Anti pneumococcal antibody activity in nasopharyngeal secretions in healthy adults and children

Effect of prior vaccination on carriage rates of Streptococcus pneumoniae in older adults: A longitudinal surveillance study

INTRODUCTION

Pneumococcus is a commensal of the upper respiratory tract and colonization is common in young children. Carriage studies have provided insights on vaccine effects in children and may also be useful for assessing vaccines in adults. However, culture based prevalence studies in older adults describe low colonization rates. Therefore, we assessed cumulative incidence of pneumococcal colonization in older adults using polymerase chain reaction (PCR) targeting the lytA gene and risk factors for carriage.

METHODS

100 community-dwelling adults ≥65 years were enrolled the winter of 2015 and followed biweekly for 12 months. Medical, vaccination and illness history as well as nasopharyngeal (NP) and oropharyngeal (OP) samples were collected. Combined OP and NP were incubated in enrichment broth and screened using real-time lytA PCR. Samples from new colonization events (lytA PCR+) were cultured on gentamicin blood agar plates. Isolates identified by colony morphology as S. pneumoniae were serotyped using a multiplex combined immunoassay-PCR platform which classifies 96 serotypes. Cumulative incidence of pneumococcal carriage was calculated and risk factors for carriage assessed.

RESULTS

The cumulative incidence of colonization was 41% by PCR and 14% by culture. Monthly prevalence ranged from 0 to 17% by PCR and 1 to 4% by culture with peaks in the spring and fall. Demographics were similar between colonized and never colonized subjects although colonized were younger (72.4 vs. 75.0 years, P = 0.06). Vaccination with any pneumococcal vaccine before or during study period was associated with decreased risk of becoming colonized (p < 0.001) as was vaccination with either the 13-valent conjugated pneumococcal vaccine (PCV13) or 23-valent polysaccharide vaccine (PPSV23) (p < 0.001).

CONCLUSION

Pneumococcal colonization in older adults as detected by lytA PCR is frequent and pneumococcal vaccination appears to be associated with decreased risk of carriage. Further study is needed to understand the biological significance of molecular detection of pneumococcus in adults.

Impact of the Pneumococcal Conjugate Vaccine and Antibiotic Use on Nasopharyngeal Colonization by Antibiotic Nonsusceptible Streptococcus pneumoniae, Alaska, 2000[FIGURE DASH]2010

BACKGROUND

We describe the relative impact of the heptavalent pneumococcal conjugate vaccine (PCV7, introduced 2001) and antibiotic use on colonization by antibiotic-resistant pneumococci in urban Alaskan children during 2000-2010.

METHODS

We obtained nasopharyngeal swab specimens from a convenience sample of children aged <5 years at clinics annually during 2000-2004 and 2008-2010. PCV7 status and antibiotic use <90 days before enrollment were determined by interview/medical records review. Pneumococci were characterized by serotype and susceptibility to penicillin (PCN). Isolates with full PCN resistance (PCN-R) or intermediate PCN resistance (PCN-I) were classified as PCN-NS.

RESULTS

We recruited 3496 children (median, 452 per year). During 2000-2010, a range of 18-29% per year of children used PCN/amoxicillin (P value for trend = 0.09); the proportion age-appropriately vaccinated with PCV7 increased (0[FIGURE DASH]90%; P < 0.01). Among pneumococcal isolates, the PCV7-serotype proportion decreased (53-<1%; P < 0.01) and non[FIGURE DASH]PCV7-serotype proportion increased (43-95%; P < 0.01). PCN-R pneumococcal colonization prevalence decreased (23-9%; P < 0.01) and PCN-I pneumococcal colonization prevalence increased (13-24%; P < 0.01); overall PCN-NS pneumococcal colonization prevalence was unchanged. PCN-NS among colonizing PCV7-type and non[FIGURE DASH]PCV7-type pneumococci remained unchanged; a mean of 31% per year of PCV7-type and 10% per year of non[FIGURE DASH]PCV7-type isolates were PCN-R, and 10% per year of PCV7 and 20% per year of non[FIGURE DASH]PCV7-type isolates were PCN-I.

