-14 years, significant reduction in all groups. ITS analysis showed a further reduction of -0.17 % per month after the introduction of PCV13 than that before PCV7 (p = 0.006).

CONCLUSION

Our study estimated 4-6 pneumonia hospitalizations per 1000 pediatric population in Japan, with a 34 % decrease after the introduction of PCV. This study examined the nationwide effectiveness of PCV, further studies are needed in all age groups.

The Success of Resident-Associated Lumbar Punctures at a Large, Single-Center Children's Hospital

OBJECTIVES

The frequency of lumbar punctures (LPs) has declined across US children's hospitals over the past decade, potentially decreasing procedural learning opportunities for pediatric resident trainees. Our study sought to determine whether the proportion of successful LPs performed by our pediatric residents has significantly changed over time.

METHODS

This study is a single-center retrospective study to evaluate our pediatric resident LP success. We evaluated our primary outcome, proportion of overall LP success over time, using linear regression. We similarly used linear regression for proportion of successful resident-associated LPs over time. We calculated the median number of LPs of all pediatric residents during the study period.

RESULTS

We analyzed 3143 LPs from April 2012 to December 2019. Both the overall number of LPs performed and the proportion of LPs that were successful have not significantly changed over an 8-year period ( P > 0.05, P > 0.05). Similarly, the number of our resident-associated LPs and the proportion of successful resident-associated LPs have not changed over the study period ( P > 0.05, P > 0.05). Our pediatric residents performed a median of 3 LPs (interquartile range: 2-4) in the pediatric emergency department (PED) over residency.

CONCLUSIONS

Despite national trends showing decreased LP rates at pediatric hospitals, we demonstrated stable proportions of LPs and success by our pediatric residents. Pediatric residents perform a relatively low number of LPs in the PED setting alone. Future research is needed to demonstrate whether these overall low numbers in the PED translate to procedural competency after residency graduation.

Rothia from the Human Nose Inhibit Moraxella catarrhalis Colonization with a Secreted Peptidoglycan Endopeptidase

Moraxella catarrhalis is found almost exclusively within the human respiratory tract. This pathobiont is associated with ear infections and the development of respiratory illnesses, including allergies and asthma. Given the limited ecological distribution of M. catarrhalis, we hypothesized that we could leverage the nasal microbiomes of healthy children without M. catarrhalis to identify bacteria that may represent potential sources of therapeutics. Rothia was more abundant in the noses of healthy children compared to children with cold symptoms and M. catarrhalis. We cultured Rothia from nasal samples and determined that most isolates of Rothia dentocariosa and "Rothia similmucilaginosa" were able to fully inhibit the growth of M. catarrhalis in vitro, whereas isolates of Rothia aeria varied in their ability to inhibit M. catarrhalis. Using comparative genomics and proteomics, we identified a putative peptidoglycan hydrolase called secreted antigen A (SagA). This protein was present at higher relative abundance in the secreted proteomes of R. dentocariosa and R. similmucilaginosa than in those from non-inhibitory R. aeria, suggesting that it may be involved in M. catarrhalis inhibition. We produced SagA from R. similmucilaginosa in Escherichia coli and confirmed its ability to degrade M. catarrhalis peptidoglycan and inhibit its growth. We then demonstrated that R. aeria and R. similmucilaginosa reduced M. catarrhalis levels in an air-liquid interface culture model of the respiratory epithelium. Together, our results suggest that Rothia restricts M. catarrhalis colonization of the human respiratory tract in vivo. IMPORTANCE Moraxella catarrhalis is a pathobiont of the respiratory tract, responsible for ear infections in children and wheezing illnesses in children and adults with chronic respiratory diseases. Detection of M. catarrhalis during wheezing episodes in early life is associated with the development of persistent asthma. There are currently no effective vaccines for M. catarrhalis, and most clinical isolates are resistant to the commonly prescribed antibiotics amoxicillin and penicillin. Given the limited niche of M. catarrhalis, we hypothesized that other nasal bacteria have evolved mechanisms to compete against M. catarrhalis. We found that Rothia are associated with the nasal microbiomes of healthy children without Moraxella. Next, we demonstrated that Rothia inhibit M. catarrhalis in vitro and on airway cells. We identified an enzyme produced by Rothia called SagA that degrades M. catarrhalis peptidoglycan and inhibits its growth. We suggest that Rothia or SagA could be developed as highly specific therapeutics against M. catarrhalis.

Risk factors and pathogen characteristics associated with unfavorable outcomes among adults with pneumococcal meningitis in Japan, 2006 to 2016

PURPOSE

In this study, we aimed to clarify the risk factors associated with unfavorable outcomes in adults with pneumococcal meningitis (PnM).

METHODS

Surveillance was conducted between 2006 and 2016. Adults with PnM (n = 268) were followed up for outcomes within 28 days after admission using the Glasgow Outcome Scale (GOS). After classifying the patients into the unfavorable (GOS1-4) and favorable (GOS5) outcome groups, i) the underlying diseases, ii) biomarkers at admission, and iii) serotype, genotype, and antimicrobial susceptibility for all isolates were compared between both groups.

RESULTS

Overall, 58.6% of patients with PnM survived,15.3% died, and 26.1% had sequelae. The number of living days in the GOS1 group was highly heterogeneous. Motor dysfunction, disturbance of consciousness, and hearing loss were the commonest sequelae. Of the underlying diseases identified in 68.9% of the PnM patients, liver and kidney diseases were significantly associated with unfavorable outcomes. Of the biomarkers, creatinine and blood urea nitrogen, followed by platelet and C-reactive protein had the most significant associations with unfavorable outcomes. There was a significant difference in the high protein concentrations in the cerebrospinal fluid between the groups. Serotypes 23F, 6C, 4, 23A, 22F, 10A, and 12F were associated with unfavorable outcomes. These serotypes were not penicillin-resistant isolates possessing three abnormal pbp genes (pbp1a, 2x, and 2b), except for 23F. The expected coverage rate of the pneumococcal conjugate vaccine (PCV) was 50.7% for PCV15 and 72.4% for PCV20.

CONCLUSIONS

In the introduction of PCV for adults, the risk factors for underlying diseases should be prioritized over age, and serotypes with unfavorable outcomes should be considered.

Synergistic regulation of microglia differentiation by CD93 and integrin β1 in the rat pneumococcal meningitis model

Streptococcus pneumoniae is the main bacterial pathogen of meningitis worldwide, which has a high mortality rate and survivors are prone to central nervous system (CNS) sequelae. In this regard, microglia activation has been associated with injury to the CNS. The aim of this study was to investigate the relationship between CD93, integrin β1, and microglia activation. In the rat pneumococcal meningitis model, we found significant increases of CD93 and integrin β1 expression and differentiation of M1 phenotype microglia. Furthermore, we showed in vitro siRNA-mediated downregulation of CD93 and integrin β1 expression after infecting highly aggressive proliferating immortalized (HAPI) microglia cells with S. pneumoniae. We observed differentiation of S. pneumonia-infected HAPI microglia cells to the M1 phenotype and significant release of soluble CD93 (sCD93) and integrin β1 expression. Complement C1q and metalloproteinases promoted sCD93 release. We also showed that downregulation of CD93 significantly reduced differentiation to M1 microglia and increased differentiation to M2 microglia. However, addition of recombinant CD93 may regulate microglia differentiation to the M1 phenotype. Furthermore, the downregulation of integrin β1 resulted in downregulation of the CD93 protein. In conclusion, interaction between integrin β1 and CD93 promotes differentiation of microglia to the M1 phenotype, increases the release of pro-inflammatory factors, and leads to nervous system injury in pneumococcal meningitis.

