Global serotype distribution among Streptococcus pneumoniae isolates causing otitis media in children: potential implications for pneumococcal conjugate vaccines

Synthetic BSA-conjugated disaccharide related to the Streptococcus pneumoniae serotype 3 capsular polysaccharide increases IL-17A Levels, γδ T cells, and B1 cells in mice

The disaccharide (β-D-glucopyranosyluronic acid)-(1→4)-β-D-glucopyranoside represents a repeating unit of the capsular polysaccharide of Streptococcus pneumoniae serotype 3. A conjugate of the disaccharide with BSA (di-BSA conjugate) adjuvanted with aluminum hydroxide induced - in contrast to the non-adjuvanted conjugate - IgG1 antibody production and protected mice against S. pneumoniae serotype 3 infection after intraperitoneal prime-boost immunization. Adjuvanted and non-adjuvanted conjugates induced production of Th1 (IFNγ, TNFα); Th2 (IL-5, IL-13); Th17 (IL-17A), Th1/Th17 (IL-22), and Th2/Th17 cytokines (IL-21) after immunization. The concentration of cytokines in mice sera was higher in response to the adjuvanted conjugate, with the highest level of IL-17A production after the prime and boost immunizations. In contrast, the non-adjuvanted conjugate elicited only weak production of IL-17A, which gradually decreased after the second immunization. After boost immunization of mice with the adjuvanted di-BSA conjugate, there was a significant increase in the number of CD45+/CD19+ B cells, TCR+ γδ T cell, CD5+ В1 cells, and activated cells with MHC II+ expression in the spleens of the mice. IL-17A, TCR+ γδ T cells, and CD5+ В1 cells play a crucial role in preventing pneumococcal infection, but can also contribute to autoimmune diseases. Immunization with the adjuvanted and non-adjuvanted di-BSA conjugate did not elicit autoantibodies against double-stranded DNA targeting cell nuclei in mice. Thus, the molecular and cellular markers associated with antibody production and protective activity in response to immunization with the di-BSA conjugate adjuvanted with aluminum hydroxide are IL-17A, TCR+ γδ T cells, and CD5+ В1 cells against the background of increasing MHC II+ expression.

Emerging pneumococcal serotypes in Iraq: scope for improved vaccine development

Pneumococcal disease is a global public health concern as it affects the young, aged and the immunocompromised. The development of pneumococcal vaccines and their incorporation in the immunization programs has helped to reduce the global burden of disease. However, serotype replacement and the emergence of non-vaccine serotypes as well as the persistence of a few vaccine serotypes underscores the need for development of new and effective vaccines against such pneumococcal serotypes. In the Middle East, places of religious mass gatherings are a hotspot for disease transmission in addition to the global risk factors. Therefore, the periodic surveillance of pneumococcal serotypes circulating in the region to determine the effectiveness of existing prevention strategies and develop improved vaccines is warranted. Currently, there is a lack of serotype prevalence data for Iraq due to inadequate surveillance in the region. Thus, this review aims to determine the pneumococcal serotypes circulating in Iraq which may help in the development and introduction of improved pneumococcal vaccines in the country.

Recommendations and Health Technology Assessment (HTA) landscape evaluation for pediatric pneumococcal conjugate vaccines (PCV) in Europe: A systematic literature review

National Immunization Technical Advisory Groups (NITAGs) and Health Technology Assessment (HTA) agencies evaluate the value of vaccines and provide decision-making authorities with recommendations. The availability of information on disease-burden evidence considered or required for the assessment of vaccines included in national immunization programs (NIPs) is limited. The aim of this review is to summarize the epidemiologic and health economic (HE) evidence considered by NITAGs/HTA agencies when evaluating pediatric pneumococcal conjugate vaccine (PCV) NIPs. A systematic literature review of national recommendation reports for PCV NIPs in children in 31 European countries, published since 2001, was performed using NITAG/HTA agency websites, Google, MEDLINE, and EMBASE. The presence of epidemiological data was mapped, HE data was extracted, and findings were summarized. A total of 46 records for 19 countries were identified. Fifteen countries' records included a recommendation concerning implementation of PCV NIP, switching from one PCV to another or a change in vaccination schedule within an existing NIP. All of these included epidemiological invasive pneumococcal disease data, and to varying degree epidemiological data on acute otitis media and pneumonia. HE data was referenced in 13 countries' records, with 8 countries providing in-depth details on cost-effectiveness analyses. Pediatric PCV NIP recommendations were published by 61% of European countries, with varying degree of details and decision rationale. Some countries only publish the HE aspect of their rationale. The identified material can provide insight and support local policymakers and clinicians how data influenced the decision-making process in their countries.

Nanobionics: From plant empowering to the infectious disease treatment

Infectious diseases (ID) are serious threats against the global health and socio-economic conditions. Vaccination usually plays a key role in disease prevention, however, insufficient efficiency or immunogenicity may be quite challenging. Using the advanced vectors for delivery of vaccines with suitable efficiency, safety, and immune-modulatory activity, and tunable characteristics could be helpful, but there are no systematic reviews confirming the capabilities of the vaccine delivery systems for covering various types of pathogens. Furthermore, high rates of the infections, transmission, and fatal ratio and diversity of the pathogens and infection mechanisms may negatively influence vaccine effectiveness. The absence of highly-effective antibiotics against the resistant strains of bacteria and longevity of antibiotic testing have provoked increasing needs towards the application of more accurate and specific theranostic strategies including the nanotechnology-based ones. Nanobionics which is based on the charge storage and transport in the molecular structures, could be of key value in the molecular diagnostic tests and highly-specific electro-analytical methods or devices. Such devices based on the early disease diagnostics might be of critical significance against various types of diseases. This article highlights the significance of nanobionics against ID.

A Rare Case of Streptococcus Pneumoniae Causing Malignant Otitis Externa Complicated by Skull Base Osteomyelitis

Skull base osteomyelitis is an aggressive infection involving bones of the skull. It is a rare complication of malignant otitis externa, caused by the contiguous spread of the infection. Patients are mostly elderly with comorbidities that compromise immunity. It is atypical for Streptococcus species to be encountered in basilar skull osteomyelitis. Here we present the case of an 80-year-old male with multiple comorbidities including diabetes mellitus with a two-month history of right ear pain associated with occasional discharge and diminished hearing who was found to have bacteremia and basilar skull osteomyelitis with Streptococcus pneumoniae isolated from blood and otorrhea fluid cultures. This unusual presentation of S. pneumoniae related skull base osteomyelitis could be attributed to an undiagnosed pancreatic cancer at the time of presentation. Malignant otitis externa can progress into invasive disease in the head and neck; almost all cases tend to be caused by Pseudomonas aeruginosa but unusual cases, such as this, can be caused by Streptococcus pneumoniae.

Prophylactic vaccine delivery systems against epidemic infectious diseases

Prophylactic vaccines have evolved from traditional whole-cell vaccines to safer subunit vaccines. However, subunit vaccines still face problems, such as poor immunogenicity and low efficiency, while traditional adjuvants are usually unable to meet specific response needs. Advanced delivery vectors are important to overcome these barriers; they have favorable safety and effectiveness, tunable properties, precise location, and immunomodulatory capabilities. Nevertheless, there has been no systematic summary of the delivery systems to cover a wide range of infectious pathogens. We herein summarized and compared the delivery systems for major or epidemic infectious diseases caused by bacteria, viruses, fungi, and parasites. We also included the newly licensed vaccines (e.g., COVID-19 vaccines) and those close to licensure. Furthermore, we highlighted advanced delivery systems with high efficiency, cross-protection, or long-term protection against epidemic pathogens, and we put forward prospects and thoughts on the development of future prophylactic vaccines.

