Variability of Vaccine Responsiveness in Young Children

BACKGROUND

Variability in vaccine responsiveness among young children is poorly understood.

METHODS

Nasopharyngeal secretions were collected in the first weeks of life for measurement of cytokines/chemokines seeking a biomarker, and blood samples collected at age one year to identify vaccine responsiveness status, defined as low vaccine responder (LVR), normal (NVR) and high (HVR), to test for vaccine antigen-induced immune memory, and for antigen presenting cell (APC) function.

RESULTS

Significantly lower specific cytokine/chemokine levels as biosignatures, measurable in nasopharyngeal secretions at infant age 1-3 weeks old, predicted LVR status compared to NVR and HVR children. Antibiotic exposures were correlated with increased occurrence of LVR. At age 1 year old, LVRs had fewer CD4+ T-helper-1 and T-helper-2 memory cells responsive to specific vaccine antigens. APC responses observed among LVRs, both at rest and in response to TLR7/8 stimulation by R848 were suboptimal, suggesting that altered innate immunity may contribute to immune deficiency in LVRs.

CONCLUSION

Cytokine biosignatures in the first weeks of life may predict vaccine responsiveness in children during the first year of life. Antibiotic exposure associates with LVR in children. CD4+ T-cell memory induction and APC deficiencies occur in LVR children.

Variability of vaccine responsiveness in early life

Vaccinations in early life elicit variable antibody and cellular immune responses, sometimes leaving fully vaccinated children unprotected against life-threatening infectious diseases. Specific immune cell populations and immune networks may have a critical period of development and calibration in a window of opportunity occurring during the first 100 days of early life. Among the early life determinants of vaccine responses, this review will focus on modifiable factors involving development of the infant microbiota and metabolome: antibiotic exposure, breast versus formula feeding, and Caesarian section versus vaginal delivery of newborns. How microbiota may serve as natural adjuvants for vaccine responses and how microbiota-derived metabolites influence vaccine responses are also reviewed. Early life poor vaccine responsiveness can be linked to increased infection susceptibility because both phenotypes share similar immunity dysregulation profiles. An early life pre-vaccination endotype, when interventions have the highest potential for success, should be sought that predicts vaccine response trajectories.

Very early life microbiome and metabolome correlates with primary vaccination variability in children

IMPORTANCE

We show that simultaneous study of stool and nasopharyngeal microbiome reveals divergent timing and patterns of maturation, suggesting that local mucosal factors may influence microbiome composition in the gut and respiratory system. Antibiotic exposure in early life as occurs commonly, may have an adverse effect on vaccine responsiveness. Abundance of gut and/or nasopharyngeal bacteria with the machinery to produce lipopolysaccharide-a toll-like receptor 4 agonist-may positively affect future vaccine protection, potentially by acting as a natural adjuvant. The increased levels of serum phenylpyruvic acid in infants with lower vaccine-induced antibody levels suggest an increased abundance of hydrogen peroxide, leading to more oxidative stress in low vaccine-responding infants.

Window of Susceptibility to Acute Otitis Media Infection

BACKGROUND

Contemporary, quantitative data are needed to inform recommendations and decision-making regarding referral and surgeon endorsement of tympanostomy tube placement in young children with recurrent acute otitis media (AOM).

METHODS

A prospective, observational cohort study of 286 children in a primary care pediatric practice setting, who had at least 1 AOM (range 1-8). Children were followed longitudinally from 6 to 36 months old. AOMs were microbiologically confirmed by tympanocentesis for diagnostic accuracy. A window of susceptibility (WOS) was defined as AOMs closely spaced in time with no gap in occurrence >6 months. For prediction of total number of AOMs, we used a quasi-poisson generalized linear model.

RESULTS

Eighty percent of AOMs occurred during child age 6 to 21 months old. Seventy two percent of WOS intervals were <5 months and 97% were <10 months. Clinically applicable models were developed to predict which children would benefit most from tympanostomy tubes. Significant predictors were child age at the first AOM (P < .001) and daycare attendance (P = .03). The age of a child when 2, 3, or 4 AOMs had occurred allowed prediction of the number of additional AOMs that might occur. After insertion of tympanostomy tubes, 16 (52%) of 31 children had no additional AOMs.

CONCLUSIONS

Recurrent AOM occurs in a narrow WOS and number of AOMs can be predicted at time of AOM based on child age and daycare attendance. Insertion of tympanostomy tubes likely occurs in many children after the WOS to recurrent AOM has passed or only 1 more AOM may be prevented at most.

Vaccine target and carrier molecule nontypeable Haemophilus influenzae protein D dimerizes like the close Escherichia coli GlpQ homolog but unlike other known homolog dimers

We have determined the 1.8 Å X-ray crystal structure of nonlipidated (i.e., N-terminally truncated) nontypeable Haemophilus influenzae (NTHi; H. influenzae) protein D. Protein D exists on outer membranes of H. influenzae strains and acts as a virulence factor that helps invade human cells. Protein D is a proven successful antigen in animal models to treat obstructive pulmonary disease (COPD) and otitis media (OM), and when conjugated to polysaccharides also has been used as a carrier molecule for human vaccines, for example in GlaxoSmithKline Synflorix™. NTHi protein D shares high sequence and structural identify to the Escherichia coli (E. coli) glpQ gene product (GlpQ). E. coli GlpQ is a glycerophosphodiester phosphodiesterase (GDPD) with a known dimeric structure in the Protein Structural Database, albeit without an associated publication. We show here that both structures exhibit similar homodimer organization despite slightly different crystal lattices. Additionally, we have observed both the presence of weak dimerization and the lack of dimerization in solution during size exclusion chromatography (SEC) experiments yet have distinctly observed dimerization in native mass spectrometry analyses. Comparison of NTHi protein D and E. coli GlpQ with other homologous homodimers and monomers shows that the E. coli and NTHi homodimer interfaces are distinct. Despite this distinction, NTHi protein D and E. coli GlpQ possess a triose-phosphate isomerase (TIM) barrel domain seen in many of the other homologs. The active site of NTHi protein D is located near the center of this TIM barrel. A putative glycerol moiety was modeled in two different conformations (occupancies) in the active site of our NTHi protein D structure and we compared this to ligands modeled in homologous structures. Our structural analysis should aid in future efforts to determine structures of protein D bound to substrates, analog intermediates, and products, to fully appreciate this reaction scheme and aiding in future inhibitor design.

Antibiotic Use and Vaccine Antibody Levels

BACKGROUND

The majority of children are prescribed antibiotics in the first 2 years of life while vaccine-induced immunity develops. Researchers have suggested a negative association of antibiotic use with vaccine-induced immunity in adults, but data are lacking in children.

METHODS

From 2006 to 2016, children aged 6 to 24 months were observed in a cohort study. A retrospective, unplanned secondary analysis of the medical record regarding antibiotic prescriptions and vaccine antibody measurements was undertaken concurrently. Antibody measurements relative to diphtheria-tetanus-acellular pertussis (DTaP), inactivated polio (IPV), Haemophilus influenzae type b (Hib), and pneumococcal conjugate (PCV) vaccines were made.

RESULTS

In total, 560 children were compared (342 with and 218 without antibiotic prescriptions). Vaccine-induced antibody levels to several DTaP and PCV antigens were lower (P < .05) in children given antibiotics. A higher frequency of vaccine-induced antibodies below protective levels in children given antibiotics occurred at 9 and 12 months of age (P < .05). Antibiotic courses over time was negatively associated with vaccine-induced antibody levels. For each antibiotic course the child received, prebooster antibody levels to DTaP antigens were reduced by 5.8%, Hib by 6.8%, IPV by 11.3%, and PCV by 10.4% (all P ≤ .05), and postbooster antibody levels to DTaP antigens were reduced by 18.1%, Hib by 21.3%, IPV by 18.9%, and PCV by 12.2% (all P < .05).

CONCLUSIONS

Antibiotic use in children <2 years of age is associated with lower vaccine-induced antibody levels to several vaccines.

Pneumonia, Sinusitis, Influenza and Other Respiratory Illnesses in Acute Otitis Media-Prone Children

BACKGROUND

Recurrent acute otitis media in the first years of life can be explained by immune dysfunction. Consequently, it would be expected that otitis-prone (OP) children would be more susceptible to other infectious diseases, especially respiratory infections, since a component of the immune problem involves nasopharyngeal innate immunity.

