Nonencapsulated Streptococcus pneumoniae causes otitis media during single-species infection and during polymicrobial infection with nontypeable Haemophilus influenzae

Pneumococcal colonization and coinfecting respiratory viruses in children under 5 years in Addis Ababa, Ethiopia: a prospective case-control study

A comprehensive understanding of the dynamics of Streptococcus pneumoniae colonization in conjunction with respiratory virus infections is essential for enhancing our knowledge of the pathogenesis and advancing the development of effective preventive strategies. Therefore, a case-control study was carried out in Addis Ababa, Ethiopia to investigate the colonization rate of S. pneumoniae and its coinfection dynamics with respiratory viruses among children under the age of 5 years. Samples from the nasopharyngeal and/or oropharyngeal, along with socio-demographic and clinical information, were collected from 420 children under 5 years old (210 cases with lower respiratory tract infections and 210 controls with conditions other than respiratory infections.). A one-step Multiplex real-time PCR using the Allplex Respiratory Panel Assays 1-4 was performed to identify respiratory viruses and bacteria. Data analysis was conducted using STATA software version 17. The overall colonization rate of S. pneumoniae in children aged less than 5 years was 51.2% (215/420). The colonization rates in cases and controls were 54.8% (115/210) and 47.6% (100/210), respectively (p = 0.14). Colonization rates were observed to commence at an early age in children, with a colonization rate of 48.9% and 52.7% among infants younger than 6 months controls and cases, respectively. The prevalence of AdV (OR, 3.11; 95% CI [1.31-8.19]), RSV B (OR, 2.53; 95% CI [1.01-6.78]) and HRV (OR, 1.7; 95% CI [1.04-2.78]) tends to be higher in children who tested positive for S. pneumoniae compared to those who tested negative for S. pneumoniae. Further longitudinal research is needed to understand and determine interaction mechanisms between pneumococci and viral pathogens and the clinical implications of this coinfection dynamics.

Otitis media: recent advances in otitis media vaccine development and model systems

Otitis media is an inflammatory disorder of the middle ear caused by airways-associated bacterial or viral infections. It is one of the most common childhood infections as globally more than 80% of children are diagnosed with acute otitis media by 3 years of age and it is a common reason for doctor's visits, antibiotics prescriptions, and surgery among children. Otitis media is a multifactorial disease with various genetic, immunologic, infectious, and environmental factors predisposing children to develop ear infections. Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis are the most common culprits responsible for acute otitis media. Despite the massive global disease burden, the pathogenesis of otitis media is still unclear and requires extensive future research. Antibiotics are the preferred treatment to cure middle ear infections, however, the antimicrobial resistance rate of common middle ear pathogens has increased considerably over the years. At present, pneumococcal and influenza vaccines are administered as a preventive measure against otitis media, nevertheless, these vaccines are only beneficial in preventing carriage and/or disease caused by vaccine serotypes. Otitis media caused by non-vaccine serotype pneumococci, non-typeable H. influenza, and M. catarrhalis remain an important healthcare burden. The development of multi-species vaccines is an arduous process but is required to reduce the global burden of this disease. Many novel vaccines against S. pneumoniae, non-typeable H. influenza, and M. catarrhalis are in preclinical trials. It is anticipated that these vaccines will lower the disease burden and provide better protection against otitis media. To study disease pathology the rat, mouse, and chinchilla are commonly used to induce experimental acute otitis media to test new therapeutics, including antibiotics and vaccines. Each of these models has its advantages and disadvantages, yet there is still a need to develop an improved animal model providing a better correlated mechanistic understanding of human middle ear infections, thereby underpinning the development of more effective otitis media therapeutics. This review provides an updated summary of current vaccines against otitis media, various animal models of otitis media, their limitations, and some future insights in this field providing a springboard in the development of new animal models and novel vaccines for otitis media.