Nasopharyngeal carriage rates and serotype distribution of Streptococcus pneumoniae among school children with acute otitis media in Central Java, Indonesia

Streptococcus pneumoniae is a common bacterial pathogen that causes acute otitis media (AOM) in children. In this study, we investigated nasopharyngeal carriage rates and serotype distributions of S. pneumoniae among school children with AOM in Banyumas Regency, Central Java, Indonesia, from 2018 to 2019. Nasopharyngeal swab specimens and demographic data were collected from 122 children between the ages of 6 and 12. The specimens were cultured for the identification of S. pneumoniae, and serotyping was performed using a sequential multiplex PCR assay. We found that the S. pneumoniae carriage rate was 73 % (89/122) among children with AOM. Serotypes 23A (11 %) and 6A/6B (10 %) were the most common serotypes among the 91 cultured S. pneumoniae strains, followed by 3 (8 %), 14 (7 %), 6C/6D (7 %), 11A/11D (6 %), 15B/15C (4 %) and 35 B (4 %). Moreover, 41 % of the strains could be covered by the 13-valent pneumococcal conjugate vaccine, PCV13. In conclusion, high nasopharyngeal carriage rates of S. pneumoniae were found in school children with AOM, with almost half of the strains being the vaccine-type. This finding provides a baseline for nasopharyngeal carriage of S. pneumoniae in school children with AOM and supports the implementation of pneumococcal conjugate vaccines in Indonesia.

Impact of the 13-valent pneumococcal conjugate vaccine on acute otitis media and acute sinusitis epidemiology in British Columbia, Canada

BACKGROUND

Numerous studies have characterized the 13-valent pneumococcal conjugate vaccine (PCV13) programme's beneficial effects on acute otitis media (AOM) and acute sinusitis (AS) rates in children; however, few studies have examined the impact on adults.

OBJECTIVES

This retrospective cohort study evaluates the overall effect of the PCV13 immunization programme on the incidence of AOM and AS at the population level.

METHODS

Health administrative databases were linked to assess outpatient visits, hospitalizations and antibiotic utilization from 2000 to 2018. Multivariable Poisson regression was used to evaluate the impact of the PCV13 vaccine programme (2011-18) compared with the pre-PCV13 era (2000-10), overall and by age.

RESULTS

From 2000 to 2018, the incidence of AOM decreased by 50% (62 to 31 per 1000 population) while sinusitis decreased by 18% (33 to 27 per 1000 population). In the PCV13 era, the incidence of AOM declined [incidence rate ratio (IRR): 0.70; 95% CI: 0.70-0.70], in parallel with decreased incidence of antibiotic utilization (IRR: 0.65; 95% CI: 0.64-0.65). A reduction was also observed in the incidence of AS during the PCV13 era compared with the pre-PCV13 era (IRR: 0.88; 95% CI: 0.88-0.88), mainly driven by declines among those younger than 65 years of age. In contrast, an increase in AS incidence was noted in individuals aged ≥65 years (IRR: 1.03; 95% CI: 1.02-1.03). A decrease in antibiotic prescription rates for sinusitis was observed for those under 65 years of age.

CONCLUSIONS

The PCV13 immunization programme is associated with a reduction in the incidence of AOM and AS. Moreover, the associated use of antibiotics for these diagnoses has comparably decreased across paediatric, as well as adult populations.

Streptococcus pneumoniae Serotypes Carried by Young Children and Their Association With Acute Otitis Media During the Period 2016-2019

Background: Streptococcus pneumoniae (Sp) is a major cause of acute otitis media (AOM). Pneumococcal conjugate vaccine (PCV) programs have altered pneumococcal serotype epidemiology in disease and carriage. In this study, we used samples collected during a cross-sectional study to examine if the clinical picture of acute otitis media (AOM) in young children exposed to the PCV program in Belgium was related to the carried pneumococcal strains, and if their carriage profile differed from healthy children attending daycare centers. Material/Methods: In three collection periods from February 2016 to May 2018, nasopharyngeal swabs and background characteristics were collected from children aged 6-30 months either presenting at their physician with AOM (AOM-group) or healthy and attending day care (DCC-group). Clinical signs of AOM episodes and treatment schedule were registered by the physicians. Sp was detected, quantified, and characterized using both conventional culture analysis and real-time PCR analysis. Results: Among 3,264 collected samples, overall pneumococcal carriage and density were found at similar rates in both AOM and DCC. As expected non-vaccine serotypes were most frequent: 23B (AOM: 12.3%; DCC: 17.4%), 11A (AOM: 7.5%; DCC: 7.4%) and 15B (AOM: 7.5%; DCC: 7.1%). Serotypes 3, 6C, 7B, 9N, 12F, 17F, and 29 were more often found in AOM than in DCC (p-value < 0.05), whereas 23A and 23B were less often present in AOM (p-value < 0.05). Antibiotic non-susceptibility of Sp strains was similar in both groups. No predictors of AOM severity were identified. Conclusion: In the present study, overall carriage prevalence and density of S. pneumoniae were found similar in young children with AOM and in healthy children attending day-care centers in Belgium. Certain serotypes not currently included in the PCV vaccines were found to be carried more often in children with AOM than in DCC, a finding that might suggest a relationship between these serotypes and AOM.

Biochemical, genetic and transcriptional characterization of multibacteriocin production by the anti-pneumococcal dairy strain Streptococcus infantarius LP90

Streptococcus pneumoniae infections are one of the major causes of morbility and mortality worldwide. Although vaccination and antibiotherapy constitute fundamental and complementary strategies against pneumococcal infections, they present some limitations including the increase in non-vaccine serotypes and the emergence of multidrug-resistances, respectively. Ribosomally-synthesized antimicrobial peptides (i.e. bacteriocins) produced by Lactic Acid Bacteria (LAB) may represent an alternative or complementary strategy to antibiotics for the control of pneumococal infections. We tested the antimicrobial activity of 37 bacteriocinogenic LAB, isolated from food and other sources, against clinical S. pneumoniae strains. Streptococcus infantarius subsp. infantarius LP90, isolated from Venezuelan water-buffalo milk, was selected because of its broad and strong anti-pneumococcal spectrum. The in vitro safety assessment of S. infantarius LP90 revealed that it may be considered avirulent. The analysis of a 19,539-bp cluster showed the presence of 29 putative open reading frames (ORFs), including the genes encoding 8 new class II-bacteriocins, as well as the proteins involved in their secretion, immunity and regulation. Transcriptional analyses evidenced that the induction factor (IF) structural gene, the bacteriocin/IF transporter genes, the bacteriocin structural genes and most of the bacteriocin immunity genes were transcribed. MALDI-TOF analyses of peptides purified using different multichromatographic procedures revealed that the dairy strain S. infantarius LP90 produces at least 6 bacteriocins, including infantaricin A₁, a novel anti-pneumococcal two-peptide bacteriocin.

Pneumococcal serotype 19A is the major cause of pediatric acute otitis media with ruptured tympanic membrane in Addis Ababa, Ethiopia, 5 years after the introduction of the ten-valent pneumococcal conjugate vaccine

INTRODUCTION

In Ethiopia, there is a lack of data on pneumococcal serotypes causing acute otitis media (AOM) in children. We aimed to study the etiology, pneumococcal serotypes and antimicrobial resistance patterns of isolates from children with AOM with spontaneous perforation of the tympanic membrane (SPTM).

METHODS

We carried out a prospective observational study in children with AOM with SPTM, aged 0-15 years in Addis Ababa, Ethiopia. Middle ear fluid was collected using sterile swabs, cultured and antibiotic susceptibility testing was performed. Serotypes of Streptococcus pneumoniae were determined by sequencing the cpsB gene and by the Quellung reaction.

RESULTS

A total of 55 children were enrolled. Out of 55 samples that were cultured, 52 (94.5%) were culture positive for a total of 66 bacterial species, and 56.4% (31/55) samples were positive for 41 (62.1%) known pathogenic bacterial species. The most common pathogenic bacterial isolates were S. pneumoniae (36.6%), Staphylococcus aureus (19.5%), Streptococcus pyogenes (14.6%) and Haemophilus influenzae (12.2%). Serotype 19A (73.3%) was the predominant pneumococcal serotype. There was a high rate of non-susceptibility to penicillin (86.6%) and trimethoprim/sulfamethoxazole (80%) among pneumococcal isolates. Out of 21 different isolates tested for amoxicillin susceptibility, 15 (71.4%) were resistant.