Immunostimulants for preventing respiratory tract infection in children: A systematic review and meta-analysis

Childhood acute respiratory tract infections (ARTIs) are a significant cause of morbidity and mortality, so, immunostimulants have been used as a preventative measure. Despite this, there is no updated evidence regarding the safety and efficacy of immunostimulant drugs for this purpose. This study aimed to determine the effectiveness and safety of immunostimulants in preventing ARTIs in children based on the most recent scientific evidence. Data sources such as PubMed, Cochrane Central Register of Controlled Trials, Embase, Google Scholar, and Scopus were searched from 1965 to 10 January 2022 to identify randomized controlled trials (RCTs) comparing immunostimulants administered by any method, with placebo to prevent ARTIs on children under 18 years of age without immunodeficiencies, anatomical, genetic, or allergic conditions. In order to analyze data from the studies, we used Review Manager 5.4 (The Cochrane Collaboration, 2020), assessed the certainty of the evidence with Grading of Recommendations, Assessment, Development and Evaluations (GRADE), and assessed the quality and risk of bias of the studies using the RoB tool 1.0. Further, outcomes were combined and analyzed using meta-analysis, subgroup analysis, and sensitivity analysis. Throughout the review, we included 72 placebo-controlled clinical trials involving 12,229 children. The meta-analyses, however, included only 38 studies (52.8%) with 4643 children (38% of the total) with data on mean number of ARTIs. These studies demonstrated a reduction in the ARTIs (MD –1.12 [95%CI –1.39 to −0.85]) and ratio of means of ARTIs (0.61 [95%CI 0.54–0.69]), corresponding to a percentage reduction of 39% (95%CI, 46%–31%) with moderate-quality data. Nevertheless, since there was considerable to substantial heterogeneity and bias was unclear in all domains in 32 out of 72 trials, the quality of the evidence for efficacy was deemed low. Only 14 trials reported adverse events.

The review indicates that immunostimulants reduce the incidence of ARTIs by 40% on average in susceptible children, despite low-quality evidence, heterogeneity, and the possibility of publication bias. However, further studies are needed to establish immunostimulants' safety and efficacy profiles.

This review was conducted without the support of any funding and has no registered number.

Streptococcus pneumoniae vaccination strategies and its expected impact on penicillin non-susceptibility in children under the age of five: Let's recap!

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The efficacy of PCVs currently used in children under 5 years of age is threatened by the emergence of invasive and resistant non-vaccine serotypes worldwide.

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Resistant NVT strains are emerging in IPD in children < 5 years mainly serotypes 24F, 15A, 11A and 33F along with serotype 19A in PCV-10 settings.

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Continuous surveillance is necessary in IPD in children under five to monitor the long-term effect of PCV-10 and PCV-13 on penicillin resistance trends.

The impact of pneumococcal conjugate vaccines (PCVs) on invasive pneumococcal disease (IPD) burden has been extensively studied in children aged<5 years; however, a pooled estimation of the effect of PCVs on penicillin non-susceptible pneumococci (PNSP) has not yet been performed. We aimed to identify whether the introduction of PCV-10 and PCV-13 had led to the decrease of the overall PNSP rate in children < 5 years. We conducted a systematic review of published surveillance studies reporting the rate of PNSP rates in children < 5 in countries where PCV10/13 were introduced. The overall observed trend onwards the introduction of PCV-10 and PCV-13 is a decrease in PNSP among children < 5 years in surveillance sites located in PCV-13 countries. We identified an increase of PNSP rates (serotype 19A) in PCV-10 settings. Resistant NVT strains are emerging in IPD in children < 5 years mainly serotypes 24F, 15A, 11A and 33F along with serotype 19A in PCV-10 settings. Continuous surveillance is necessary in IPD in children under five to monitor the long-term effect of PCV-10 and PCV-13 on penicillin resistance trends.

Recognition and Outcomes of Pneumococcal Meningitis in 2 Tertiary Pediatric Hospitals Since the Introduction of the 13-Valent Pneumococcal Conjugate Vaccine

OBJECTIVES

The aims of the study were to analyze the demographics, presentation, laboratory findings, and complications of pediatric Streptococcus pneumoniae meningitis since the introduction of the 13-valent pneumococcal conjugate vaccine, to improve recognition, and to minimize patient morbidity and mortality.

METHODS

This study used a retrospective analysis of pediatric pneumococcal meningitis cases at 2 tertiary healthcare systems in the Southeastern United States from 2010 to 2018.

RESULTS

We describe 21 cases of pneumococcal meningitis. All patients presented with fever, 95% had altered mental status by history or examination, and 48% had meningeal signs. Forty-three percent had seen another provider within 48 hours of admission. Forty-eight percent had delay in lumbar puncture (LP) of more than 6 hours after antibiotic administration, decreasing rates of positive cerebrospinal fluid cultures from 100% to 40% (P < 0.001). Decision to delay LP was due to either low suspicion for meningitis (n = 4) or clinical instability (n = 6) and was associated with lower rates of meningeal signs (P = 0.014) and higher rates of altered mental status on examination (P = 0.031). Fourteen patients (67%) were up-to-date on pneumococcal immunization. Serotypes were determined in 16 cases, with 2 patients (13%) immunized against the strain that infected them. Primary outcomes included seizures (48%), hearing loss (48%), cranial nerve palsy (33%), and death (5%). Delay in LP with low suspicion for meningitis was associated with longer hospital length of stay approaching statistical significance (P = 0.053).

CONCLUSIONS

Pneumococcal meningitis remains a relevant and potentially fatal disease despite widespread use of 13-valent pneumococcal conjugate vaccine. Its diagnosis is often delayed during interactions with physicians, which may put patients at increased risk for poor clinical outcomes.

Mucosal vaccines: wisdom from now and then

The oral and nasal cavities are covered by the mucosal epithelium that starts at the beginning of the aero-digestive tract. These mucosal surfaces are continuously exposed to environmental antigens including pathogens and allergens and are thus equipped with a mucosal immune system that mediates initial recognition of pathogenicity and initiates pathogen-specific immune responses. At the dawn of our scientific effort to explore the mucosal immune system, dental science was one of the major driving forces as it provided insights into the importance of mucosal immunity and its application for the control of oral infectious diseases. The development of mucosal vaccines for the prevention of dental caries was thus part of a novel approach that contributed to building the scientific foundations of the mucosal immune system. Since then, mucosal immunology and vaccines have gone on a scientific journey to become one of the major entities within the discipline of immunology. Here, we introduce our past and current efforts and future directions for the development of mucosal vaccines, specifically a rice-based oral vaccine (MucoRice) and a nanogel-based nasal vaccine, with the aim of preventing and controlling gastrointestinal and respiratory infectious diseases using the interdisciplinary fusion of mucosal immunology with agricultural science and biomaterial engineering, respectively.

Epidemiology of non-vaccine serotypes of Streptococcus pneumoniae before and after universal administration of pneumococcal conjugate vaccines

The universal administration of pneumococcal conjugate vaccines (PCVs) had been demonstrated as an effective way to prevent Streptococcus pneumoniae infection. However, the immunity induced by PCVs protected against the infections caused by vaccine serotypes, which were usually more frequent than non-vaccine serotypes (NVTs). The prevalence and pathogenicity of NVTs after universal vaccination have caused widespread concern. We reviewed the epidemiology of non-PCV13 S. pneumoniae before and after PCV13 introduction, and explored the potential reasons for the spread of NVTs. Emerging and spreading NVTs can be regarded as the focus for future serotype epidemiological survey and vaccine optimization.AbbreviationsIPD: invasive pneumococcal disease PCV: pneumococcal conjugate vaccines VT: vaccine serotypeNVT: non-vaccine serotype.

Epidemiology of Pediatric Meningitis in South Korea From 2010 to 2018: A Population-based Retrospective Cohort Study

BACKGROUND

Studies evaluating the epidemiology of pediatric meningitis are limited in our region. This study aimed to describe recent trends in the incidence of pediatric meningitis.

