Nasopharyngeal bacterial interactions in children

Clinical Characteristics and Severity Predictors of Pediatric Adenovirus Infections

Adenovirus infections impose a significant disease burden on children and can result in poor clinical outcomes, thus requiring intensive care and potentially leading to fatality. We retrospectively analyzed pediatric adenovirus cases from 2018 to 2023 at a children's hospital in Taiwan and collected data regarding patients' clinical symptoms, imaging results, and laboratory findings. Multiple logistic regression was used to identify predictors of severe cases requiring intensive care. Our study revealed that adenovirus cases were more common in the winter, with a post-COVID-19 surge observed in 2023. A total of 576 pediatric adenovirus cases were collected, including 27 (4.7%) severe cases and 3 (0.5%) fatal cases. Severe cases were younger and exhibited higher frequencies of dyspnea, decreased activity, and diagnoses of bronchopneumonia/pneumonia and genetic disorders. Compared with nonsevere cases, severe cases also demonstrated more patchy opacity, lobar consolidation, pleural effusion, and bacterial coinfection. Multivariable analysis revealed that the most significant predictors of severe cases were dyspnea (aOR 18.5 [95% CI 3.792-90.257]), patchy opacity (3.391 [1.150-9.994]), lobar consolidation (116.388 [8.555-1583.393]), pleural effusion (9.117 [0.917-90.630]), and invasive bacterial coinfection (60.469 [4.047-903.555]), which are newly recognized predictors, thus highlighting the need for increased clinical vigilance.

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.

Trend change of nasopharyngeal colonization with Streptococcus pneumoniae and non-typeable Haemophilus influenzae in children attending daycare centres: nationwide population-based study, South Korea 2014 and 2019

BACKGROUND

Nasopharyngeal (NP) colonization with Streptococcus pneumoniae and non-typeable Haemophilus influenzae (NTHi) is common in children, and may evolve as the source of invasive infections. In Korea, the pneumococcal conjugate vaccines (PCVs) were introduced >10 years ago, enabling the authors to study the effect of the vaccine in preventing carriage.

METHODS

NP swabs were taken and a household survey was conducted at daycare centres located in different regions of Korea in 2014 and 2019. Pneumococcal serotypes were identified using the Quellung method and sequencing. NTHi were identified based on pilA and bexA genes.

RESULTS

In total, 1460 NP swabs were obtained with pneumococcal carriage rates of 36.4-42.1% and NTHi carriage rates of 36.5-26.7%. Among children carrying pneumococci, a significant increase was seen in serotype 23A between 2014 and 2019 (from 12.6% to 22.0%; P=0.005). Children who had received PCV were at lower risk of vaccine-type carriage (2.9% vs 0.8%; P=0.005).

CONCLUSIONS

Between 2014 and 2019, the proportion of children carrying serotype 23A increased significantly, while the carriage rate of NTHi decreased. Continuous surveillance is needed to assess the long-term effects of the PCVs on carriage dynamics of pneumococcus and NTHi.

Nasopharyngeal Carriage of Methicillin-Resistant Staphylococcus aureus (MRSA) among Sickle Cell Disease (SCD) Children in the Pneumococcal Conjugate Vaccine Era

The aim of this cross-sectional study was to investigate Staphylococcus aureus nasopharyngeal carriage epidemiology in relation to other nasopharyngeal bacterial colonizers among sickle cell disease (SCD) children about five years into pneumococcal conjugate vaccine 13 (PCV-13) introduction in Ghana. The study involved bacteriological culture of nasopharyngeal swabs obtained from 202 SCD children recruited from the Princess Marie Louise Children's Hospital. S. aureus isolates were identified using standard methods and subjected to antimicrobial susceptibility testing using the Kirby-Bauer disc diffusion method. Cefoxitin-resistant S. aureus isolates were screened for carriage of the mecA, pvl, and tsst-1 genes using multiplex polymerase chain reaction. The carriage prevalence of S. aureus was 57.9% (n = 117), and that of methicillin-resistant S. aureus (MRSA) was 3.5% (n = 7). Carriage of the mecA, pvl, and tsst-1 genes were respectively demonstrated in 20.0% (n = 7), 85.7% (n = 30), and 11.4% (n = 4) of the cefoxitin-resistant S. aureus isolates. PCV-13 vaccination (OR = 0.356, p = 0.004) and colonization with coagulase-negative staphylococci (CoNS) (OR = 0.044, p < 0.0001) each protected against S. aureus carriage. However, none of these and other features of the participants emerged as a determinant of MRSA carriage. The following antimicrobial resistance rates were observed in MRSA compared to methicillin-sensitive S. aureus: clindamycin (28.6% vs. 4.3%), erythromycin (42.9% vs. 19.1%), tetracycline (100% vs. 42.6%), teicoplanin (14.3% vs. 2.6%), penicillin (100% vs. 99.1%), amoxiclav (28.6% vs. 3.5%), linezolid (14.3% vs. 0.0%), ciprofloxacin (42.9% vs. 13.9%), and gentamicin (42.9% vs. 13.0%). The proportion of S. aureus isolates that were multidrug resistant was 37.7% (n = 46). We conclude that S. aureus was the predominant colonizer of the nasopharynx of the SCD children, warranting the continuous monitoring of this risk group for invasive S. aureus infections.

Nasopharyngeal Carriage and Antimicrobial Susceptibility Profile of Staphylococcus aureus among Children under Five Years in Accra

This cross-sectional study investigated the Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus (MRSA) nasopharyngeal carriage epidemiology in Accra approximately five years post-pneumococcal conjugate vaccines introduction in the country. Archived nasopharyngeal swabs collected from 410 children aged under five years old were bacteriologically cultured. The resultant S. aureus isolates were subjected to antimicrobial susceptibility testing and screening for carriage of the mecA and LukF-PV (pvl) genes, following standard procedures. The data obtained were analyzed with Statistical Products and Services Solutions (SPSS) using descriptive statistics and Chi square tests of associations. The isolated bacteria decreased across coagulase-negative Staphylococci (47.3%, n = 194), S. aureus (23.2%, n = 95), Diphtheroids (5.4%, n = 22), Micrococcus species (3.7%, n = 15), Klebsiella pneumoniae (3.2%, n = 13), Moraxella species and Citrobacter species (1.5% each, n = 6), Escherichia coli, Enterobacter species, and Pseudomonas species (0.9% each, n = 2). The MRSA carriage prevalence was 0.49% (n = 2). Individuals aged 37-48 months recorded the highest proportion of S. aureus carriage (32.6%, 31/95). Resistance of S. aureus to the antibiotics tested were penicillin G (97.9%, n = 93), amoxiclav (20%, n = 19), tetracycline (18.9%, n = 18), erythromycin (5.3%, n = 5), ciprofloxacin (2.1%, n = 2), gentamicin (1.1%, n = 1), cotrimoxazole, clindamycin, linezolid, and teicoplanin (0% each). No inducible clindamycin resistance was observed for the erythromycin-resistant isolates. Three (3.2%) of the isolates were multidrug resistant, of which 66.7% (2/3) were MRSA. The pvl gene was associated with 59.14% (55/93) of the methicillin-sensitive S. aureus (MSSA) isolates, but was not detected among any of the MRSA isolates.

Interactions of Bacteriophages and Bacteria at the Airway Mucosa: New Insights Into the Pathophysiology of Asthma

The airway epithelium is the primary site where inhaled and resident microbiota interacts between themselves and the host, potentially playing an important role on allergic asthma development and pathophysiology. With the advent of culture independent molecular techniques and high throughput technologies, the complex composition and diversity of bacterial communities of the airways has been well-documented and the notion of the lungs' sterility definitively rejected. Recent studies indicate that the microbial composition of the asthmatic airways across the spectrum of disease severity, differ significantly compared with healthy individuals. In parallel, a growing body of evidence suggests that bacterial viruses (bacteriophages or simply phages), regulating bacterial populations, are present in almost every niche of the human body and can also interact directly with the eukaryotic cells. The triptych of airway epithelial cells, bacterial symbionts and resident phages should be considered as a functional and interdependent unit with direct implications on the respiratory and overall homeostasis. While the role of epithelial cells in asthma pathophysiology is well-established, the tripartite interactions between epithelial cells, bacteria and phages should be scrutinized, both to better understand asthma as a system disorder and to explore potential interventions.

