Effect of pneumococcal conjugate vaccine on nasopharyngeal bacterial colonization during acute otitis media

High frequencies of nonviral colds and respiratory bacteria colonization among children in rural Western Uganda

Introduction

Respiratory illness is the most common childhood disease globally, especially in developing countries. Previous studies have detected viruses in approximately 70-80% of respiratory illnesses.

Methods

In a prospective cohort study of 234 young children (ages 3-11 years) and 30 adults (ages 22-51 years) in rural Western Uganda sampled monthly from May 2019 to August 2021, only 24.2% of nasopharyngeal swabs collected during symptomatic disease had viruses detectable by multiplex PCR diagnostics and metagenomic sequencing. In the remaining 75.8% of swabs from symptomatic participants, we measured detection rates of respiratory bacteria Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae by quantitative PCR.

Results

100% of children tested positive for at least one bacterial species. Detection rates were 87.2%, 96.8%, and 77.6% in children and 10.0%, 36.7%, and 13.3% for adults for H. influenzae, M. catarrhalis, and S. pneumoniae, respectively. In children, 20.8% and 70.4% were coinfected with two and three pathogens, respectively, and in adults 6.7% were coinfected with three pathogens but none were coinfected with two. Detection of any of the three pathogens was not associated with season or respiratory symptoms severity, although parsing detection status by symptoms was challenged by children experiencing symptoms in 80.3% of monthly samplings, whereas adults only reported symptoms 26.6% of the time. Pathobiont colonization in children in Western Uganda was significantly more frequent than in children living in high-income countries, including in a study of age-matched US children that utilized identical diagnostic methods. Detection rates were, however, comparable to rates in children living in other Sub-Saharan African countries.

Discussion

Overall, our results demonstrate that nonviral colds contribute significantly to respiratory disease burden among children in rural Uganda and that high rates of respiratory pathobiont colonization may play a role. These conclusions have implications for respiratory health interventions in the area, such as increasing childhood immunization rates and decreasing air pollutant exposure.

Otopathogens in the middle ear and nasopharynx of children with recurrent acute otitis media

OBJECTIVE

This study aimed to describe the microbiology of the middle ear and nasopharynx, determining the prevalence of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis in a group of children vaccinated with pneumococcal conjugate vaccine (PCV) who underwent ventilation tube insertion for recurrent acute otitis media.

METHODS

We analyzed 278 middle ear effusion and 139 nasopharyngeal samples obtained from 139 children who underwent myringotomy and ventilation tube insertion for recurrent acute otitis media between June 2017 and June 2021. The children's ages ranged from 9 months to 9 years, 10 months, with a median of 21 months. The patients had no signs of acute otitis media or respiratory tract infection and were not on antibiotic therapy at the time of the procedure. The middle ear effusion and nasopharyngeal samples were collected with an Alden-Senturia aspirator and a swab, respectively. Bacteriological studies and multiplex PCR were performed for the detection of the three pathogens. Direct molecular determination of pneumococcal serotypes was performed by real-time PCR. The chi-square test was used to verify associations between categorical variables and measures of strength of association based on prevalence ratios, considering a 95% confidence interval a 5% significance level.

RESULTS

Vaccination coverage was 77.7% with the basic regimen plus booster dose and 22.3% with the basic regimen alone. Middle ear effusion culture identified H. influenzae in 27 children (19.4%), S. pneumoniae in 7 (5.0%), and M. catarrhalis in 7 (5.0%). PCR detected H. influenzae in 95 children (68.3%), S. pneumoniae in 52 (37.4%), and M. catarrhalis in 23 (16.5%), a three-to seven-fold increase compared to culture. In the nasopharynx, culture isolated H. influenzae in 28 children (20.1%), S. pneumoniae in 29 (20.9%), and M. catarrhalis in 12 (8.6%). PCR identified H. influenzae in 84 children (60.4%), S. pneumoniae in 58 (41.7%), and M. catarrhalis in 30 (21.5%), a two-to three-fold increase in detection. The most common pneumococcal serotype was 19A, both in the ears and the nasopharynx. In the ears, of the 52 children who had pneumococcus, 24 (46.2%) had serotype 19A. In the nasopharynx, of the 58 patients who had pneumococcus, 37 (63.8%) had serotype 19A. Of all 139 children, 53 (38.1%) had polymicrobial samples (more than 1 of the 3 otopathogens) in the nasopharynx. Of the 53 children who had polymicrobial samples in the nasopharynx, 47 (88.7%) also had 1 of the 3 otopathogens in the middle ear, mainly H. influenzae (40%-75.5%), especially when it was found in the nasopharynx in conjunction with S. pneumoniae.

CONCLUSION

The prevalence of bacteria in a group of Brazilian children immunized with the PCV who required ventilation tube insertion for recurrent acute otitis media was similar to that reported in other parts of the world after the advent of PCV. H. influenzae was the most frequent bacteria, both in the nasopharynx and the middle ear, while S. pneumoniae serotype 19A was the most common pneumococcus in the nasopharynx and middle ear. Polymicrobial colonization of the nasopharynx was strongly associated with detection of H. influenzae in the middle ear.

Longitudinal investigation of pathogenic bacterial colonization in early childhood: Emphasis on the determinants of Moraxella catarrhalis colonization

BACKGROUND

Moraxella catarrhalis is a common, potential pathogen colonizing the respiratory tract in children. However, there is little information regarding the determinants of M. catarrhalis colonization and disease development.

METHODS

A population-based cohort study was conducted to collect nasopharyngeal swabs from children aged 1, 2, 4, 6, 12, 18, 24, 36, and 60 months for the detection of four common respiratory tract pathogens, including Staphylococcus aureus, M. catarrhalis, Streptococcus pneumoniae, and Haemophilus influenzae. Questionnaires on breastfeeding status were administered during each visit.

RESULTS

A total of 921 children were enrolled between 2012 and 2018. S.aureus was the most common pathogen, although the rates declined during the initial 18 months of life; in contrast, the other three pathogens increased during the first 5 years of life. M. catarrhalis was the second most common colonizing pathogen in all age groups, with prevalence ranging from 0.8% (7/842) at one month to 20.4% (33/162) at 60 months of age. Breastfed children (odds ratio [OR]: 0.56; 95% confidence interval [CI]: 0.35-0.92; P = 0.02) had a lower potential for M. catarrhalis carriage; however, infants with a longer duration of exclusive breastfeeding (OR: 1.12; 95% CI: 1.01-1.25; P = 0.04), especially >12 months of age, had a higher rate of M. catarrhalis carriage.

CONCLUSION

Breastfeeding should be promoted because it may be correlated with a lower risk of M. catarrhalis carriage. However, an extended period of exclusive breastfeeding may be positively associated with M. catarrhalis colonization.