DESIGN

Cohort study with prospective identification of all physician-diagnosed, medically attended respiratory illness visits in children 6 months to 5 years of age to determine the incidence of pneumonia, acute sinusitis, influenza and other bacterial and viral infections among OP compared with non-OP (NOP) children. Tympanocentesis to microbiologically confirm acute otitis media disease.

RESULTS

Two hundred eighty-five children were studied. Thirty-nine met a standard definition of stringently defined OP (sOP) determined by tympanocentesis and 246 were NOP. sOP children had increased frequency of presumptive respiratory infections, pneumonia (6-fold higher, P < 0.001), sinusitis (2.1-fold higher, P = 0.026) and influenza (2.9-fold higher, P = 0.002), compared with NOP children. Demographic and risk factor covariate-adjusted fold difference between sOP and NOP children for all respiratory infection illness visits was 2.4-fold (P < 0.00001) at 6-18 months of age, 2.2-fold (P < 0.00001) at 18-30 months of age and at age and 2.4-fold (P = 0.035) higher at 30 to 42 months. For both sOP and NOP children, more frequent medically attended respiratory infection illness visits from 6-18 months of age predicted more frequent visits experienced from 18-60 months of age.

CONCLUSIONS

Clinicians should be aware of a significant increased likelihood of bacterial and viral respiratory infection proneness among OP children.

Nasopharyngeal microbiome composition associated with Streptococcus pneumoniae colonization suggests a protective role of Corynebacterium in young children

Streptococcus pneumoniae (Spn) is a leading respiratory tract pathogen that colonizes the nasopharynx (NP) through adhesion to epithelial cells and immune evasion. Spn actively interacts with other microbiota in NP but the nature of these interactions are incompletely understood. Using 16S rRNA gene sequencing, we analyzed the microbiota composition in the NP of children with or without Spn colonization. 96 children were included in the study cohort. 74 NP samples were analyzed when children were 6 months old and 85 NP samples were analyzed when children were 12 months old. We found several genera that correlated negatively or positively with Spn colonization, and some of these correlations appeared to be influenced by daycare attendance or other confounding factors such as upper respiratory infection (URI) or Moraxella colonization. Among these genera, Corynebacterium showed a consistent inverse relationship with Spn colonization with little influence by daycare attendance or other factors. We isolated Corynebacterium propinquum and C. pseudodiphtheriticum and found that both inhibited the growth of Spn serotype 22F strain in vitro.

Rising Pneumococcal Antibiotic Resistance in the Post-13-Valent Pneumococcal Conjugate Vaccine Era in Pediatric Isolates From a Primary Care Setting

BACKGROUND

Antibiotic-resistant Streptococcus pneumoniae strains may cause infections that fail to respond to antimicrobial therapy. Results reported from hospitalized patients with invasive, bacteremic infections may not be the same as those observed in a primary care setting where young children receive care for noninvasive infections. Young children experience the highest burden of pneumococcal disease. The aim of this study was to determine the antibiotic susceptibility of S. pneumoniae strains isolated from children in a primary care setting in the post-13-valent pneumococcal conjugate vaccine (PCV13) era.

METHODS

This was a prospective collection of 1201 isolates of S. pneumoniae from 2006 through 2016 in a primary care setting. Antibiotic susceptibility testing to 16 different antibiotics of 10 classes was performed. Participants were children aged 6-36 months. Nasopharyngeal swabs were obtained from patients during acute otitis media (AOM) visits and routine healthy visits. Middle ear fluid was obtained by tympanocentesis.

RESULTS

After introduction of PCV13, antibiotic susceptibility of pneumococci, especially to penicillin, initially improved largely due to disappearance of serotype 19A, included in PCV13. However, beginning in 2013, antibiotic susceptibility among pneumococcal strains began decreasing due to new serotypes not included in PCV13. In addition to reduced susceptibility to penicillin, the most recent isolates show reduced susceptibility to third-generation cephalosporins, fluoroquinolones, and carbapenems, antibiotics commonly used to treat life-threatening, invasive pneumococcal diseases.

CONCLUSIONS

In recent years, pneumococcal nasopharyngeal and AOM isolates from children exhibit reduced susceptibility to penicillin, third-generation cephalosporin, fluoroquinolone, and carbapenem antibiotics. The new strains have a different profile of resistance compared to the pre-PCV13 era.

Nasopharyngeal microbiome analyses in otitis-prone and otitis-free children

OBJECTIVES

About 10-15% children develop frequent acute otitis media (AOM) confirmed by tympanocentesis. These children are designated sOP (stringently defined otitis-prone) because all AOM episodes have been microbiologically confirmed. The cause of otitis-proneness in sOP children is multi-factorial, including frequent otopathogen nasopharyngeal (NP) colonization and deficiency in innate and adaptive immune responses. A largely unexplored contributor to otitis proneness is NP microbiome composition. Since the microbiome modulates otopathogen NP colonization and immune responses, we hypothesized that the NP microbiome composition in sOP children might be dysregulated.

METHODS

We performed 16S rRNA sequencing to analyze microbiome composition in 157 NP samples from 28 sOP and 68 AOM-free children when they were 6 months or 12 months old and healthy. Bioinformatic approaches were employed to examine the composition difference between the two populations and its correlation with changes in levels of inflammatory cytokines.

RESULTS

A different global microbiome profile and reduced alpha diversity was observed in the NP microbiome of sOP children when 6 months old, compared with that from AOM-free children of the same age. This difference was resolved when groups were compared at 12 months old. We found 4 bacterial genera-Bacillus, Veillonella, Gemella, and Prevotella-correlated with higher levels of pro-inflammatory cytokines in the NP. Those 4 bacterial genera were in lower abundance in sOP compared to AOM-free children.

CONCLUSION

Dysbiosis occurs in the NP microbiome of sOP children at an early age even when they were healthy. This dysbiosis correlates with a lower inflammatory state in the NP of these children.

Comparison of specific in-vitro virulence gene expression and innate host response in locally invasive vs colonizer strains of Streptococcus pneumoniae

Among Rochester NY children, a dramatic increase in nasopharyngeal (NP) colonization by non-vaccine pneumococcal serotypes 35B and 15A occurred during years 2010-2015, after introduction of 13-valent pneumococcal conjugate vaccine (PCV13). In our population, serotype 35B strains colonized in the nasopharynx (NP) but infrequently caused acute otitis media (AOM) whereas serotype 15A strains displayed virulence, evidenced by causing AOM. To explain the virulence difference, virulence genes expression between 35B and 15A, as well as the host's immune response during asymptomatic colonization were analyzed. We investigated differences in regulation of 19 virulence genes for differences in virulence using RT-PCR in 20 35B and 14 15A strains and measured gene expression of 9 host innate cytokines in the NP to assess the mucosal inflammatory response during asymptomatic colonization. Comparing 35B versus 15A strains, genes for competence ComA and RrgC were upregulated; capsular (Cps2D) and virulence genes (PfbA, PcpA and PhtE) were downregulated among 35B strains. PavB, LytA, LytB, NanA, CiaR, PhtD, LuxS, PspA and pneumolysin (Ply) showed no difference. IL17 and IL23 gene expression were > tenfold higher during 35B compared to 15A strain asymptomatic colonization. Only IL23 showed significant difference. In the first 5 years after introduction of PCV13, serotype 35B strains emerged as asymptomatic colonizers and 15A strains emerged to cause AOM in young children. Various genes (PfbA, PcpA, Cps2D and PhtE) among tested in this analysis were downregulated in 35B whereas ComA and RrgC were significantly upregulated. For the host's cytokine response, IL23 proinflammatory response which is essential for the differentiation of Th17 lymphocytes in the NP of children with 35B strains was significantly higher than the response to 15A during asymptomatic colonization.