Revealing In Silico that Bacteria's Outer Membrane Proteins may Help our Bodies Replicate and Carry Severe Acute Respiratory Syndrome Coronavirus 2

Some studies in the literature show that viruses can affect bacteria directly or indirectly, and viruses use their own specific ways to do these interactions. Furthermore, it is said that bacteria are prone to attachment mammalian cells during a viral illness using their surface proteins that bind to host extracellular matrix proteins such as fibronectin, fibrinogen, vitronectin, and elastin. A recent study identified the cooperation between bacteria and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in silico, in vitro, and in vivo. Like this study, we hypothesized that more bacteria protein might help SARS-CoV-2 transport and attach to angiotensin-converting enzyme 2 (ACE2). The bacteria's outer membrane proteins (OMPs) we chose were not random; they had to be on the outer surface of the bacteria because these proteins on the outer surface should have a high probability of interacting with both the spike protein and ACE2. We obtained by using bioinformatics tools that there may be binding between both ACE2 and spike protein of these bacteria's OMPs. Protein-protein interaction results also supported our hypothesis. Therefore, based on our predicted results, these bacteria OMPs may help SARS-CoV-2 move in our body, and both find and attach to ACE2. It is expected that these inferences obtained from the bioinformatics results may play a role in the SARS-CoV-2 virus reaching host cells. Thus, it may bring a different perspective to studies on how the virus can infect host cells.

Non-typeable Haemophilus influenzae chronic colonization in chronic obstructive pulmonary disease (COPD)

Haemophilus influenzae is the most common cause of bacterial infection in the lungs of chronic obstructive pulmonary disease (COPD) patients and contributes to episodes of acute exacerbation which are associated with increased hospitalization and mortality. Due to the ability of H. influenzae to adhere to host epithelial cells, initial colonization of the lower airways can progress to a persistent infection and biofilm formation. This is characterized by changes in bacterial behaviour such as reduced cellular metabolism and the production of an obstructive extracellular matrix (ECM). Herein we discuss the multiple mechanisms by which H. influenzae contributes to the pathogenesis of COPD. In particular, mechanisms that facilitate bacterial adherence to host airway epithelial cells, biofilm formation, and microbial persistence through immune system evasion and antibiotic tolerance will be discussed.

Antibacterial activity of a DNA topoisomerase I inhibitor versus fluoroquinolones in Streptococcus pneumoniae

The DNA topoisomerase complement of Streptococcus pneumoniae is constituted by two type II enzymes (topoisomerase IV and gyrase), and a single type I enzyme (topoisomerase I). These enzymes maintain the DNA topology, which is essential for replication and transcription. While fluoroquinolones target the type II enzymes, seconeolitsine, a new antimicrobial agent, targets topoisomerase I. We compared for the first time the in vitro effect of inhibition of topoisomerase I by seconeolitsine and of the type II topoisomerases by the fluoroquinolones levofloxacin and moxifloxacin. We used three isogenic non-encapsulated strains and five non-vaccine serotypes isolates belonging to two circulating pneumococcal clones, ST63⁸ (2 strains) and ST156^9V (3 strains). Each group contained strains with diverse susceptibility to fluoroquinolones. Minimal inhibitory concentrations, killing curves and postantibiotic effects were determined. Seconeolitsine demonstrated the fastest and highest bactericidal activity against planktonic bacteria and biofilms. When fluoroquinolone-susceptible planktonic bacteria were considered, seconeolitsine induced postantibiotic effects (1.00−1.87 h) similar than levofloxacin (1.00−2.22 h), but longer than moxifloxacin (0.39−1.71 h). The same effect was observed in sessile bacteria forming biofilms. Seconeolitsine induced postantibiotic effects (0.84−2.31 h) that were similar to those of levofloxacin (0.99−3.32 h) but longer than those of moxifloxacin (0.89−1.91 h). The greatest effect was observed in the viability and adherence of bacteria in the postantibiotic phase. Seconeolitsine greatly reduced the thickness of the biofilms formed in comparison with fluoroquinolones: 2.91 ± 0.43 μm (seconeolitsine), 7.18 ± 0.58 μm (levofloxacin), 17.08 ± 1.02 μm (moxifloxacin). When fluoroquinolone-resistant bacteria were considered, postantibiotic effects induced by levofloxacin and moxifloxacin, but not by seconeolitsine, were shorter, decreasing up to 5-fold (levofloxacin) or 2-fold (moxifloxacin) in planktonic cells, and up to 1.7 (levofloxacin) or 1.4-fold (moxifloxacin) during biofilm formation. Therefore, topoisomerase I inhibitors could be an alternative for the treatment of pneumococcal diseases, including those caused by fluoroquinolone-resistant isolates.