CONCLUSIONS

Pneumococcal serotype 19A was the predominant cause of AOM with SPTM in children in Addis Ababa, Ethiopia, 5 years after introduction of PCV10. There was a high rate of resistance to commonly prescribed antibiotics. The study highlights the need for wide scale surveillance of the etiology and antimicrobial susceptibility of AOM in Ethiopian children.

Mastoiditis with Streptococcus pneumoniae serotype 19A in one-dose PCV13 vaccinated three-month-old infant

Pneumococcal conjugate vaccines (PCV) have been widely used in high-income countries for more than a decade, resulting in a dramatic reduction in pneumococcal disease caused by vaccine serotypes. PCV has been included in Turkey's National Immunization Programme since 2009 with PCV7 and continued with PCV13 from 2011. We presented a three-month-old infant who developed mastoiditis secondary to S. pneumoniae serotype 19A after acute otitis media.

Etiology of acute otitis media and phenotypic-molecular characterization of Streptococcus pneumoniae isolated from children in Liuzhou, China

Background

The etiology and epidemiology of acute otitis media (AOM) are poorly understood in China. This study aimed to describe the etiology of AOM and the phenotypic and molecular characteristics of AOM-causing Streptococcus pneumoniae (S.pneumoniae) recovered from Chinese children.

Methods

A retrospective study was conducted to enrol patients younger than 18 years diagnosed as AOM. Middle ear fluid specimens were collected then cultured for bacterial pathogens. All S.pneumoniae isolates were tested for antibiotic susceptibility, serotypes, virulence genes, antibiotic resistant determinants and sequence types.

Results

The dominant otopathogen among AOM children was S.pneumoniae (54.4%). Among S.pneumoniae isolates, there were 97.3, 97.3 and 75.7% isolates resistant to erythromycin, tetracycline and trimethoprim-sulfamethoxazole, respectively. There was 72.8% S.pneumoniae with multidrug resistance. The dominant sequence types (STs) were ST271 and ST320, whereas the prevailing serotypes were 19F and 19A. The 7-valent and 13-valent pneumococcal conjugate vaccine (PCV) coverage among AOM children were 73.0 and 94.6%, respectively. Additionally, we found that CC271 expressed more of mef(A/E) (P < 0.001), pspA (P = 0.022) and sipA (P < 0.001) than non-CC271 isolates.

Conclusion

The high prevalence of international multidrug-resistant clone (Taiwan^19F-14) in China necessitates continued dedication to expand PCV13 immunization and better control of antibiotic use in China.

Streptococcus pneumoniae's Virulence and Host Immunity: Aging, Diagnostics, and Prevention

Streptococcus pneumoniae is an infectious pathogen responsible for millions of deaths worldwide. Diseases caused by this bacterium are classified as pneumococcal diseases. This pathogen colonizes the nasopharynx of its host asymptomatically, but overtime can migrate to sterile tissues and organs and cause infections. Pneumonia is currently the most common pneumococcal disease. Pneumococcal pneumonia is a global health concern and vastly affects children under the age of five as well as the elderly and individuals with pre-existing health conditions. S. pneumoniae has a large selection of virulence factors that promote adherence, invasion of host tissues, and allows it to escape host immune defenses. A clear understanding of S. pneumoniae's virulence factors, host immune responses, and examining the current techniques available for diagnosis, treatment, and disease prevention will allow for better regulation of the pathogen and its diseases. In terms of disease prevention, other considerations must include the effects of age on responses to vaccines and vaccine efficacy. Ongoing work aims to improve on current vaccination paradigms by including the use of serotype-independent vaccines, such as protein and whole cell vaccines. Extending our knowledge of the biology of, and associated host immune response to S. pneumoniae is paramount for our improvement of pneumococcal disease diagnosis, treatment, and improvement of patient outlook.

Impact of pneumococcal conjugate vaccines on otitis media: A review of measurement and interpretation challenges

Acute otitis media (AOM) is among the most frequent childhood diseases and is caused by various bacterial and viral etiological agents. In this article, we provide an overview of published studies assessing the impact of higher-valent pneumococcal conjugate vaccines (PCVs) on AOM. In some instances, reports of PCV impact on complications of AOM have been included. While randomized controlled trials (RCTs) allow for the most precise assessment of vaccine efficacy against AOM, observational studies provide answers to questions regarding the public health value of these vaccines in real-life settings. We discuss the challenges that arise when measuring PCV impact on AOM in observational studies: the local variability of viral and bacterial etiology, differences in case ascertainment, care-seeking behavior, standards of care and diagnosis of AOM (e.g. use of incisions), as well as declining baseline AOM incidence that can already be in place before PCV introduction, and how these factors can impact the results and their interpretation.

Pneumococcal vaccination reduces the risk of community-acquired pneumonia in children

BACKGROUND

The seven-valent pneumococcal conjugate vaccine (PCV7) was introduced to Japan in 2009, after which there was a rapid decline in invasive pneumococcal disease. There are few data, however, on the effectiveness of PCV7 against community-acquired pneumonia (CAP). We conducted an ambispective cohort study among children aged 0-6 years old who attended day-care centers.

METHODS

A total of 624 children at 10 day-care centers in Sapporo, Japan participated in the study. The parents reported whether their child had received PCV7 one or more times, as well as the exact dates of vaccination from records in maternal and child health handbooks marked by pediatricians. Each CAP event was reported by parents according to doctor diagnosis. A Cox proportional hazards regression model was used to calculate the hazard ratio (HR) and 95%CI of CAP incidence reduced by PCV7 inoculation.

RESULTS

During the observational period, 94 subjects contracted CAP. After adjusting for potentially confounding variables, inoculation with PCV7 was significantly associated with a reduced risk of CAP (HR, 0.22; 95%CI: 0.13-0.34). On stratified analysis by age, PCV7 was significantly associated with a reduced risk of CAP in both children aged <3 years (HR, 0.31; 95%CI: 0.14-0.71), and those ≥3 years (HR, 0.20; 95%CI: 0.09-0.43).

CONCLUSION

PCV7 is highly effective in reducing the risk of CAP in children attending day-care centers.

Total synthesis of a Streptococcus pneumoniae serotype 12F CPS repeating unit hexasaccharide

The Gram-positive bacterium Streptococcus pneumoniae causes severe disease globally. Vaccines that prevent S. pneumoniae infections induce antibodies against epitopes within the bacterial capsular polysaccharide (CPS). A better immunological understanding of the epitopes that protect from bacterial infection requires defined oligosaccharides obtained by total synthesis. The key to the synthesis of the S. pneumoniae serotype 12F CPS hexasaccharide repeating unit that is not contained in currently used glycoconjugate vaccines is the assembly of the trisaccharide β-D-GalpNAc-(1→4)-[α-D-Glcp-(1→3)]-β-D-ManpNAcA, in which the branching points are equipped with orthogonal protecting groups. A linear approach relying on the sequential assembly of monosaccharide building blocks proved superior to a convergent [3 + 3] strategy that was not successful due to steric constraints. The synthetic hexasaccharide is the starting point for further immunological investigations.

Recent epidemiology of Streptococcus pneumoniae in nasopharynxes of Korean children with acute otitis media

BACKGROUND

This prospective study was performed to evaluate serotype distribution, multilocus sequence typing, and antibiotic susceptibility of Streptococcus pneumoniae identified in Korean children with acute otitis media (AOM) after the introduction of a 7-valent pneumococcal conjugate vaccine (PCV7).

METHODS

Nasopharyngeal aspirates were collected from children diagnosed with AOM in seven hospitals in Korea. The bacteria identified in these samples and the serotypes, sequence types (STs), and antibiotic susceptibilities of S. pneumoniae isolates were evaluated.

RESULTS

A total of 390 children were enrolled, and bacteria were identified in 376 (96.4%) children. S. pneumoniae, Haemophilus influenzae and Moraxella catarrhalis were identified in 155 (39.7%), 127 (32.6%) and 86 (22.1%) children, respectively. Serotype 19A (22.4%) was the most common S. pneumoniae serotype, with serogroups 11 (14.7%) and 15 (13.5%) following. ST320 (23.5%) was the most common ST; ST166 (17.0%) and ST83 (8.5%) followed. The overall susceptibility rates of S. pneumoniae to oral penicillin V and amoxicillin/clavulanate were 2.6% and 53.2%, respectively. The susceptibility rate to cefditoren was 91.0%; however, the rates for other cephalosporins were less than 10.0%. Compared with other serogroups, S. pneumoniae serogroups 19, 11, and 15 showed significantly lower susceptibility rates to all the antibiotics tested.