METHODS

We estimated national trends in hospitalization rates for pediatric meningitis (<18 years) by analyzing data from the Health Insurance Review and Assessment database between 2010 and 2018. Meningitis cases were identified based on International Classification of Diseases, Tenth Revision (ICD-10) codes and hospitalization rates were calculated.

RESULTS

In this national population-based study, a total of 119,644 hospitalizations and 58 deaths due to pediatric meningitis were identified. The hospitalization rates of pediatric bacterial meningitis have declined by 50.0%, from 3.4 per 100,000 in 2010 to 1.7 per 100,000 in 2018. The mortality rates for bacterial and viral meningitis were 2.0% and 0.002%, respectively. Despite the decreased annual incidence of bacterial meningitis, its mortality rate did not change significantly during the study period. The only risk factor identified for mortality in bacterial meningitis patients among age group, sex, region of residence, and season was age below 1 year (P < 0.001). As children under 1 year have a high-mortality rate (4.2%), patients in this age group require close monitoring. The reasons behind indistinct seasonal patterns of bacterial meningitis warrant further investigation.

CONCLUSIONS

Childhood bacterial meningitis has shown a significant decline in incidence from 2010 to 2018. In contrast, viral meningitis has not shown a trend over time. Knowledge of these changes may aid clinicians in the decision-making process and management of meningitis patients.

Pneumococcal Carriage in Burkina Faso After 13-Valent Pneumococcal Conjugate Vaccine Introduction: Results From 2 Cross-sectional Population-Based Surveys

Background

Burkina Faso, a country in Africa’s meningitis belt, introduced 13-valent pneumococcal conjugate vaccine (PCV13) in October 2013, with 3 primary doses given at 8, 12 and 16 weeks of age. To assess whether the new PCV13 program controlled pneumococcal carriage, we evaluated overall and serotype-specific colonization among children and adults during the first 3 years after introduction.

Methods

We conducted 2 population-based, cross-sectional, age-stratified surveys in 2015 and 2017 in the city of Bobo-Dioulasso. We used standardized questionnaires to collect sociodemographic, epidemiologic, and vaccination data. Consenting eligible participants provided nasopharyngeal (all ages) and oropharyngeal (≥5 years only) swab specimens. Swab specimens were plated onto blood agar either directly (2015) or after broth enrichment (2017). Pneumococci were serotyped by conventional multiplex polymerase chain reaction. We assessed vaccine effect by comparing the proportion of vaccine-type (VT) carriage among colonized individuals from a published baseline survey (2008) with each post-PCV survey.

Results

We recruited 992 (2015) and 1005 (2017) participants. Among children aged <5 years, 42.8% (2015) and 74.0% (2017) received ≥2 PCV13 doses. Among pneumococcal carriers aged <1 year, VT carriage declined from 55.8% in 2008 to 36.9% in 2017 (difference, 18.9%; 95% confidence interval, 1.9%–35.9%; P = .03); among carriers aged 1–4 years, VT carriage declined from 55.3% to 31.8% (difference, 23.5%; 6.8%–40.2%; P = .004); and among participants aged ≥5 years, no significant change was observed.

Conclusion

Within 3 years of PCV13 implementation in Burkina Faso, we documented substantial reductions in the percentage of pneumococcal carriers with a VT among children aged <5 years, but not among persons aged ≥5 years. More time, a change in the PCV13 schedule, or both, may be needed to better control pneumococcal carriage in this setting.

Identifying UK travellers at increased risk of developing pneumococcal infection: a novel algorithm

BACKGROUND

In 2016, the travel subcommittee of the UK Joint Committee on Vaccination and Immunisation (JCVI) recommended that 13-valent PCV (PCV13) could be offered to travellers aged over 65 years, visiting countries without infant PCV immunization programmes. This study aimed to identify, collate and review the available evidence to identify specific countries where UK travellers might be at an increased risk of developing pneumococcal infection. The data were then used to develop an algorithm, which could be used to facilitate implementation of the JCVI recommendation.

METHODS

We conducted a systematic search of the published data available for pneumococcal disease, PCV vaccine implementation, coverage data and programme duration by country. The primary data sources used were World Health Organization databases and the International Vaccine Access Centre Vaccine Information and Epidemiology Window-hub database. Based on the algorithm, the countries were classified into 'high overall risk', 'intermediate overall risk' and 'low overall risk' from an adult traveller perspective. This could determine whether PCV13 should be recommended for UK adult travellers.

RESULTS

A data search for a total of 228 countries was performed, with risk scores calculated for 188 countries. Overall, 45 countries were classified as 'high overall risk', 86 countries as 'intermediate overall risk', 57 countries as 'low overall risk' and 40 countries as 'unknown'.

CONCLUSION

To our knowledge this is the first attempt to categorize the risk to UK adult travellers of contracting pneumococcal infection in each country, globally. These findings could be used by national travel advisory bodies and providers of travel vaccines to identify travellers at increased risk of pneumococcal infection, who could be offered PCV immunization.

Delays in Diagnosis and Treatment of Bacterial Meningitis in NYC: Retrospective Cohort Analysis

Community-acquired bacterial meningitis (CABM) morbidity and mortality remains high in those infected. Rapid diagnosis and treatment is paramount to reducing mortality and improving outcome. This retrospective cohort study aims to assess the time from presentation to diagnosis and treatment of vaccine preventable CABM as well as identify possible factors associated with delays in diagnosis and antibiotic administration. A retrospective chart review was conducted of individuals who presented to Columbia University Irving Medical Center (CUIMC), Children’s Hospital of New York (CHONY), Mount Sinai Medical Center, and Weill Cornell Medical Center with BM due to Haemophilus influenzae type B, Streptococcus pneumoniae, and Neisseria meningitidis between January 1, 2012 and December 31, 2017. Diagnosis was delayed by more than 8 hours in 13 patients (36.1%) and 5 individuals (13.9%) had a delay of 4 hours or more from presentation to the administration of antibiotics with appropriate CNS coverage. All of these patients were also initially misdiagnosed at an outpatient clinic, outside hospital, or emergency department. This retrospective study identified febrile and/or viral infections not otherwise specified and otitis media as the most common misdiagnoses underlying delays from presentation to diagnosis and to antibiotic treatment in those with BM.

Impact of vaccination on carriage of and infection by antibiotic-resistant bacteria: a systematic review and meta-analysis

This systematic review and meta-analysis aims to quantify the impact of vaccination on the incidence and prevalence of nonsusceptible infections and investigates the impact of vaccination programs on serotype replacement. We searched a comprehensive set of databases. Identified studies were assessed using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach and resulting evidence was analyzed using random-effect meta-analyses. Nineteen studies on pneumococcal conjugate vaccines (PCV) met our inclusion criteria. PCV decreases the incidence of nonsusceptible pneumococcal infections (PIs) by 56.91% (95% confidence interval [CI], −50.90% to −62.91%) and the probability of carriage of nonsusceptible pneumococcal bacteria by 28.10% (95% CI, −13.25% to −42.95%). The effect of PCV on PIs becomes higher when only serotypes specifically targeted by the vaccine are taken into account (−80.98%; 95% CI, −70.34% to −91.52%), while it becomes lower when all the PIs, including both susceptible and nonsusceptible PIs, are considered (−48.30%; 95% CI, −31.55% to −65.08%). The effect of PCV is found greater in populations with high prevalence of human immunodeficiency virus and for PCV covering a higher number of serotypes. Findings from this study suggest that vaccination programs may be an effective tool to prevent the spread of PIs and may play a significant role in tackling antimicrobial resistance.