Immune Network Modeling Predicts Specific Nasopharyngeal and Peripheral Immune Dysregulation in Otitis-Prone Children

Acute otitis media (AOM) pathogenesis involves nasopharyngeal colonization by potential otopathogens and a viral co-infection. Stringently-defined otitis prone (sOP) children show characteristic patterns of immune dysfunction. We hypothesized that otitis proneness is largely a result of altered signaling between immune components that are otherwise competent, resulting in increased susceptibility to infection by bacterial otopathogens. To test this, we constructed a regulatory immune network model linking immune cells and signaling elements known to be involved in AOM and/or dysregulated in sOP children. The alignment of immune response mechanisms with data from in vivo and in vitro experimental observations produced 82 putative immune network models, each describing variants of immune regulatory networks consistent with available observations. Analysis of these models suggested that new measurements of serum levels of IL-4 and CXCL8 could refine competing models and resulted in the elimination of 38 of the models. Further analysis of the remaining 44 models suggested specific deviations in the predicted regulation of nasopharyngeal and peripheral immunity during response to AOM. Specifically, immune responses active in sOP children during AOM were characterized by early and constitutive activation of pro-inflammatory signaling in the nasopharynx and a Th2- and Treg-dominated profile in the periphery. We conclude that sOP children have altered regulation of key immune mediators during both health and pathogenesis. This altered regulation may be amenable to therapeutic intervention.

Impaired Proinflammatory Response in Stringently Defined Otitis-prone Children During Viral Upper Respiratory Infections

BACKGROUND

Viral upper respiratory infections (URIs) are common and often precipitate acute otitis media (AOM), caused by bacterial otopathogens, in young children. Acute inflammatory responses initiated in the early phase of viral URI contribute to preventing the development of AOM. Stringently-defined otitis-prone (sOP) children are susceptible to recurrent AOM.

METHODS

We assessed proinflammatory cytokine and chemokine levels in the nasopharynxes during viral URIs, and examined the different nasopharyngeal responses between viral URI events and the following AOM episodes in both sOP and non-otitis-prone (NOP) children.

RESULTS

The sOP children exhibited significantly more AOM episodes per child (8.86-fold higher), viral URIs (P < .0001), and viral URIs followed by AOMs (P < .0001) than the NOP children. The sOP children had lower nasal proinflammatory levels of interleukin (IL)-6 (P = .05), IL-10 (P = .001), tumor necrosis factor (TNF)-α (P = .004), and regulated on activation, normal T-cell-expressed and -secreted (RANTES; P = .002) than NOP children during viral URIs. NOP children had higher levels of IL-6 (P = .02), IL-10 (P = .02), interferon-γ (P = .003), TNF-α (P = .006), IL-1β (P = .022), monocyte chemoattractant protein 1 (P = .028), RANTES (P = .005), IL-2 (P = .002), and IL-17 (P = .007) during viral URIs versus AOMs following the URIs, when compared to sOP children.

CONCLUSIONS

We conclude that sOP children have more frequent viral URIs than NOP children, due to deficient antiviral nasopharyngeal proinflammatory cytokine and chemokine responses.

Synchrony in serum antibody response to conserved proteins of Moraxella catarrhalis in young children

Conserved Moraxella catarrhalis (Mcat) proteins, oligopeptide permease (Opp)A, hemagglutinin (Hag), outer membrane protein (OMP) CD, Pilin A clade 2 (PilA2), and Moraxella surface protein (Msp) 22 have been studied as vaccine candidates. Children who experience frequent acute otitis media (AOM) confirmed with pathogen identification by tympanocentesis are referred to as stringently-defined otitis prone (sOP). Synchrony of serum antibody responses against 5 Mcat proteins, OppA, Hag, OMP CD, PilA2, and Msp22 resulting from nasopharyngeal colonization and AOM was studied for 85 non-otitis prone (NOP) children and 34 sOP children. Changes in serum IgG were quantitated with ELISA. Serum IgG antibody levels against OppA, Hag, OMP CD, and Msp22 rose in synchrony in NOP and sOP children; that is, the proteins appeared equally and highly immunogenic in children at age 6 to 22-25 months old and then leveled off in their rise at 22-25 to 30 months old. In contrast, rises of PilA2 were slow from 6 months old and kept constant and did not level off significantly before 30 months old. OppA, Hag, OMP CD, and Msp22 elicited a synchronous acquisition of naturally-induced serum antibody in young children. A multi-valent Mcat protein vaccine combining OppA, Hag, OMP CD, and Msp22 may exhibit less antigen competition when administered as a combination vaccine in young children.

Comparison of pneumococcal conjugate vaccine (PCV-13) cellular immune responses after primary and booster doses of vaccine

Since their widespread use, pneumococcal conjugate vaccines (PCVs) have proven effective at reducing both invasive and noninvasive pneumococcal diseases and nasopharyngeal carriage of Streptococcus pneumoniae (Spn). To establish this level of protection, a three-dose schedule with a single booster (3 + 1) was the immunization regime in the USA. Alternatively, WHO-approved schedules of 3 + 0 and 2 + 1 are now becoming adopted in many countries to reduce the cost of vaccination. Sustained protection from pneumococcal disease and carriage requires persisting levels of antibody and cellular immune memory. Although antibody responses to PCVs are well studied, less is known concerning the cellular response to the vaccine in young children. In this report, circulating PCV-13 serotype-specific B and T cell memory in paired blood samples from children before and after PCV13 dose 3 and booster immunizations was analyzed to determine changes in the adaptive immune response. No significant differences in memory B cell populations were detected comparing post dose 2 vs. post dose 3. However, the booster dose significantly increased the frequency of Spn-specific memory B cells compared to the pre-booster. Spn-specific memory T cells were not detected with the method used. These data suggest that booster vaccination increases Spn-specific memory B cells that may impact long-term protective antibody titers.

Immunologic dysfunction contributes to the otitis prone condition

Acute Otitis Media (AOM) is a multifactorial disease occurring mostly in young children who are immunologically naïve to AOM pathogens. This review focuses on work from Rochester NY, USA over the past 12 years among young children who had AOM infections microbiologically-confirmed by tympanocentesis, so called "stringently-defined". Among stringently-defined otitis prone children deficiencies in fundamental immune defense mechanisms have been identified that contribute to the propensity of young children to experience recurrent AOM. Dysfunction in innate immune responses that cause an immunopathological impact in the nasopharynx have been discovered including inadequate proinflammatory cytokine response and poor epithelial cell repair. Adaptive immunity defects in B cell function and immunologic memory resulting in low levels of antibody to otopathogen-specific antigens allows repeated infections. CD4+ and CD8+ T cell function and memory defects significantly contribute. The immune profile of an otitis prone child resembles that of a neonate through the first year of life. Immunologic deficits in otitis prone children cause them to be unusually vulnerable to viral upper respiratory infections and respond inadequately to routine pediatric vaccines.

Panel 3: Genomics, precision medicine and targeted therapies

OBJECTIVE

To review the most recent advances in human and bacterial genomics as applied to pathogenesis and clinical management of otitis media.

DATA SOURCES

PubMed articles published since the last meeting in June 2015 up to June 2019.

REVIEW METHODS

A panel of experts in human and bacterial genomics of otitis media was formed. Each panel member reviewed the literature in their respective fields and wrote draft reviews. The reviews were shared with all panel members, and a merged draft was created. The panel met at the 20th International Symposium on Recent Advances in Otitis Media in June 2019, discussed the review and refined the content. A final draft was made, circulated, and approved by the panel members.

CONCLUSION

Trans-disciplinary approaches applying pan-omic technologies to identify human susceptibility to otitis media and to understand microbial population dynamics, patho-adaptation and virulence mechanisms are crucial to the development of novel, personalized therapeutics and prevention strategies for otitis media.

IMPLICATIONS FOR PRACTICE

In the future otitis media prevention strategies may be augmented by mucosal immunization, combination vaccines targeting multiple pathogens, and modulation of the middle ear microbiome. Both treatment and vaccination may be tailored to an individual's otitis media phenotype as defined by molecular profiles obtained by using rapidly developing techniques in microbial and host genomics.

Comparative Analysis of Microbiome in Nasopharynx and Middle Ear in Young Children With Acute Otitis Media

Acute otitis media (AOM) is the most common pediatric infection for which antibiotics are prescribed in the United States. The role of the respiratory tract microbiome in pathogenesis and immune modulation of AOM remains unexplored. We sought to compare the nasopharyngeal (NP) microbiome of children 1 to 3 weeks prior to onset of AOM vs. at onset of AOM, and the NP microbiome with the microbiome in middle ear (ME). Six children age 6 to 24 months old were studied. Nasal washes (NW) were collected at healthy visits 1 to 3 weeks prior to AOM and at onset of AOM. The middle ear fluids (MEF) were collected by tympanocentesis at onset of AOM. Samples were stored in Trizol reagents or phosphate-buffered saline (PBS) at -80°C until use. The microbiome was characterized by 16S rRNA gene sequencing. Taxonomic designations and relative abundance of bacteria were determined using the RDP classifier tool through QIIME. Cumulative sum scaling normalization was applied before determining bacterial diversity and abundance. Shannon diversity index was calculated in Microsoft excel. The relative abundance of each bacteria species was compared via Mann-Whitney U test. We found that the NW microbiome of children during healthy state or at baseline was more diverse than microbiome during AOM. At AOM, no significant difference in microbiome diversity was found between NW and MEF, although some bacteria species appear to differ in MEF than in NW. The microbiome of samples stored in PBS had significant greater diversity than samples stored in Trizol reagent.