A longitudinal hospital-based epidemiology study to assess acute otitis media incidence and nasopharyngeal carriage in Korean children up to 24 months

This study was conducted to assess the nasopharyngeal (NP) carriage and acute otitis media (AOM) occurrence in Korean children who received pneumococcal conjugate vaccines (PCVs). The longitudinal study was conducted through four consecutive visits. At each visit, NP aspirates were obtained and subjects were asked to visit if AOM occurred. A total of 305 subjects were enrolled and received PCV13 (n = 182) or PCV10 (n = 123). In the PCV13 group, the NP carriage of Streptococcus pneumoniae at each visit was 2.7%, 14.8%, 18.7%, and 15.9%, respectively. Non-typeable Haemophilus influenzae (NTHi) was 3.3%, 2.7%, 2.7%, and 5.5%, and that of Moraxella catarrhalis was 1.1%, 9.3%, 4.9%, and 0.5%. In the PCV10 group, the NP carriage of S. pneumoniae at each visit was 3.3%, 7.3%, 6.5%, and 4.1%, respectively. That of NTHi was 2.4%, 4.1%, 1.6%, and 0.8%, and that of M. catarrhalis was 4.1%, 0.8%, 0.8%, and 0.0%. AOM occurrence in the PCV13 group observed after the primary dose and before booster dose was 20.9%, occurrence after booster dose was 11.0%, and the incidence of two or more AOM was 11.0%. In the PCV10 group, AOM occurrence was 9.8%, 7.3%, respectively, and the incidence of two or more AOM was 2.4%. The predominant S. pneumoniae isolated were non-vaccine type (10A, 15A, and 15B). In this study, AOM occurrence was lower in the PCV10 group than in the PCV13 group. This seems to be related to ecological changes that lead to differences in NP carriage, especially S. pneumoniae and NTHi.

Longitudinal investigation of nasopharyngeal pneumococcal carriage in early childhood: The PATCH birth cohort study

Streptococcus pneumoniae is a common cause of infectious diseases such as pneumonia and sepsis. Its colonization is thought to be the first step in the development of invasive pneumococcal diseases. This study aimed to investigate pneumococcal colonization patterns in early childhood. A longitudinal birth cohort study was conducted for investigating nasopharyngeal colonized pneumococci at 1, 6, 12, 18, 24, and 36 months of age, particularly focusing on the serotype distribution and antimicrobial susceptibilities. Pneumococcal conjugate vaccine (PCV) effect on nasopharyngeal colonization was also assessed. During 2013-2017, 855 infants were enrolled and a total of 107 isolates were recovered from 95 infants during the first three years of life. In this period, the prevalence of pneumococcal colonization increased, with values ranging from 0.2% (2/834) at 1 month of age to 5.9% (19/323) at 36 months of age. The investigation of serotype revealed that 81.1% (73/90) belonged to the non-PCV13 serotypes-23A, 15A, 15C, and 15B. Moreover, PCV13 serotypes significantly decreased during 2014-2015, when routine PCV13 vaccination was initiated in Taiwan. PCV13 introduction may lead to the reduction in the rates of pneumococcal isolates resistant (R) to penicillin. Under conditional PCV13 vaccination, pneumococcal isolates primarily belonged to non-PCV13 serotypes. This non-PCV13 serotype replacement exhibited lower rates of penicillin R isolates, suggesting that PCV13 administration may reduce the antibiotic-nonsusceptible pneumococcal disease burden and antibiotic use.

Pneumococcal susceptibility to antibiotics in carriage: a 17 year time series analysis of the adaptive evolution of non-vaccine emerging serotypes to a new selective pressure environment

BACKGROUND

Pneumococcal conjugate vaccine (PCV) implementations led to major changes in serotype distribution and antibiotic resistance in carriage, accompanied by changes in antibiotic consumption.

OBJECTIVES

To assess the dynamic patterns of antimicrobial non-susceptibility across non-PCV13 serotypes following PCV implementations.

METHODS

We conducted a quasi-experimental interrupted time series analysis based on a 17 year French nationwide prospective cohort. From 2001 to 2018, 121 paediatricians obtained nasopharyngeal swabs from children with acute otitis media who were aged 6 months to 2 years. The main outcome was the rate of penicillin-non-susceptible pneumococci (PNSP), analysed by segmented regression.

RESULTS

We enrolled 10 204 children. After PCV13 implementation, the PNSP rate decreased (-0.5% per month; 95% CI -0.9 to -0.1), then, after 2014, the rate slightly increased (+0.7% per month; 95% CI +0.2 to +1.2). Global antibiotic use within the previous 3 months decreased over the study period (-22.2%; 95% CI -33.0 to -11.3), but aminopenicillin use remained high. Among the main non-PCV13 serotypes, four dynamic patterns of penicillin susceptibility evolution were observed, including unexpected patterns of serotypes emerging while remaining or even becoming penicillin susceptible. In contrast to PNSP strains, for these latter patterns, the rate of co-colonization with Haemophilus influenzae increased concomitant with their emergence.

CONCLUSIONS

In a context of continuing high antibiotic selective pressure, a progressive increase in PNSP rate was observed after 2014. However, we highlighted an unexpected variability in dynamic patterns of penicillin susceptibility among emerging non-PCV13 serotypes. Antibiotic resistance may not be the only adaptive mechanism to antimicrobial selective pressure, and co-colonization with H. influenzae may be involved.

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.

Experimental Evolution In Vivo To Identify Selective Pressures during Pneumococcal Colonization

Experimental evolution is a powerful technique to understand how populations evolve from selective pressures imparted by the surrounding environment. With the advancement of whole-population genomic sequencing, it is possible to identify and track multiple contending genotypes associated with adaptations to specific selective pressures. This approach has been used repeatedly with model species in vitro, but only rarely in vivo Herein we report results of replicate experimentally evolved populations of Streptococcus pneumoniae propagated by repeated murine nasal colonization with the aim of identifying gene products under strong selection as well as the population genetic dynamics of infection cycles. Frameshift mutations in one gene, dltB, responsible for incorporation of d-alanine into teichoic acids on the bacterial surface, evolved repeatedly and swept to high frequency. Targeted deletions of dltB produced a fitness advantage during initial nasal colonization coupled with a corresponding fitness disadvantage in the lungs during pulmonary infection. The underlying mechanism behind the fitness trade-off between these two niches was found to be enhanced adherence to respiratory cells balanced by increased sensitivity to host-derived antimicrobial peptides, a finding recapitulated in the murine model. Additional mutations that are predicted to affect trace metal transport, central metabolism, and regulation of biofilm production and competence were also selected. These data indicate that experimental evolution can be applied to murine models of pathogenesis to gain insight into organism-specific tissue tropisms.IMPORTANCE Evolution is a powerful force that can be experimentally harnessed to gain insight into how populations evolve in response to selective pressures. Herein we tested the applicability of experimental evolutionary approaches to gain insight into how the major human pathogen Streptococcus pneumoniae responds to repeated colonization events using a murine model. These studies revealed the population dynamics of repeated colonization events and demonstrated that in vivo experimental evolution resulted in highly reproducible trajectories that reflect the environmental niche encountered during nasal colonization. Mutations impacting the surface charge of the bacteria were repeatedly selected during colonization and provided a fitness benefit in this niche that was counterbalanced by a corresponding fitness defect during lung infection. These data indicate that experimental evolution can be applied to models of pathogenesis to gain insight into organism-specific tissue tropisms.

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.