In vitro Photodynamic Therapy of Polymicrobial Biofilms Commonly Associated With Otitis Media

Otitis media (OM) is a prevalent pediatric infection characterized by painful inflammation of the middle ear. There are more than 700 million cases of OM diagnosed globally each year, with 50% of affected children under 5 years of age. Further, OM is the most common reason for children to receive antibiotic treatment in developed countries. The most recent work on this dynamic disease indicates that biofilms and polymicrobial infections play a role in recurrent OM and chronic OM, which are difficult to eradicate using standard antibiotic protocols. Antimicrobial photodynamic therapy (aPDT) is a promising new strategy for the treatment of resistant bacteria and persistent biofilms which lead to chronic infections. While PDT continues to be successfully used for oncological, dermatological, and dental applications, our work focuses on the efficacy of aPDT as it relates to otopathogens responsible for OM. Previous studies from our laboratory and others have shown that non-typeable Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis, the three most common otopathogens, are susceptible to different forms of aPDT. However, many cases of OM involve multiple bacteria and to date no one has investigated the efficacy of this technology on these complex polymicrobial biofilms. We treated polymicrobial biofilms of the three most common otopathogens with the photosensitizer Chlorin e6 (Ce6) and a continuous wave 405 ± 10 nm light emitted diode. Our data show significant bactericidal activity on polymicrobial biofilms associated with OM. These studies indicate that aPDT warrants further analysis as a possible treatment for OM and our results provide the foundation for future studies designed to identify the optimal aPDT parameters for polymicrobial biofilm-associated infections of the middle ear.

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

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

Co-carriage of Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis among three different age categories of children in Hungary

Background

The nasopharynx can from time to time accommodate otherwise pathogenic bacteria. This phenomenon is called asymptomatic carriage. However, in case of decreased immunity, viral infection or any other enhancing factors, severe disease can develop. Our aim in this study was to survey the nasal carriage rates of four important respiratory pathogens in three different age groups of children attending nurseries, day-care centres and primary schools. This is the first study from Hungary about the asymptomatic carriage of H. influenzae and M. catarrhalis.

Methods

Altogether 580 asymptomatic children were screened in three Hungarian cities. Samples were collected from both nostrils with cotton swabs. The identification was based on both colony morphology and species-specific PCRs. Serotyping was performed for S. pneumoniae, H. influenzae and M. catarrhalis. Antibiotic susceptibility was determined with agar dilution, according to the EUCAST guidelines. Clonality was examined by PFGE.

Results and conclusions

Whereas the carriage rates of S. pneumoniae, H. influenzae and M. catarrhalis clearly decreased with age, that of S. aureus showed an opposite tendency. Multiple carriage was least prevalent if S. aureus was one of the participants. The negative association between this bacterium and the others was statistically significant. For pneumococcus, the overall carriage rate was lower compared to earlier years, and PCV13 serotypes were present in only 6.2% of the children. The majority of H. influenzae isolates was non-typeable and no type b was detected; serotype A was dominant among M. catarrhalis. All four bacteria were more sensitive to antibiotics compared to clinical isolates. No MRSAs were detected, but we found three mupirocin resistant strains. The positive effect of Hib- and PCV-vaccination is undoubted. Continued surveillance of these pathogens is required.

Moraxella catarrhalis Promotes Stable Polymicrobial Biofilms With the Major Otopathogens

Otitis media (OM) is a prevalent pediatric infection characterized by painful inflammation of the middle ear. The Gram-negative diplococcus Moraxella catarrhalis is a commensal of the nasopharynx and one of three leading causative agents of OM. The most recent work on this multifaceted disease indicates that biofilms and polymicrobial infections play a pivotal role in recurrent and chronic OM, which are difficult to eradicate using standard antibiotic protocols. Although there have been significant advances in OM research, the actual bacterial and viral interactions leading to pathogenesis remain largely uncharacterized. However, colonization and persistence in the nasopharynx is clearly an essential first step. In this study, we assessed the role M. catarrhalis plays in the co-colonization and persistence of the other major otopathogens, Streptococcus pneumoniae and non-typeable Haemophilus influenzae (NTHi). We characterized both monomicrobial and polymicrobial biofilms using an in vitro nasopharyngeal colonization model. Biofilm assays were designed to mimic the nasopharynx and bacterial persistence was quantified over time. NTHi showed a steady and significant decline in viability over 20–48 h when this organism was in a dual species biofilm with S. pneumoniae. However, when M. catarrhalis was present in the polymicrobial biofilm NTHi survived for 48 h at 10⁷ CFU per mL. In addition, an isogenic M. catarrhalis catalase-deficient mutant was also fully capable of protecting NTHi from the bactericidal activity of S. pneumoniae in a polymicrobial biofilm. Our results show that M. catarrhalis promotes a favorable environment for stable polymicrobial biofilms by enhancing the survival of NTHi in the presence of S. pneumoniae. These data suggest that colonization with M. catarrhalis promotes stable co-colonization with other otopathogens.

Acute otitis media in infants younger than two months of age: Epidemiologic and microbiologic characteristics in the era of pneumococcal conjugate vaccines

OBJECTIVES

To evaluate the epidemiology, microbiology, Streptococcus pneumoniae serotypes distribution and serious bacterial infections (SBIs) occurrence in infants <2 months of age with tympanocentesis-documented acute otitis media (AOM), before and after the introduction of pneumococcal conjugate vaccines (PCVs).

METHODS

The medical records of all hospitalized infants with AOM who underwent tympanocentesis during 2005-2014 were reviewed.

RESULTS

Of the 303 infants with AOM who were diagnosed by an ENT specialist, 182 underwent tympanocentesis, 92 during 2005-2009 (prevaccine period) and 90 during 2010-2014 (postvaccine period). Streptococcus pneumoniae and nontypeable Hemophilus influenzae were isolated in 46/92 (50%) and 37/92 (40.2%) patients during 2005-2009 and decreased to 27/90 (30%) and 21/90 (23.3%). Respectively, during 2010-2014 (P = 0.006 and P = 0.001). The proportion of culture-negative patients increased from 18/92 (19.6%) during 2005-2009 to 32/90 (35.6%) during 2010-2014 (P = 0.02). There were only 6 (3.3%) patients <2 weeks of age. The most common S. pneumoniae vaccine serotypes isolated during 2005-2009 were 5, 3, 1, 19F and 14 (15.2%, 13.0%, 10.9%, 6.5%, and 4.3%, respectively) and 3, 5, 1, 14 and 19A (22.2%, 11.1%, 7.4%, 7.4%, and 7.4%, respectively) during 2010-2014. The proportion of culture-positive patients decreased during 2013-2014 compared with 2011-2012 (7/18, 38.9% vs. 40/54, 74.1%, P = 0.007). Serotypes 1 and 5 were not isolated during 2013-2014 and serotype 19A was not isolated during 2011-2014. . SBIs were recorded in 23/182 (12.64%) patients and urinary tract infections represented 19/23 (82.61%) of them (Escherichia coli isolated in 12, 63.2%).

CONCLUSIONS

The overall number of AOM cases needing tympanocentesis seen at the PER and the proportion of S. pneumoniae and nontypeable H. influenzae-AOM decreased while the proportion of culture-negative AOM increased following the introduction of PCVs. SBIs associated with AOM were frequent and were represented mostly by urinary tract infections caused by pathogens unrelated to the etiologic agents of AOM.

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.

Effect of the 13-valent pneumococcal conjugate vaccine on nasopharyngeal carriage by respiratory pathogens among Greenlandic children

Background: In 2010, Greenland introduced the 13-valent pneumococcal conjugate vaccine (Prevnar 13®– PCV-13) in the childhood immunisation program. The authors aimed to evaluate the impact of PCV-13 on nasopharyngeal carriage of bacteria frequently associated with respiratory infections in children.

Method: In 2013 a cross-sectional population-based study of nasopharyngeal carriage was conducted among Greenlandic children aged 0–6 years and results were compared with an equivalent study from 2011. Nasopharyngeal swab samples were tested for Streptococcus pneumoniae, non-typeable Haemophilus influenzae, Moraxella catarrhalis and Staphylococcus aureus. Pneumococcal serotyping was performed by Quellung reaction and serotype-specific antisera. Statistical analysis included logistic regression models, adjusting for known risk factors.