Development and Modification of an Outcome Measure to Follow Symptoms of Children with Sinusitis

OBJECTIVE

To develop a parent-reported Pediatric Rhinosinusitis Symptom Scale (PRSS) that could be used to monitor symptoms of young children with acute sinusitis in response to therapy.

STUDY DESIGN

We developed an 8-item symptom severity scale and evaluated its internal reliability, construct validity, and responsiveness in children 2-12 years of age with acute sinusitis. Parents of 258 children with acute sinusitis completed the PRSS at the time of diagnosis, as a diary at home, and at the follow-up visit at days 10-12. Based on psychometric results and additional parent feedback, we revised the scale. We evaluated the revised version in 185 children with acute sinusitis.

RESULTS

Correlations between the scale and reference measures on the day of enrollment were in the expected direction and of the expected magnitude. PRSS scores at the time of presentation correlated with radiographic findings (P < .001), functional status (P < .001), and parental assessment of overall symptom severity (P < .001). Responsiveness (standardized response mean) and test-retest reliability of the revised scale were good (2.17 and 0.75, respectively).

CONCLUSIONS

We have developed an outcome measure to track the symptoms of acute sinusitis. Data presented here support the use of the PRSS as a measure of change in symptom burden in clinical trials of children with acute sinusitis.

Intranasal coinfection model allows for assessment of protein vaccines against nontypeable Haemophilus influenzae in mice

PURPOSE

Nontypeable Haemophilus influenzae (NTHi) is a commensal in the human nasopharynx and the cause of pneumonia, meningitis, sinusitis, acute exacerbations of chronic obstructive pulmonary disease and acute otitis media (AOM). AOM is the most common ailment for which antibiotics are prescribed in the United States. With the emergence of new strains of antibiotic-resistant bacteria, finding an effective and broad coverage vaccine to protect against AOM-causing pathogens has become a priority. Mouse models are a cost-effective and efficient way to help determine vaccine efficacy. Here, we describe an NTHi AOM model in C57BL/6J mice, which also utilizes a mouse-adapted H1N1 influenza virus to mimic human coinfection.

METHODOLOGY

We tested our coinfection model using a protein vaccine formulation containing protein D, a well-studied NTHi vaccine candidate that can be found in the 10-valent Streptococcus pneumoniae conjugate vaccine. We verified the usefulness of our mouse model by comparing bacterial loads in the nose and ear between protein D-vaccinated and control mice.

RESULTS

While there was no measurable difference in nasal bacterial loads, we did detect significant differences in the bacterial loads of ear washes and ear bullae between vaccinated and control mice.

CONCLUSION

The results from this study suggest that our NTHi AOM coinfection model is useful for assessing protein vaccines.

Pneumococcal whole-cell and protein-based vaccines: changing the paradigm

INTRODUCTION

Epidemiologic evaluations of Streptococcus pneumoniae nasopharyngeal (NP) colonization and pneumococcal disease suggest that newer serotypes in future formulations of pneumococcal conjugate vaccines (PCVs) are needed and there may need to be continued reformulations because there are many new emerging serotypes expressed by pneumococci. Areas covered: Mechanisms of protection by next-generation whole-cell vaccine (WCV) and/or multi-component pneumococcal purified protein vaccines (PPVs) in development for prevention of pneumococcal infections. Expert commentary: A long-term strategy for prevention of pneumococcal disease will likely include WCV and PPVs. However these vaccines will impact disease pathogenesis in a different manner than PCVs. Prevention of pneumococcal NP colonization should not be expected, nor is it desirable because risks for NP colonization by other replacement organisms into the ecological niche vacated by all pneumococci may have consequences. The expression biology of capsule and surface protein antigens are phase dependent. Therefore, the immune response will be different and the mechanism of protection divergent. WCVs and PPVs may be alternative strategies in low income developing countries to protect against invasive disease and reduce NP carriage load.

Modeling specific antibody responses to natural immunization to predict a correlate of protection against infection before commencing a clinical vaccine trial

BACKGROUND

Clinical trials of vaccines for children to prevent acute otitis media (AOM) infections caused by the bacteria Streptococcus pneumonia (Spn) are in Phase I. The objective of this study was to use serum antibody measurements to pneumococcal purified protein candidate antigens that occurred after natural "immunization" to predict a correlate of protection response needed following an injectable vaccine against AOM in children.

METHODS

590 nasal and serum samples were collected from 129 healthy children at 6, 9, 12, 15, 18, 24 and 30-36 months of age and when the child developed AOM. Middle ear fluid to detect Spn was collected at every episode of AOM. Quantitative ELISA was used to determine serum IgG against 7 Spn vaccine antigens: PspA clade 3, PspA clade 5, PhtD, PhtE, LytB, PcpA and Ply. A correlate of protection (COP) was estimated by regressing AOM events against age adjusted antibody levels induced by nasopharyngeal colonization and AOM infections, using logistic regression and generalized estimating equation methods.

RESULTS

A significant COP was found for Spn PhtD (p = 0.0015), PhtE (p = 0.00034), LytB (p = 0.004), PcpA (p = 0.002), and Ply (p = 0.007) between higher antibody levels and reduced frequency of AOM. We estimated that a 2-fold higher antibody level in a child than the mean antibody level induced by NP colonization (after adjusting for subject age) to PhtD, LytB, PcpA, PhtE or Ply reduced the risk of AOM by 14-21%, a 4-fold higher level reduced it by 25-38% and a 10-fold higher level reduced it by 39-54%.

CONCLUSION

We developed a model to predict the necessary level of serum antibody and fold higher above a threshold to PhtD, PhtE, LytB, PcpA and Ply that would correlate with a reduced likelihood of AOM in children age 6-24 months old if enrolled in a Phase III clinical efficacy trial.

TLR agonist combinations that stimulate Th type I polarizing responses from human neonates

Each year millions of neonates die due to vaccine preventable infectious diseases. Our study seeks to develop novel neonatal vaccines and improve immunogenicity of early childhood vaccines by incorporating TLR agonist-adjuvant combinations that overcome the inherent neonatal Th2 bias and stimulate Th1 polarizing response from neonatal APCs. We systematically stimulated cord blood mononuclear cells with single and multiple combinations of TLR agonists and measured levels of IL-12p70, IFN-γ, IFN-α, IL-10, IL-13, TNF-α, IL-6 and IL-1β from cell culture supernatants. APC-specific surface expression levels of costimulatory markers CD40, CD83 and PD-L1 were assessed by flow cytometry. Whole blood assays were included to account for the effect of plasma inhibitory factors and APC intracellular TNF-α and IL-12p40 secretions were measured. We found robust Th1 polarizing IL-12p70, IFN-γ and IFN-α responses when cord blood APCs were stimulated with TLR agonist combinations that contained Poly I:C, Monophosphoryl Lipid A (MPLA) or R848. Addition of class A CpG oligonucleotide (ODN) to Th1 polarizing TLR agonist combinations significantly reduced cord blood IL-12p70 and IFN-γ levels and addition of a TLR2 agonist induced significantly high Th2 polarizing IL-13. Multi-TLR agonist combinations that included R848 induced lower inhibitory PD-L1 expression on cord blood classical dendritic cells than CpG ODN-containing combinations. Incorporation of combination adjuvants containing TLR3, TLR4 and TLR7/8 agonists to neonatal vaccines may be an effective strategy to overcome neonatal Th2 bias.

Three Innate Cytokine Biomarkers Predict Presence of Acute Otitis Media and Relevant Otopathogens

BACKGROUND

1.1Diagnosis of Acute Otitis Media (AOM) is challenging, resulting in frequent over diagnosis and improper prescription of antibiotics. A serum biomarker of AOM would significantly improve pediatric care for this common illness.