Synthesis and delivery of Streptococcus pneumoniae capsular polysaccharides by recombinant attenuated Salmonella vaccines

Pneumococcal infection-caused diseases are responsible for substantial morbidity and mortality worldwide. Traditional pneumococcal vaccines are developed based on purified capsular polysaccharides (CPS) or CPS conjugated to a protein carrier. Production processes of the traditional vaccines are laborious, and thereby increase the vaccine cost and limit their use in developing nations. A cost-effective pneumococcal vaccine using the recombinant attenuated Salmonella vaccine (RASV) was developed in this study. We cloned and expressed genes for seven serotypes of CPSs in the RASV strain. The RASV-delivered CPSs induced robust humoral and cell-mediated responses and mediated efficient protection of mice against pneumococcal infection. Our work provides an innovative strategy for mass producing low-cost bioconjugated polysaccharide vaccines for needle-free mucosal delivery against pneumococcal infections.

Streptococcus pneumoniae capsular polysaccharides (CPSs) are major determinants of bacterial pathogenicity. CPSs of different serotypes form the main components of the pneumococcal vaccines Pneumovax, Prevnar7, and Prevnar13, which substantially reduced the S. pneumoniae disease burden in developed countries. However, the laborious production processes of traditional polysaccharide-based vaccines have raised the cost of the vaccines and limited their impact in developing countries. The aim of this study is to develop a kind of low-cost live vaccine based on using the recombinant attenuated Salmonella vaccine (RASV) system to protect against pneumococcal infections. We cloned genes for seven different serotypes of CPSs to be expressed by the RASV strain. Oral immunization of mice with the RASV-CPS strains elicited robust Th1 biased adaptive immune responses. All the CPS-specific antisera mediated opsonophagocytic killing of the corresponding serotype of S. pneumoniae in vitro. The RASV-CPS2 and RASV-CPS3 strains provided efficient protection of mice against challenge infections with either S. pneumoniae strain D39 or WU2. Synthesis and delivery of S. pneumoniae CPSs using the RASV strains provide an innovative strategy for low-cost pneumococcal vaccine development, production, and use.

Test Characteristics of Cerebrospinal Fluid Gram Stain to Identify Bacterial Meningitis in Infants Younger Than 60 Days

ABSTRACT

In our cohort of 20,947 infants aged 60 days or younger, cerebrospinal fluid Gram stain had a sensitivity of 34.3% (95% confidence interval, 28.1%-41.1%) and a positive predictive value of 61.4% (95% confidence interval, 52.2%-69.8%) for positive cerebrospinal fluid culture, suggesting that Gram stain alone may lead to both underdiagnosis and overdiagnosis of bacterial meningitis.

Long-term population effects of infant 10-valent pneumococcal conjugate vaccination on pneumococcal meningitis in Finland

BACKGROUND

No previous studies have reported long-term follow-up of ten-valent pneumococcal conjugate vaccine (PCV10) program impact on pneumococcal meningitis (PM). We assessed the effects of infant PCV10 program on PM incidence, mortality and serotype distribution in children and adults during 7 years after introduction.

METHODS

We conducted a population-based observational study. A case of PM was defined as isolation of Streptococcus pneumoniae from cerebrospinal fluid or, a patient with S. pneumoniae isolated from blood and an ICD-10 hospital discharge diagnosis of bacterial meningitis within 30 days before or after positive culture date.We compared age- and serotype-specific incidence and associated 30-day mortality rates in 2011-2017 (PCV10 period) with those in 2004-2010 (pre-PCV10 baseline) by using Poisson regression models. Absolute rate differences and 95% confidence intervals (CIs) were calculated from the parameter estimates by using delta method.

RESULTS

During the PCV10 period, the overall incidence of PCV10 serotype meningitis decreased by 68% (95%CI 57%-77%), and the overall PM incidence by 27% (95%CI: 12%-39%). In age groups 0-4, 50-64, and ≥ 18 years, the overall PM incidence was reduced by 64%, 34% and 19%, respectively. In adults ≥ 65 years of age, a 69% reduction in PCV10 serotypes was offset by 157% (56%-342%) increase in non-PCV10 serotypes. The overall PM-related mortality rate decreased by 42% (95%CI 4%-65%). Overall case fatality proportion (CFP) was 16% in pre-PCV10 period and 12% in PCV10 period (p = 0.41); among persons 50-64 years the CFP decreased from 25% to 10% (p = 0.04).

CONCLUSIONS

We observed substantial impact and herd protection for vaccine-serotype PM and associated mortality after infant PCV10 introduction. However, in older adults ≥ 65 years of age, PM burden remains unchanged due to serotype replacement.

Declines in the Number of Lumbar Punctures Performed at United States Children's Hospitals, 2009-2019

OBJECTIVE

To evaluate trends in lumbar puncture (LP) performance among US children's hospitals to assess how these trends may impact pediatric resident trainee exposure to LP.

STUDY DESIGN

We quantified LPs for emergency department (ED) and inpatient encounters at 29 US children's hospitals from 2009 to 2019. LP was defined by either a LP procedure code or cerebrospinal fluid culture billing code. Temporal trends and hospital variation in LP were assessed using logistic regression analysis.

RESULTS

A total of 215 030 LPs were performed during the study period (0.8% of all encounters). Twenty six thousand and five hundred twenty three and 16 696 LPs were performed in the 2009 and 2018 academic years, respectively (overall 37.1% reduction, per-year OR, 0.935; 95% CI, 0.922-0.948; P < .001), and the rate of LP decreased from 10.9 per 1000 hospital encounters to 6.0 per 1000 hospital encounters over the same period.

CONCLUSIONS

LP rates have declined across US children's hospitals over the past decade, potentially resulting in reduced clinical exposure for pediatric resident trainees. Improved procedural simulation during residency may augment the clinical experience.

A hospital-based study on etiology and prognosis of bacterial meningitis in adults

Bacterial meningitis is a neurological emergency with high morbidity and mortality. We herein investigated clinical features, etiology, antimicrobial susceptibility profiles, and prognosis of bacterial meningitis in adults from a single tertiary center. We retrospectively reviewed medical records of patients with laboratory-confirmed bacterial meningitis from 2007 to 2016. Patients with recent neurosurgery, head trauma, or indwelling neurosurgical devices were classified as having healthcare-related meningitis. Causative microorganisms were identified by analyzing cerebrospinal fluid (CSF) and blood cultures, and antimicrobial susceptibility profiles were evaluated. We performed multiple logistic regression analysis to identify factors associated with unfavorable outcomes. We identified 161 cases (age, 55.9 ± 15.5 years; male, 50.9%), of which 43 had community-acquired and 118 had healthcare-related meningitis. CSF and blood culture positivity rates were 91.3% and 30.4%, respectively. In community-acquired meningitis patients, Klebsiella pneumoniae (25.6%) was the most common isolate, followed by Streptococcus pneumoniae (18.6%) and Listeria monocytogenes (11.6%). The susceptibility rates of K. pneumoniae to ceftriaxone, cefepime, and meropenem were 85.7%, 81.3%, and 100%, respectively. Among healthcare-related meningitis patients, the most common bacterial isolates were coagulase-negative staphylococci (28.0%), followed by Staphylococcus aureus (16.1%) and Enterobacter spp. (13.6%). Neurological complications occurred in 39.1% of the patients and the 3-month mortality rate was 14.8%. After adjusting for covariates, unfavorable outcome was significantly associated with old age (odds ratio [OR] 1.03, 95% confidence interval [CI] 1.00–1.06), neurological complications (OR 4.53, 95% CI 1.57–13.05), and initial Glasgow coma scale ≤ 8 (OR 19.71, 95% CI 4.35–89.40). Understanding bacterial pathogens and their antibiotic susceptibility may help optimize antimicrobial therapy in adult bacterial meningitis.