Result: A total of 377 nasopharyngeal samples were collected. Overall carriage rate of S. pneumoniae remained unchanged from 2011 to 2013 (51% and 56%, p=0.13), but significant serotype shifts were observed among both vaccinated and unvaccinated children with marked reductions in carriage of vaccine-type pneumococci, counterbalanced by increasing carriage of non-vaccine types. Carriage rate of S. aureus decreased significantly among vaccinated children whereas that of M. catarrhalis increased.

Conclusion: PCV-13 introduction in Greenland is associated with significant changes in nasopharyngeal bacterial carriage. Continued surveillance is warranted to clarify whether these changes are persistent, and affect the pattern of respiratory and invasive diseases in Greenland.

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.

Changes Over Time in Nasopharyngeal Colonization in Children Under 2 Years of Age at the Time of Diagnosis of Acute Otitis Media (1999-2014)

Background

In children with acute otitis media (AOM), a decrease in nasopharyngeal (NP) colonization with vaccine serotypes of Streptococcus pneumoniae has been noted since the introduction of pneumococcal conjugate vaccines (PCVs). The purpose of this study is to describe corresponding changes in colonization with Haemophilus influenzae.

Methods

In 4 separate studies, we obtained NP cultures from children aged 6-23 months presenting with AOM. Cohort 1 was recruited before routine use of PCV7 (1999-2000); 93% of children in cohort 2 (2003-2005) and 100% in cohort 3 (2006-2009) received ≥2 doses of PCV7. All children in cohort 4 (2012-2014) received ≥2 doses of PCV13. Isolates of H. influenzae were tested for ß-lactamase production; ß-lactamase negative isolates from cohorts 3 and 4 underwent susceptibility testing.

Results

A total of 899 children were evaluated. NP colonization with H. influenzae was found in 26% of children in cohort 1 (n = 175), 41% in cohort 2 (n = 87), 33% in cohort 3 (n = 282), and 29% in cohort 4 (n = 355). Colonization with H. influenzae increased initially from cohort 1 to cohort 2 (P = .01), then decreased across cohorts 2, 3, and 4 (P = .03, test for trend). The prevalence rates of ß-lactamase production were 27%, 42%, 33%, and 30% in each of the 4 cohorts, respectively (P = .50).

Conclusions

Although an initial increase in H. influenzae colonization was observed, suggesting an impact of PCVs, the most recent prevalence rates of NP colonization with H. influenzae and ß-lactamase production were like those observed before universal administration of PCV7. This knowledge is critical to guide appropriate treatment recommendations for children with AOM.

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

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

Panel 6: Vaccines

Objective To review the literature on progress regarding (1) effectiveness of vaccines for prevention of otitis media (OM) and (2) development of vaccine antigens for OM bacterial and viral pathogens. Data Sources PubMed database of the National Library of Science. Review Methods We performed literature searches in PubMed for OM pathogens and candidate vaccine antigens, and we restricted the searches to articles in English that were published between July 2011 and June 2015. Panel members reviewed literature in their area of expertise. Conclusions Pneumococcal conjugate vaccines (PCVs) are somewhat effective for the prevention of pneumococcal OM, recurrent OM, OM visits, and tympanostomy tube insertions. Widespread use of PCVs has been associated with shifts in pneumococcal serotypes and bacterial pathogens associated with OM, diminishing PCV effectiveness against AOM. The 10-valent pneumococcal vaccine containing Haemophilus influenzae protein D (PHiD-CV) is effective for pneumococcal OM, but results from studies describing the potential impact on OM due to H influenzae have been inconsistent. Progress in vaccine development for H influenzae, Moraxella catarrhalis, and OM-associated respiratory viruses has been limited. Additional research is needed to extend vaccine protection to additional pneumococcal serotypes and other otopathogens. There are likely to be licensure challenges for protein-based vaccines, and data on correlates of protection for OM vaccine antigens are urgently needed. Implications for Practice OM continues to be a significant health care burden globally. Prevention is preferable to treatment, and vaccine development remains an important goal. As a polymicrobial disease, OM poses significant but not insurmountable challenges for vaccine development.

Impact of the pneumococcal conjugate vaccine on serotype distribution of adult non-invasive Streptococcus pneumoniae isolates in Tokai region, Japan, 2008-2016

The introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) in February 2010 markedly reduced the burden of invasive pneumococcal disease and changed serotype distribution in Japan. In November 2013, PCV7 was replaced by the 13-valent pneumococcal conjugate vaccine (PCV13). We investigated the serotype distribution and susceptibility trends of non-invasive Streptococcus pneumoniae isolates collected from adult patients. A total of 504 pneumococcal isolates were collected during 4 periods between 2008 and 2016 (Period 1; between June 2008 and April 2009, Period 2; between September 2010 and March 2011, Period 3; between October 2011 and March 2012, Period 4; between August 2015 and January 2016). The coverage of PCV7 and PCV13 significantly decreased from 38.6% and 60.5% in Period 1 to 6.6% and 31.1% in Period 4. This change was mainly due to a large decrease in the frequency of serotype 19F, 6B, and 14. Serotype 3 was the most frequently isolated, and gradually increased. Additionally, non-PCV13 serotypes 11A, 33F, and 35B significantly increased. Most of the PCV7 serotypes 19F, 23F, 6B, and 14 had mutations of penicillin-binding protein genes and macrolide resistance genes, and these serotypes showed low susceptibilities to cefdinir and clarithromycin. On the other hand, a significant change in susceptibility to various antimicrobial agents was not observed throughout the study period, except for decreased susceptibility to carbapenems. Continuous surveillance studies of pneumococcal serotype changes and drug susceptibility are necessary in future.

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

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

Sulfate-binding protein, CysP, is a candidate vaccine antigen of Moraxella catarrhalis

Moraxella catarrhalis causes otitis media in children and respiratory tract infections in adults with chronic obstructive pulmonary disease (COPD). A vaccine to prevent M. catarrhalis infections would have an enormous impact globally in preventing morbidity caused by M. catarrhalis in these populations. Using a genome mining approach we have identified a sulfate binding protein, CysP, of an ATP binding cassette (ABC) transporter system as a novel candidate vaccine antigen. CysP expresses epitopes on the bacterial surface and is highly conserved among strains. Immunization with CysP induces potentially protective immune responses in a murine pulmonary clearance model. In view of these features that indicate CysP is a promising vaccine antigen, we conducted further studies to elucidate its function. These studies demonstrated that CysP binds sulfate and thiosulfate ions, plays a nutritional role for the organism and functions in intracellular survival of M. catarrhalis in human respiratory epithelial cells. The observations that CysP has features of a vaccine antigen and also plays an important role in growth and survival of the organism indicate that CysP is an excellent candidate vaccine antigen to prevent M. catarrhalis otitis media and infections in adults with COPD.