METHODS

1.2Serum samples were studied from 197 children 6-36 months old during health, during viral Upper Respiratory Infection (URI) without middle ear involvement, and at the onset of AOM (confirmed by tympanocentesis). Serum concentrations of S100A12, IL-10, and ICAM-1 were measured by ELISA. Otopathogens were identified by culture of middle ear fluid. A predictive model for infection and causative otopathogen was developed based on density distributions of the measured cytokines.

RESULTS

1.3A biomarker score derived from subject age and serum concentrations of S100A12, IL-10, and ICAM-1 was significantly able to distinguish both between health and disease and between upper respiratory infections with and without middle ear involvement (AOM vs URI), and further predicted the specific causative bacterial pathogen. This biomarker could also identify recurrent OM-prone children.

CONCLUSIONS

1.4For the first time we show that a biomarker risk score derived from serum cytokine levels can predict the presence of bacterial AOM, the likely Otopathogen, and the recurrent OM-prone child.

CLINICAL SIGNIFICANCE

1.5(1) AOM is a widespread pediatric infection with a substantial economic burden. (2) Three serum cytokines can discriminate between URI and AOM, reducing over diagnosis. (3) Prediction of responsible pathogen enables targeted antibiotic prescription.

Haemophilus influenzae-protein D specific antibody correlate with protection against acute otitis media in young children

BACKGROUND

Haemophilus influenzae (Hi) causes respiratory infections and pathogenesis of this microbe begins in the human nasopharynx (NP). The objective of this study was to assess the correlation of NP colonization-induced serum antibody levels to Hi protein D with risk of acute otitis media (AOM) in children <2 yr.

METHODS

455 sera from 213 children (age 6-24 months old) were collected when they were colonized with Hi and when the children developed AOM. Presence of Hi during AOM was confirmed by culture of middle ear fluid. Quantitative ELISA was used to determine serum IgG against protein D antigen.

RESULTS

Asymptomatic Hi NP colonization reduced the risk of future AOM infections. Higher serum IgG titers against Hi protein D were correlated with reduced future AOM risk.

CONCLUSION

Colonization by Hi reduces future AOM risk. Higher antibody levels against protein D correlates with lower risk of AOM caused by Hi.

Streptococcus pneumoniae burden and nasopharyngeal inflammation during acute otitis media

Streptococcus pneumoniae (Spn) is a common respiratory pathogen and a frequent cause of acute otitis media (AOM) in children. The first step in bacterial pathogenesis of AOM is the establishment of asymptomatic colonization in the nasopharynx. We studied Spn bacterial burden in conjunction with neutrophil recruitment and inflammatory gene transcription and cytokine secretion in samples of nasal wash collected from normal and otitis-prone children during health, viral upper respiratory infection without middle ear involvement (URI) and AOM. We found no significant associations between otitis-prone status and any of the measured parameters. However, Spn bacterial burden was significantly correlated with neutrophil recruitment, transcription of IL-8, TNF-α and SOD2, and secretion of TNF-α. We also found that transcription of IL-8 and TNF-α mRNA by neutrophils was significantly correlated with the secretion of these cytokines into the nasopharynx. We conclude that Spn bacterial burden in the NP is a major determinant of neutrophil recruitment to the NP and activity during URI and AOM, and that neutrophils are contributors to the secretion of IL-8 and TNF-α in the NP when the Spn burden is high.

Comparison of direct-plating and broth-enrichment culture methods for detection of potential bacterial pathogens in respiratory secretions

OBJECTIVE

We compared the recovery of potential respiratory bacterial pathogens and normal flora from nasopharyngeal specimens collected from children during health and at the onset of acute otitis media (AOM) by selective direct-plating and overnight broth-enrichment.

METHODS

Overall, 3442 nasal wash (NW) samples collected from young children were analysed from a 10-year prospective study. NWs were cultured by (1) direct-plating to TSAII/5 % sheep blood agar and chocolate agar plates and (2) overnight broth-enrichment in BacT/ALERT SA-broth followed by plating. Standard microbiology techniques were applied to identify three dominant respiratory bacterial pathogens: Streptococcus pneumoniae (Spn), Haemophilus influenzae (Hflu) and Moraxella catarrhalis (Mcat) as well as two common nasal flora, Staphylococcus aureus (SA) and alpha-haemolytic Streptococci (AHS).Results/Key findings. Direct-plating of NW resulted in isolation of Spn from 37.8 %, Hflu from 13.6 % and Mcat from 33.2 % of samples. In comparison, overnight broth-enrichment isolated fewer Spn (30.1 %), Hflu (6.2 %) and Mcat (16.2 %) (P<0.001-0.0001). Broth-enrichment resulted in significant increased isolation of SA (6.0 %) and AHS (30.1 %) (P<0.0001). Competition between bacterial species in broth when both species were detected by direct-plating was assessed, and it was found that SA and AHS out-competed other species during broth-enrichment when samples were collected from healthy children but not during AOM. In middle ear fluids (MEF) at the onset of AOM, broth-enrichment resulted in higher recovery of Spn (+10.4 %, P<0.001), Hflu (+4.4 %, P=0.39) and Mcat (+13.5 %, <0.001).

CONCLUSION

Broth-enrichment significantly reduces the accurate detection of bacterial respiratory pathogens and increases identification of SA and AHS in NW. Broth-enrichment improves detection of bacterial respiratory pathogens in MEF samples.

Cross-reactivity in β-Lactam Allergy

β-Lactam drugs (penicillins, amoxicillin, and cephalosporins) account for 42.6% of all severe drug-induced anaphylaxis. In this review, we focus on clinically significant immunologic cross-reactivity in patients with confirmed penicillin allergy to cephalosporins, and the structural involvement of the R₁ and R₂ chemical side chains of the cephalosporins causing IgE-mediated cross-reactivity with penicillin and other cephalosporins. Skin tests predict IgE-mediated reactions and showed cross-reactivity between penicillins and early generation cephalosporins that shared side chains, but confirmatory challenge data are lacking. Later-generation cephalosporins, which have distinct side chains, do not have any skin test cross-reactivity with penicillin/amoxicillin. There is debate as to the involvement of R₂ side chains as the antigenic determinants that cause IgE-mediated hypersensitivity with various cephalosporins. Avoidance of cephalosporins, when they are the drug of choice in a penicillin-allergic individual, results in significant morbidity that outweighs the low risk of anaphylaxis. We conclude that there is ample evidence to allow the safe use of cephalosporins in patients with isolated confirmed penicillin or amoxicillin allergy.

Epidemiology of Acute Otitis Media in the Postpneumococcal Conjugate Vaccine Era

OBJECTIVES

To study the epidemiology of acute otitis media (AOM), especially the otitis-prone condition, during the pneumococcal conjugate vaccines 7 and 13 era.

METHODS

Six hundred and fifteen children were prospectively managed from 6 to 36 months of life during a 10-year time frame (June 2006-June 2016). All clinical diagnoses of AOM were confirmed by tympanocentesis and bacterial culture of middle ear fluid.

RESULTS

By 1 year of age, 23% of the children experienced ≥1 episode of AOM; by 3 years of age, 60% had ≥1 episodes of AOM, and 24% had ≥3 episodes. The peak incidence occurred at 6 to 12 months of life. Multivariable analysis of demographic and environmental data revealed a significantly increased risk of AOM associated with male sex, non-Hispanic white race, family history of recurrent AOM, day care attendance, and early occurrence of AOM. Risk factors for stringently defined (tympanocentesis-confirmed) otitis proneness, in which children suffered at least 3 episodes of AOM in a 6-month period or at least 4 within a year, were male sex, day care attendance, and family history of AOM, whereas breastfeeding in the first 6 months of life was protective. Stringently defined otitis prone children were also likely to experience their first AOM episode at a younger age. The proportion of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis causing AOM had dynamic changes during the past decade.

CONCLUSIONS

We conclude that the epidemiology but not the risk factors for AOM have undergone substantial changes since the introduction of pneumococcal conjugate vaccines.