Characterization of MSlys, the endolysin of Streptococcus pneumoniae phage MS1

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MSlys is a choline binding protein from pneumococcal MS1 phage.

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Planktonic and biofilm S. pneumoniae cells are affected by MSlys treatment.

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MSlys is active against isolates from otitis media infections and works in the conditions commonly found in this environment.

Despite the use of pneumococcal conjugate vaccines, the number of infections related to Streptococcus pneumoniae continues to be alarming.

Herein, we identified, characterized the MSlys endolysin encoded in the phage MS1. We further tested its antimicrobial efficacy against planktonic and biofilm cells, assessing the culturability of cells and biofilm structure by scanning electron microscopy, and confocal laser scanning microscopy.

The modular MSlys endolysin consists of an amidase catalytic domain and a choline-binding domain. MSlys is active against isolates of children with otitis media, and conditions close to those found in the middle ear. Treatment with MSlys (2 h, 4 μM) reduced planktonic cultures by 3.5 log10 CFU/mL, and 24- and 48-h-old biofilms by 1.5 and 1.8 log10 CFU/mL, respectively. Imaging of the biofilms showed thinner and damaged structures compared to control samples.

The recombinantly expressed MSlys may be a suitable candidate for treating pneumococcal infections, including otitis media.

Unsolved problems and new medical approaches to otitis media

INTRODUCTION

Otitis media (OM) is a spectrum of infectious and inflammatory diseases that involve the middle ear. It includes acute otitis media (AOM), otitis media with effusion (OME) and chronic suppurative otitis media (CSOM).

AREAS COVERED

This manuscript discusses some of the emerging and unsolved problems regarding OM, and some of the newly developed prophylactic and therapeutic medical measures.

EXPERT OPINION

In recent years, considerable progress in the knowledge of OM physiopathology has been made. However, although extremely common, diseases included under OM have not been adequately studied, and many areas of development, evolution and possible treatments of these pathologies are not defined. It is necessary that these deficiencies be quickly overcome if we want to reduce the total burden of a group of diseases that still have extremely high medical, social and economic relevance.

Panel 7 - Pathogenesis of otitis media - a review of the literature between 2015 and 2019

OBJECTIVE

To perform a comprehensive review of the literature from July 2015 to June 2019 on the pathogenesis of otitis media. Bacteria, viruses and the role of the microbiome as well as the host response are discussed. Directions for future research are also suggested.

DATA SOURCES

PubMed database of the National Library of Medicine.

REVIEW METHODS

PubMed was searched for any papers pertaining to OM pathogenesis between July 2015 and June 2019. If in English, abstracts were assessed individually for their relevance and included in the report. Members of the panel drafted the report based on these searches and on new data presented at the 20th International Symposium on Recent Advances in Otitis Media.

CONCLUSIONS

The main themes that arose in OM pathogenesis were around the need for symptomatic viral infections to develop disease. Different populations potentially having different mechanisms of pathogenesis. Novel bacterial otopathogens are emerging and need to be monitored. Animal models need to continue to be developed and used to understand disease pathogenesis.

IMPLICATIONS FOR PRACTICE

The findings in the pathogenesis panel have several implications for both research and clinical practice. The most urgent areas appear to be to continue monitoring the emergence of novel otopathogens, and the need to develop prevention and preventative therapies that do not rely on antibiotics and protect against the development of the initial OM episode.