CONCLUSION

S. pneumoniae serotype 19A, serogroups 11 and 15 were the major nasopharyngeal-colonizing bacteria in Korean children with AOM after the introduction of PCV7. These relatively prevalent serotype/serogroups showed lower antibiotic susceptibility rates.

Prevention of early episodes of otitis media by pneumococcal vaccines might reduce progression to complex disease

Otitis media is a common childhood infection of the middle ear and a major cause of morbidity. This multifactorial disease manifests as a spectrum of clinical syndromes from uncomplicated acute otitis media to more complex recurrent and chronic cases (frequently polymicrobial), with the major pathogens involved being Streptococcus pneumoniae and non-typeable Haemophilus influenzae. Pneumococcal conjugate vaccines (PCVs) target only a few serotypes that cause otitis media; however, results from studies suggest that existing PCVs can prevent early episodes of disease associated with vaccine serotypes, resulting in a reduction of subsequent complex cases caused by non-vaccine serotypes and other otopathogens, which contribute considerably to the disease burden. In this Review, we discuss the role of pneumococcus in the disease continuum and assess clinical evidence showing the effect of prevention of early episodes on the complex interplay between bacterial species implicated in otitis media.

Influence of HLA-DR polymorphism and allergic sensitization on humoral immune responses to intact pneumococcus in a transgenic mouse model

Asthma is independently associated with HLA-DR3 and increased risks of pneumococcal diseases. We aimed to determine whether HLA-DR polymorphism (HLA-DRB1*03), sensitization to house dust mite (HDM), or their interaction affects humoral immune responses to pneumococcal polysaccharide and protein antigens of intact pneumococci. Induction of serum titers of anti-pneumococcal polysaccharide and anti-surface protein IgM and IgG in response to immunization with intact pneumococci (Pn) serotype 14 was determined using humanized HLA-DR3 and DR2 transgenic mice. Transgenic mice were sensitized by injecting HDM and challenged with intranasal HDM. Mice were subsequently immunized with heat-killed Pn14 at day 24. Serum titers of anti-phosphorylcholine (PC) IgM and IgG, anti-pneumococcal polysaccharide, capsular type 14 (PPS14) IgM and IgG, and anti-pneumococcal surface protein A (PspA) IgG were measured. We included a total of 44 mice (22 DR3 and 22 DR2 mice) and half of mice in each group were sensitized with HDM (i.e. 22 HDM-sensitized and 22 control mice). HDM-sensitized mice, irrespective of HLA-DR polymorphism, had significantly lower humoral immune responses. HLA-DR3 mice, irrespective of HDM sensitization, elicited a significantly lower anti-PC IgG response. In contrast, the anti-PspA IgG response was higher in DR3 relative to DR2 mice. The effect of HDM sensitization on lowering humoral immune responses to Pn14 was observed in DR3 mice regardless of the nature of the antigen, whereas such decreases were observed only for the anti-PPS14 IgG and anti-PC IgM responses in DR2 mice. HDM sensitization lowered humoral immune responses to intact pneumococcus and this effect was significantly modified by the HLA-DR polymorphism.

Automated glycan assembly of a S. pneumoniae serotype 3 CPS antigen

Vaccines against S. pneumoniae, one of the most prevalent bacterial infections causing severe disease, rely on isolated capsular polysaccharide (CPS) that are conjugated to proteins. Such isolates contain a heterogeneous oligosaccharide mixture of different chain lengths and frame shifts. Access to defined synthetic S. pneumoniae CPS structures is desirable. Known syntheses of S. pneumoniae serotype 3 CPS rely on a time-consuming and low-yielding late-stage oxidation step, or use disaccharide building blocks which limits variability. Herein, we report the first iterative automated glycan assembly (AGA) of a conjugation-ready S. pneumoniae serotype 3 CPS trisaccharide. This oligosaccharide was assembled using a novel glucuronic acid building block to circumvent the need for a late-stage oxidation. The introduction of a washing step with the activator prior to each glycosylation cycle greatly increased the yields by neutralizing any residual base from deprotection steps in the synthetic cycle. This process improvement is applicable to AGA of many other oligosaccharides.

Developing Peptide Mimotopes of Capsular Polysaccharides and Lipopolysaccharides Protective Antigens of Pathogenic Burkholderia Bacteria

Burkholderia pseudomallei (BP) and Burkholderia mallei (BM) are two species of pathogenic Burkholderia bacteria. Our laboratory previously identified four monoclonal antibodies (MAbs) that reacted against Burkholderia capsular polysaccharides (PS) and lipopolysaccharides (LPS) and effectively protected against a lethal dose of BP/BM infections in mice. In this study, we used phage display panning against three different phage peptide libraries to select phage clones specifically recognized by each of the four protective MAbs. After sequencing a total of 179 candidate phage clones, we examined in detail six selected phage clones carrying different peptide inserts for the specificity of binding by the respective target MAbs. Chemically synthesized peptides corresponding to those displayed by the six phage clones were conjugated to keyhole limpet hemocyanin carrier protein and tested for their binding specificity to the respective protective MAbs. The study revealed that four of the six peptides, all derived from the library displaying dodecapeptides, functioned well as "mimotopes" of Burkholderia PS and LPS as demonstrated by a high degree of specific competition against the binding of three protective MAbs to BP and BM. Our results suggest that the four selected peptide mimics corresponding to PS/LPS protective antigens of BP and BM could potentially be developed into peptide vaccines against pathogenic Burkholderia bacteria.

Severity of pneumococcal versus non-pneumococcal acute otitis media in children

BACKGROUND

Pneumococcal acute otitis media (AOM) has been previously considered as a more severe disease than that caused by other otopathogens, based on clinical and/or otologic scores. We sought to test this hypothesis in the pneumococcal conjugated vaccine (PCV) era.

METHODS

Children <6 years who presented with 'severe' AOM episodes with middle ear fluid (MEF) cultures during 2008-2013 were retrospectively identified. 'Severe' AOM episodes were considered if tympanocentesis was required or if spontaneous otorrhea was present. Data were extracted for demographics, clinical and laboratory tests. Children were categorised according to their PCV status as 'unimmunised' or 'PCV7/PCV13 immunised' and according to their MEF culture results into the 'pneumococcal' or the 'non-pneumococcal' group. Leukocytosis was defined as white blood cells (WBC) count >15 000/μL, and elevated C-reactive protein (CRP) level was considered as >50 mg/L.

RESULTS

Of 295 eligible AOM episodes, 106 (36%) were culture positive. Children in the pneumococcal group (65, 61%) had a significantly higher WBC counts and higher CRP levels, were more often <2 years old and were more prone to complicate with acute mastoiditis (AM), compared to children in the non-pneumococcal group, P = 0.03, P = 0.02, P = 0.04 and P = 0.03, respectively. In the pneumococcal group, unimmunised children had higher WBC counts when compared with PCV13-immunised children (P = 0.04), but there were no appreciable differences in CRP levels between unimmunised and PCV7/PCV13-immunised children.

CONCLUSION

Pneumococcal AOM is associated with higher leukocytosis and CRP levels than non-pneumococcal AOM. Circulating Streptococcus pneumoniae strains causing 'severe' AOM in PCV13-immunised children yielded lower inflammatory responses when compared with unimmunised children.