Choline Binding Proteins from Streptococcus pneumoniae: A Dual Role as Enzybiotics and Targets for the Design of New Antimicrobials

Streptococcus pneumoniae (pneumococcus) is an important pathogen responsible for acute invasive and non-invasive infections such as meningitis, sepsis and otitis media, being the major cause of community-acquired pneumonia. The fight against pneumococcus is currently hampered both by insufficient vaccine coverage and by rising antimicrobial resistances to traditional antibiotics, making necessary the research on novel targets. Choline binding proteins (CBPs) are a family of polypeptides found in pneumococcus and related species, as well as in some of their associated bacteriophages. They are characterized by a structural organization in two modules: a functional module (FM), and a choline-binding module (CBM) that anchors the protein to the choline residues present in the cell wall through non-covalent interactions. Pneumococcal CBPs include cell wall hydrolases, adhesins and other virulence factors, all playing relevant physiological roles for bacterial viability and virulence. Moreover, many pneumococcal phages also make use of hydrolytic CBPs to fulfill their infectivity cycle. Consequently, CBPs may play a dual role for the development of novel antipneumococcal drugs, both as targets for inhibitors of their binding to the cell wall and as active cell lytic agents (enzybiotics). In this article, we review the current state of knowledge about host- and phage-encoded pneumococcal CBPs, with a special focus on structural issues, together with their perspectives for effective anti-infectious treatments.

The Vaccine Candidate Substrate Binding Protein SBP2 Plays a Key Role in Arginine Uptake, Which Is Required for Growth of Moraxella catarrhalis

Moraxella catarrhalis is an exclusively human pathogen that is an important cause of otitis media in children and lower respiratory tract infections in adults with chronic obstructive pulmonary disease. A vaccine to prevent M. catarrhalis infections would have an enormous global impact in reducing morbidity resulting from these infections. Substrate binding protein 2 (SBP2) of an ABC transporter system has recently been identified as a promising vaccine candidate antigen on the bacterial surface of M. catarrhalis. In this study, we showed that SBP1, -2, and -3 individually bind different basic amino acids with exquisite specificity. We engineered mutants that each expressed a single SBP from this gene cluster and showed in growth experiments that SBP1, -2, and -3 serve a nutritional function through acquisition of amino acids for the bacterium. SBP2 mediates uptake of arginine, a strict growth requirement of M. catarrhalis. Adherence and invasion assays demonstrated that SBP1 and SBP3 play a role in invasion of human respiratory epithelial cells, consistent with a nutritional role in intracellular survival in the human respiratory tract. This work demonstrates that the SBPs of an ABC transporter system function in the uptake of basic amino acids to support growth of M. catarrhalis. The critical role of SBP2 in arginine uptake may contribute to its potential as a vaccine antigen.

The infant nasopharyngeal microbiome impacts severity of lower respiratory infection and risk of asthma development

The nasopharynx (NP) is a reservoir for microbes associated with acute respiratory infections (ARIs). Lung inflammation resulting from ARIs during infancy is linked to asthma development. We examined the NP microbiome during the critical first year of life in a prospective cohort of 234 children, capturing both the viral and bacterial communities and documenting all incidents of ARIs. Most infants were initially colonized with Staphylococcus or Corynebacterium before stable colonization with Alloiococcus or Moraxella. Transient incursions of Streptococcus, Moraxella, or Haemophilus marked virus-associated ARIs. Our data identify the NP microbiome as a determinant for infection spread to the lower airways, severity of accompanying inflammatory symptoms, and risk for future asthma development. Early asymptomatic colonization with Streptococcus was a strong asthma predictor, and antibiotic usage disrupted asymptomatic colonization patterns. In the absence of effective anti-viral therapies, targeting pathogenic bacteria within the NP microbiome could represent a prophylactic approach to asthma.

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The nasopharynx microbiome of infants has a simple structure dominated by six genera

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Microbiome composition affects infection severity and pathogen spread to lower airways

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Early asymptomatic colonization with Streptococcus increases risk of asthma

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Antibiotic usage disrupts asymptomatic colonization patterns

Vaccines for Nontypeable Haemophilus influenzae: the Future Is Now

Infections due to nontypeable Haemophilus influenzae result in enormous global morbidity in two clinical settings: otitis media in children and respiratory tract infections in adults with chronic obstructive pulmonary disease (COPD). Recurrent otitis media affects up to 20% of children and results in hearing loss, delays in speech and language development and, in developing countries, chronic suppurative otitis media. Infections in people with COPD result in clinic and emergency room visits, hospital admissions, and respiratory failure. An effective vaccine would prevent morbidity, help control health care costs, and reduce antibiotic use, a major contributor to the global crisis in bacterial antibiotic resistance. The widespread use of the pneumococcal conjugate vaccines is causing a relative increase in H. influenzae otitis media. The partial protection against H. influenzae otitis media induced by the pneumococcal H. influenzae protein D conjugate vaccine represents a proof of principle of the feasibility of a vaccine for nontypeable H. influenzae. An ideal vaccine antigen should be conserved among strains, have abundant epitopes on the bacterial surface, be immunogenic, and induce protective immune responses. Several surface proteins of H. influenzae have been identified as potential vaccine candidates and are in various stages of development. With continued research, progress toward a broadly effective vaccine to prevent infections caused by nontypeable H. influenzae is expected over the next several years.

Changing trends of acute otitis media bacteriology in central Israel in the pneumococcal conjugate vaccines era

BACKGROUND

The widespread use of 7-valent pneumococcal conjugate vaccine (PCV7) has changed acute otitis media (AOM) bacteriology. Only scattered data with regard to this effect of PCV13 have been published so far.

METHODS

We retrospectively identified children <6 years of age who presented to our hospital with AOM, and had middle ear fluid (MEF) cultures obtained during tympanocentesis or from spontaneous otorrhea during 2008-2013, when PCV7 (2009) and PCV13 (2010) were gradually introduced in the Israeli National Immunization Program. Data were extracted for demographics, clinical and microbiologic parameters, according to vaccination status.

RESULTS

Of the 295 eligible AOM episodes reported in 279 children, 224 (76%) had MEF cultures from tympanocentesis and 71 (24%) from spontaneous otorrhea. Boys and children <2 years of age contributed 178 (60%) and 219 (74%) AOM episodes, respectively. Acute mastoiditis complicated 58 (20%) of these episodes. None of the children were PCV immunized in 2008, but >90% had received ≥1 PCV dose(s) by 2011 or later. Of the 106 (36%) MEF cultures which tested positive for otopathogens, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and multiple bacteria grew in 60 (57%), 39 (37%), 2 (2%) and 5 (5%) episodes, respectively. S. pneumonia-positive MEF culture rate in unimmunized children (31, 69%) was significantly higher than in PCV7-immunized children (22, 59%) or PCV13-immunized children (12, 50%), P = 0.04 and P = 0.02, respectively.

CONCLUSION

PCV7 and PCV13 implementations in the Israeli National Immunization Program were associated with a rapid reduction of "severe" pneumococcal AOM episodes.

Moraxella catarrhalis AcrAB-OprM efflux pump contributes to antimicrobial resistance and is enhanced during cold shock response

Moraxella catarrhalis is a common pathogen of the human respiratory tract. Multidrug efflux pumps play a major role in antibiotic resistance and virulence in many Gram-negative organisms. In the present study, the role of the AcrAB-OprM efflux pump in antibiotic resistance was investigated by constructing mutants that lack the acrA, acrB, and oprM genes in M. catarrhalis strain O35E. We observed a moderate (1.5-fold) decrease in the MICs of amoxicillin and cefotaxime and a marked (4.7-fold) decrease in the MICs of clarithromycin for acrA, acrB, and oprM mutants in comparison with the wild-type O35E strain. Exposure of the M. catarrhalis strains O35E and 300 to amoxicillin triggered an increased transcription of all AcrAB-OprM pump genes, and exposure of strains O35E, 300, and 415 to clarithromycin enhanced the expression of acrA and oprM mRNA. Inactivation of the AcrAB-OprM efflux pump genes demonstrated a decreased ability to invade epithelial cells compared to the parental strain, suggesting that acrA, acrB, and oprM are required for efficient invasion of human pharyngeal epithelial cells. Cold shock increases the expression of AcrAB-OprM efflux pump genes in all three M. catarrhalis strains tested. Increased expression of AcrAB-OprM pump genes after cold shock leads to a lower accumulation of Hoechst 33342 (H33342), a substrate of AcrAB-OprM efflux pumps, indicating that cold shock results in increased efflux activity. In conclusion, the AcrAB-OprM efflux pump appears to play a role in the antibiotic resistance and virulence of M. catarrhalis and is involved in the cold shock response.