Stringently Defined Otitis Prone Children Demonstrate Deficient Naturally Induced Mucosal Antibody Response to Moraxella catarrhalis Proteins

Moraxella catarrhalis (Mcat) is a prominent mucosal pathogen causing acute otitis media (AOM). We studied Mcat nasopharyngeal (NP) colonization, AOM frequency and mucosal antibody responses to four vaccine candidate Mcat proteins: outer membrane protein (OMP) CD, oligopeptide permease (Opp) A, hemagglutinin (Hag), and Pilin A clade 2 (PilA2) from stringently defined otitis prone (sOP) children, who experience the greatest burden of disease, compared to non-otitis prone (NOP) children. sOP children had higher NP colonization of Mcat (30 vs. 22%, P = 0.0003) and Mcat-caused AOM rates (49 vs. 24%, P < 0.0001) than NOP children. Natural acquisition of mucosal antibodies to Mcat proteins OMP CD (IgG, P < 0.0001), OppA (IgG, P = 0.018), Hag (IgG and IgA, both P < 0.0001), and PilA2 (IgA, P < 0.0001) was lower in sOP than NOP children. Higher levels of mucosal IgG to Hag (P = 0.039) and PilA2 (P = 0.0076), and IgA to OMP CD (P = 0.010), OppA (P = 0.030), and PilA2 (P = 0.043) were associated with lower carriage of Mcat in NOP but not sOP children. Higher levels of mucosal IgG to OMP CD (P = 0.0070) and Hag (P = 0.0003), and IgA to Hag (P = 0.0067) at asymptomatic colonization than those at onset of AOM were associated with significantly lower rate of Mcat NP colonization progressing to AOM in NOP compared to sOP children (3 vs. 26%, P < 0.0001). In conclusion, sOP children had a diminished mucosal antibody response to Mcat proteins, which was associated with higher frequencies of asymptomatic NP colonization and NP colonization progressing to Mcat-caused AOM. Enhancing Mcat antigen-specific mucosal immune responses to levels higher than achieved by natural exposure will be necessary to prevent AOM in sOP children.

Reduced T-Helper 17 Responses to Streptococcus pneumoniae in Infection-Prone Children Can Be Rescued by Addition of Innate Cytokines

Background

T-helper (Th) 17 cells are important in the control of Streptococcus pneumoniae. We sought to understand the mechanism of failure of Th17 immunity resulting in S. pneumoniae infections in children <2 years old.

Methods

Peripheral blood mononuclear cells (PBMCs) from infection-prone (IP) and non-IP (NIP) children 9-18 months old were examined for their responses to heat-killed S. Pneumoniae, using flow cytometry, reverse-transcription polymerase chain reaction, and enzyme-linked immunoassay. We measured cytokine production, proliferation, and differentiation of Th17 cells and the expression of transcription factors in response to S. pneumoniae.

Results

PBMCs of IP children stimulated with heat-killed S. pneumoniae had significantly reduced percentages of CD4+ Th1 (interleukin2, tumor necrosis factor α) and Th17 (interleukin 17A) cells compared with NIP children. Addition of exogenous Th17-promoting cytokines (interleukin 6, 1β, and 23 and transforming growth factor β) restored CD4+ Th17 cell function in cells from IP children to levels measured in NIP children.

Conclusions

Reduced Th17 responses to S. pneumoniae in PBMCs of IP children can be rescued by addition of Th17-promoting cytokines.

Serum antibody response to Moraxella catarrhalis proteins in stringently defined otitis prone children

BACKGROUND

Moraxella catarrhalis (Mcat) is a frequent pathogen of acute otitis media (AOM) in young children. Here we prospectively assessed naturally-induced serum antibodies to four Mcat vaccine candidate proteins in stringently defined otitis prone (sOP) and non-otitis prone (NOP) children age 6-36months old following nasopharyngeal (NP) colonization, at onset of AOM and convalescence from AOM.

METHODS

Serum IgG and IgM antibody against recombinant Mcat proteins, oligopeptide permease A (OppA), outer membrane protein (OMP) CD, hemagglutinin (Hag), and PilA clade 2 (PilA2), were quantitated by ELISA.

RESULTS

During NP colonization by Mcat all four antigens were immunogenic in both sOP and NOP children. However, sOP children had lower antibody responses than NOP children across age 6-36months, similar to our findings for protein vaccine candidates of Streptococcus pneumoniae (Spn) and Nontypeable Haemophilus influenzae (NTHi). sOP children displayed a later and lower peak of antibody rise than NOP children for all four antigens during NP colonization of Mcat. The age-dependent increase of antibody ranked as OppA>Hag5-9>OMP CD>PilA2 in both sOP and NOP children. Lower serum antibody levels to the Mcat antigens were measured in sOP compared to NOP children at the onset of AOM. We did not find a consistent significant increase of antibody at the convalescence phase after an AOM event.

CONCLUSIONS

sOP children is a highly vulnerable population that mount lower serum antibody responses to Mcat candidate vaccine proteins compared to NOP children during asymptomatic NP carriage and at onset of AOM.

Decreased TNF family receptor expression on B-cells is associated with reduced humoral responses to Streptococcus pneumoniae infections in young children

An underdeveloped or impaired immune response in young children is associated with increased susceptibility to Streptococcus pneumonia (Spn) infections. We determined serum antibody titers against 3 Spn vaccine candidate proteins and vaccine serotype polysaccharide antigens in a group of Spn infection prone 9-18months old and found lower IgG antibody titers to all tested antigens compared to age-matched non-infection-prone children. We also found the children had significantly reduced percentages of total memory B-cells, switched memory B-cells and plasma cells. We sought a mechanistic explanation for that result by examination of TNF family receptors (TNFRs) TACI, BCMA, and BAFFR receptor expression on B-cells and found significantly lower BAFFR and TACI expression; significantly lower proliferation of B-cells stimulated with exogenous BAFF; and diminished expression of co-stimulatory receptors B7-1 and B7-2 among infection prone vs. non-prone children. We conclude that lower expression of TNFRs, lower proliferation of B-cells in response to BAFF and lower expression of B7-1 and B7-2 by B-cells may contribute to reduced antibody responses to Spn and consequent infection proneness in young children.

A PCR-based method for quantifying neutrophils in human nasal secretions

Neutrophil recruitment to the nasopharynx (NP) is a central event in resolution of NP-initiated microbial infections. A vigorous neutrophil response in infected tissues is also associated with the outcome of adverse tissue pathology. Therefore, differences in infection-induced tissue neutrophil numbers may correlate with pathogenesis events. Existing methods of quantifying neutrophils require evaluation of NP samples within hours of procurement as flow cytometry based cell quantification methods require live neutrophil cells. Therefore, we developed a novel RT-PCR method that could reliably quantify neutrophil counts in frozen NP wash samples. mRNA transcripts of the genes encoding CD16, CD18, and CD62L were identified as neutrophil-specific in NP samples and not significantly variable in response to stimulation by heat killed bacteria, and can be used to derive an accurate assessment of neutrophil content in a sample even in the presence of epithelial cells. Using flow cytometry as a comparator, the method was validated in human NP wash samples. We conclude that this PCR-based method should prove useful for providing a quantitative estimate of neutrophil recruitment to the NP during infection and pathogenesis.

Correlation of higher antibody levels to pneumococcal proteins with protection from pneumococcal acute otitis media but not protection from nasopharyngeal colonization in young children

OBJECTIVES

We previously found that nasopharyngeal (NP) colonization by Streptococcus pneumoniae elicits mucosal antibody responses to three protein vaccine candidates: pneumococcal histidine triad protein D (PhtD), pneumococcal choline-binding protein A (PcpA), and detoxified pneumolysin (PlyD1). Here we sought to determine if mucosal antibody levels to the proteins correlated with protection from acute otitis media (AOM) and NP colonization.

METHODS

A total of 228 NP samples were prospectively collected from 100 healthy infants at 6-24 months of age. Whenever children were diagnosed with AOM, middle ear fluids were collected to confirm the diagnosis by microbiological culture. NP mucosal IgG and IgA were quantified by ELISA.

RESULTS

Higher NP mucosal antibody levels to S. pneumoniae proteins correlated with significantly decreased likelihood of developing AOM caused by S. pneumoniae during 3 to 12 months of subsequent prospective monitoring. Specifically, children who did not experience AOM (n=111samples) caused by S. pneumoniae had two- to five-fold higher mucosal IgG levels to PcpA (all p values <0.01), six- to eight-fold higher IgA to PhtD (all p values <0.05); two- to three-folder higher IgA to PcpA (all p values <0.05), and two- to three-fold higher IgA to PlyD1 (p 0.08, p 0.03 and p 0.08) compared with children who did experience AOM (n=18samples). No association between mucosal antibody levels to the three proteins and NP colonization with S. pneumoniae was found.