CONCLUSIONS

Overall, PCN-NS pneumococcal colonization remained unchanged during 2000-2010 because increased colonization by predominantly PCN-I non-PCV7 serotypes offset decreased colonization by predominantly PCN-R PCV7 serotypes. Proportion PCN-NS did not increase within colonizing pneumococcal serotype groups (PCV7 vs. non-PCV7) despite stable PCN use in our population.

Modelling the co-occurrence of Streptococcus pneumoniae with other bacterial and viral pathogens in the upper respiratory tract

Otitis media (OM) is a major burden for all children, particularly for Australian Aboriginal children. Streptococcus pneumoniae, Moraxella catarrhalis, Haemophilus influenzae and viruses (including rhinovirus and adenovirus) are associated with OM. We investigated nasopharyngeal microbial interactions in 435 samples collected from 79 Aboriginal and 570 samples from 88 non-Aboriginal children in Western Australia. We describe a multivariate random effects model appropriate for analysis of longitudinal data, which enables the identification of two independent levels of correlation between pairs of pathogens. At the microbe level, rhinovirus infection was positively correlated with carriage of S. pneumoniae, H. influenzae and M. catarrhalis, and adenovirus with M. catarrhalis. Generally, there were positive associations between bacterial pathogens at both the host and microbe level. Positive viral–bacterial associations at the microbe level support previous findings indicating that viral infection can predispose an individual to bacterial carriage. Viral vaccines may assist in reducing the burden of bacterial disease.

Report from a WHO Working Group: standard method for detecting upper respiratory carriage of Streptococcus pneumoniae

BACKGROUND

Numerous studies evaluating the efficacy of conjugate pneumococcal vaccines are being conducted or planned throughout the world. Some of these studies are evaluating the effect of vaccine on nasopharyngeal (NP) carriage.

METHODS

The World Health Organization established a Working Group comprised of representatives from these trials and other NP colonization experts to establish core, standardized methods for the study of pneumococcal NP colonization that could be used in these trials. The intent was to reduce or eliminate variability in key methods which themselves could contribute to variability of observed pneumococcal NP colonization. In this way variability of vaccine effects between trials on NP colonization could more easily be analyzed for population or vaccine differences without the confounding effect caused by differences in study methodology.

RESULTS

This paper presents the evidence base supporting the need for standardized NP colonization study methods, the methods themselves (Core Consensus Methods), including collection techniques, culture media, equipment, serotyping, storage of specimens and transport of isolates agreed on by the Working Group as well as a discussion of research priorities.

CONCLUSIONS

The Core Consensus Methods provide a common methodology to conduct pneumococcal NP colonization studies with minimum interstudy method variability. The intention is to allow more meaningful comparisons of study results from conjugate pneumococcal vaccine trials.

Report from a WHO working group: standard method for detecting upper respiratory carriage of Streptococcus pneumoniae

BACKGROUND

Numerous studies evaluating the efficacy of conjugate pneumococcal vaccines are being conducted or planned throughout the world. Some of these studies are evaluating the effect of vaccine on nasopharyngeal (NP) carriage.

METHODS

The World Health Organization established a Working Group composed of representatives from these trials and other NP colonization experts to establish core, standardized methods for the study of pneumococcal NP colonization that could be used in these trials. The intent was to reduce or eliminate variability in key methods which themselves could contribute to variability of observed pneumococcal NP colonization. In this way variability of vaccine effects between trials on NP colonization could more easily be analyzed for population or vaccine differences without the confounding effect caused by differences in study methodology.

RESULTS

This paper presents the evidence base supporting the need for standardized NP colonization study methods, the methods themselves (Core Consensus Methods found in the electronic version of this article at www.pidj.com and on the WHO website at http://www.who.int/vaccines-research/rd/docsrd.shtml), including collection techniques, culture media, equipment, serotyping, storage of specimens and transport of isolates agreed on by the Working Group as well as a discussion of research priorities.

CONCLUSIONS

The Core Consensus Methods provide a common methodology to conduct pneumococcal NP colonization studies with minimum interstudy method variability. The intention is to allow more meaningful comparisons of study results from conjugate pneumococcal vaccine trials.