Molecular characterization of clinical isolates of Moraxella catarrhalis by randomly amplified polymorphic DNA fingerprinting

Moraxella catarrhalis, a less virulent microorganism that colonizes the upper respiratory tract, has recently been associated with lower respiratory disease, especially in HIV-positive immunocompromised individuals and children. Here, we correlated the DNA clustering pattern of 24 clinical isolates of M. catarrhalis for β-lactamase production and drug resistance, from different disease groups using three different arbitrarily selected primers, P1 (5'-TCACGATGCA-3'), P14 (5'-GATCAAGTCC-3') and P17 (5'-GATCTGACAC-3'). M. catarrhalis revealed three distinct banding patterns with primer P1, four with P14 and P17. 71% (n = 17) of the isolates revealed pattern 2 with primer P1, which discriminated majority (12/21) of the isolates grouped under the major branch of the dendrogram. The minor branch had only three isolates. Separation of M. catarrhalis into two subpopulations (major and minor clusters) with primer P1 is suggestive of diverse genetic lineage. A high level of concordance between RAPD and antibiotic profile was observed. Clustering of M. catarrhalis recovered from different disease groups reflect the identical clinical background or the common geographical/temporal factors. The presence or absence of β-lactamase in a cluster confirmed their single source of origin.

ModM DNA methyltransferase methylome analysis reveals a potential role for Moraxella catarrhalis phasevarions in otitis media

Moraxella catarrhalis is a significant cause of otitis media and exacerbations of chronic obstructive pulmonary disease. Here, we characterize a phase-variable DNA methyltransferase (ModM), which contains 5'-CAAC-3' repeats in its open reading frame that mediate high-frequency mutation resulting in reversible on/off switching of ModM expression. Three modM alleles have been identified (modM1-3), with modM2 being the most commonly found allele. Using single-molecule, real-time (SMRT) genome sequencing and methylome analysis, we have determined that the ModM2 methylation target is 5'-GAR(m6)AC-3', and 100% of these sites are methylated in the genome of the M. catarrhalis 25239 ModM2 on strain. Proteomic analysis of ModM2 on and off variants revealed that ModM2 regulates expression of multiple genes that have potential roles in colonization, infection, and protection against host defenses. Investigation of the distribution of modM alleles in a panel of M. catarrhalis strains, isolated from the nasopharynx of healthy children or middle ear effusions from patients with otitis media, revealed a statistically significant association of modM3 with otitis media isolates. The modulation of gene expression via the ModM phase-variable regulon (phasevarion), and the significant association of the modM3 allele with otitis media, suggests a key role for ModM phasevarions in the pathogenesis of this organism.

Impact of the pneumococcal conjugate vaccine on serotype distribution and susceptibility trends of pediatric non-invasive Streptococcus pneumoniae isolates in Tokai, Japan over a 5-year period

Introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) in February 2010 markedly reduced the burden of invasive pneumococcal disease (IPD) and changed serotype distribution in Japan. We investigated the serotype distribution and susceptibility trends of non-invasive Streptococcus pneumoniae isolates collected from pediatric patients. A total of 564 pneumococcal isolates were collected over a 5-year period between 2008 and 2012. The coverage of PCV7 significantly decreased throughout the study period, from 49.3% in period 1 (between June 2008 and April 2009) to 23.4% in period 4 (between October 2011 and March 2012). This change was mainly due to a large decrease in the frequency of 19F (from 20.6% to 9.9%) and 6B (from 10.3% to 2.7%) and an increase in serotype 3 (from 5.1% to 13.5%) and serogroup 15 (from 4.4% to 9.0%). According to serotype replacement, the susceptible ratios of S. pneumoniae to β-lactams increased slightly while macrolide resistance remained high. The high frequency of macrolide-resistant pneumococcal isolates may continue because of the high frequency of erm(B) in replace serotypes such as serotype 3 and serogroup 15. The continuous surveillance study is essential following the introduction of a second generation 13-valent pneumococcal conjugate vaccine (PCV13).

Predicting response to antimicrobial therapy in children with acute sinusitis

OBJECTIVE

To determine prognostic factors that independently predict response to antimicrobial therapy in children with acute sinusitis.

STUDY DESIGN

A total of 206 children meeting a priori clinical criteria for acute sinusitis who were prescribed antimicrobial therapy by their primary care provider were included. The severity of symptoms in the 8-12 days after treatment was initiated was followed with the use of a validated scale. We examined the univariate and multivariate association between factors present at the time of diagnosis (symptoms, signs, nasopharyngeal culture result, radiograph results) and time to resolution of symptoms. This study was conducted 8-10 years after the 7-valent pneumococcal conjugate vaccination was introduced but before introduction of the 13-valent pneumococcal conjugate vaccination.

RESULTS

Children with proven nasopharyngeal colonization with Streptococcus pneumoniae improved more rapidly (6.5 vs 8.5 median days to symptom resolution) than those who were not colonized with S pneumoniae. Age and radiograph findings did not predict time to symptom resolution.

CONCLUSIONS

In children with acute sinusitis, proven nasopharyngeal colonization with S pneumoniae at presentation independently predicted time to symptom resolution. Future randomized, placebo-controlled trials could investigate the usefulness of testing for the presence of nasopharyngeal pathogens as a predictor of response to treatment.

Use of the Chinchilla model to evaluate the vaccinogenic potential of the Moraxella catarrhalis filamentous hemagglutinin-like proteins MhaB1 and MhaB2

Moraxella catarrhalis causes significant health problems, including 15–20% of otitis media cases in children and ∼10% of respiratory infections in adults with chronic obstructive pulmonary disease. The lack of an efficacious vaccine, the rapid emergence of antibiotic resistance in clinical isolates, and high carriage rates reported in children are cause for concern. In addition, the effectiveness of conjugate vaccines at reducing the incidence of otitis media caused by Streptococcus pneumoniae and nontypeable Haemophilus influenzae suggest that M. catarrhalis infections may become even more prevalent. Hence, M. catarrhalis is an important and emerging cause of infectious disease for which the development of a vaccine is highly desirable. Studying the pathogenesis of M. catarrhalis and the testing of vaccine candidates have both been hindered by the lack of an animal model that mimics human colonization and infection. To address this, we intranasally infected chinchilla with M. catarrhalis to investigate colonization and examine the efficacy of a protein-based vaccine. The data reveal that infected chinchillas produce antibodies against antigens known to be major targets of the immune response in humans, thus establishing immune parallels between chinchillas and humans during M. catarrhalis infection. Our data also demonstrate that a mutant lacking expression of the adherence proteins MhaB1 and MhaB2 is impaired in its ability to colonize the chinchilla nasopharynx, and that immunization with a polypeptide shared by MhaB1 and MhaB2 elicits antibodies interfering with colonization. These findings underscore the importance of adherence proteins in colonization and emphasize the relevance of the chinchilla model to study M. catarrhalis–host interactions.