Molecular typing, antibiotic susceptibility, and biofilm production in nonencapsulated Streptococcus pneumoniae isolated from children in Japan

The prevalence of nonencapsulated Streptococcus pneumoniae (NESp) has increased with the introduction of pneumococcal conjugate vaccines in children; however, the bacteriological characteristics of NESp have not been sufficiently clarified. In this study, NESp strains isolated from the nasopharyngeal carriage of children from four nursery schools in Japan were analyzed for molecular type, antibiotic susceptibility, and biofilm productivity. A total of 152 putative S. pneumoniae strains were identified by optochin-susceptibility analysis, of which 21 were not serotypeable by slide agglutination, quellung reaction, or multiplex PCR. Among these 21 strains, three were lytA-negative and, therefore, not S. pneumoniae. The remaining 18 strains were positive for lytA, ply, pspK, and bile solubility and were confirmed as NESp. Therefore, the isolation rate of NESp in the S. pneumoniae strains in this study was 12.0% (18/149). Molecular-typing analyses classified five strains as two existing sequence types (STs; ST7502 and ST7786), and 13 strains formed four novel STs. Horizontal spread was suspected, because strains with the same ST were often isolated from the same nursery school. The NESp isolates were generally susceptible to most antimicrobials, with the exception of macrolides; however, all isolates possessed more than one abnormal penicillin-binding protein gene. Furthermore, NESp strains were more effective than encapsulated counterparts at forming biofilms, which showed obvious differences in morphology. These data indicated that NESp strains should be continuously monitored as emerging respiratory pathogens.

Biofilm production by Haemophilus influenzae and Streptococcus pneumoniae isolated from the nasopharynx of children with acute otitis media

Background

Biofilm production by Haemophilus influenzae and Streptococcus pneumoniae has been implicated in the pathogenesis of otitis media, mainly in chronic and recurrent cases. We studied the “in vitro” biofilm production by these 2 species isolated alone or together from the nasopharynx of children with acute otitis media.

Methods

The studied strains were from 3 pneumococcal conjugate vaccine (PCV) periods: pre-PCV7, post-PCV7/pre-PCV13 and post-PCV13. A modified microtiter plate assay with crystal violet stain was used to study the biofilm production of 182 H. influenzae and 191 S. pneumoniae strains.

Results

Overall, 117/181 (64.6%) H. influenzae and 128/191 (66.8%) S. pneumoniae strains produced biofilm. The proportion of biofilm-producing H. influenzae strains was greater with than without the isolation of S. pneumoniae in the same sample (75.5% vs 52.3%, p = 0.001). Conversely, the proportion of biofilm-producing S. pneumoniae strains was not affected by the presence or not of H. influenzae (66.3% vs 67.4%). S. pneumoniae serotypes 6B, 15B/C, 19A, 35F and 35B were the better biofilm producers (80%). Serotypes 11A, 14, 15A, 19F and 19A were more associated with H. influenzae biofilm-producing strains. Overall, 89/94 (94.6%) of cases with combined isolation showed biofilm production by S. pneumoniae or H. influenzae.

Conclusion

This study emphasizes the high proportion of biofilm production by H. influenzae and S. pneumoniae strains isolated from the nasopharynx of children with acute otitis media, which reinforces the results of studies suggesting the importance of biofilm in the pathogenesis of acute otitis media.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3657-9) contains supplementary material, which is available to authorized users.

Hyperencapsulated mucoid pneumococcal isolates from patients with cystic fibrosis have increased biofilm density and persistence in vivo

Mucoid bacteria, predominately Pseudomonas aeruginosa, are commonly associated with decline in pulmonary function in children with cystic fibrosis (CF), and are thought to persist at least in part due to a greater propensity toward forming biofilms. We isolated a higher frequency of mucoid Streptococcus pneumoniae (Sp) expressing high levels of capsular polysaccharides from sputa from children with CF, compared to those without CF. We compared biofilm formation and maturation by mucoid and non-mucoid isolates of Sp collected from children with and without CF. Non-mucoid Sp serotype 19A and 19F isolates had significantly higher levels of biofilm initiation and adherence to CF epithelial cells than did serotype 3 isolates. However, strains expressing high levels of capsule had significantly greater biofilm maturation, as evidenced by increased density and thickness in static and continuous flow assays via confocal microscopy. Finally, using a serotype 3 Sp strain, we showed that highly encapsulated mucoid phase variants predominate during late adherence and better colonize CFTR-/- as compared to wild-type mice in respiratory infection studies. These findings indicate that overexpression of capsule can enhance the development of mature pneumococcal biofilms in vitro, and may contribute to pneumococcal colonization in CF lung disease.