Nonencapsulated Streptococcus pneumoniae: Emergence and Pathogenesis

While significant protection from pneumococcal disease has been achieved by the use of polysaccharide and polysaccharide-protein conjugate vaccines, capsule-independent protection has been limited by serotype replacement along with disease caused by nonencapsulated Streptococcus pneumoniae (NESp). NESp strains compose approximately 3% to 19% of asymptomatic carriage isolates and harbor multiple antibiotic resistance genes. Surface proteins unique to NESp enhance colonization and virulence despite the lack of a capsule even though the capsule has been thought to be required for pneumococcal pathogenesis. Genes for pneumococcal surface proteins replace the capsular polysaccharide (cps) locus in some NESp isolates, and these proteins aid in pneumococcal colonization and otitis media (OM). NESp strains have been isolated from patients with invasive and noninvasive pneumococcal disease, but noninvasive diseases, specifically, conjunctivitis (85%) and OM (8%), are of higher prevalence. Conjunctival strains are commonly of the so-called classical NESp lineages defined by multilocus sequence types (STs) ST344 and ST448, while sporadic NESp lineages such as ST1106 are more commonly isolated from patients with other diseases. Interestingly, sporadic lineages have significantly higher rates of recombination than classical lineages. Higher rates of recombination can lead to increased acquisition of antibiotic resistance and virulence factors, increasing the risk of disease and hindering treatment. NESp strains are a significant proportion of the pneumococcal population, can cause disease, and may be increasing in prevalence in the population due to effects on the pneumococcal niche caused by pneumococcal vaccines. Current vaccines are ineffective against NESp, and further research is necessary to develop vaccines effective against both encapsulated and nonencapsulated pneumococci.

Streptococcus pneumoniae Serotype Distribution and Pneumococcal Conjugate Vaccine Serotype Coverage among Pediatric Patients in East and Southeast Asia, 2000-2014: a Pooled Data Analysis

Pneumococcal infection is one of the leading causes of death worldwide, especially in children of developing and underdeveloped countries. Capsular polysaccharide-based vaccines are available for the prevention of this disease. A 7-valent pneumococcal conjugate vaccine (PCV7) was licensed in 2000 for use in children less than two years of age. Subsequently, to broaden the protection, 10-valent (PCV10) and 13-valent (PCV13) vaccines were licensed in 2009 and 2010, respectively. All of these conjugate vaccines elicit an immune response that only provides protection against the infection of S. pneumoniae serotypes included in the formulation. Profiles of S. pneumoniae serotype distribution and serotype coverage for both PCV7 and PCV13 have been reported in some Asian countries/territories. But the published results cannot provide conclusive information due to the difference in studied population and geographic areas. The goals of this review are to obtain an accurate estimate of serotype coverage for PCV7, PCV10, and PCV13 and examine the change in the S. pneumoniae serotype distribution after PCV7 use among pediatric patients in East and Southeast Asia through the analysis of pooled data that were published in the English literature between 2000 and 2014.

Antibiotic resistance of Streptococcus pneumoniae in children with acute otitis media treatment failure

OBJECTIVES

The emergence of antibiotic-resistant bacteria is a major cause of treatment failure in children with acute otitis media (AOM). This study aimed to analyze the types of bacterial strains in fluid isolated from the middle ear of children with AOM who did not respond to oral antibiotic treatment. We also determined the antibiotic resistance of the most frequently isolated bacterial strain (Streptococcus pneumoniae) found in these children.

METHODS

This was a prospective study of 157 children with AOM aged from 6 months to 7 years admitted due to unsuccessful oral antibiotic treatment. All children underwent a myringotomy, and samples of the middle ear fluid were collected for bacteriological examination.

RESULTS

Positive bacterial cultures were obtained in 104 patients (66.2%), with Streptococcus pneumoniae (39.69%), Haemophilus influenzae (16.03%) Staphylococcus aureus (16.03%), Staphylococcus haemolyticus (6.9%) and Streptococcus pyogenes (5.34%) found most frequently. The majority (65.4%) of S. pneumoniae strains were penicillin-intermediate-resistant or penicillin-resistant, and 67.2% strains of S. pneumoniae were multidrug-resistant.

CONCLUSIONS

We identified S. pneumoniae as the most frequently isolated pathogen from the middle ear in children with AOM treatment failure and determined that the majority of strains were antibiotic-resistant. We propose that the microbiological identification of bacterial strains and their degree of antibiotic resistance should be performed prior to therapy in order to choose the most appropriate antibiotic therapy for children with AOM treatment failure.

Pneumococcal vaccination reduced the risk of acute otitis media: Cohort study

BACKGROUND

Seven-valent pneumococcal conjugate vaccine (PCV7) was introduced to Japan in 2009, and after that invasive pneumococcal disease has gradually decreased. There are few data, however, on the effectiveness of PCV7 against acute otitis media (AOM) in Japan.

METHODS

From 10 daycare centers in Sapporo, Japan, 614 parents participated in the survey. Each parent reported whether their child subject had received one or more doses of PCV7, and, if so, the exact dates of receiving PCV7 were verified by reviewing their maternal and child health handbooks marked by a pediatrician. AOM was diagnosed by otorhinolaryngologist or pediatrician. Cox's proportional hazard model was used for calculating the hazard ratio (HR) of AOM incidence reduced by PCV7 inoculation.

RESULTS

Inoculation of PCV7 significantly reduced the risk of AOM (crude HR, 0.63; 95%CI: 0.50-0.79). Adjusting for potentially confounding variables reduced the risk further (adjusted HR, 0.32; 95%CI: 0.23-0.44). On stratification by subject age on 30 April 2012, PCV7 was significantly associated with a reduced risk of AOM in both infants < 3 years old, and in children ≥ 3 years.

CONCLUSION

PCV7 is effectiveness in reducing the risk of AOM both in infants < 3 years old, and in young children ≥ 3 years in Japan.

Bacterial and Respiratory Viral Interactions in the Etiology of Acute Otitis Media in HIV-infected and HIV-uninfected South African Children

BACKGROUND

Bacteria and respiratory viruses are implicated in the pathogenesis of acute otitis media (AOM); however, data from low-middle income countries are sparse. We investigated the etiology of AOM in HIV-infected (HIV+), HIV-uninfected (HIV-) and HIV-exposed clinically asymptomatic for HIV-infection (HEU) South African children.

METHODS

Children ≥3 months to <5 years of age with AOM were enrolled between May 2009 and April 2010 (NCT01031082). Middle ear fluid samples were cultured for bacteria; antibacterial susceptibility was done and serotyping undertaken for Streptococcus pneumoniae and Haemophilus influenzae. Nasopharyngeal aspirates were analyzed for respiratory viruses using immunofluorescence assay and polymerase chain reaction.

RESULTS

Of 260 AOM episodes (HIV+:15; HIV-:182; HEU:63), bacteria were found in 54.6%, including Haemophilus influenzae (30.8%), 98.8% of which were nontypeable, and Streptococcus pneumoniae (20.4%), Staphylococcus aureus (15.8%), Moraxella catarrhalis (5.0%) and Streptococcus pyogenes (1.5%). Nonsusceptibility of Streptococcus pneumoniae to penicillin was 64.2%. Respiratory viruses were detected in 74.2% of cases. Human rhinovirus was most frequently detected (37.7%), followed by adenovirus (14.2%) and human bocavirus (11.5%) overall and irrespective of HIV status. Respiratory viruses were identified concurrently with S. pneumoniae, H. influenzae, M. catarrhalis (76.9-78.8%) and Staphylococcus aureus (63.4%) cultured from middle ear fluid, as well as in 72.0% of episodes negative for any bacteria.

CONCLUSION

The study suggests that respiratory viruses and pathogenic bacteria play an important role in the development of AOM in children. A similar spectrum of pathogens was observed independently of HIV status. Vaccines targeting both nontypeable Haemophilus influenzae and S. pneumoniae may have a broad impact on AOM in South Africa.

Etiology and epidemiology of children with acute otitis media and spontaneous otorrhea in Suzhou, China

BACKGROUND

There are scare data about bacterial etiology and the antibiotic susceptibility, serotype distribution and molecular characteristics of pneumococci in children with acute otitis media (AOM) in China.

METHODS

A prospective study was conducted in Suzhou University Affiliated Children's Hospital. All children under 18 years of age diagnosed as AOM and with spontaneous otorrhea were offered enrollment, and collection of middle ear fluid was then cultured for bacterial pathogens. The antibiotic susceptibility, serotypes, macrolide resistance genes and sequence types of Streptococcus pneumoniae strains were identified.