RNA-Seq-based analysis of the physiologic cold shock-induced changes in Moraxella catarrhalis gene expression

BACKGROUND

Moraxella catarrhalis, a major nasopharyngeal pathogen of the human respiratory tract, is exposed to rapid downshifts of environmental temperature when humans breathe cold air. The prevalence of pharyngeal colonization and respiratory tract infections caused by M. catarrhalis is greatest in winter. We investigated how M. catarrhalis uses the physiologic exposure to cold air to regulate pivotal survival systems that may contribute to M. catarrhalis virulence.

RESULTS

In this study we used the RNA-seq techniques to quantitatively catalogue the transcriptome of M. catarrhalis exposed to a 26 °C cold shock or to continuous growth at 37 °C. Validation of RNA-seq data using quantitative RT-PCR analysis demonstrated the RNA-seq results to be highly reliable. We observed that a 26 °C cold shock induces the expression of genes that in other bacteria have been related to virulence a strong induction was observed for genes involved in high affinity phosphate transport and iron acquisition, indicating that M. catarrhalis makes a better use of both phosphate and iron resources after exposure to cold shock. We detected the induction of genes involved in nitrogen metabolism, as well as several outer membrane proteins, including ompA, m35-like porin and multidrug efflux pump (acrAB) indicating that M. catarrhalis remodels its membrane components in response to downshift of temperature. Furthermore, we demonstrate that a 26 °C cold shock enhances the induction of genes encoding the type IV pili that are essential for natural transformation, and increases the genetic competence of M. catarrhalis, which may facilitate the rapid spread and acquisition of novel virulence-associated genes.

CONCLUSION

Cold shock at a physiologically relevant temperature of 26 °C induces in M. catarrhalis a complex of adaptive mechanisms that could convey novel pathogenic functions and may contribute to enhanced colonization and virulence.

Role of the zinc uptake ABC transporter of Moraxella catarrhalis in persistence in the respiratory tract

Moraxella catarrhalis is a human respiratory tract pathogen that causes otitis media in children and lower respiratory tract infections in adults with chronic obstructive pulmonary disease. We have identified and characterized a zinc uptake ABC transporter that is present in all strains of M. catarrhalis tested. A mutant in which the znu gene cluster is knocked out shows markedly impaired growth compared to the wild type in medium that contains trace zinc; growth is restored to wild-type levels by supplementing medium with zinc but not with other divalent cations. Thermal-shift assays showed that the purified recombinant substrate binding protein ZnuA binds zinc but does not bind other divalent cations. Invasion assays with human respiratory epithelial cells demonstrated that the zinc ABC transporter of M. catarrhalis is critical for invasion of respiratory epithelial cells, an observation that is especially relevant because an intracellular reservoir of M. catarrhalis is present in the human respiratory tract and this reservoir is important for persistence. The znu knockout mutant showed marked impairment in its capacity to persist in the respiratory tract compared to the wild type in a mouse pulmonary clearance model. We conclude that the zinc uptake ABC transporter mediates uptake of zinc in environments with very low zinc concentrations and is critical for full virulence of M. catarrhalis in the respiratory tract in facilitating intracellular invasion of epithelial cells and persistence in the respiratory tract.

Nasopharyngeal microbial interactions in the era of pneumococcal conjugate vaccination

The nasopharynx of children is often colonised by microorganisms such as Streptococcus pneumoniae (the pneumococcus) that can cause infections including pneumonia and otitis media. In this complex environment, bacteria and viruses may impact each other through antagonistic as well as synergistic interactions. Vaccination may alter colonisation dynamics, evidenced by the rise in non-vaccine serotypes following pneumococcal conjugate vaccination. Discovery of an inverse relationship between S. pneumoniae and Staphylococcus aureus carriage generated concern that pneumococcal vaccination could increase S. aureus carriage and disease. Here we review data on co-colonisation of pathogens in the nasopharynx, focusing on S. pneumoniae and the impact of pneumococcal vaccination. Thus far, pneumococcal vaccination has not had a sustained impact on S. aureus carriage but it is associated with an increase in non-typeable Haemophilus influenzae in acute otitis media aetiology. Advances in bacterial and viral detection methodologies have facilitated research in nasopharyngeal microbiology and will aid investigation of potential vaccine-induced changes, particularly when baseline studies can be conducted prior to pneumococcal vaccine introduction.

The diagnosis and management of acute otitis media

This evidence-based clinical practice guideline is a revision of the 2004 acute otitis media (AOM) guideline from the American Academy of Pediatrics (AAP) and American Academy of Family Physicians. It provides recommendations to primary care clinicians for the management of children from 6 months through 12 years of age with uncomplicated AOM. In 2009, the AAP convened a committee composed of primary care physicians and experts in the fields of pediatrics, family practice, otolaryngology, epidemiology, infectious disease, emergency medicine, and guideline methodology. The subcommittee partnered with the Agency for Healthcare Research and Quality and the Southern California Evidence-Based Practice Center to develop a comprehensive review of the new literature related to AOM since the initial evidence report of 2000. The resulting evidence report and other sources of data were used to formulate the practice guideline recommendations. The focus of this practice guideline is the appropriate diagnosis and initial treatment of a child presenting with AOM. The guideline provides a specific, stringent definition of AOM. It addresses pain management, initial observation versus antibiotic treatment, appropriate choices of antibiotic agents, and preventive measures. It also addresses recurrent AOM, which was not included in the 2004 guideline. Decisions were made on the basis of a systematic grading of the quality of evidence and benefit-harm relationships. The practice guideline underwent comprehensive peer review before formal approval by the AAP. This clinical practice guideline is not intended as a sole source of guidance in the management of children with AOM. Rather, it is intended to assist primary care clinicians by providing a framework for clinical decision-making. It is not intended to replace clinical judgment or establish a protocol for all children with this condition. These recommendations may not provide the only appropriate approach to the management of this problem.

Pili play an important role in enhancing the bacterial clearance from the middle ear in a mouse model of acute otitis media with Moraxella catarrhalis

Moraxella catarrhalis is a Gram-negative aerobic diplococcus that is currently the third most frequent cause of bacterial acute otitis media (AOM) in children. In this study, we developed an experimental murine AOM model by inoculating M. catarrhalis in the middle ear bulla and studied the local response to this inoculation, and modulation of its course by the pili of M. catarrhalis. The pili-positive and pili-negative M. catarrhalis showed differences in bacterial clearance and infiltration of inflammatory cells in the middle ear. Pili-negative M. catarrhalis induced a more delayed and prolonged immune response in the middle ear than that of pili-positive M. catarrhalis. TLR2, -4, -5 and -9 mRNA expression was upregulated in neutrophils that infiltrated the middle ear cavity during AOM caused by both pili-positive and pili-negative bacteria. TLR5 mRNA expression and TLR5 protein in the neutrophils were induced more robustly by pili-positive M. catarrhalis. This immune response is likely to be related to neutrophil function such as toll-like 5-dependent phagocytosis. Our results show that mice may provide a useful AOM model for studying the role of M. catarrhalis. Furthermore, we show that pili play an important role in enhancing M. catarrhalis clearance from the middle ear that is probably mediated through neutrophil-dependent TLR5 signaling.