Animal models of acute otitis media - A review with practical implications for laboratory research

Considerable animal research has focused on developing new strategies for the prevention and treatment of acute otitis media (AOM). Several experimental models of AOM have thus been developed. A PubMed search of the English literature was conducted from 1975 to July 2016 using the search terms "animal model" and "otitis media" from which 91 published studies were included for analysis, yielding 123 animal models. The rat, mouse and chinchilla are the preferred animals for experimental AOM models with their individual advantages and disadvantages. The most common pathogens used to create AOM are Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. Streptococcus pneumoniae (types 3, 23 and 6A) and non-typeable Haemophilus influenzae (NTHi) are best options for inoculation into rat and mouse models. Adding viral pathogens such as RSV and Influenza A virus, along with creating ET dysfunction, are useful adjuncts in animal models of AOM. Antibiotic prophylaxis may interfere with the inflammatory response without a significant reduction in animal mortality.

Gene Acquisition by a Distinct Phyletic Group within Streptococcus pneumoniae Promotes Adhesion to the Ocular Epithelium

Streptococcus pneumoniae (pneumococcus) displays broad tissue tropism and infects multiple body sites in the human host. However, infections of the conjunctiva are limited to strains within a distinct phyletic group with multilocus sequence types ST448, ST344, ST1186, ST1270, and ST2315. In this study, we sequenced the genomes of six pneumococcal strains isolated from eye infections. The conjunctivitis isolates are grouped in a distinct phyletic group together with a subset of nasopharyngeal isolates. The keratitis (infection of the cornea) and endophthalmitis (infection of the vitreous body) isolates are grouped with the remainder of pneumococcal strains. Phenotypic characterization is consistent with morphological differences associated with the distinct phyletic group. Specifically, isolates from the distinct phyletic group form aggregates in planktonic cultures and chain-like structures in biofilms grown on abiotic surfaces. To begin to investigate the association between genotype and epidemiology, we focused on a predicted surface-exposed adhesin (SspB) encoded exclusively by this distinct phyletic group. Phylogenetic analysis of the gene encoding SspB in the context of a streptococcal species tree suggests that sspB was acquired by lateral gene transfer from Streptococcus suis. Furthermore, an sspB deletion mutant displays decreased adherence to cultured cells from the ocular epithelium compared to the isogenic wild-type and complemented strains. Together these findings suggest that acquisition of genes from outside the species has contributed to pneumococcal tissue tropism by enhancing the ability of a subset of strains to infect the ocular epithelium causing conjunctivitis. IMPORTANCE Changes in the gene content of pathogens can modify their ability to colonize and/or survive in different body sites in the human host. In this study, we investigate a gene acquisition event and its role in the pathogenesis of Streptococccus pneumoniae (pneumococcus). Our findings suggest that the gene encoding the predicted surface protein SspB has been transferred from Streptococcus suis (a distantly related streptococcal species) into a distinct set of pneumococcal strains. This group of strains distinguishes itself from the remainder of pneumococcal strains by extensive differences in genomic composition and by the ability to cause conjunctivitis. We find that the presence of sspB increases adherence of pneumococcus to the ocular epithelium. Thus, our data support the hypothesis that a subset of pneumococcal strains has gained genes from neighboring species that enhance their ability to colonize the epithelium of the eye, thus expanding into a new niche.

A Moraxella catarrhalis vaccine to protect against otitis media and exacerbations of COPD: An update on current progress and challenges

Moraxella catarrhalis is a major cause of morbidity and mortality worldwide, especially causing otitis media in young children and exacerbations of chronic obstructive pulmonary disease in adults. This pathogen uses several virulence mechanisms to colonize and survive in its host, including adherence and invasion of host cells, formation of polymicrobial biofilms with other bacterial pathogens, and production of β-lactamase. Given the global impact of otitis media and COPD, an effective vaccine to prevent M. catarrhalis infection would have a huge impact on the quality of life in both patient populations by preventing disease, thus reducing morbidity and health care costs. A number of promising vaccine antigens have been identified for M. catarrhalis. The development of improved animal models of M. catarrhalis disease and identification of a correlate of protection are needed to accelerate vaccine development. This review will discuss the current state of M. catarrhalis vaccine development, and the challenges that must be addressed to succeed.