The nasopharynx and the middle ear. Inflammatory reactions in middle ear disease

The host-parasite interactions in the nasopharynx with bacterial colonization and antigen uptake in the lymphoid tissue, the adenoid, has an impact on the maturation of local and systemic immunity. The adenoid is a part of mucosa associated lymphoid tissue and is responsible for both effector and inductor functions in the nasopharynx. Increasing evidence supports the role of serum antibody in protecting the middle ear cavity from disease. There is evidence for a minor immunologic defect in a number of children with recurrent episodes of AOM.

Molecular characterization of pneumococcal nasopharynx isolates collected from children during their first 2 years of life

Pneumococcal colonization was studied in 19 children monitored from birth through the age of 2 years. For this purpose, pneumococcal isolates were characterized by capsular typing, restriction fragment end labeling (RFEL), and penicillin-binding protein (PBP) genotyping. Fifty-eight isolates were collected and were found to belong to 10 capsular types, 31 RFEL types, and 7 PBP genotypes. Thirty-nine percent of the isolates had reduced susceptibility to penicillin. All seven highly resistant strains (MICs, > 1 microgram/ml) were identical to the pandemic clone 23F. Children were culture positive between one and eight times at 13 scheduled visits. Although the infants were frequently recolonized with different strains, colonization with one particular strain often persisted for several months. Isolation of a previously detected capsular type was common, and the chromosomal homogeneity tended to be high when it occurred. Horizontal transfer of capsular genes between strains of different RFEL types was demonstrated in one child. The ecological advantage of transfer of capsular genes is unclear unless survival of the organism on a mucosal surface may be linked to immunoprotective pressure against particular capsular types.

Recurrent acute otitis media: the significance of age at onset

In order to assess the relationship between recurrent acute otitis media (rAOM) and age at first acute otitis media (AOM) episode, a prospective cohort of 3754 Norwegian children born in 1992-1993 was followed from birth to 2 years. Recurrent acute otitis media was defined by the criterion of four or more episodes of AOM during a 12-month period. Approximately 5.4% of the children experienced rAOM before the age of 2. Furthermore, children whose first AOM episode occurred before the age of 9 months were at a significantly higher risk for developing rAOM compared to children whose first AOM episode was 10-12 months. In children who had the first ear infection during the first 9 months of life, one-quarter developed rAOM before the age of 2. Multiple logistic regression analysis adjusted for confounding showed that gender and a familial history of atopy were significantly associated with rAOM. In conclusion, the present study found an association between age at first AOM episode and the later subsequent AOM proneness. Additionally, both gender and a family history of atopy seemed to predispose towards otitis-proneness.

Cytokines in nasopharyngeal secretions; evidence for defective IL-1 beta production in children with recurrent episodes of acute otitis media

The host-parasite relationship in the nasopharynx of young children with bacterial colonization and antigen uptake in the mucosa and lymphatic tissue provides an opportunity to investigate infectious/inflammatory processes and responses. IL-1 beta, IL-6 and tumour necrosis factor-alpha (TNF-alpha) were analysed in nasopharyngeal secretions and serum from children with or without recurrent episodes of acute otitis media, from healthy adults and adults with or without recurrent episodes of acute otitis media, from healthy adults and adults with hypogammaglobulinaemia or selective deficiency of IgG3. Nasopharyngeal secretions generally contained substantial amounts of IL-1 beta, IL-6 and TNF-alpha. In contrast, IL-1 beta, IL-6 and TNF-alpha were not detectable in sera on the same occasion. Children were found to have higher levels of IL-1 beta, IL-6 and TNF-alpha than healthy adults and than adults with immunodeficiency. High levels of IL-1 beta were associated with low or undetectable levels of IL-6 and TNF-alpha, whereas the opposite pattern was seen in association with low levels of IL-1 beta. This was especially true for children with recurrent episodes of acute otitis media (RAOM). In children with nasopharyngeal colonization with Haemophilus influenzae, significantly higher levels of IL-1 beta, IL-6 and TNF-alpha (P = 0.0001, respectively) were found compared with non-colonized children. Notably, the RAOM children exhibited significantly lower levels of IL-1 beta, IL-6, and TNF-alpha in nasopharyngeal secretions (P = 0.0001, 0.01 and 0.0001, respectively) than healthy children. These results demonstrate local production of inflammatory cytokines in nasopharynx, related to bacterial colonization, and suggest that children with RAOM are poor nasopharyngeal cytokine producers.