CONCLUSION

Higher NP mucosal IgG levels to PcpA, and IgA to PhtD, PcpA and PlyD1 correlate with reduced risk of development of S. pneumoniae AOM infection but not with reduced risk of NP colonization in young children.

Controversies in the Medical Management of Persistent and Recurrent Acute Otitis Media Recommendations of a Clinical Advisory Committee

Streptococcus pneumoniae is the predominant bacterial pathogen associated with acute otitis media (AOM), causing an estimated 7 million cases annually in the United States. Bacterial resistance should be considered when selecting an antimicrobial agent for otitis media. Significant increases in drug-resistant S pneumoniae are documented worldwide, and less than 50% of S pneumoniae strains are fully susceptible to penicillin in some regions of the United States. Although amoxicillin is recommended for uncomplicated AOM, treatment guidelines should be flexible and adaptable, taking into consideration local and regional susceptibility patterns, the age of the patient, the frequency of prior infections, and the response to prior therapy. Resistant organisms are more prevalent in children younger than 2 years of age and in those who have recurrent or persistent AOM. Overdiagnosing AOM, selecting inappropriate empiric therapy, or both, leads to overuse and misuse of antibiotics and causes increased drug resistance. This article reviews persistent and recurrent AOM and discusses the pitfalls of diagnosis and the practical limitations of current treatment recommendations.

Trivalent pneumococcal protein vaccine protects against experimental acute otitis media caused by Streptococcus pneumoniae in an infant murine model

BACKGROUND

Currently licensed serotype-based pneumococcal vaccines are effective in preventing invasive pneumococcal diseases, but less effective in preventing non-bacteremic pneumonia and acute otitis media (AOM). We previously reported that a trivalent pneumococcal protein recombinant vaccine (PPrV) protected against pneumonia in a murine model. Here we evaluated PPrV protection against AOM in an infant murine model.

METHODS

C57BL/6J mice were intramuscularly vaccinated at 1-3weeks of age with monovalent pneumococcal histidine triad protein D (PhtD), or pneumococcal choline binding protein A (PcpA), or detoxified pneumolysin (PlyD1), or trivalent vaccine, and transtympanically challenged at 7-8weeks of age with 1×10²CFU of pneumococcal strain BG7322 (6A) or 1×10⁴CFU of pneumococcal nontypeable strain 0702064MEF. Serum IgG titers were determined by ELISA. At 24 and 48h post infection (hpi), animals were sacrificed and middle ear fluid (MEF) samples were collected to determine pneumococcal CFUs.

RESULTS

We found that vaccination of infant mice with monovalent and trivalent pneumococcal proteins elicited significant serum IgG antibody responses to corresponding component proteins. Vaccination with PhtD reduced BG7322 bacterial burdens in MEF at both 24 (p=0.05) and 48hpi (p=0.16). Vaccination with PcpA significantly reduced the bacterial burdens in MEF at both 24 (p=0.02) and 48hpi (p=0.004), and PlyD1 significantly reduced bacterial burden in MEF at 48hpi (p=0.02). Vaccination with trivalent PPrV (PhtD, PcpA and PlyD1) significantly reduced Spn burdens in MEF at both 24 (p=0.001) and 48hpi (p<0.0001). Similar reductions of bacterial burdens were found when the vaccinated animals were challenged with a non-typeable Spn strain. Vaccinated mice had significantly milder inflammatory cytokine levels (IL-1β, IL-6, TNF-α, MIP-2 and KC) in middle ears at 24hpi (all p values<0.05).

CONCLUSION

Trivalent PPrV confers protection against pneumococcal AOM in an infant murine model.

Ten-Year Study of the Stringently Defined Otitis-prone Child in Rochester, NY

This review summarizes a prospective, longitudinal 10-year study in Rochester, NY, with virtually every clinically diagnosed acute otitis media (AOM) confirmed by bacterial culture of middle ear fluid. Children experiencing 3 episodes within 6 months or 4 episodes in 12 months were considered stringently defined otitis prone (sOP). We found stringent diagnosis compared with clinical diagnosis reduced the frequency of children meeting the OP definition from 27% to 6% resulting in 14.8% and 2.4% receiving tympanostomy tubes, respectively. Significantly more often respiratory syncytial virus infection led to AOM in sOP than non-otitis-prone children that correlated with diminished total respiratory syncytial virus-specific serum IgG. sOP children produced low levels of antibody to Streptococcus pneumoniae and Haemophilus influenzae candidate vaccine protein antigens and to routine pediatric vaccines. sOP children generated significantly fewer memory B cells, functional and memory T cells to otopathogens following nasopharyngeal colonization and AOM than non-otitis-prone children and they had defects in antigen-presenting cells.

Inflammation-associated cytokine analysis identifies presence of respiratory bacterial pathogens in the nasopharynx

We sought to determine if inflammatory cytokines are induced during asymptomatic nasopharyngeal (NP) colonization by the common respiratory bacteria Streptococcus pneumoniae (Spn), non-typeable Haemophilus influenzae (NTHi) and Moraxella catarrhalis (Mcat). 85 serum samples were studied from 85 children 6-36 months of age when children were healthy and potentially NP colonized with Spn, NTHi or Mcat. Immunoassays were used to quantitate serum sICAM-1, IL-10 and S100A12 levels. Logistic regression was used to develop a predictive model for NP colonization probability for causative bacterial pathogen presence. Serum levels of sICAM-1, IL-10 and S100A12 increased during asymptomatic NP colonization by Spn, NTHi and Mcat. In a statistical model using risk scoring, we found high positive predictive and negative value, sensitivity and specificity when using these three cytokines to identify the presence of Spn, NTHi and Mcat in the NP. For the first time, we show that inflammatory cytokines are induced in serum during asymptomatic NP colonization by Spn, NTHi and Mcat.

Emerging Streptococcus pneumoniae Strains Colonizing the Nasopharynx in Children After 13-valent Pneumococcal Conjugate Vaccination in Comparison to the 7-valent Era, 2006-2015

BACKGROUND

After introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) in the United States in 2000, emergence of replacement serotypes occurred, leading to the introduction of a 13-valent pneumococcal conjugate vaccine (PCV13) in 2010 that contained all PCV7 serotypes plus 6 additional serotypes (1, 3, 5, 6A, 7F and 19A). Here, we describe a 9-year prospective, longitudinal study characterizing Streptococcus pneumoniae strains colonizing the nasopharynx (NP) of young children based on serotype, sequence type (ST) and antibiotic susceptibility during the PCV7 and PCV13 eras.

METHODS

NP samples were obtained for pneumococcal identification from prospectively followed children at 6, 9, 12, 15, 18, 24 and 30 months of age. A total of 1072 visits during the PCV7 era (June 2006 to September 2010) and 2044 visits during the PCV13 era (October 2010 to September 2015) were included from 665 children. Serotyping and multilocus sequence typing types of Streptococcus pneumoniae isolates were evaluated along with their antibiotic resistance pattern.

RESULTS

A total of 1045 Streptococcus pneumoniae were isolated; 350 during the PCV7 era and 685 during the PCV13 era. The most common serotypes identified during the PCV7 era were 19A and 23B compared with 35B, 23B and 21 in PCV13 era. Serotypes 15A/B/C emerged in equal proportion during the PCV13 era. Serotypes 16 and 20 were only observed in the PCV13 era. NP carriage of 19A persisted 5 years after PCV13 introduction (5% of all isolates). Multilocus ST 199 remained a dominant ST during both the PCV7 and PCV13 eras, and ST558 and ST62 emerged after PCV13. Antibiotic resistance to penicillin, ceftriaxone, cefotaxime, erythromycin, tetracycline and trimethoprim/sulfamethoxazole significantly decreased from the PCV7 to the PCV13 era.

CONCLUSIONS

Serotypes 35B, 23B, 21 and 15A/B/C rapidly emerged as NP colonizers in the early PCV13 era. Genetically divergent strains with ST558 and ST62 emerged. Resistance to common antibiotics declined after the introduction of PCV13.