Rapid and direct molecular detection of Streptococcus pneumoniae and Haemophilus influenzae isolated in oropharynx and nasal cavity of children

There is a direct correlation between asymptomatic oropharyngeal colonization by pathogenic bacteria and the prevalence of paediatric respiratory infections. Streptococcus pneumoniae and Haemophilus influenzae are common cause of serious bacterial infections such as meningitis in children. This study aimed to monitor healthy children to detect asymptomatic carriers of S. pneumoniae and H. influenzae. In the present cross-sectional study, real-time PCR assay was developed and evaluated in comparison with culture for direct detection of S. pneumoniae and H. influenzae in 123 oropharynx and nasal cavity specimens from healthy children in Ilam, Iran. In addition, virulence factor (ply and hpd) and iron uptake (tbpA and piuA) genes were evaluated by PCR. Our results demonstrated that among all isolates only 14 S. pneumoniae and eight H. influenzae were identified by phenotypic methods, whereas 37 and 21 S. pneumoniae and H. influenzae were identified, respectively, by real-time PCR assay. All S. pneumoniae and H. influenzae isolates possessed tbpA and piuA genes. Also, 81% (30/37) of S. pneumoniae isolates were positive for ply gene, which encoded pneumolysin, as well as 90% (19/21) of H. influenzae isolates were positive for hpd gene. Simultaneous colonization of S. pneumoniae and H. influenzae could indicate the importance of monitoring of healthy children to identification of carriers.

The dynamics and interactions of respiratory pathogen carriage among French pilgrims during the 2018 Hajj

We conducted this study to describe the dynamics of the acquisition of respiratory pathogens, their potential interactions and risk factors for possible lower respiratory tract infection symptoms (LRTI) among French pilgrims during the 2018 Hajj. Each participant underwent four successive systematic nasopharyngeal swabs before and during their stay in Saudi Arabia. Carriage of the main respiratory pathogens was assessed by PCR. 121 pilgrims were included and 93.4% reported respiratory symptoms during the study period. The acquisition of rhinovirus, coronaviruses and Staphylococcus aureus occurred soon after arrival in Saudi Arabia and rates decreased gradually after days 5 and 6. In contrast, Streptococcus pneumoniae and Klebsiella pneumoniae carriage increased progressively until the end of the stay in Saudi Arabia. Haemophilus influenzae and Moraxella catarrhalis carriage increased starting around days 12 and 13, following an initial clearance. Influenza viruses were rarely isolated. We observed an independent positive mutual association between S. aureus and rhinovirus carriage and between H. influenzae and M. catarrhalis carriage. Dual carriage of H. influenzae and M. catarrhalis was strongly associated with S. pneumoniae carriage (OR = 6.22). Finally, our model showed that M. catarrhalis carriage was negatively associated with K. pneumoniae carriage. Chronic respiratory disease was associated with symptoms of LRTI. K. pneumoniae, M. catarrhalis-S. aureus and H. influenzae-rhinovirus dual carriage was associated with LRTI symptoms. Our data suggest that RTIs at the Hajj are a result of complex interactions between a number of respiratory viruses and bacteria.

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.

Performance of the Biomark HD real-time qPCR System (Fluidigm) for the detection of nasopharyngeal bacterial pathogens and Streptococcus pneumoniae typing

Traditional qPCR assays for pneumococcal detection and serotype characterization require large sample volume, is expensive and labor intensive. We aimed to develop a quantitative nanofluidic Fluidigm assay to overcome some of these shortcomings. A quantitative Fluidigm assay was established to detect 11 bacterial pathogens, 55 pneumococcal serotypes and 6 serotypes of H. influenzae. The Fluidigm assay results were compared to conventional qPCR and culture. All reactions in the Fluidigm assay effectively amplified their respective targets with high sensitivity and specificity compared to qPCR. There was excellent concordance between qPCR and Fluidigm for detection of carriage prevalence (kappa > 0.75) and density (Rho > 0.95). Fluidigm identified an additional 7 (4.2%) serotypes over those detected by qPCR. There was a modest concordance between culture and Fluidigm for the majority of reactions detecting S. pneumoniae serotypes/serogroups (kappa > 0.6), with Fluidigm identifying an additional 113 (39.1%) serotypes. Discordant results between the three methods were associated with a low carriage density. The Fluidigm assay was able to detect common pneumococcal serotypes, H. influenzae serotypes, and other common nasopharyngeal bacterial organisms simultaneously. Deployment of this assay in epidemiological studies could provide better insight into the effect of PCV immunization on the nasopharyngeal microbiota in the community.

Lower Airway Bacterial Colonization Patterns and Species-Specific Interactions in Chronic Obstructive Pulmonary Disease

Little is known about interactions between nontypeable Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae, and Pseudomonas aeruginosa in the lower respiratory tract in chronic obstructive pulmonary disease (COPD) patients. We characterized colonization by these four bacterial species, determined species-specific interactions, and estimated the effects of host factors on bacterial colonization among COPD patients. We conducted a prospective cohort study in veterans with COPD that involved monthly clinical assessment and sputum cultures with an average duration of follow-up of 4.5 years. Cultures were used for bacterial identification. We analyzed bacterial interactions using generalized linear mixed models after controlling for clinical and demographic variables. The outcomes of interest were the relationships between bacteria based on clinical status (stable or exacerbation). One hundred eighty-one participants completed a total of 8,843 clinic visits, 30.8% of which had at least one of the four bacteria isolated. H. influenzae was the most common bacterium isolated (14.4%), followed by P. aeruginosa (8.1%). In adjusted models, S. pneumoniae colonization was positively associated with H. influenzae colonization (odds ratio [OR], 2.79; 95% confidence interval [CI], 2.03 to 3.73). We identified negative associations between P. aeruginosa and H. influenzae (OR, 0.15; 95% CI, 0.10 to 0.22) and P. aeruginosa and M. catarrhalis (OR, 0.51; 95% CI, 0.35 to 0.75). Associations were similar during stable and exacerbation visits. Recent antimicrobial therapy was associated with a lower prevalence of S. pneumoniae, H. influenzae, and M. catarrhalis, but not P. aeruginosa Our findings support the presence of specific interspecies interactions between common bacteria in the lower respiratory tracts of COPD patients. Further work is necessary to elucidate the mechanisms of these complex interactions that shift bacterial species.

Pneumococcal vaccine impacts on the population genomics of non-typeable Haemophilus influenzae

The implementation of pneumococcal conjugate vaccines (PCVs) has led to a decline in vaccine-type disease. However, there is evidence that the epidemiology of non-typeable Haemophilus influenzae (NTHi) carriage and disease can be altered as a consequence of PCV introduction. We explored the epidemiological shifts in NTHi carriage using whole genome sequencing over a 5-year period that included PCV13 replacement of PCV7 in the UK’s National Immunization Programme in 2010. Between 2008/09 and 2012/13 (October to March), nasopharyngeal swabs were taken from children <5 years of age. Significantly increased carriage post-PCV13 was observed and lineage-specific associations with Streptococcus pneumoniae were seen before but not after PCV13 introduction. NTHi were characterized into 11 discrete, temporally stable lineages, congruent with current knowledge regarding the clonality of NTHi. The increased carriage could not be linked to the expansion of a particular clone and different co-carriage dynamics were seen before PCV13 implementation when NTHi co-carried with vaccine serotype pneumococci. In summary, PCV13 introduction has been shown to have an indirect effect on NTHi epidemiology and there exists both negative and positive, distinct associations between pneumococci and NTHi. This should be considered when evaluating the impacts of pneumococcal vaccine design and policy.

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.

Antibody responses against Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis in children with acute respiratory infection with or without nasopharyngeal bacterial carriage

BACKGROUND

We studied Immunoglobulin G (IgG) antibody responses against Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis in young children with acute viral type respiratory infection and analyzed the findings in a multivariate model including age, nasopharyngeal carriage of the tested bacteria and pneumococcal vaccination.