Characterization and Specification of a Trivalent Protein-Based Pneumococcal Vaccine Formulation Using an Adjuvant-Free Nanogel Nasal Delivery System

We previously developed a safe and effective nasal vaccine delivery system using a self-assembled nanosized hydrogel (nanogel) made from a cationic cholesteryl pullulan. Here, we generated three pneumococcal surface protein A (PspA) fusion antigens as a universal pneumococcal nasal vaccine and then encapsulated each PspA into a nanogel and mixed the three resulting monovalent formulations into a trivalent nanogel-PspA formulation. First, to characterize the nanogel-PspA formulations, we used native polyacrylamide gel electrophoresis (PAGE) to determine the average number of PspA molecules encapsulated per nanogel molecule. Second, we adopted two methods-a densitometric method based on lithium dodecyl sulfate (LDS)-PAGE and a biologic method involving sandwich enzyme-linked immunosorbent assay (ELISA)-to determine the PspA content in the nanogel formulations. Third, treatment of nanogel-PspA formulations by adding methyl-β-cyclodextrin released each PspA in its native form, as confirmed through circular dichroism (CD) spectroscopy. However, when nanogel-PspA formulations were heat-treated at 80 °C for 16 h, CD spectroscopy showed that each PspA was released in a denatured form. Fourth, we confirmed that the nanogel-PspA formulations were internalized into nasal mucosa effectively and that each PspA was gradually released from the nanogel in epithelial cells in mice. Fifth, LDS-PAGE densitometry and ELISA both indicated that the amount of trivalent PspA was dramatically decreased in the heat-treated nanogel compared with that before heating. When mice were immunized nasally using the heat-treated formulation, the immunologic activity of each PspA was dramatically reduced compared with that of the untreated formulation; in both cases, the immunologic activity correlated well with the content of each PspA as determined by LDS-PAGE densitometry and ELISA. Finally, we confirmed that the trivalent nanogel-PspA formulation induced equivalent titers of PspA-specific serum IgG and mucosal IgA Abs in immunized mice. These results show that the specification methods we developed effectively characterized our nanogel-based trivalent PspA nasal vaccine formulation.

Drastic reduction in pneumococcal meningitis in children owing to the introduction of pneumococcal conjugate vaccines: Longitudinal analysis from 2002 to 2016 in Japan

INTRODUCTION

The characteristics of pneumococcal isolates and their associations with outcomes in pediatric meningitis are unclear. This study aimed to clarify serotypes and resistance genotypes of Streptococcus pneumoniae from children with meningitis and evaluate the patient prognoses and backgrounds.

METHODS

Large-scale surveillance was conducted from 2002 to 2016 through periods I-V. Serotypes and penicillin (PEN) resistance genotypes were analyzed for pneumococcal isolates (n = 459) and cerebrospinal fluid (CSF) samples (n = 25). Furthermore, underlying diseases (n = 251), prognoses (n = 202), and laboratory data were evaluated.

RESULTS

The number of meningitis cases decreased drastically after the introduction of 7-valent pneumococcal conjugate vaccine (PCV7) to -53.6% and after switching to PCV13 to -70.2%. In particular, this reduction was apparent at ≤3 years of age. The proportion of the PCV7 serotype decreased sharply from 70.1% before introduction to 2.6% during period V; however, the non-vaccine type increased from 17.5% to 87.2%. The PEN resistance rate (gPRSP) was decreased from approximately 49% to 12.2% during period V. Among cases revealed prognosis, sequelae and mortality rates were 16.3% and 5.4%, respectively. The rate of the patients with underlying diseases was 26.3% and relatively high in ≥6 years. Laboratory data associated with a poor prognosis were low white blood cell count (<12.7 × 10³/μL), low platelet count (<28.1 × 10⁴/μL), low CSF-glucose (<36 mg/dL), and high CSF-protein (≥142 mg/dL).

CONCLUSIONS

Changes in serotype prevalence warrant continuous monitoring to observe future trends of pneumococcal meningitis, and further developments in multivalent conjugate vaccines are required.

Serotypes and Vaccine Coverage of Streptococcus Pneumoniae Colonization in the Nasopharynx of Thai Children in Congested Areas in Chiang Mai

Streptococcus pneumoniae causes around 10% of all deaths in children younger than five years of age. This study aimed to examine the serogroups/serotypes of S. pneumoniae colonization and vaccine serotype coverage of this organism among Thai children. Nasopharyngeal swabs of children less than or equal to 15 years of age were obtained in congested areas in Chiang Mai from 1 February 2013 to 1 August 2013. The serotyping of S. pneumoniae isolates was performed using the ImmuLex™ kit and the vaccine serotype coverage for this organism was evaluated. A total of 292 children were enrolled. One hundred and thirty children (44.5%) had nasopharyngeal colonization with Streptococcus pneumoniae. Eighty-seven (66.9%) isolates were from children younger than five years of age, seventeen (13.1%) were from children aged 6-10 years, and twenty-six (20%) were from children aged 11-15 years. The five most common serogroups/serotypes isolated were 6 (6A, 6B, 6C) (46.1%), 23 (23F, 23A, 23B) (14.6%), 19 (19F, 19A, 19B, 19C) (8.5%), 15 (15F, 15A, 15B, 15C) (6.9%), and 14 (6.1%). Vaccine serotype coverages in pneumococcal conjugate vaccines (PCV):PCV7, PCV10, and PCV13 were 79.1%, 83.6%, and 85.9%, respectively. There were significant increases in coverage between PCV7 and PCV10 (from 79.1% to 83.6%, p < 0.001), PCV7 and PCV13 (from 79.1% to 85.9%, p < 0.001), and PCV10 and PCV13 (from 83.6% to 85.9%, p < 0.001). The majority of pneumococcal serogroup/serotype colonization in the nasopharynx of Thai children in the studied areas was included in the current licensed pneumococcal conjugated vaccines (PCVs). PCV vaccination should be considered for high-risk children to reduce the incidence of invasive pneumococcal disease among Thai children.

Pneumococcal Encounter With the Blood-Brain Barrier Endothelium

Meningitis, the inflammation of the protective membrane surrounding the brain and spinal cord (known as meninges), is a condition associated with high mortality rates and permanent neurological sequelae in a significant proportion of survivors. The opportunistic pathogen Streptococcus pneumoniae (SPN/pneumococcus) is the leading cause of bacterial meningitis in adults and older children. Following infection of the lower respiratory tract and subsequent bloodstream invasion, SPN breaches the blood-brain barrier endothelium for invasion of the central nervous system. Transcytosis, a mode of passage through the endothelial cells has been identified as the predominant route of pneumococcal blood-brain barrier trafficking. Herein, we review the interactions enabling SPN invasion into the brain endothelial cells, events involved in the tug-of-war between pneumococcal virulence factors and host intracellular defense machineries and pneumococcal strategies for evasion of host defenses and successful transendothelial trafficking.

Expression, purification, and characterization of pneumococcal PsaA-PspA fusion protein

Streptococcus pneumoniae is a gram-positive bacterial pathogen causing invasive pneumonia, meningitis, otitis media, and bacteremia. Owing to the current pitfalls of polysaccharide and polysaccharide-conjugate vaccines, protein vaccines are considered promising candidates against pneumonia. Pneumococcal surface protein A (PspA) and pneumococcal surface adhesin A (PsaA) are virulence proteins showing good immunogenicity and protective effects against S. pneumoniae strains in mice. In this study, we expressed the fusion protein PsaA-PspA, which consists of PsaA and the N-terminal region of PspA family 1 and 2, in Escherichia coli. We describe a novel and effective method to purify PsaA-PspA using hydroxyapatite and two-step chromatography. After determining the optimal induction conditions and a series of purification steps, we obtained PsaA-PspA fusion protein with over 95% purity at a final yield of 22.44% from the starting cell lysate. The molecular weight of PsaA-PspA was approximately 83.6 kDa and its secondary structure was evaluated by circular dichroism. Immunization with the purified protein induced high levels of IgG antibodies in mice. Collectively, these results demonstrate that our purification method can effectively produce high-purity PsaA-PspA fusion protein with biological activity and chemical integrity, which can be widely applied to the purification of other PspA subclass proteins.