RESULTS

From January 2011 to December 2013, a total of 229 cases of AOM with spontaneous otorrhea were identified; of these, 159 (69.4%) middle ear fluid specimens were tested positive for bacterial pathogens. The leading cause was S. pneumoniae (47.2%), followed by Staphylococcus aureus (18.8%) and Haemophilus influenzae (7.4%). The antibiotic resistance rates of S. pneumoniae isolates to erythromycin were 99.1%, and the nonsusceptible rate to penicillin was 54.6%. The most common serotypes identified were 19A (45.1%) and 19F (35.4%). The coverage against PCV7 serotypes for this outcome was 56.1% and of PCV13 was 97.6%. The macrolide resistance was mainly mediated by both ermB and mefA/E genes (88.6%). The CC271 was the major clonal complex identified.

CONCLUSIONS

S. pneumoniae was a leading cause for AOM in children in Suzhou, China. Antibiotics resistance rates of S. pneumoniae were high and mainly due to the spread of CC271 clonal complex.

Bacterial etiology of acute otitis media and characterization of pneumococcal serotypes and genotypes among children in Moscow, Russia

BACKGROUND

We aimed to describe bacterial etiology of acute otitis media (AOM) and characterize resistance, serotypes and genotype profiles of AOM-causing pneumococci recovered in Moscow children.

METHODS

Children with AOM and an available middle ear fluid specimen were prospectively enrolled in this study. Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae and Moraxella catarrhalis were considered as true otopathogens. All pneumococcal isolates were serotyped using the Quellung reaction; multidrug-resistant (MDR) pneumococci underwent multilocus sequence typing.

RESULTS

In 172 of 541 enrolled AOM patients (32%) at least 1 otopathogen was recovered, with S. pneumoniae having the highest rate of 63% (109/172). When adjusted for antibiotic treatment before sampling, in untreated patients the rate of culture-positive AOM was 35% (124/352), S. pneumoniae had a prevalence of 69% (86/124), S. pyogenes 19% (24/124), H. influenzae 13% (16/124) and M. catarrhalis 9% (11/124). Among 107 examined pneumococci, 45% were penicillin-nonsusceptible, 34 and 30% were resistant to erythromycin and clindamycin, respectively; 30% had an MDR phenotype, but no amoxicillin-resistant isolates were found. Ten of 32 (31%) MDR pneumococci related to clonal complex 320, the remaining isolates belonged to 7 different clonal complex. Six leading serotypes were 19F (27%), 3 (12%), 6B (11%), 14 (11%), 19A (9%) and 23F (8%); overall polysaccharide conjugate vaccine13 coverage was 93%.

CONCLUSIONS

S. pneumoniae, the leading bacterial AOM pathogen in Moscow children, is characterized by a substantial rate of antibiotic nonsusceptibility and clonality. A polysaccharide conjugate vaccine with expanded coverage seems to fit the current AOM pneumococcal serotype distribution in Russia better.

What is behind the ear drum? The microbiology of otitis media and the nasopharyngeal flora in children in the era of pneumococcal vaccination

AIM

This study aims to describe the microbiology of middle ear fluid (MEF) in a cohort of children vaccinated with Streptococcus pneumoniae conjugate vaccine (PCV7) having ventilation tube insertion. Nasopharyngeal (NP) carriage of otopathogens in these children is compared with children without history of otitis media.

METHODS

Between May and November 2011, MEF and NP samples from 325 children aged <3 years were collected in three major centres in New Zealand at the time of ventilation tube insertion. An age-matched non-otitis-prone comparison group of 137 children had NP samples taken. A questionnaire was completed by both groups.

RESULTS

Immunisation coverage with at least one dose of PCV7 was 97%. Haemophilus influenzae was cultured in 19.4% of MEF and was polymerase chain reaction (PCR) positive in 43.4%. S. pneumoniae and Moraxella catarrhalis were cultured in <10% of MEF samples but were PCR positive for 23.1% and 38.7%, respectively. H. influenzae was the most common organism isolated from NP samples (60%) in the grommet group, while M. catarrhalis (56%) was the most common in the non-otitis prone group. S. pneumoniae was more commonly found in the nasopharynx of children with ear disease (41% vs. 29%). 19F was the most prominent S. pneumoniae serotype in NP samples of both groups, but no serotype dominated in MEF. Ninety-five per cent of H. influenzae isolates were confirmed to be non-typeable H. influenzae.

CONCLUSION

In this cohort of children with established ear disease requiring surgical intervention, non-typeable H. influenzae is the dominant pathogen in both the nasopharynx and MEF.

Decline in antibiotic resistance and changes in the serotype distribution of Streptococcus pneumoniae isolates from children with acute otitis media; a 2001-2011 survey by the French Pneumococcal Network

Streptococcus pneumoniae is an important cause of acute otitis media (AOM). The aim of this study was to evaluate trends in antibiotic resistance and circulating serotypes of pneumococci isolated from middle ear fluid of French children with AOM during the period 2001-2011, before and after the introduction of the PCV-7 (2003) and PCV-13 (2010) vaccines. Between 2001 and 2011 the French pneumococcal surveillance network analysed the antibiotic susceptibility of 6683 S. pneumoniae isolated from children with AOM, of which 1569 were serotyped. We observed a significant overall increase in antibiotic susceptibility. Respective resistance (I+R) rates in 2001 and 2011 were 76.9% and 57.3% for penicillin, 43.0% and 29.8% for amoxicillin, and 28.6% and 13.0% for cefotaxime. We also found a marked reduction in vaccine serotypes after PCV-7 implementation, from 63.0% in 2001 to 13.2% in 2011, while the incidence of the additional six serotypes included in PCV-13 increased during the same period, with a particularly high proportion of 19A isolates. The proportion of some non-PCV-13 serotypes also increased between 2001 and 2011, especially 15A and 23A. Before PCV-7 implementation, most (70.8%) penicillin non-susceptible pneumococci belonged to PCV-7 serotypes, whereas in 2011, 56.8% of penicillin non-susceptible pneumococci belonged to serotype 19A. Between 2001 and 2011, antibiotic resistance among pneumococci responsible for AOM in France fell markedly, and PCV-7 serotypes were replaced by non-PCV-7 serotypes, especially 19A. We are continuing to assess the impact of PCV-13, introduced in France in 2010, on pneumococcal serotype circulation and antibiotic resistance.

Haemophilus influenzae type b as an important cause of culture-positive acute otitis media in young children in Thailand: a tympanocentesis-based, multi-center, cross-sectional study

Background

Streptococcus pneumoniae (S. pneumoniae) and Haemophilus influenzae (H. influenzae) are considered major causes of bacterial acute otitis media (AOM) worldwide, but data from Asia on primary causes of AOM are limited. This tympanocentesis-based, multi-center, cross-sectional study assessed bacterial etiology and antimicrobial susceptibility of AOM in Thailand.

Methods

Children 3 to 59 months presenting with AOM (< 72 hours of onset) who had not received prescribed antibiotics, or subjects who received prescribed antibiotics but remained symptomatic after 48–72 hours (treatment failures), were eligible. Study visits were conducted from April 2008 to August 2009. Bacteria were identified from middle ear fluid collected by tympanocentesis or spontaneous otorrhea swab sampling (< 20% of cases). S. pneumoniae and H. influenzae serotypes were determined and antimicrobial resistance was also assessed.

Results

Of the 123 enrolled children, 112 were included in analysis and 48% of the 118 samples were positive for S. pneumoniae (23% (27/118)), H. influenzae (18% (21/118)), Moraxella catarrhalis (6% (7/118)) or Streptococcus pyogenes (3% (4/118)). The most common pneumococcal serotypes were 19F (26%) and 14 (22%). The majority of H. influenzae isolates were encapsulated (18/21), with 13 type b (Hib) representing 62% of all H. influenzae isolate or 11% of all samples (13/118), and there were only 3 non-typeable isolates. Despite high antibiotic resistance, amoxicillin/clavulanate susceptibility was high. No pneumococcal vaccine use was reported.