Molecular characterization of pneumococcal surface protein K, a potential pneumococcal vaccine antigen

The pneumococcal capsule is indispensable for pathogenesis in systemic infections; however, many pneumococcal diseases, including conjunctivitis, otitis media, and some systemic infections in immunocompromised patients, are caused by nonencapsulated Streptococcus pneumoniae (NESp). Null capsule clade 1 (NCC1), found in group 2 NESp, expresses pneumococcal surface protein K (PspK) and is becoming prevalent among pneumococcal organisms owing to the widespread use of pneumococcal conjugate vaccines. Despite its clinical importance, the molecular mechanisms underlying the prevalence of NCC1 have not been fully elucidated. Here, we investigated the role of the R3 domain of PspK in the epithelial cell adherence of NCC1. We found that the R3 domain of PspK mediated NCC1 adherence via its direct interaction with the epithelial surface protein annexin A2. Additionally, neutralization with purified recombinant PspK-R3 or rabbit anti-UD:R3 IgG inhibited binding of NESp to lung epithelial cells in vitro. Immunization with the 'repeat' domain of PspK-R3 or PspK-UD:R3 effectively elicited mucosal and systemic immune responses against PspK-R3 and provided protection against nasopharyngeal, lung, and middle ear colonization of NESp in mice. Additionally, we found that rabbit anti-UD:R3 IgG bound to PspC-R1 of the encapsulated TIGR4 strain and that UD:R3 immunization provided protection against nasopharyngeal and lung colonization of TIGR4 and deaths by TIGR4 and D39 in mice. Further studies using 68 pneumococcal clinical isolates showed that 79% of clinical isolates showed cross-reactivity to rabbit anti-UD:R3 IgG. About 87% of serotypes in the 13-valent pneumococcal conjugate vaccine (PCV) and 68% of non-vaccine serotypes were positive for cross-reactivity with rabbit anti-UD:R3 IgG. Thus, the R3 domain of PspK may be an effective vaccine candidate for both NESp and encapsulated Sp.

Juglone alleviates pneumolysin-induced human alveolar epithelial cell injury via inhibiting the hemolytic activity of pneumolysin

Streptococcus pneumoniae (the pneumococcus) is an opportunistic pathogen responsible for several human diseases, including acute otitis media, pneumonia, sepsis and bacterial meningitis, and possesses numerous virulence factors associated with pneumococcal infection and pathogenesis. With the capacity to form pores in cholesterol-rich membranes, pneumolysin (PLY) is a key virulence factor of S. pneumoniae and causes severe tissue damage during pneumococcal infection. Juglone (JG), a natural 1,4-naphthoquinone widely found in the roots, leaves, woods and fruits of Juglandaceae walnut trees, inhibits PLY-induced hemolysis via inhibition of the oligomerization of PLY and exhibits minimal anti-S. pneumoniae activity. In addition, when human alveolar epithelial (A549) cells were co-cultured with PLY and JG, PLY-mediated cell injury was significantly alleviated. These results indicate that JG directly interacts with PLY to reduce the cytotoxicity of the toxin in human alveolar epithelial cells. Hence, JG is an effective inhibitor of PLY and protects lung cells from PLY-mediated cell injury. This study also provides the basis for the development of anti-virulence drugs for the treatment of S. pneumoniae infections.