Moraxella catarrhalis: from interactions with the host immune system to vaccine development

Moraxella catarrhalis is a human-restricted commensal that over the last two decades has developed into an emerging respiratory tract pathogen. The bacterial species is equipped with various adhesins to facilitate its colonization. Successful evasion of the human immune system is a prerequisite for Moraxella infection. This strategy involves induction of an excessive proinflammatory response, intervention of granulocyte recruitment to the infection site, activation of selected pattern recognition receptors and cellular adhesion molecules to counteract the host bacteriolytic attack, as well as, finally, reprogramming of antigen presenting cells. Host immunomodulator molecules are also exploited by Moraxella to aid in resistance against complement killing and host bactericidal molecules. Thus, breaking the basis of Moraxella immune evasion mechanisms is fundamental for future invention of effective therapy in controlling Moraxella infection.

Respiratory syncytial virus promotes Moraxella catarrhalis-induced ascending experimental otitis media

Otitis media (OM) is a polymicrobial disease wherein prior or concurrent infection with an upper respiratory tract virus plays an essential role, predisposing the middle ear to bacterial invasion. In episodes of acute bacterial OM, respiratory syncytial virus (RSV) is the most commonly isolated virus and thus serves as an important co-pathogen. Of the predominant bacterial agents of OM, the pathogenesis of disease due to Moraxella catarrhalis is the least well understood. Rigorous study of M.catarrhalis in the context of OM has been significantly hindered by lack of an animal model. To bridge this gap, we assessed whether co-infection of chinchillas with M. catarrhalis and RSV would facilitate ascension of M. catarrhalis from the nasopharynx into the middle ear. Chinchillas were challenged intranasally with M. catarrhalis followed 48 hours later by intranasal challenge with RSV. Within 7 days, 100% of nasopharynges were colonized with M. catarrhalis and homogenates of middle ear mucosa were also culture-positive. Moreover, within the middle ear space, the mucosa exhibited hemorrhagic foci, and a small volume of serosanguinous effusion was present in one of six ears. To improve upon this model, and based on epidemiologic data, nontypeable Haemophilus influenzae (NTHI) was included as an additional bacterial co-pathogen via intranasal administration four days before M. catarrhalis challenge. With this latter protocol, M. catarrhalis was cultured from the nasopharynx and middle ear homogenates of a maximum of 88% and 79% animals, respectively, for up to 17 days after intranasal challenge with M. catarrhalis. Additionally, hemorrhagic foci were observed in 79% of middle ears upon sacrifice. Thus, these data demonstrated that co-infection with RSV and NTHI predisposed to M. catarrhalis-induced ascending experimental OM. This model can be used both in studies of pathogenesis as well as to investigate strategies to prevent or treat OM due to M. catarrhalis.

Long-term effects of pneumococcal conjugate vaccine on nasopharyngeal carriage of S. pneumoniae, S. aureus, H. influenzae and M. catarrhalis

Background

Shifts in pneumococcal serotypes following introduction of 7-valent pneumococcal conjugate vaccine (PCV-7) may alter the presence of other bacterial pathogens co-inhabiting the same nasopharyngeal niche.

Methodology/Principal Findings

Nasopharyngeal prevalence rates of S. pneumoniae, S. aureus, H. influenzae and M. catarrhalis were investigated before, 3 and 4.5 years after introduction of PCV-7 in the national immunisation program in children at 11 and 24 months of age, and parents of 24-month-old children (n≈330/group) using conventional culture methods. Despite a virtual disappearance of PCV-7 serotypes over time, similar overall pneumococcal rates were observed in all age groups, except for a significant reduction in the 11-month-old group (adjusted Odds Ratio after 4.5 years 0.48, 95% Confidence Interval 0.34–0.67). Before, 3 and 4.5 years after PCV-7 implementation, prevalence rates of S. aureus were 5%, 9% and 14% at 11 months of age (3.59, 1.90–6.79) and 20%, 32% and 34% in parents (1.96, 1.36–2.83), but remained similar at 24 months of age, respectively. Prevalence rates of H. influenzae were 46%, 65% and 65% at 11 months (2.22, 1.58–3.13), 52%, 73% and 76% at 24 months of age (2.68, 1.88–3.82) and 23%, 30% and 40% in parents (2.26, 1.58–3.33), respectively. No consistent changes in M. catarrhalis carriage rates were observed over time.

Conclusions/Significance

In addition to large shifts in pneumococcal serotypes, persistently higher nasopharyngeal prevalence rates of S. aureus and H. influenzae were observed among young children and their parents after PCV-7 implementation. These findings may have implications for disease incidence and antibiotic treatment in the post-PCV era.

Innate immunity and the role of defensins in otitis media

Otitis media is the most common pediatric disease in developed countries and a significant cause of morbidity and hearing loss in developing countries. The innate immune system is essential to protecting the middle ear from infection. Defensins, broad-spectrum cationic antimicrobial peptides, have been implicated in prevention of and the early response to acute otitis media; however, the mechanisms by which defensins and other antimicrobial molecules mediate this protection have not been completely elucidated. In both animal otitis media models and human middle ear epithelial cell culture models, β-defensins are highly induced and effectively kill the common pathogens associated with otitis media. We review the importance of innate immunity in protecting the middle ear and recent advances in understanding the roles of defensins and other antimicrobial molecules in the prevention and treatment of otitis media. The extremely high prevalence of otitis media, in spite of sophisticated innate and adaptive immune systems, is a vexing problem for clinicians and scientists. We therefore also review mechanisms by which bacteria evade innate immune defenses.

Nasopharyngeal microbiota in infants with acute otitis media

Background. Interspecies interactions of the nasopharyngeal microbiota are likely to be involved in the pathogenesis of acute otitis media (AOM). Capturing the breadth of microbial interactions requires a detailed description of the microbiota during health and AOM.

Methods. The nasopharyngeal microbiota of 163 infants with (n = 153) or without (n = 10) AOM was characterized using nasopharyngeal swabs and multiplexed pyrosequencing of 16S rRNA. Nasopharyngeal swab specimens were collected during 4 winter seasons from 2004 through 2010 for infants with AOM and during 2010 for controls.

Results. Fifty-eight bacterial families were identified, of which Moraxellaceae, Streptococcaceae, and Pasteurellaceae were the most frequent. Commensal families were less prevalent in infants with AOM than in controls. In infants with AOM, prior exposure to antimicrobials and administration of the heptavalent conjugated pneumococcal polysaccharide vaccine (PCV7) were also associated with reduced prevalence of distinct commensal families (Streptococcaceae and Corynebacteriaceae). In addition, antimicrobial exposure increased the prevalence of Enterobacteriaceae and the abundance of Pasteurellaceae. Other factors, such as age, sex, day care, and a history of recurrent AOM, did not influence the microbiota.

Conclusions. Infants’ nasopharyngeal microbiota undergoes significant changes during AOM and after exposure to antimicrobials and PCV7, which is mainly attributable to reduced prevalence of commensal bacterial families.

Effect of pneumococcal vaccination on nasopharyngeal carriage of Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus in Fijian children

The 7-valent pneumococcal conjugate vaccine (PCV7) reduces carriage of vaccine type Streptococcus pneumoniae but leads to replacement by nonvaccine serotypes and may affect carriage of other respiratory pathogens. We investigated nasopharyngeal carriage of S. pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus in Fijian infants participating in a pneumococcal vaccine trial using quantitative PCR. Vaccination did not affect pathogen carriage rates or densities, whereas significant differences between the two major ethnic groups were observed.