METHODS

We included 227 children aged 6-23 months with acute respiratory infection. Nasopharyngeal aspirates were tested for bacterial carriage through detection of messenger RNA (mRNA) transcript with nCounter analysis. Acute and convalescent serum samples were tested for IgG antibody response against eight pneumococcal proteins, three proteins from H. influenzae and five proteins from M. catarrhalis in a fluorescent multiplex immunoassay.

RESULTS

A two-fold or greater increase in antibodies to S. pneumoniae, H. influenzae and M. catarrhalis was detected in 27.8, 9.7 and 14.1%, respectively. Nasopharyngeal carriage of each of the studied bacteria was not associated with antibody response detection against each respective bacterium. Furthermore, neither age nor pneumococcal vaccination were independently associated to detection of antibody response against the studied bacteria. Children who carried H. influenzae had higher frequency of colonization by M. catarrhalis (175 [80.3%] vs. 2 [22.2%]; p < .001) than those without H. influenzae. Also, children with acute otitis media tended to have higher frequency of antibody response to S. pneumoniae.

CONCLUSION

Nasopharyngeal colonization by S. pneumoniae, H. influenzae and M. catarrhalis did not induce significant increases in antibody levels to these bacteria. Carriage of pathogenic bacteria in the nasopharynx is not able to elicit antibody responses to protein antigens similar to those caused by symptomatic infections.

Bacterial-Host Interactions: Physiology and Pathophysiology of Respiratory Infection

It has long been thought that respiratory infections are the direct result of acquisition of pathogenic viruses or bacteria, followed by their overgrowth, dissemination, and in some instances tissue invasion. In the last decades, it has become apparent that in contrast to this classical view, the majority of microorganisms associated with respiratory infections and inflammation are actually common members of the respiratory ecosystem and only in rare circumstances do they cause disease. This suggests that a complex interplay between host, environment, and properties of colonizing microorganisms together determines disease development and its severity. To understand the pathophysiological processes that underlie respiratory infectious diseases, it is therefore necessary to understand the host-bacterial interactions occurring at mucosal surfaces, along with the microbes inhabiting them, during symbiosis. Current knowledge regarding host-bacterial interactions during asymptomatic colonization will be discussed, including a plausible role for the human microbiome in maintaining a healthy state. With this as a starting point, we will discuss possible disruptive factors contributing to dysbiosis, which is likely to be a key trigger for pathobionts in the development and pathophysiology of respiratory diseases. Finally, from this renewed perspective, we will reflect on current and potential new approaches for treatment in the future.

Epidemiological Features and Antibiotic Resistance Patterns of Haemophilus influenzae Originating from Respiratory Tract and Vaginal Specimens in Pediatric Patients

STUDY OBJECTIVE

Haemophilus influenzae (H. influenzae) is a common pathogen of respiratory tract infections in children, however, as a possible cause of vulvovaginitis in prepubertal girls, its epidemiological features, antibiotic-resistance patterns, and treatment are seldom noted. DESIGN, SETTING, PARTICIPANTS, INTERVENTIONS, AND MAIN OUTCOME MEASURES: Specimens obtained from patients were inoculated on Haemophilus selective medium; and drug-sensitivities tests were determined using the disk diffusion method. A cefinase disk was used to detect β-lactamase.

RESULTS

A total of 610 H. influenzae strains, 81.6% (498/610) from the respiratory tract and 18.0% (110/610) from the vagina, were identified in the Children's Hospital in 2015. The age of the children with respiratory tract strains were significantly younger than those with vaginal strains (P < .001). The H. influenzae isolation rate in May was the highest. The β-lactamase positive rate was 51.5% (314/610), and 52.5% (320/610) were resistant to ampicillin. The susceptibilities rates to cefuroxime, ampicillin/sulbactam, cefotaxime, clarithromycin, and sulfamethoxazole-trimethoprim were 72.1% (440/610), 95.9%, 96.4% (588/610), 81.8% (499/610), and 36.4% (222/610), respectively. Higher resistance to ampicillin, cefuroxime, clarithromycin, and sulfamethoxazole-trimethoprim were found in respiratory tract strains, compared with vaginal strains (P < .05). All of the patients with H. influenzae in the respiratory tract were cured with oral or intravenous β-lactam antibiotics. Of all patients with vaginal strains, 50% (55/110) were cured with topical ofloxacin gel, and 44.5% (49/110) were cured with oral β-lactam antibiotics.

CONCLUSION

The drug-resistance rates of H. influenzae isolated from vagina were lower than those from the respiratory tract. Topical ofloxacin gel or oral β-lactam antibiotics are effective treatments to eliminate the H. influenza causing infection in the vagina.

Nasopharyngeal polymicrobial colonization during health, viral upper respiratory infection and upper respiratory bacterial infection

OBJECTIVES

We sought to understand how polymicrobial colonization varies during health, viral upper respiratory infection (URI) and acute upper respiratory bacterial infection to understand differences in infection-prone vs. non-prone patients.

METHODS

Nasopharyngeal (NP) samples were collected from 74 acute otitis media (AOM) infection-prone and 754 non-prone children during 2094 healthy visits, 673 viral URI visits and 631 AOM visits. Three otopathogens Streptococcus pneumoniae (Spn), Nontypeable Haemophilus influenzae (NTHi), and Moraxella catarrhalis (Mcat) were identified by culture.

RESULTS

NP colonization rates of multiple otopathogens during health were significantly lower than during viral URI, and during URI they were lower than at onset of upper respiratory bacterial infection in both AOM infection-prone and non-prone children. AOM infection-prone children had higher polymicrobial colonization rates than non-prone children during health, viral URI and AOM. Polymicrobial colonization rates of AOM infection-prone children during health were equivalent to that of non-prone children during viral URI, and during viral URI were equivalent to that of non-prone during AOM infection. Spn colonization was positively associated with NTHi and Mcat colonization during health, but negatively during AOM infection.

CONCLUSION

The infection-prone patients more frequently have multiple potential bacterial pathogens in the NP than the non-prone patients. Polymicrobial interaction in the NP differs during health and at onset of infection.

Epidemiology of Otitis Media with Spontaneous Perforation of the Tympanic Membrane in Young Children and Association with Bacterial Nasopharyngeal Carriage, Recurrences and Pneumococcal Vaccination in Catalonia, Spain - The Prospective HERMES Study

The Epidemiology of otitis media with spontaneous perforation of the tympanic membrane and associated nasopharyngeal carriage of bacterial otopathogens was analysed in a county in Catalonia (Spain) with pneumococcal conjugate vaccines (PCVs) not included in the immunization programme at study time. A prospective, multicentre study was performed in 10 primary care centres and 2 hospitals (June 2011-June 2014), including all otherwise healthy children ≥2 months ≤8 years with otitis media presenting spontaneous tympanic perforation within 48h. Up to 521 otitis episodes in 487 children were included, showing by culture/PCR in middle ear fluid (MEF): Haemophilus influenzae [24.2%], both Streptococcus pneumoniae and H. influenzae [24.0%], S. pneumoniae [15.9%], Streptococcus pyogenes [13.6%], and Staphylococcus aureus [6.7%]. Culture-negative/PCR-positive otitis accounted for 31.3% (S. pneumoniae), 30.2% (H. influenzae) and 89.6% (mixed S. pneumoniae/H. influenzae infections). Overall, incidence decreased over the 3-year study period, with significant decreases in otitis by S. pneumoniae and by H. influenzae, but no decreases for mixed S. pneumoniae/H. influenzae infections. Concordance between species in nasopharynx and MEF was found in 58.3% of cases, with maximal rates for S. pyogenes (71.8%), and with identical pneumococcal serotype in 40.5% of cases. Most patients (66.6%) had past episodes. PCV13 serotypes were significantly more frequent in first episodes, in otitis by S. pneumoniae as single agent, and among MEF than nasopharyngeal isolates. All non-PCV13 serotypes separately accounted for <5% in MEF. Up to 73.9% children had received ≥1 dose of PCV, with lower carriage of PCV13 serotypes than among non-vaccinated children. Pooling pneumococcal isolates from MEF and nasopharynx, 30% were multidrug resistant, primarily belonging to serotypes 19A [29.8%], 24A [14.3%], 19F [8.3%] and 15A [6.0%]. Our results suggest that increasing PCV13 vaccination would further reduce transmission of PCV13 serotypes with special benefits for youngest children (with none or uncompleted vaccine schedules), preventing first otitis episodes and subsequent recurrences.