Impaired mucociliary motility enhances antigen-specific nasal IgA immune responses to a cholera toxin-based nasal vaccine

Nasal mucosal tissues are equipped with physical barriers, mucus and cilia, on their surface. The mucus layer captures inhaled materials, and the cilia remove the inhaled materials from the epithelial layer by asymmetrical beating. The effect of nasal physical barriers on the vaccine efficacy remains to be investigated. Tubulin tyrosine ligase-like family, member 1 (Ttll1) is an essential enzyme for appropriate movement of the cilia on respiratory epithelium, and its deficiency (Ttll1-KO) leads to mucus accumulation in the nasal cavity. Here, when mice were intra-nasally immunized with pneumococcal surface protein A (PspA, as vaccine antigen) together with cholera toxin (CT, as mucosal adjuvant), Ttll1-KO mice showed higher levels of PspA-specific IgA in the nasal wash and increased numbers of PspA-specific IgA-producing plasma cells in the nasal passages when compared with Ttll1 hetero (He) mice. Mucus removal by N-acetylcysteine did not affect the enhanced immune responses in Ttll1-KO mice versus Ttll1-He mice. Immunohistological and flow cytometry analyses revealed that retention time of PspA in the nasal cavity in Ttll1-KO mice was longer than that in Ttll1-He mice. Consistently, uptake of PspA by dendritic cells was higher in the nasopharynx-associated lymphoid tissue (NALT) of Ttll1-KO mice than that of Ttll1-He mice. These results indicate that the ciliary function of removing vaccine antigen from the NALT epithelial layer is a critical determinant of the efficacy of nasal vaccine.

Characterization of Escherichia coli isolates potentially covered by ExPEC4V and ExPEC10V, that were collected from post-transrectal ultrasound-guided prostate needle biopsy invasive urinary tract and bloodstream infections

There is an increasing incidence of infectious complications caused by extraintestinal pathogenic Escherichia coli (ExPEC) after transrectal ultrasound-guided prostate needle biopsy (TRUS-PNB), and a need for prophylaxis methods effective against associated antibiotic-resistant organisms. We aimed to identify the O-serotypes of ExPEC isolates collected in a sample of 60 patients with invasive ExPEC disease (IED) after TRUS-PNB, by serotype-specific agglutination and polymerase chain reaction (PCR) assays. The prevalence of O-serotypes included in a tetravalent ExPEC vaccine was 38.3% by agglutination and 46.7% by PCR, while the prevalence of O-serotypes included in a decavalent vaccine was 58.3% and 73.3%, respectively. Therefore, compared to the tetravalent vaccine, the decavalent vaccine would theoretically provide coverage for serotypes carried by a higher proportion of circulating ExPEC in patients undergoing TRUS-PNB, including a high proportion of antibiotic-resistant organisms.

Targeting the complement system in bacterial meningitis

Bacterial meningitis is most commonly caused by Streptococcus pneumoniae and Neisseria meningitidis and continues to pose a major public health threat. Morbidity and mortality of meningitis are driven by an uncontrolled host inflammatory response. This comprehensive update evaluates the role of the complement system in upregulating and maintaining the inflammatory response in bacterial meningitis. Genetic variation studies, complement level measurements in blood and CSF, and experimental work have together led to the identification of anaphylatoxin C5a as a promising treatment target in bacterial meningitis. In animals and patients with pneumococcal meningitis, the accumulation of neutrophils in the CSF was mainly driven by C5-derived chemotactic activity and correlated positively with disease severity and outcome. In murine pneumococcal meningitis, adjunctive treatment with C5 antibodies prevented brain damage and death. Several recently developed therapeutics target C5 conversion, C5a, or its receptor C5aR. Caution is warranted because treatment with C5 antibodies such as eculizumab also inhibits the formation of the membrane attack complex, which may result in decreased meningococcal killing and increased meningococcal disease susceptibility. The use of C5a or C5aR antagonists to specifically target the harmful anaphylatoxins-induced effects, therefore, are most promising and present opportunities for a phase 2 clinical trial.

New Strategy Is Needed to Prevent Pneumococcal Meningitis

BACKGROUND

Polysaccharide conjugate vaccines (PCVs) target the pneumococcal capsular types that most commonly cause fatal pneumonia and sepsis. Because these types were eliminated by the vaccines, it became apparent that in immunized populations, most invasive pneumococcal diseases, including bacteremia, sepsis and complicated pneumonia, were greatly reduced. However, the protective effects of PCVs against another invasive disease, meningitis, has shown much less or no decrease in disease incidence.

METHODS

References were identified through searches of PubMed for articles published from January 1930 to the present by use of specific search terms. Relevant articles were also identified through searches in Google and Google Scholar. Relevant references cited in those articles were also reviewed.

RESULTS

Even in the presence of the PCVs, meningitis rates in children have been reported globally to be as high as 13 per 100,000 annually. Widespread use of vaccines resulted in the emergence of a broad diversity of replacement non-PCV type strains. These strains generally failed to cause sepsis, but caused meningitis of comparable severity and levels similar to, or in excess of, prior pneumococcal meningitis rates. This is probably because these non-PCV type strains do not survive well in the blood, therefore possibly entering the brain through nonhematogenous routes.

CONCLUSIONS

Because virtually all cases of pneumococcal meningitis lead to either permanent neurologic sequelae or death, it would be well worth the effort to develop a new vaccine capable of preventing pneumococcal meningitis regardless of capsular type. Such a vaccine would need to protect against colonization with most, if not all, pneumococci.

Development of Next Generation Streptococcus pneumoniae Vaccines Conferring Broad Protection

Streptococcus pneumoniae is a major pathogen causing pneumonia with over 2 million deaths annually, especially in young children and the elderly. To date, at least 98 different pneumococcal capsular serotypes have been identified. Currently, the vaccines for prevention of S. pneumoniae infections are the 23-valent pneumococcal polysaccharide-based vaccine (PPV23) and the pneumococcal conjugate vaccines (PCV10 and PCV13). These vaccines only cover some pneumococcal serotypes and are unable to protect against non-vaccine serotypes and unencapsulated S. pneumoniae. This has led to a rapid increase in antibiotic-resistant non-vaccine serotypes. Hence, there is an urgent need to develop new, effective, and affordable pneumococcal vaccines, which could cover a wide range of serotypes. This review discusses the new approaches to develop effective vaccines with broad serotype coverage as well as recent development of promising pneumococcal vaccines in clinical trials. New vaccine candidates are the inactivated whole-cell vaccine strain (Δpep27ΔcomD mutant) constructed by mutations of specific genes and several protein-based S. pneumoniae vaccines using conserved pneumococcal antigens, such as lipoprotein and surface-exposed protein (PspA). Among the vaccines in Phase 3 clinical trials are the pneumococcal conjugate vaccines, PCV-15 (V114) and 20vPnC. The inactivated whole-cell and several protein-based vaccines are either in Phase 1 or 2 trials. Furthermore, the recent progress of nanoparticles that play important roles as delivery systems and adjuvants to improve the performance, as well as the immunogenicity of the nanovaccines, are reviewed.

Conjugate vaccines dramatically reshaped the epidemiology of bacterial meningitis in a well-defined child population

AIM

We explored the impact of vaccination on bacterial meningitis in a well-defined population of children on the island of Crete, Greece, over a 27-y period.

METHODS

This was a retrospective observational study of all mandatory notifications of bacterial meningitis in patients aged 1 mo-14 y from 1991 to 2017.

RESULTS

There were 245 patients with proven (n = 227) or suspected (n = 18) bacterial meningitis, and eight deaths were recorded, giving a case fatality rate of 3.3%. The mean annual incidence rate (IR) per 100 000 children was 4.9 for Neisseria meningitidis, 2.2 for Streptococcus pneumoniae and 0.4 for Haemophilus influenzae type b (Hib). Cases of meningitis C dropped significantly after the conjugate meningitis C vaccine was licensed for routine vaccination in Greece in 2000 (IR of 1.5 vs 0.3, P < 0.028) while the Streptococcus pneumoniae cases showed a threefold decrease after the PCV13 vaccine was licensed in Greece in 2009 (IR 2.7 vs 1.0, P < 0.03). Vaccination had already eliminated Hib in Greece in the 1990s.