Increase in serotype 19A prevalence and amoxicillin non-susceptibility among paediatric Streptococcus pneumoniae isolates from middle ear fluid in a passive laboratory-based surveillance in Spain, 1997-2009

BACKGROUND

Conjugate vaccines, such as the 7-valent conjugate vaccine (PCV7), alter serotype nasopharyngeal carriage, potentially increasing cases of otitis media by non-vaccine serotypes.

METHODS

All paediatric middle ear fluid (MEF) isolates received in the Spanish Reference Laboratory for Pneumococci through a passive, laboratory-based surveillance system from January 1997 to June 2009 were analysed. Data from 1997 to 2000 were pooled as pre-vaccination period. Trends over time were explored by linear regression analysis.

RESULTS

A total of 2,077 isolates were analysed: 855 belonging to PCV7 serotypes, 466 to serotype 19A, 215 to serotype 3, 89 to serotype 6A and 452 to other serotypes (< 40 isolates each). Over time, there has been a decreasing trend for PCV7 serotypes (R(2) = 0.944; p < 0.001, with significant decreasing trends for serotypes 19F, 14, 23F and 9V), and increasing trends for serotype 19A (R(2) = 0.901; p < 0.001), serotype 3 (R(2) = 0.463; p = 0.030) and other non-PCV7 serotypes (R(2) = 0.877; p < 0.001), but not for serotype 6A (R(2) = 0.311; p = 0.094). Considering all isolates, amoxicillin non-susceptibility showed an increasing trend (R(2) = 0.528; p = 0.017). Regarding serotype 19A, increasing trends in non-susceptibility to penicillin (R(2) = 0.726; p = 0.001), amoxicillin (R(2) = 0.804; p < 0.001), cefotaxime (R(2) = 0.546; p = 0.005) and erythromycin (R(2) = 0.546; p = 0.009) were found, with amoxicillin non-susceptibility firstly detected in 2003 (7.4%) and increasing up to 38.0% in 2009. In PCV7 serotypes (which prevalence decreased from 70.7% during 1997-2000 to 10.6% in 2009) amoxicillin non-susceptibility rates showed an increasing trend (R(2) = 0.702; p = 0.002). However, overall, amoxicillin non-susceptibility (≈25% in 2008-9) could be mainly attributed to serotype 19A (> 35% isolates) since PCV7 strains represented < 11% of total clinical isolates.

CONCLUSIONS

In contrast to reports on invasive pneumococcal strains, in MEF isolates the reduction in the prevalence of PCV7 serotypes was not associated with decreases in penicillin/erythromycin non-susceptibility. The high prevalence of serotype 19A among paediatric MEF isolates and the amoxicillin non-susceptibility found in this serotype are worrisome since amoxicillin is the most common antibiotic used in the treatment of acute otitis media. These data suggest that non-PCV7 serotypes (mainly serotype 19A followed by serotypes 3 and 6A) are important etiological agents of acute otitis media and support the added value of the broader coverage of the new 13-valent conjugate vaccine.

Haemophilus influenzae infections in the H. influenzae type b conjugate vaccine era

The widespread use of Haemophilus influenzae type b (Hib) conjugate vaccines has nearly eradicated invasive Hib disease where the vaccines are used. This success was accompanied by a shift in capsular serotypes of invasive H. influenzae disease, with nontypeable strains replacing type b strains as the most common bloodstream isolate, but there is no convincing evidence of a true increase in the incidence of non-serotype b invasive infections. H. influenzae causes predominantly mucosal infections. The introduction of vaccines for otitis media and global shifts in antimicrobial susceptibility emphasize the importance of continued surveillance of H. influenzae colonization and disease patterns.

Predominance of nontypeable Haemophilus influenzae in children with otitis media following introduction of a 3+0 pneumococcal conjugate vaccine schedule

In Australia the 7-valent pneumococcal conjugate vaccine (PCV7) is administered at 2, 4 and 6 months of age, with no booster dose. Information on bacterial carriage and the aetiology of recurrent acute otitis media (rAOM) after introduction of PCV7 using the 3+0 schedule is required to evaluate the potential impact of second generation pneumococcal vaccines. We found that 2-4 years after introduction of PCV7 in the National Immunisation Program, nontypeable Haemophilus influenzae (NTHi) was the predominant pathogen isolated from the nasopharynx and middle ear of children with a history of rAOM. Compared with healthy controls (n=81), NTHi and Streptococcus pneumoniae carriage rates were significantly higher in children with a history of rAOM (n=186) (19% vs. 56% p<0.0001 and 26% vs. 41%, p=0.02, respectively). Carriage of PCV7 pneumococcal serotypes was rare, whereas PCV7-related and non-PCV7 serotypes were isolated of 38% of cases and 24% of controls. Serotype 19A was the most common serotype isolated from the nasopharynx and middle ear and accounted for 36% (14/39) of total pneumococcal isolates with reduced susceptibility to cotrimoxazole. Of the 119 children carrying NTHi, 17% of isolates were β-lactamase positive. The scarcity of PCV7 serotypes in children with and without a history of rAOM indicates that the 3+0 PCV7 schedule is preventing carriage and rAOM from PCV7 serotypes. Introduction of new vaccines in Australia with increased pneumococcal serotype and pathogen coverage, including 19A and NTHi, should decrease the circulation of antibiotic-resistant bacteria and reduce the burden of rAOM.

WITHDRAWN: Decongestants and antihistamines for acute otitis media in children

BACKGROUND

Acute otitis media (AOM) is a common and important source of morbidity in children, although the majority of cases resolve spontaneously. While frequently recommended, decongestant and antihistamine therapy is of unclear benefit.

OBJECTIVES

To determine the efficacy of decongestant and antihistamine therapy in children with AOM on outcomes of AOM resolution, symptom resolution, medication side effects, and complications of AOM.

SEARCH STRATEGY

In this updated review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 2); MEDLINE (January 2004 to May 2007); and EMBASE (July 2003 to May 2007).

SELECTION CRITERIA

Randomized controlled trials (RCTs) evaluating decongestant or antihistamine treatment for children with AOM were included. Patient-oriented outcomes were considered most relevant.

DATA COLLECTION AND ANALYSIS

The review authors independently evaluated studies for inclusion, performed validity assessments and completed data extraction. Dichotomous data were pooled to generate relative risks; homogeneity was assessed using approximate chi-square tests.

MAIN RESULTS

No new studies were included following this updated search. Fifteen trials involving 2695 people were included. Only the combined decongestant-antihistamine group demonstrated statistically lower rates of persistent AOM at the two week period (fixed relative risk (RR) 0.76; 95% confidence interval (CI) 0.60 to 0.96; number needed to treat (NNT) 10). No benefit was found for early cure rates, symptom resolution, prevention of surgery or other complications. There was a five to eight -fold increased risk of side effects for those receiving an intervention, which reached statistical significance for all decongestant groupings. Validity sub analyses demonstrated that lower quality studies found benefit, while analysis of those studies with higher validity scores found no benefit of treatment.

AUTHORS' CONCLUSIONS

Given lack of benefit and increased risk of side effects, these data do not support the use of decongestant treatment in children with AOM. There was a small statistical benefit from combination medication use but the clinical significance is minimal and study design may be biasing the results. Thus, the routine use of antihistamines for treating AOM in children cannot be recommended.