Increased Nasopharyngeal Density and Concurrent Carriage of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis Are Associated with Pneumonia in Febrile Children

Background

We assessed nasopharyngeal (NP) carriage of five pathogens in febrile children with and without acute respiratory infection (ARI) of the upper (URTI) or lower tract, attending health facilities in Tanzania.

Methods

NP swabs collected from children (N = 960) aged 2 months to 10 years, and with a temperature ≥38°C, were utilized to quantify bacterial density of S. pneumoniae (Sp), H. influenzae (Hi), M. catarrhalis (Mc), S. aureus (Sa), and N. meningitidis (Nm). We determined associations between presence of individual species, densities, or concurrent carriage of all species combination with respiratory diseases including clinical pneumonia, pneumonia with normal chest radiography (CXR) and endpoint pneumonia.

Results

Individual carriage, and NP density, of Sp, Hi, or Mc, but not Sa, or Nm, was significantly associated with febrile ARI and clinical pneumonia when compared to febrile non-ARI episodes. Density was also significantly increased in severe pneumonia when compared to mild URTI (Sp, p<0.002; Hi p<0.001; Mc, p = 0.014). Accordingly, concurrent carriage of Sp⁺, Hi⁺, and Mc⁺, in the absence of Sa^- and Nm^-, was significantly more prevalent in children with ARI (p = 0.03), or clinical pneumonia (p<0.001) than non-ARI, and in children with clinical pneumonia (p = 0.0007) than URTI. Furthermore, Sp⁺, Hi⁺, and Mc⁺ differentiated children with pneumonia with normal CXR, or endpoint pneumonia, from those with URTI, and non-ARI cases.

Conclusions

Concurrent NP carriage of Sp, Hi, and Mc was a predictor of clinical pneumonia and identified children with pneumonia with normal CXR and endpoint pneumonia from those with febrile URTI, or non-ARI episodes.

Longitudinal investigation of nasopharyngeal methicillin-resistant Staphylococcus aureus colonization in early infancy: The PATCH birth cohort study

OBJECTIVES

The study aimed to determine the long-term Staphylococcus aureus colonization patterns and strain relatedness, and the association between maternal and infant colonization in infancy.

METHODS

A birth cohort study was conducted from January 2012 to November 2014. Nasopharyngeal swabs for S. aureus detection were collected from infants at the age of 1, 2, 4, 6 and 12 months and from mothers when their children were 1-month-old.

RESULTS

In total, 254 samples were collected at each planned visit during the first 12-month study. The prevalence of S. aureus colonization decreased in the first year of life, ranging from 61.0% (155/254) at the age of 1 month to 12.2% (31/254) at 12 months. Persistent colonization, defined as a positive culture on four or five occasions, was detected in only 13.8% (35/254) of carriers. Most of the persistent carriers were colonized with methicillin-resistant S. aureus (MRSA) only, and among persistent MRSA carriers, 61.1% (11/18) had indistinguishable genotypes. Of the mothers with MRSA colonization, 77.1% (27/35) had infants who were concomitantly colonized at the age of 1 month; 70.4% (19/27) of the infant-mother paired isolates belonged to indistinguishable or related subtypes, which suggests that surrounding carriers, probably their mothers, may be the possible source for MRSA acquisition in early infancy.

CONCLUSIONS

Staphylococcus aureus colonization including MRSA was commonly observed in our cohort. Strains of persistent MRSA among infant-mother pairs were usually of indistinguishable genotypes. Therefore, horizontal spread within households is possibly an important factor related to infant MRSA colonization.

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.

Ten-Year Study of Acute Otitis Media in Rochester, NY

This review summarizes a prospective, longitudinal 10-year study in Rochester, NY, involving 760 children where virtually all clinically diagnosed acute otitis media (AOM) was confirmed by bacterial culture of middle ear fluid. This review describes detection of otopathogens in middle ear fluid, nasopharyngeal (NP) otopathogen colonization patterns, AOM risk factor analysis, biomarkers of AOM and antibody responses to NP colonization by otopathogens. After licensure of PCV13, there was an immediate drop in AOM caused by Streptococcus pneumoniae (Spn) vaccine serotypes and shortly thereafer an increase in nonvaccine types 16, 21 and 35B. When NP co-colonization occurred, nontypeable Haemophilus influenzae (NTHi) predominated over Spn to cause AOM, and NTHi and Spn both predominated over Moraxella catarrhalis. Transcriptome analysis of peripheral blood mononuclear cells identified unique signatures for NTHi AOM compared with Spn AOM. Elevation of 3 cytokines in serum (S100A12, intercellular adhesion molecule 1 and interleukin 10) accurately predicted the presence and recovery from AOM and the likely otopathogen. NP colonization was an immunizing event.

Nasopharyngeal bacterial carriage in young children in Greenland: a population at high risk of respiratory infections

The incidence of childhood respiratory infections in Greenland is among the highest globally. We performed a population-based study of 352 Greenlandic children aged 0-6 years aiming to describe rates and risk factors for carriage of four key bacteria associated with respiratory infections, their antimicrobial susceptibility and inter-bacterial associations. Nasopharyngeal swabs were tested for Streptococcus pneumoniae grouped by serotypes included (VT) or not included (NVT) in the 13-valent pneumococcal conjugate vaccine, non-typable Haemophilus influenzae (NTHi), Staphylococcus aureus and Moraxella catarrhalis. S. pneumoniae was detected from age 2 weeks with a peak carriage rate of 60% in 2-year-olds. Young age and having siblings attending a daycare institution were associated with pneumococcal carriage. Overall co-colonization with ⩾2 of the studied bacteria was 52%. NTHi showed a positive association with NVT pneumococci and M. catarrhalis, respectively, M. catarrhalis was positively associated with S. pneumoniae, particular VT pneumococci, whereas S. aureus were negatively associated with NTHi and M. catarrhalis. Nasopharyngeal bacterial carriage was present unusually early in life and with frequent co-colonization. Domestic crowding increased odds of carriage. Due to important bacterial associations we suggest future surveillance of pneumococcal conjugate vaccine's impact on carriage in Greenland to also include other pathogens.

Novel Strategy To Protect against Influenza Virus-Induced Pneumococcal Disease without Interfering with Commensal Colonization

Streptococcus pneumoniae commonly inhabits the nasopharynx as a member of the commensal biofilm. Infection with respiratory viruses, such as influenza A virus, induces commensal S. pneumoniae to disseminate beyond the nasopharynx and to elicit severe infections of the middle ears, lungs, and blood that are associated with high rates of morbidity and mortality. Current preventive strategies, including the polysaccharide conjugate vaccines, aim to eliminate asymptomatic carriage with vaccine-type pneumococci. However, this has resulted in serotype replacement with, so far, less fit pneumococcal strains, which has changed the nasopharyngeal flora, opening the niche for entry of other virulent pathogens (e.g., Streptococcus pyogenes, Staphylococcus aureus, and potentially Haemophilus influenzae). The long-term effects of these changes are unknown. Here, we present an attractive, alternative preventive approach where we subvert virus-induced pneumococcal disease without interfering with commensal colonization, thus specifically targeting disease-causing organisms. In that regard, pneumococcal surface protein A (PspA), a major surface protein of pneumococci, is a promising vaccine target. Intradermal (i.d.) immunization of mice with recombinant PspA in combination with LT-IIb(T13I), a novel i.d. adjuvant of the type II heat-labile enterotoxin family, elicited strong systemic PspA-specific IgG responses without inducing mucosal anti-PspA IgA responses. This response protected mice from otitis media, pneumonia, and septicemia and averted the cytokine storm associated with septic infection but had no effect on asymptomatic colonization. Our results firmly demonstrated that this immunization strategy against virally induced pneumococcal disease can be conferred without disturbing the desirable preexisting commensal colonization of the nasopharynx.