CONCLUSION

Bacterial meningitis cases decreased in children following the introduction of the meningitis C and PCV13 vaccines in Greece. Hib had already disappeared and significant reductions in meningitis C and Streptococcus pneumoniae were observed.

Effect of Pneumococcal Conjugate Vaccines on Pneumococcal Meningitis, England and Wales, July 1, 2000-June 30, 2016

We describe the effects of the 7-valent (PCV7) and 13-valent (PCV13) pneumococcal conjugate vaccines on pneumococcal meningitis in England and Wales during July 1, 2000–June 30, 2016. Overall, 84,473 laboratory-confirmed invasive pneumococcal disease cases, including 4,160 (4.9%) cases with meningitis, occurred. PCV7 implementation in 2006 did not lower overall pneumococcal meningitis incidence because of replacement with non–PCV7-type meningitis incidence. Replacement with PCV13 in 2010, however, led to a 48% reduction in pneumococcal meningitis incidence by 2015–16. The overall case-fatality rate was 17.5%: 10.7% among patients <5 years of age, 17.3% among patients 5–64 years of age, and 31.9% among patients >65 years of age. Serotype 8 was associated with increased odds of death (adjusted odds ratio 2.9, 95% CI 1.8–4.7). In England and Wales, an effect on pneumococcal meningitis was observed only after PCV13 implementation. Further studies are needed to assess pneumococcal meningitis caused by the replacing serotypes.

Changing Epidemiology and Predisposing Factors for Invasive Pneumococcal Disease at Two Australian Tertiary Hospitals

BACKGROUND

Invasive pneumococcal disease (IPD) is associated with significant morbidity and mortality in children. Universal pneumococcal conjugate vaccination has changed the epidemiology of IPD. In vaccinated children, IPD can be a marker of an underlying immunodeficiency.

METHODS

This is a retrospective audit of children younger than 18 years with IPD admitted to 2 tertiary pediatric hospitals in Australia between 2011 and 2017. Data on predisposing conditions, immunologic evaluation, pneumococcal serotype, antibiotic susceptibility and treatment were collected.

RESULTS

During the 7-year period, there were 131 presentations with IPD in 127 children; 3 children had recurrent IPD. Patients presented with sepsis (41%), empyema (29%), meningitis (18%), mastoiditis (12%), pneumonia (10%) and septic arthritis (4%). In 19 (15%) presentations, risk factors for IPD were present, including malignancy, hematologic disorder, chronic liver disease, chronic kidney disease and cochlear implant. Pneumococcal serotypes were determined in 78/131 (60%) of presentations: the most frequent serotypes were 19A (19%), 3 (13%), 7F (10%) and 19F (8%) and non-vaccine serotypes 22F (8%), 35B (6%), 15A (4%) and 38 (4%). Overall, 11% of isolates were non-susceptible to ceftriaxone. Only 36 patients (32%) had an immunologic evaluation, and 4 patients had proven or probable immunodeficiency.

CONCLUSION

Although pneumococcal conjugate vaccine serotypes 19A, 3, 19F and 7F remain frequent causes of IPD, non-vaccine serotypes are emerging. Our data support vancomycin treatment for children with pneumococcal meningitis given 11% of our isolates were not susceptible to ceftriaxone. It is important to consider underlying conditions predisposing to IPD in a population with high rates of pneumococcal vaccination.

The Modified Surface Killing Assay Distinguishes between Protective and Nonprotective Antibodies to PspA

The most important finding of this study is that the MSKA can be used as an in vitro functional assay. Such an assay will be critical for the development of PspA-containing vaccines. The other important findings relate to the locations and nature of the protection-eliciting epitopes of PspA. There are limited prior data on the locations of protection-eliciting PspA epitopes, but those data along with the data presented here make it clear that there is not a single epitope or domain of PspA that can elicit protective antibody and there exists at least one region of the αHD which seldom elicits protective antibody. Moreover, these data, in concert with prior data, strongly make the case that protective epitopes in the αHD are highly conformational (≥100-amino-acid fragments of the αHD are required), whereas at least some protection-eliciting epitopes in the proline-rich domain are encoded by ≤15-amino-acid sequences.

Pneumococcal surface protein A (PspA) elicits antibody protective against lethal challenge by Streptococcus pneumoniae and is a candidate noncapsular antigen for inclusion in vaccines. Evaluation of immunity to PspA in human trials would be greatly facilitated by an in vitro functional assay able to distinguish protective from nonprotective antibodies to PspA. Mouse monoclonal antibodies (MAbs) to PspA can mediate killing by human granulocytes in the modified surface killing assay (MSKA). To determine if the MSKA can distinguish between protective and nonprotective MAbs, we examined seven MAbs to PspA. All bound recombinant PspA, as detected by enzyme-linked immunosorbent assay and Western blotting; four gave strong passive protection against fatal challenge, two were nonprotective, and the seventh one only delayed death. The four that were able to provide strong passive protection were also most able to enhance killing in the MSKA, the two that were not protective in mice were not effective in the MSKA, and the MAb that was only weakly protective in mice was weakly effective in the MSKA (P < 0.001). One of the four most protective MAbs tested reacted to the proline-rich domain of PspA. Two of the other most protective MAbs and the weakly protective MAb reacted with a fragment from PspA’s α-helical domain (αHD), containing amino acids (aa) 148 to 247 from the N terminus of PspA. The fourth highly protective MAb recognized none of the overlapping 81- or 100-aa fragments of PspA. The two nonprotective MAbs recognized a more N-terminal αHD fragment (aa 48 to 147).

IMPORTANCE The most important finding of this study is that the MSKA can be used as an in vitro functional assay. Such an assay will be critical for the development of PspA-containing vaccines. The other important findings relate to the locations and nature of the protection-eliciting epitopes of PspA. There are limited prior data on the locations of protection-eliciting PspA epitopes, but those data along with the data presented here make it clear that there is not a single epitope or domain of PspA that can elicit protective antibody and there exists at least one region of the αHD which seldom elicits protective antibody. Moreover, these data, in concert with prior data, strongly make the case that protective epitopes in the αHD are highly conformational (≥100-amino-acid fragments of the αHD are required), whereas at least some protection-eliciting epitopes in the proline-rich domain are encoded by ≤15-amino-acid sequences.

Serotype Distribution and Antimicrobial Resistance of Invasive and Noninvasive Streptococcus pneumoniae Isolates in Korea between 2014 and 2016

Background

Several factors contribute to differences in Streptococcus pneumoniae serotype distribution. We investigated the serotype distribution and antimicrobial resistance of S. pneumoniae isolated between 2014 and 2016 in Korea.

Methods

We collected a total of 1,855 S. pneumoniae isolates from 44 hospitals between May 2014 and May 2016, and analyzed the serotypes by sequential multiplex PCR. We investigated the distribution of each serotype by patient age, source of the clinical specimen, and antimicrobial resistance pattern.

Results

The most common serotypes were 11A (10.1%), followed by 19A (8.8%), 3 (8.5%), 34 (8.1%), 23A (7.3%), and 35B (6.2%). The major invasive serotypes were 3 (12.6%), 19A (7.8%), 34 (7.8%), 10A (6.8%), and 11A (6.8%). Serotypes 10A, 15B, 19A, and 12F were more common in patients ≤5 years old, while serotype 3 was more common in patients ≥65 years old compared with the other age groups. The coverage rates of pneumococcal conjugate vaccine (PCV)7, PCV10, PCV13, and pneumococcal polysaccharide vaccine 23 were 11.8%, 12.12%, 33.3%, and 53.6%, respectively. Of the 1,855 isolates, 857 (46.2%) were multi-drug resistant (MDR), with serotypes 11A and 19A predominant among the MDR strains. The resistance rates against penicillin, cefotaxime, and levofloxacin were 22.8%, 12.5%, and 9.4%, respectively.