Safe use of selected cephalosporins in penicillin-allergic patients: A meta-analysis

Background

Recent analysis of clinical data and a clearer understanding of the role of chemical structure in the development of cross-reactivity indicate that the increased risk of an allergic reaction to a cephalosporin in penicillin-allergic patients is smaller than previously postulated.

Method

Medline and EMBASE databases were searched with the keywords: cephalosporin, penicillin, allergy, and crosssensitivity for the years 1960 through 2005. Among 219 articles retrieved, 9 served as source material for this evidence-based meta-analysis.

Results

A significant increase in allergic reactions to cephalothin (odds ratio [OR] = 2.5; 95% confidence interval [CI] = 1.1 to 5.5), cephaloridine (OR = 8.7; CI = 5.9 to 12.8), and cephalexin (OR = 5.8; CI = 3.6 to 9.2), and all first generation cephalosporins plus cefamandole (OR = 4.8; CI = 3.7 to 6.2) were observed in penicillin allergic patients; no increase was observed with second generation cephalosporins (OR = 1.1; CI, 0.6 to 2.1) or third generation cephalosporins (OR = 0.5; CI = 0.2 to 1.1). Clinical challenges, skin testing, and monoclonal antibody studies point to the paramount importance of similarities in side chain structure to predict cross-allergy between cephalosporins and penicillins.

Conclusion

First-generation cephalosporins have cross-allergy with penicillins, but cross-allergy is negligible with second-and third-generation cephalosporins. Particular emphasis should be placed on the role of chemical structure in determining the risk of cross-reactivity between specific agents. 2007 American Academy of Otolaryngology-Head and Neck Surgery Foundation. All rights reserved.

Serum cytokine biomarkers accurately predict presence of acute otitis media infection and recovery caused by Haemophilus influenzae

OBJECTIVE

We sought to develop an optimal model using a combination of serum biomarker pro-inflammatory and dampening inflammatory cytokine proteins to predict the presence of acute otitis media (AOM) infection and recovery caused by Nontypeable Haemophilus influenzae (NTHi).

METHODS

88 serum samples were studied from 34 children 6-36 months of age at healthy visits, at onset of AOM diagnosed by qualified pediatricians and confirmed by tympanocentesis to be caused by NTHi and follow up 3 weeks to 4 months later. Immunoassays were used to quantitate serum S100A12, IL-10 and sICAM-1 cytokine levels. Middle ear fluids permitted identification of otopathogens. Logistic regression was used to develop a predictive model for infection probability and recovery.

RESULTS

A significant association between serum S100A12 and IL-10 cytokine levels as biomarkers of AOM infection was found for NTHi. Almost all NTHi positive AOMs could be predicted by calculations using serum S100A12 and IL-10 levels in a statistical model we derived. Including measurements of sICAM-1 did not improve predictability of NTHi AOM or recovery beyond that achieved using S100A12 and IL-10. The model showed clearly the ability of low biomarker scores to predict cure at follow-up once biomarker lag was correctly modeled.

CONCLUSION

We developed a serum molecular biomarker risk score that can predict the presence and recovery from AOM caused by the common respiratory bacteria NTHi that causes the infection in the clinical context of possible AOM.

Developing a vaccine to prevent otitis media caused by nontypeable Haemophilus influenzae

Nontypeable Haemophilus influenzae (NTHi) is a predominant organism of the upper respiratory nasopharyngeal microbiota. Its disease spectrum includes otitis media, sinusitis, non-bacteremic pneumonia and invasive infections. Protein-based vaccines to prevent NTHi infections are needed to alleviate these infections in children and vulnerable populations such as the elderly and those with chronic obstructive pulmonary disease (COPD). One NTHi protein is included in a pneumococcal conjugate vaccine and has been shown to provide efficacy. Our lab has been interested in understanding the immunogenicity of NTHi vaccine candidates P6, protein D and OMP26 for preventing acute otitis media in young children. We expect that continued investigation and progress in the development of an efficacious protein based vaccine against NTHi infections is achievable in the near future.

Functional Immune Cell Differences Associated With Low Vaccine Responses in Infants

BACKGROUND

We sought to understand why some children respond poorly to vaccinations in the first year of life.

METHODS

A total of 499 children (6-36 months old) provided serum and peripheral blood mononuclear cell samples after their primary and booster vaccination. Vaccine antigen-specific antibody levels were analyzed with enzyme-linked immunosorbent assay, and frequency of memory B cells, functional T-cell responses, and antigen-presenting cell responses were assessed in peripheral blood mononuclear cell samples with flow cytometric analysis.

RESULTS

Eleven percent of children were low vaccine responders, defined a priori as those with subprotective immunoglobulin G antibody levels to ≥66% of vaccines tested. Low vaccine responders generated fewer memory B cells, had reduced activation by CD4(+) and CD8(+) T cells on polyclonal stimulation, and displayed lower major histocompatibility complex II expression by antigen-presenting cells.

CONCLUSIONS

We conclude that subprotective vaccine responses in infants are associated with a distinct immunologic profile.

Next generation protein based Streptococcus pneumoniae vaccines

All currently available Streptococcus pneumoniae (Spn) vaccines have limitations due to their capsular serotype composition. Both the 23-valent Spn polysaccharide vaccine (PPV) and 7, 10, or 13-valent Spn conjugate vaccines (PCV-7, 10, -13) are serotype-based vaccines and therefore they elicit only serotype-specific immunity. Emergence of replacement Spn strains expressing other serotypes has consistently occurred following introduction of capsular serotype based Spn vaccines. Furthermore, capsular polysaccharide vaccines are less effective in protection against non-bacteremic pneumonia and acute otitis media (AOM) than against invasive pneumococcal disease (IPD). These shortcomings of capsular polysaccharide-based Spn vaccines have created high interest in development of non-serotype specific protein-based vaccines that could be effective in preventing both IPD and non-IPD infections. This review discusses the progress to date on development of Spn protein vaccine candidates that are highly conserved by all Spn strains, are highly conserved, exhibit maximal antigenicity and minimal reactogenicity to replace or complement the current capsule-based vaccines. Key to development of a protein based Spn vaccine is an understanding of Spn pathogenesis. Based on pathogenesis, a protein-based Spn vaccine should include one or more ingredients that reduce NP colonization below a pathogenic inoculum. Elimination of all Spn colonization may not be achievable or even advisable. The level of expression of a target protein antigen during pathogenesis is another key to the success of protein based vaccines.. As with virtually all currently licensed vaccines, production of a serum antibody response in response to protein based vaccines is anticipated to provide protection from Spn infections. A significant advantage that protein vaccine formulations can offer over capsule based vaccination is their potential benefits associated with natural priming and boosting to all strains of Spn. One of the most universal and comprehensive approaches of identifying novel vaccine candidates is the investigation of human sera from different disease stages of natural infections. Antigens that are robustly reactive in preliminary human serum screening constitute a pathogen-specific antigenome. This strategy has identified a number of Spn protein vaccine candidates that are moving forward in human clinical trials.

Synchrony in serum antibody response to conserved proteins of Streptococcus pneumoniae in young children

Conserved Streptococcus pneumoniae (Spn) proteins are currently under investigation as vaccine candidates. We recently identified a subset of children prone to frequent acute otitis media (AOM) that we refer to as stringently-defined otitis prone (sOP). We investigated the synchrony of serum antibody responses against 5 Spn protein vaccine antigens, PhtD, LytB, PcpA, PhtE, and PlyD1 resulting from nasopharyngeal colonization and AOM in sOP children (49 observations) and non-otitis prone (NOP) children (771 observations). Changes in serum IgG and IgM were quantitated with ELISA. IgG antibody concentrations against PhtD, PcpA, and PlyD1 rose in synchrony in sOP and NOP children; that is, the proteins appeared equally and highly immunogenic in children at age 6 to 15 months and then leveled off in their rise at 15 to 25 months. In contrast, rises in concentrations to PhtE and LytB were significantly slower and had not peaked in children even at 25 months of age, consistent with lower immunogenicity. Serum IgM responses against PhtD and PlyD1 were in synchrony in children at age 6-25 months old. PcpA did not induce a significant increase of serum IgM response in children, suggesting that primary responses to PcpA occurred prior to children attaining age 6 months old. PhtD, PcpA, and Ply elicit a synchronous natural acquisition of serum antibody in young children suggesting that a trivalent Spn protein vaccine combining PhtD, PcpA, and PlyD1 would be less likely to display antigen competition when administered as a combination vaccine in young children.