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.

The role of respiratory viruses in the etiology of bacterial pneumonia: An ecological perspective

Pneumonia is the leading cause of death among children less than 5 years old worldwide. A wide range of viral, bacterial and fungal agents can cause pneumonia: although viruses are the most common etiologic agent, the severity of clinical symptoms associated with bacterial pneumonia and increasing antibiotic resistance makes bacterial pneumonia a major public health concern. Bacterial pneumonia can follow upper respiratory viral infection and complicate lower respiratory viral infection. Secondary bacterial pneumonia is a major cause of influenza-related deaths. In this review, we evaluate the following hypotheses: (i) respiratory viruses influence the etiology of pneumonia by altering bacterial community structure in the upper respiratory tract (URT) and (ii) respiratory viruses promote or inhibit colonization of the lower respiratory tract (LRT) by certain bacterial species residing in the URT. We conducted a systematic review of the literature to examine temporal associations between respiratory viruses and bacteria and a targeted review to identify potential mechanisms of interactions. We conclude that viruses both alter the bacterial community in the URT and promote bacterial colonization of the LRT. However, it is uncertain whether changes in the URT bacterial community play a substantial role in pneumonia etiology. The exception is Streptococcus pneumoniae where a strong link between viral co-infection, increased carriage and pneumococcal pneumonia has been established.

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.

The host immune dynamics of pneumococcal colonization: implications for novel vaccine development

The human nasopharynx (NP) microbiota is complex and diverse and Streptococcus pneumoniae (pneumococcus) is a frequent member. In the first few years of life, children experience maturation of their immune system thereby conferring homeostatic balance in which pneumococci are typically rendered as harmless colonizers in the upper respiratory environment. Pneumococcal carriage declines in many children before they acquire capsular-specific antibodies, suggesting a capsule antibody-independent mechanism of natural protection against pneumococcal carriage in early childhood. A child's immune system in the first few years of life is Th2-skewed so as to avoid inflammation-induced immunopathology. Understanding Th1/Th2 and Th17 ontogeny in early life and how adjuvant vaccine formulations shift the balance of T helper-cell differentiation, may facilitate the development of new protein-based pneumococcal vaccines. This article will discuss the immune dynamics of pneumococcal colonization in infants. The discussion aims to benefit the design and improvement of protein subunit-based next-generation pneumococcal vaccines.

Interaction between Streptococcus pneumoniae and Staphylococcus aureus in paediatric patients suffering from an underlying chronic disease

Little is known about the interaction between Streptococcus pneumoniae and Staphylococcus aureus in school-age children and adolescents suffering from an underlying chronic disease. To increase our knowledge in this regard, an oropharyngeal swab was obtained from school-age children and adolescents suffering from asthma (n = 423), cystic fibrosis (CF) (n = 212) and type 1 diabetes mellitus (DM1) (n = 296). S. pneumoniae detection and serotyping were performed using a real-time polymerase chain reaction, and S. aureus detection was performed using the RIDAGENE MRSA system. Among asthmatic, CF and DM1 patients, both pathogens were identified in 65/423 (15.4%), 21/212 (9.9%) and 62/296 (20.9%) children, respectively; S. pneumoniae alone was identified in 127/434 (30.0%), 21/212 (9.9%) and 86/296 (29.1%), respectively; S. aureus alone was identified in 58/434 (13.7%), 78/212 (36.8%) and 49/296 (16.6%), respectively. S. pneumoniae colonisation rates were higher in younger children and declined with age, whereas the frequency of S. aureus colonisation was quite similar in the different age groups. Among asthmatic and CF patients aged 6-9 years, S. aureus carriage was significantly higher in children who were positive for S. pneumoniae (P <0.05). No significant association emerged between S. aureus carriage and carriage of S. pneumoniae serotypes included in the pneumococcal conjugate vaccines (PCVs). This study shows for the first time that school-age children and adolescents with asthma, CF and DM1 are frequently colonised by S. pneumoniae and S. aureus and that no negative relationship seems to exist between these pathogens. Moreover, the supposed protection offered by PCV administration against S. aureus colonisation was not demonstrated.

Correlation of Bacterial Isolates from Middle Ear and Nasopharynx in Patients with Chronic Suppurative Otitis Media in Ilorin, Nigeria

PURPOSE

To determine the association between isolates in the middle ear (ME) and nasopharynx of patients with chronic otitis media in Ilorin, north-central Nigeria.

METHODS

An ethically approved case control study was carried out in the Ear, Nose, and Throat clinic amongst consenting cases using normal subjects as controls. A microbiology investigation form giving the results for otoscopy, aspirate and swabs was filled out for both the ME and nasopharynx. The experimental procedure was carried out and bacteria were identified according to colony characteristics, morphological appearance, Gram-staining, and standard biochemical testing. Data obtained were analysed with SPSS version 16.0 and Epi Info 3.5.1 using the mean, standard deviation and chi-square results.

RESULT

A total of 140 cases and 70 controls, were recruited. The Gram stain reaction of the ME aspirates were positive in 28.6% and negative in 71.4% of cases. Nasopharyngeal swabs revealed 64.3% Gram positive and 35.7% negative organisms. Overall, there was no relationship between the ME and nasopharyngeal isolates amongst cases, with a P value of 0.000. However, there was a relationship amongst the isolate from the nasopharynx of cases and controls, with the exception of Klebsiella pneumoniae, at P < 0.009.

CONCLUSION

There was no relationship amongst the bacterial isolate from the ME and nasopharyngeal specimen of patients with otitis media.

Nasopharyngeal Bacterial Carriage in the Conjugate Vaccine Era with a Focus on Pneumococci

Seven-valent pneumococcal conjugate vaccine (PCV7) was included in the UK national immunisation program in 2006, and this was replaced by thirteen-valent PCV in 2010. During this time, the carriage of vaccine-type Streptococcus pneumoniae decreased but pneumococcal carriage remained stable due to increases in non-vaccine-type S. pneumoniae. Carriage studies have been undertaken in various countries to monitor vaccine-type replacement and to help predict the serotypes, which may cause invasive disease. There has been less focus on how conjugate vaccines indirectly affect colonization of other nasopharyngeal bacteria. If the nasopharynx is treated as a niche, then bacterial dynamics are accepted to occur. Alterations in these dynamics have been shown due to seasonal changes, antibiotic use, and sibling/day care interaction. It has been shown that, following PCV7 introduction, an eradication of pneumococcal vaccine types has resulted in increases in the abundance of other respiratory pathogens including Haemophilus influenzae and Staphylococcus aureus. These changes are difficult to attribute to PCV7 introduction alone and these studies do not account for further changes due to PCV13 implementation. This review aims to describe nasopharyngeal cocarriage of respiratory pathogens in the PCV era.

Factors Affecting Staphylococcus aureus Colonization of the Nasopharynx in the First 6 Months of Life

BACKGROUND

Staphylococcal aureus (SA) colonization in early infancy is common, but the pattern and factors affecting its acquisition and persistence in the first few months of life are not well studied. The aim is to study the rate of SA nasopharyngeal (NP) colonization at monthly intervals in the first 6 months of life and its association with environmental and host factors and other pathogenic NP bacteria.

METHODS

Data from a prospective study were analyzed on bacterial cultures of 1765 NP swabs from 367 infants who were followed from birth to 6 months of age. Demographic, breastfeeding, cigarette smoke exposure and day care attendance data were collected at each monthly visit.