Conclusions

S. pneumoniae and H. influenzae, both frequently antibiotic resistant, were leading causes of bacterial AOM and there was an unexpectedly high burden of Hib in this population unvaccinated by any Hib conjugate vaccine. Conjugate vaccines effective against pneumococcus and H. influenzae could potentially reduce the burden of AOM in this population.

Efficacy of pneumococcal nontypable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) in young Latin American children: A double-blind randomized controlled trial

BACKGROUND

The relationship between pneumococcal conjugate vaccine-induced antibody responses and protection against community-acquired pneumonia (CAP) and acute otitis media (AOM) is unclear. This study assessed the impact of the ten-valent pneumococcal nontypable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) on these end points. The primary objective was to demonstrate vaccine efficacy (VE) in a per-protocol analysis against likely bacterial CAP (B-CAP: radiologically confirmed CAP with alveolar consolidation/pleural effusion on chest X-ray, or non-alveolar infiltrates and C-reactive protein ≥ 40 µg/ml); other protocol-specified outcomes were also assessed.

METHODS AND FINDINGS

This phase III double-blind randomized controlled study was conducted between 28 June 2007 and 28 July 2011 in Argentine, Panamanian, and Colombian populations with good access to health care. Approximately 24,000 infants received PHiD-CV or hepatitis control vaccine (hepatitis B for primary vaccination, hepatitis A at booster) at 2, 4, 6, and 15-18 mo of age. Interim analysis of the primary end point was planned when 535 first B-CAP episodes, occurring ≥2 wk after dose 3, were identified in the per-protocol cohort. After a mean follow-up of 23 mo (PHiD-CV, n = 10,295; control, n = 10,201), per-protocol VE was 22.0% (95% CI: 7.7, 34.2; one-sided p = 0.002) against B-CAP (conclusive for primary objective) and 25.7% (95% CI: 8.4%, 39.6%) against World Health Organization-defined consolidated CAP. Intent-to-treat VE was 18.2% (95% CI: 5.5%, 29.1%) against B-CAP and 23.4% (95% CI: 8.8%, 35.7%) against consolidated CAP. End-of-study per-protocol analyses were performed after a mean follow-up of 28-30 mo for CAP and invasive pneumococcal disease (IPD) (PHiD-CV, n = 10,211; control, n = 10,140) and AOM (n = 3,010 and 2,979, respectively). Per-protocol VE was 16.1% (95% CI: -1.1%, 30.4%; one-sided p = 0.032) against clinically confirmed AOM, 67.1% (95% CI: 17.0%, 86.9%) against vaccine serotype clinically confirmed AOM, 100% (95% CI: 74.3%, 100%) against vaccine serotype IPD, and 65.0% (95% CI: 11.1%, 86.2%) against any IPD. Results were consistent between intent-to-treat and per-protocol analyses. Serious adverse events were reported for 21.5% (95% CI: 20.7%, 22.2%) and 22.6% (95% CI: 21.9%, 23.4%) of PHiD-CV and control recipients, respectively. There were 19 deaths (n = 11,798; 0.16%) in the PHiD-CV group and 26 deaths (n = 11,799; 0.22%) in the control group. A significant study limitation was the lower than expected number of captured AOM cases.

CONCLUSIONS

Efficacy was demonstrated against a broad range of pneumococcal diseases commonly encountered in young children in clinical practice.

TRIAL REGISTRATION

www.ClinicalTrials.gov NCT00466947.

In vitro biofilm formation by Streptococcus pneumoniae as a predictor of post-vaccination emerging serotypes colonizing the human nasopharynx

The increasing use of the 7-valent pneumococcal conjugate vaccine has been accompanied by the rise of non-vaccine serotypes colonizing the human nasopharynx. The vast majority of infections are caused by microorganisms that grow in biofilms. It has recently been shown that the formation of Streptococcus pneumoniae biofilms in vivo and in vitro is hindered by the presence of capsular polysaccharide. The biofilm-forming capacity of pneumococcal clinical isolates with different types of capsular polysaccharide and various isogenic transformants was examined. Strains of serotypes 19A and 19F, but not 19B and 19C, formed ≥ 80% of the quantity of biofilm associated with a non-encapsulated control strain. Strains of serogroup 6 also showed significant biofilm-forming capacity. The capsules of serotypes 19A and 19F, and serogroup 6 contain the disaccharides α-D-Glcp-(1→2)-α-L-Rhap-(1→ and α-D-Glcp-(1→3)-α-L-Rhap-(1→. Serotype 18A and serotypes 18B/18C have very similar capsular disaccharides: α-D-GlcpNAc-(1→3)-β-L-Rhap-(1→ and α-D-Glcp-(1→3)-β-L-Rhap-(1→ respectively. However, the strains of serogroup 18 showed impaired biofilm formation. These results indicate that the chemical composition/structure of the capsular polysaccharide is crucial to the biofilm-forming capacity of pneumococcal serotypes. Testing of the in vitro biofilm-forming ability of isogenic transformants expressing different capsular polysaccharides may help predict the emergence of colonizing, non-vaccine serotypes.

A live-attenuated pneumococcal vaccine elicits CD4+ T-cell dependent class switching and provides serotype independent protection against acute otitis media

Acute otitis media (AOM) caused by Streptococcus pneumoniae remains one of the most common infectious diseases worldwide despite widespread vaccination. A major limitation of the currently licensed pneumococcal vaccines is the lack of efficacy against mucosal disease manifestations such as AOM, acute bacterial sinusitis and pneumonia. We sought to generate a novel class of live vaccines that (1) retain all major antigenic virulence proteins yet are fully attenuated and (2) protect against otitis media. A live vaccine candidate based on deletion of the signal recognition pathway component ftsY induced potent, serotype-independent protection against otitis media, sinusitis, pneumonia and invasive pneumococcal disease. Protection was maintained in animals coinfected with influenza virus, but was lost if mice were depleted of CD4(+) T cells at the time of vaccination. The live vaccine induced a strong serum IgG2a and IgG2b response that correlated with CD4(+) T-cell mediated class switching. Deletion of genes required for microbial adaptation to the host environment is a novel live attenuated vaccine strategy yielding the first experimental vaccine effective against pneumococcal otitis media.

Bacterial etiology of acute otitis media in the era prior to universal pneumococcal vaccination in Taiwanese children

BACKGROUND

Acute otitis media (AOM) is one of the most frequent bacterial infections in children. Streptococcus pneumoniae and nontypeable Haemophilus influenzae (NTHi) are the two major bacterial pathogens. Pneumococcal conjugate vaccine was introduced into Taiwan in 2005 and only some children were vaccinated. This retrospective study assessed the bacterial etiology of AOM and its antimicrobial susceptibility in the era prior to universal pneumococcal vaccination in Taiwan.

METHODS

From December 2009 to November 2011, children presenting with AOM and having a middle ear effusion sample collected by tympanocentesis were enrolled. The study period was divided into two parts. Demographic data of patients and antibiotic susceptibility of the pathogens were collected and analyzed. Serotypes of S. pneumoniae were identified.

RESULTS

Among the 151 episodes, 46% of samples found bacterial pathogens. S. pneumoniae and NTHi were the leading causes of AOM, detected in 55.7% and 22.9% of bacterial AOM episodes, respectively. The prevalent serotypes of S. pneumoniae were 19 A and 19 F. Significantly more pneumococcal and serotype 19 A AOM were found in the later study period (18.4% vs. 33.3%, p = 0.0036; 10.5% vs. 24.0%, p = 0.028). Among the 39 S. pneumoniae isolates, 11 strains (28.2%) were penicillin-susceptible. Of the 16 NTHi, 10 (62.5%) were susceptible to amoxicillin/clavulanate and all were susceptible to cefotaxime.

CONCLUSION

S. pneumoniae and NTHi were the leading causes of AOM in Taiwanese children in the study period. An increase in patient numbers and proportion of pneumococcal and serotype 19 A AOM occurred. Antimicrobial nonsusceptibility was common in the predominant pathogens.

Pneumococcal serotypes causing acute otitis media among children in Barcelona (1992-2011): emergence of the multiresistant clone ST320 of serotype 19A

BACKGROUND

There is scarce information about changes in serotypes and clonal types of Streptococcus pneumoniae causing acute otitis media (AOM) in recent years, particularly in European countries.