Conclusions

There were significant changes in the major S. pneumoniae serotypes in the community. Non-PCV13 serotypes increased in patients ≤5 years old following the introduction of national immunization programs with the 10- and 13-polyvalent vaccines.

Diagnostic Practices for Suspected Community-Acquired Central Nervous System Infection in the Post-Conjugate Vaccine Era

OBJECTIVE

The aim of this study was to evaluate diagnostic practices for suspected community-acquired central nervous system (CNS) infection in an urban pediatric population.

METHODS

This is an observational, retrospective single-center review of cerebrospinal fluid (CSF) studies in children, 1 month to 21 years old, evaluated for suspected CNS infection from 2004 to 2014. Cases of suspected nosocomial meningitis were excluded. The frequency of N-methyl-D-aspartate receptor antibody (NMDAR ab) encephalitis was analyzed from 2010 to 2014.

RESULTS

A total of 940 unique patient visits with CSF studies were included in the final analysis. There were 940 bacterial cultures sent; 4 (0.42%) grew suspected CSF bacterial pathogens, and 18 (1.9%) grew organisms that were suspected contaminants. Bacterial pathogens included late-onset group B Streptococcus in 3 infants younger than 3 months and Streptococcus pneumoniae in an unvaccinated 9-year-old child. Viral CNS infection was 7.5 times more frequent than bacterial infection. Enterovirus was the only virus isolated. Five cases positive for NMDAR ab were identified since 2010.

CONCLUSIONS

Bacterial studies were performed more frequently than viral and other studies. Cerebrospinal fluid bacterial culture was nearly 5 times more likely to yield a contaminant than a pathogen. The frequency of viral infection was likely underestimated as only 20% were tested, mainly by culture, which is suboptimal. These data suggest diagnostic practices for the evaluation of suspected community-acquired CNS infections in children need to be modified to reflect current epidemiology and highlight the need for greater accessibility to polymerase chain reaction for viral diagnostics. Furthermore, NMDAR ab-mediated encephalitis should be considered early in children presenting with suggestive symptoms.

Protective responses of an engineered PspA recombinant antigen against Streptococcus pneumoniae

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In this study, two immunogenic antigens based on recombinant PspA proteins were immunized mice.

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The protective effects of developed anti-PspA antibodies in mice in intranasal and intraperitoneal challenges were proved.

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Based on the obtained results, immunization with the B-regions of PspA antigens are crucial in protection of challenged mice with S. pneumoniae strains.

Streptococcus pneumoniae is a major pathogen in human respiratory tract which causes significant morbidity and mortality across from the world. Currently available vaccines are not completely effective and cannot cover all pathogenic strains so there is an important need to develop an alternative cost-effective vaccine, based on conserved protein antigens. Pneumococcal surface protein A (PspA) is one of interesting candidates for development of a serotype-independent vaccine against pneumococcal infections. PspA is grouped into two major families with five clades, and broad-reacting PspA-based vaccines should contain at least one functional fragment from each of the two families.

In this study, we developed two immunogenic antigens based on recombinant PspA proteins that including the different antigenic regions of PspA from both two families. The cross-reactivity of antibodies elicited against two PspA proteins PspAB1-5 and PspA₄ABC and their role in complement deposition with three strains of pneumococci were tested. The protective effects of developed anti-PspA antibodies in mice in intranasal and intraperitoneal challenges were evaluated using a strain from clade 2. Sera from immunized mice with PspAB_1-5 in comparison with PspA₄ABC was able to deposit more C3 complement component on surface of pneumococci bearing diverse PspA from both families 1 and 2, and immunized mice with the PspAB_1-5 showed a higher protection than PspA₄ABC in pneumococcal challenges.

The obtained results from this study indicate that a PspA-based antigen composed of B region from all clades in addition to conserved domains, can provide a significant protection against multiple strains of S. pneumoniae and may overcome the limitation of polysaccharide vaccines.

Risk factor profiles and clinical outcomes for children and adults with pneumococcal infections in Singapore: A need to expand vaccination policy?

Invasive pneumococcal infection is a major cause of morbidity and mortality worldwide despite the availability of pneumococcal vaccines. The aim of this study was to re-evaluate the clinical syndromes, prognostic factors and outcomes for pneumococcal disease in adults and children in Singapore during the period before and after the introduction of the pneumococcal vaccine. We retrospectively analyzed a large cohort of patients admitted to the four main public hospitals in Singapore with S. pneumoniae infection between 1997 and 2013. A total of 889 (64% of all isolates identified in the clinical laboratories) cases were included in the analysis; 561 (63.1%) were adult (≥16 years) cases with a median age of 62 years and 328 (36.9%) were paediatric cases with a median age of 3 years. Bacteraemic pneumonia was the most common syndrome in both groups (69.3% vs. 44.2%), followed by primary bacteraemia without pneumonia (14.3% vs. 13.4%), meningitis (6.4% vs. 7.6%) and non-bacteraemic pneumonia (5.2% vs. 21%). The major serotypes in adults were 3, 4, 6B, 14, 19F and 23F whereas in children they were 14, 6B and 19F, accounting both for nearly half of pneumococcal disease cases. No particular serotype was associated with mortality or severity of the pneumococcal disease. Overall mortality rate was 18.5% in adults and 3% in children. Risk factors for mortality included acute cardiac events in adults, meningitis in children and critical illness and bilateral pulmonary infiltrates in both adults and children. Penicillin resistance was not associated with increased mortality. Our results agree with global reports that the course of pneumococcal disease and its clinical outcome were more severe in adults than in children. The main serotypes causing invasive disease were mostly covered by the vaccines in use. The high mortality rates reflect an urgent need to increase vaccination coverage in both adults and children to tackle this vaccine-preventable infection.

Impact of pneumococcal conjugate vaccines introduction on antibiotic resistance of Streptococcus pneumoniae meningitis in children aged 5 years or younger, Israel, 2004 to 2016

Background

Empiric treatment of pneumococcal meningitis includes ceftriaxone with vancomycin to overcome ceftriaxone resistant disease. The addition of vancomycin bears a risk of adverse events, including increased antibiotic resistance. We assessed antibiotic resistance rates in pneumococcal meningitis before and after pneumococcal conjugate vaccine (PCV) implementation.

Methods

All pneumococcal meningitis episodes in children aged 5 years and younger, from 2004 to 2016, were extracted from the nationwide bacteremia and meningitis surveillance database. For comparison purposes, we defined pre-PCV period as 2004–2008 and PCV13 period as 2014–2016. Minimal inhibitory concentration (MIC) > 0.06 and > 0.5 μg/mL were defined as penicillin and ceftriaxone resistance, respectively.

Results

Overall, 325 episodes were identified. Pneumococcal meningitis incidence rates declined non-significantly by 17%, comparing PCV13 and pre-PCV periods. Throughout the study, 90% of isolates were tested for antibiotic susceptibility, with 26.6%, 2.1% and 0% of isolates resistant to penicillin, ceftriaxone and vancomycin, respectively. Mean proportions (± SD) of meningitis caused by penicillin-resistant pneumococci were 40.5% ± 8.0% and 9.6% ± 7.4% in the pre-PCV and the PCV13 periods, respectively, resulting in an overall 83.9% reduction (odd ratio:0.161; 95% confidence interval: 0.059–0.441) in penicillin resistance rates. The proportions of meningitis caused by ceftriaxone resistant pneumococci were 5.0% ± 0.8% in the pre-PCV period, but no ceftriaxone resistant isolates were identified since 2010.

Conclusions

PCV7/PCV13 sequential introduction resulted in > 80% reduction of penicillin- resistant pneumococcal meningitis and complete disappearance of ceftriaxone resistant disease. These trends should be considered by the treating physician when choosing an empiric treatment for pneumococcal meningitis.