RESULTS

The rate of infants colonized with SA was highest at age 1 month (25%) and declined to lowest rate by age 6 months (12%). The proportion of SA strains that was methicillin-resistant SA was also highest at age 1 month and declined rapidly by age 4 months (18% vs. 6%, P = 0.05). Colonization with Streptococcus pneumoniae (SP), nontypeable Haemophilus influenzae (NTHI) and Moraxella catarrhalis (MC) increased at different rates up to age 6 months. Univariate analysis showed that SA colonization rate was significantly lower with increasing age, black race, day care attendance, and colonization with NTHI, MC and SP (P < 0.05). Multivariate analysis showed that this effect was independently associated only with increasing age and MC colonization (P < 0.05). Furthermore, the time to first acquisition of SA from one month of age onwards was significantly associated with day care attendance, and NTHI and MC colonization. None of the infants colonized with SA developed SA infections through age 6 months.

CONCLUSIONS

SA colonization of NP begins very early in life and declines quickly. Methicillin-resistant SA has lower ability to maintain prolonged colonization status than methicillin-susceptible strains in the first 6 months of life. As the NP is colonized with other respiratory bacterial pathogens, the colonization with SA declines; however, this effect is stronger with Gram-negative bacteria, such as NTHI and MC.

Long-term impact of pneumococcal polysaccharide vaccination on nasopharyngeal carriage in children previously vaccinated with various pneumococcal conjugate vaccine regimes

Previously, the Fiji Pneumococcal Project (FiPP) evaluated reduced dose immunization schedules that incorporated pneumococcal protein conjugate and/or polysaccharide vaccine (PCV7 and 23vPPV, respectively). Immune hyporesponsiveness was observed in children vaccinated with 23vPPV at 12 months of age compared with children who did not receive 23vPPV. Here we assess the long-term impact of 23vPPV vaccination on nasopharyngeal carriage rates and densities of Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus and Moraxella catarrhalis. Nasopharyngeal swabs (n=194) were obtained from healthy children who participated in FiPP (now aged 5-7 years). S. pneumoniae were isolated and identified by standard culture-based methods, and serotyped using latex agglutination and the Quellung reaction. Carriage rates and densities of S. pneumoniae, H. influenzae, S. aureus and M. catarrhalis were determined using real-time quantitative PCR. There were no differences in the rate or density of S. pneumoniae, H. influenzae or M. catarrhalis carriage by PCV7 dose or 23vPPV vaccination in the vaccinated participants overall. However, differences were observed between the two main ethnic groups: Fijian children of Indian descent (Indo-Fijian) were less likely to carry S. pneumoniae, H. influenzae and M. catarrhalis, and there was evidence of a higher carriage rate of S. aureus compared with indigenous Fijian (iTaukei) children. Polysaccharide vaccination appeared to have effects that varied between ethnic groups, with 23vPPV vaccination associated with a higher carriage rate of S. aureus in iTaukei children, while there was a lower carriage rate of S. pneumoniae associated with 23vPPV vaccination in Indo-Fijian children. Overall, polysaccharide vaccination had no long-term impact on pneumococcal carriage, but may have impacted on S. aureus carriage and have varying effects in ethnic groups, suggesting current WHO vaccine schedule recommendations against the use of 23vPPV in children under two years of age are appropriate.

Nasopharyngeal bacterial burden and antibiotics: Influence on inflammatory markers and disease severity in infants with respiratory syncytial virus bronchiolitis

OBJECTIVES

Animal studies suggest that RSV increases nasopharyngeal (NP) bacterial colonization facilitating bacterial infections. We investigated the influence of antibiotic treatment and colonization with potentially pathogenic bacteria on inflammatory markers and disease severity in RSV-infected in infants.

METHODS

Healthy young infants hospitalized with RSV bronchiolitis (n = 136) and age-matched healthy controls (n = 23) were enrolled and NP samples cultured for potentially pathogenic bacteria including: Gram-positive bacteria (GPB): Staphylococcus aureus, Streptococcus pneumoniae, β-hemolytic Streptococcus; and Gram-negative bacteria (GNB): Moraxella catarrhalis and Haemophilus influenzae. Clinical parameters and plasma IL-8, IL-6 and TNF-α concentrations were compared according to the bacterial class and antibiotic treatment.

RESULTS

Antibiotic treatment decreased by 10-fold NP bacterial recovery. Eighty-one percent of RSV infants who did not receive antibiotics before sample collection were colonized with pathogenic bacteria. Overall, GNB were identified in 21% of patients versus 4% of controls who were mostly colonized with GPB. Additionally, in RSV patients NP white blood cell counts (p = 0.026), and blood neutrophils (p = 0.02) were higher in those colonized with potentially pathogenic bacteria versus respiratory flora. RSV patients colonized with GNB had higher plasma IL-8 (p = 0.01) and IL-6 (p < 0.01) concentrations than controls, and required longer duration of oxygen (p = 0.049).

CONCLUSIONS

Infants with RSV bronchiolitis colonized with potentially pathogenic bacteria had increased numbers of mucosal and systemic inflammatory cells. Specifically, colonization with GNB was associated with higher concentrations of proinflammatory cytokines and a trend towards increased disease severity.

Pathogenic bacterial nasopharyngeal colonization and its impact on respiratory diseases in the first year of life: the PATCH Birth Cohort Study

BACKGROUND

For acute respiratory diseases caused by bacteria, colonization in the respiratory tracts is often the first sign, although nasopharynx is the major source of secretions containing pathogens. To understand the pathogenesis of respiratory tract diseases, it is important to analyze the establishment of nasopharyngeal bacterial colonization.

METHODS

Infants with nasopharyngeal swabs were examined at the age of 1, 2, 4, 6 and 12 months for the detection of pathogens, including Streptococcus pneumoniae, Hemophilus influenzae, Moraxella catarrhalis, Streptococcus pyogenes and Staphylococcus aureus. The methods used for detection were bacterial culture and multiplex polymerase chain reaction.

RESULTS

From January 2012 to August 2013, a total of 320 neonates were enrolled, and 120 of them completed the first 12-month study. Staphylococcus aureus was the most common pathogen at all 5 time points while the rates declined; in contrast, the other 4 increased during the first year of life. Of our series, the multiplex polymerase chain reaction detection rates were higher than those of bacterial culture. More than 50% of Staphylococcus aureus was methicillin-resistant, and the trend decreased in the same period. In the analysis of factors associated with the development of infant wheeze, infants with maternal atopy [odds ratio (OR): 3.26; 95% confidence interval (CI): 1.20-8.88; P = 0.02] and pneumococcal colonization (OR: 15.64; 95% CI: 3.25-75.35; P = 0.001) had higher rates of wheeze.

CONCLUSIONS

Bacterial interactions may result in differing pathogen prevalence in the first year of life. In addition, nasopharyngeal pneumococcal colonization may have an effect on the risk of infant wheeze. The result could help clinicians to clarify the relation between bacterial colonization and respiratory illnesses in infancy.

Livestock-associated MRSA in household members of pig farmers: transmission and dynamics of carriage, a prospective cohort study

This prospective cohort study describes carriage of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) in household members from 49 farrowing pig farms in the Netherlands (2010–2011). Of 171 household members, 4% were persistent MRSA nasal carriers, and the MRSA prevalence on any given sampling moment was 10% (range 7-11%). Working in the stables (of which 98% was MRSA-positive, prevalence ratio (PR) = 2.11 per 10 hours), working with sows (PR=1.97), and living with an MRSA-positive pig farmer (PR=4.63) were significant determinants for MRSA carriage. Significant protective factors were carriage of methicillin-susceptible Staphylococcus aureus (MSSA) (PR=0.50), and wearing a facemask when working in the stables (37% decreased prevalence). All MRSA strains during the study period were known livestock-associated types. The bacteriophage φ3 was not found in household members. Transmission from pigs and the environment appeared to be important determinants; human-to-human transmission could not sufficiently be differentiated. Wearing a facemask when working in the stables and carriage of MSSA are potential interventional targets.