METHODS

Pneumococcal serotypes and clones from S. pneumoniae strains isolated from children with AOM who were attended at Hospital Sant Joan de Déu, Barcelona (1992 to 2011), were studied. Heptavalent pneumococcal conjugate vaccine (PCV7) was introduced in June 2001. We defined 3 periods: prevaccine period 1992 to 2001, early vaccine period 2002 to 2006 and late vaccine period 2007 to 2011.

RESULTS

There were 376 pneumococcal strains causing AOM, and 373 (99.2%) of them were serotyped. AOM caused by PCV7 serotypes declined significantly: 161 of 245 (65.7%) episodes in 1992 to 2001 versus 22 of 67 (32.8%) in 2002 to 2006 versus 8 of 61 (13.1%) in 2007 to 2011 P < 0.001. In the last period (2007 to 2011), the potential serotype coverage for the PCV10 was 16.4% and for the PCV13 was 68.9% (P < 0.001). Serotype 19A increased from 5.7% in 1992 to 2001 to 42.6% in 2007 to 2011 (P < 0.001). Among strains with penicillin minimal inhibitory concentration ≥0.12 μg/mL (n = 241), serotype 19A rose from 2.3% in the first period to 57.9 % in the last period (P < 0.001). The clonal-type ST320 was initially detected in 2005, and in the period 2007 to 2011, the ST320 was found in 72.7% of nonsusceptible serotype 19A isolates.

CONCLUSIONS

Among children with AOM, a rapid expansion of the multiresistant clone ST320 expressing serotype 19A has been observed in Barcelona. The implementation of PCV13, which includes this serotype, may decrease the prevalence of AOM and reduce antimicrobial resistance.

Microbiological characterization of Streptococcus pneumoniae and non-typeable Haemophilus influenzae isolates as primary causes of acute otitis media in Bulgarian children before the introduction of conjugate vaccines

Background

Pneumococcal and Haemophilus influenzae type b (Hib) vaccines were introduced in our national immunisation program in April 2010. The aims of this retrospective, laboratory-based study were to determine the serotypes and antibiotic resistance of Streptococcus pneumoniae and H. influenzae isolates from middle ear fluid (MEF) collected before the introduction of immunization.

Methods

S. pneumoniae (n = 128) and H. influenzae (n = 40) strains isolated from MEF of children with AOM between 1994 and 2011 were studied. MICs were determined by a microdilution assay. Serotyping of S. pneumoniae was done by Quellung method and PCR capsular typing was used for H. influenzae. Macrolide resistance genes were detected by PCR for erythromycin resistant S. pneumoniae (ERSP). DNA sequencing of ftsI gene was performed for ampicillin nonsusceptible H. influenzae.

Results

The most common serotypes found among children with pneumococcal AOM were 19 F (20.3%), 6B (15.6%), and 19A (10.9%). The potential coverage rates by the PCV7, PCV10 and PCV13 of children aged < 5 years were 63.6%, 66.4% and 85.5%, respectively. Reduced susceptibility to oral penicillin was seen in 68.1%; resistance to erythromycin was 46.9%. We found erm(B) gene in 56.7% of the ERSP, mef(E) gene in 25%; 15% harbored both genes erm(B) + mef(E) and 3.3% had mutations of L4 ribosomal protein. Of the 40 H. influenzae isolates 97.5% were nontypeable. Nonsusceptibility to ampicillin occurred in 25%. Ampicillin resistance groups were: β-lactamase-positive ampicillin resistant (BLPAR) strains (10%), β-lactamase-negative ampicillin resistant (BLNAR) strains (12.5%) and β-lactamase-positive amoxicillin-clavulanate resistant (BLPACR) strains (2.5%). Among BLNAR and BLPACR most of the isolates (5/6) belonged to group II, defined by the Asn526Lys substitution.

Conclusions

The levels of antibiotic resistance among S. pneumoniae and H. influenzae causing severe AOM in children are high in our settings. The existence of multidrug-resistant S. pneumoniae serotype 19A is of particular concern. The rate of BLNAR and BLPACR strains among H. influenzae isolates was 15%.

Clinical implications of pneumococcal serotypes: invasive disease potential, clinical presentations, and antibiotic resistance

Streptococcus pneumoniae can asymptomatically colonize the nasopharynx and cause a diverse range of illnesses. This clinical spectrum from colonization to invasive pneumococcal disease (IPD) appears to depend on the pneumococcal capsular serotype rather than the genetic background. According to a literature review, serotypes 1, 4, 5, 7F, 8, 12F, 14, 18C, and 19A are more likely to cause IPD. Although serotypes 1 and 19A are the predominant causes of invasive pneumococcal pneumonia, serotype 14 remains one of the most common etiologic agents of non-bacteremic pneumonia in adults, even after 7-valent pneumococcal conjugate vaccine (PCV7) introduction. Serotypes 1, 3, and 19A pneumococci are likely to cause empyema and hemolytic uremic syndrome. Serotype 1 pneumococcal meningitis is prevalent in the African meningitis belt, with a high fatality rate. In contrast to the capsule type, genotype is more closely associated with antibiotic resistance. CC320/271 strains expressing serotype 19A are multidrug-resistant (MDR) and prevalent worldwide in the era of PCV7. Several clones of MDR serotype 6C pneumococci emerged, and a MDR 6D clone (ST282) has been identified in Korea. Since the pneumococcal epidemiology of capsule types varies geographically and temporally, a nationwide serosurveillance system is vital to establishing appropriate vaccination strategies for each country.

The fundamental link between pneumococcal carriage and disease

Streptococcus pneumoniae (pneumococcus) is a major cause of worldwide mortality and morbidity, and to a large extent is vaccine-preventable. Nasopharyngeal carriage of pneumococcus precedes disease and is the source of pneumococcal spread between people. The use of vaccine effect on carriage as part of the vaccine licensure and post-vaccine introduction evaluation could facilitate and expand the licensure of new, life-saving pneumococcal vaccines and enable a comprehensive estimate of population effects after vaccine introduction. The authors provide a review of the evidence supporting pneumococcal carriage at the individual level as an immediate and necessary precursor to pneumococcal disease. Based on such a causal link between carriage and disease, the authors emphasize the role of information on pneumococcal carriage in vaccine trials and in public health decision-making.

Pneumococcal conjugate vaccines and otitis media: an appraisal of the clinical trials

Streptococcus pneumoniae is the predominant otitis media pathogen and its prevention through effective vaccination could diminish childhood illness and antibiotic use. This paper reviews 5 pneumococcal conjugate vaccine (PCV) trials that used otitis media as an endpoint: Northern California Kaiser Permanente (NCKP; vaccine, 7-valent PCV [PCV7]-CRM); Finnish Otitis Media (FinOM; vaccines, PCV7-CRM or PCV7-OMPC); Native American Trial (vaccine, PCV7-CRM); Pneumococcal Otitis Efficacy Trial (POET; vaccine, 11-valent PCV [PCV11]-PD). For the microbiological endpoint, vaccine efficacy against vaccine-serotype pneumococcal otitis media was about 60% across trials. Against the clinical endpoint of all episodes, vaccine efficacy was 7% (PCV7-CRM/NCKP), 6% (PCV7-CRM/FinOM), −1% (PCV7-OMPC/FinOM), and −0.4% (PCV7-CRM/Native American Trial); 34% against first episodes of ear, nose, and throat specialist-referral cases (PCV11-PD/POET). Both follow-up through 2 years of age, for the 5 trials, and long-term follow-up, for PCV7-CRM/NCKP and PCV7-CRM/FinOM, demonstrated greater vaccine efficacy against recurrent AOM and tympanostomy-tube placement, suggesting that vaccination against early episodes of AOM may prevent subsequent episodes of complicated otitis media. Although study designs varied by primary endpoint measured, age at follow-up, source of middle-ear fluid for culture, case ascertainment, and type of randomization, each clinical trial demonstrated vaccine efficacy against microbiological and/or clinical otitis media.