Haemophilus influenzae: recent advances in the understanding of molecular pathogenesis and polymicrobial infections

PURPOSE OF REVIEW

Non-typeable Haemophilus influenzae (NTHi) is a human-specific mucosal pathogen and one of the most common causes of bacterial infections in children and patients with chronic obstructive pulmonary disease. It is also frequently found in polymicrobial superinfections. Great strides have recently been made in the understanding of the molecular mechanisms underlying NTHi pathogenesis.

RECENT FINDINGS

By using new methodology, such as experimental human colonization models and whole-genome approaches, investigators have shed light upon the various strategies of NTHi that are involved in pathogenesis. These include the escape of the mucociliary elevator, evasion of host immunity, survival in environments with scarce nutrients, and finally participation in polymicrobial infections. Lipooligosaccharide branching, proteinous adhesins, metabolic adaption to nutrient availability and many scavenging systems are implicated in these processes. Interestingly, genome-based studies comparing virulent and commensal strains have identified many hypothetical proteins as virulence determinants, suggesting that much regarding the molecular pathogenesis of NTHi remains to be solved.

SUMMARY

NTHi is an opportunistic pathogen and highly specialized colonizer of the human respiratory tract that has developed intricate mechanisms to establish growth and survival in the human host. Continued research is needed to further elucidate NTHi host-pathogen and pathogen-pathogen interactions.

Streptococcus pneumoniae and Staphylococcus aureus carriage in healthy school-age children and adolescents

Streptococcus pneumoniae and Staphylococcus aureus are common commensals of the upper respiratory tract in children and adolescents. Understanding the relationship between these two pathogens, including their potential for mutual interference, is needed to evaluate the epidemiology of the diseases they cause, the factors that condition acquisition and carriage, and the impact of related preventative measures. We obtained oropharyngeal and nasal swabs from 497 healthy subjects aged 6-17 years. S. pneumoniae detection and serotyping were performed using a real-time PCR and S. aureus detection was performed using the RIDAGENE MRSA system. We found that 136 (27.3%) of the children were carriers of both species, 121 (24.3%) of the children carried S. pneumoniae alone and 128 (25.7%) of the children carried S. aureus alone. S. aureus carriage was similar between children who carried S. pneumoniae (136/257, 52.9 %, 95% confidence interval [CI]: 46.8-58.9%) vs those who did not (128/240, 53.3%, 95% CI: 47.0 -59.5%) and was independent of age and vaccination with 7-valent pneumococcal conjugate vaccine (PCV7). Vaccination with PCV7 did not affect S. aureus carriage [S. pneumoniae: 84/143 (58.7%, 95% CI: 50.5 -66.5%) vaccinated children vs 171/351 (48.7%, 95% CI: 43.5 -53.9%) unvaccinated children; S. aureus: 67/143 (46.9%, 95% CI: 38.9-55.0 %) vaccinated children vs 195/351 (55.6%, 95% CI: 50.3 -60.7%) unvaccinated children]. Pneumococcal serotype also did not appear to affect S. aureus carriage. These findings suggested that the carriage of S. pneumoniae did not affect that of S. aureus in older children and adolescents, regardless of age, PCV7 vaccination and pneumococcal serotype.

Correlation of nasopharyngeal cultures prior to and at onset of acute otitis media with middle ear fluid cultures

BACKGROUND

We sought to determine if nasopharyngeal (NP) cultures taken at times of healthy visits or at onset of acute otitis media (AOM) could predict the otopathogen mix and antibiotic-susceptibility of middle ear isolates as determined by middle ear fluid (MEF) cultures obtained by tympanocentesis.

METHODS

During a 7-year-prospective study of 619 children from Jun 2006-Aug 2013, NP cultures were obtained from 6-30 month olds at healthy visits and NP and MEF (by tympanocentesis) at onset of AOM episodes.

RESULTS

2601 NP and 530 MEF samples were collected. During healthy visits, S. pneumoniae (Spn) was isolated from 656 (31.7%) NP cultures compared to 253 (12.2%) for Nontypeable Haemophilus influenzae (NTHi) and 723 (34.9%) for Moraxella catarrhalis (Mcat). At onset of AOM 256 (48.3%) of 530 NP samples were culture positive for Spn, 223 (42%) for NTHi and 251 (47.4%) for Mcat, alone or in combinations. At 530 AOM visits, Spn was isolated from 152 (28.7%) of MEF compared to 196 (37.0%) for NTHi and 104 (19.6%) for Mcat. NP cultures collected at onset of AOM but not when children were healthy had predictive value for epidemiologic antibiotic susceptibility pattern assessments.

CONCLUSIONS

NP cultures at onset of AOM more closely correlate with otopathogen mix than NP cultures at healthy visits using MEF culture as the gold standard, but the correlation was too low to allow NP cultures to be recommended as a substitute for MEF culture. For epidemiology purposes, antibiotic susceptibility of MEF isolates can be predicted by NP culture results when samples are collected at onset of AOM.

Five-year prospective study of paediatric acute otitis media in Rochester, NY: modelling analysis of the risk of pneumococcal colonization in the nasopharynx and infection

During a 5-year prospective study of nasopharyngeal (NP) colonization and acute otitis media (AOM) infections in children during the 7-valent pneumococcal conjugate vaccine (PCV) era (July 2006-June 2011) we studied risk factors for NP colonization and AOM. NP samples were collected at ages 6, 9, 12, 15, 18, 24, and 30 months during well-child visits. Additionally, NP and middle ear fluid (MEF) samples were collected at onset of every AOM episode. From 1825 visits (n = 464 children), 5301 NP and 570 MEF samples were collected and analysed for potential otopathogens. Daycare attendance, NP colonization by Moraxella catarrhalis, and siblings aged <5 years increased the risk of Streptococcus pneumoniae NP colonization. NP colonization with S. pneumoniae, M. catarrhalis, or Haemophilus influenzae and a family history of OM increased the risk of AOM. Risk factors that increase the risk of pneumococcal AOM will be important to reassess as we move into a new 13-valent PCV era, especially co-colonization with other potential otopathogens.

The impact of breastfeeding on nasopharyngeal microbial communities in infants

RATIONALE

Breastfeeding elicits significant protection against respiratory tract infections in infancy. Modulation of respiratory microbiota might be part of the natural mechanisms of protection against respiratory diseases induced by breastfeeding.

OBJECTIVES

To study the association between breastfeeding and nasopharyngeal microbial communities, including all cultivable and noncultivable bacteria.

METHODS

In this observational study, we analyzed the microbiota of infants that had received exclusive breastfeeding (n = 101) and exclusive formula feeding (n = 101) at age 6 weeks and 6 months by 16S-based GS-FLX-titanium-pyrosequencing.

MEASUREMENTS AND MAIN RESULTS

At 6 weeks of age the overall bacterial community composition was significantly different between breastfed and formula-fed children (nonmetric multidimensional scaling, P = 0.001). Breastfed children showed increased presence and abundance of the lactic acid bacterium Dolosigranulum (relative effect size [RES], 2.61; P = 0.005) and Corynebacterium (RES, 1.98; P = 0.039) and decreased abundance of Staphylococcus (RES, 0.48; P 0.03) and anaerobic bacteria, such as Prevotella (RES, 0.25; P < 0.001) and Veillonella (RES, 0.33; P < 0.001). Predominance (>50% of the microbial profile) of Corynebacterium and Dolosigranulum was observed in 45 (44.6%) breastfed infants compared with 19 (18.8%) formula-fed infants (relative risk, 2.37; P = 0.006). Dolosigranulum abundance was inversely associated with consecutive symptoms of wheezing and number of mild respiratory tract infections experienced. At 6 months of age associations between breastfeeding and nasopharyngeal microbiota composition had disappeared.

CONCLUSIONS

Our data suggest a strong association between breastfeeding and microbial community composition in the upper respiratory tract of 6-week-old infants. Observed differences in microbial community profile may contribute to the protective effect of breastfeeding on respiratory infections and wheezing in early infancy. Clinical trial registered with www.clinicaltrials.gov (NCT 00189020).