Panel 4: Report of the Microbiology Panel

Objective To perform a comprehensive review of the literature from July 2011 until June 2015 on the virology and bacteriology of otitis media in children. Data Sources PubMed database of the National Library of Medicine. Review Methods Two subpanels comprising experts in the virology and bacteriology of otitis media were created. Each panel reviewed the relevant literature in the fields of virology and bacteriology and generated draft reviews. These initial reviews were distributed to all panel members prior to meeting together at the Post-symposium Research Conference of the 18th International Symposium on Recent Advances in Otitis Media, National Harbor, Maryland, in June 2015. A final draft was created, circulated, and approved by all panel members. Conclusions Excellent progress has been made in the past 4 years in advancing our understanding of the microbiology of otitis media. Numerous advances were made in basic laboratory studies, in animal models of otitis media, in better understanding the epidemiology of disease, and in clinical practice. Implications for Practice (1) Many viruses cause acute otitis media without bacterial coinfection, and such cases do not require antibiotic treatment. (2) When respiratory syncytial virus, metapneumovirus, and influenza virus peak in the community, practitioners can expect to see an increase in clinical otitis media cases. (3) Biomarkers that predict which children with upper respiratory tract infections will develop otitis media may be available in the future. (4) Compounds that target newly identified bacterial virulence determinants may be available as future treatment options for children with otitis media.

Potential impact of a Moraxella catarrhalis vaccine in COPD

Moraxella catarrhalis is the second most common cause of exacerbations in adults with COPD, resulting in enormous morbidity and mortality in this clinical setting. Vaccine development for M. catarrhalis has lagged behind the other two important causes of exacerbations in COPD, nontypeable Haemophilus influenzae and Streptococcus pneumoniae. While no licensed vaccine is currently available for M. catarrhalis, several promising candidate vaccine antigens have been identified and characterized and are close to entering clinical trials. Key steps that are required to advance vaccines for M. catarrhalis along the translational pipeline include standardization of assay systems to assess candidate antigens, identification of a reliable correlate of protection and expansion of partnerships between industry, academia and government to overcome regulatory hurdles. A vaccine to prevent M. catarrhalis infections in COPD would have a major impact in reducing morbidity, mortality and healthcare costs in COPD.

N-Acetyl-l-Cysteine and Cysteamine as New Strategies against Mixed Biofilms of Nonencapsulated Streptococcus pneumoniae and Nontypeable Haemophilus influenzae

Acute otitis media, a polymicrobial disease of the middle ear cavity of children, is a significant public health problem worldwide. It is most frequently caused by encapsulated Streptococcus pneumoniae and nontypeable Haemophilus influenzae, although the widespread use of pneumococcal conjugate vaccines is apparently producing an increase in the carriage of nonencapsulated S. pneumoniae Frequently, pneumococci and H. influenzae live together in the human nasopharynx, forming a self-produced biofilm. Biofilms present a global medical challenge since the inherent antibiotic resistance of their producers demands the use of large doses of antibiotics over prolonged periods. Frequently, these therapeutic measures fail, contributing to bacterial persistence. Here, we describe the development of an in vitro nonencapsulated S. pneumoniae-nontypeable H. influenzae biofilm system with polystyrene or glass-bottom plates. Confocal laser scanning microscopy and specific fluorescent labeling of pneumococcal cells with Helix pomatia agglutinin revealed an even distribution of both species within the biofilm. This simple and robust protocol of mixed biofilms was used to test the antimicrobial properties of two well-known antioxidants that are widely used in the clinical setting, i.e., N-acetyl-l-cysteine and cysteamine. This repurposing approach showed the high potency of N-acetyl-l-cysteine and cysteamine against mixed biofilms of nonencapsulated S. pneumoniae and nontypeable H. influenzae Decades of clinical use mean that these compounds are safe to use, which may accelerate their evaluation in humans.

Type IV Pilus Expression Is Upregulated in Nontypeable Haemophilus influenzae Biofilms Formed at the Temperature of the Human Nasopharynx

Nontypeable Haemophilus influenzae (NTHI), a commensal of the human nasopharynx (hNP), is a common cause of biofilm-associated diseases of the respiratory tract. However, NTHI biofilm biology at the average hNP temperature, i.e., 34°C, has not been well studied. Here we grew NTHI biofilms at 34°C and 37°C, to evaluate relative biofilm growth, expression, and function of the type IV pilus (Tfp), a critical adhesin important for NTHI biofilm formation. The kinetics and regulation of Tfp expression in NTHI biofilms are unclear, especially at 34°C. Tfp expression, as estimated by pilA promoter activity, was distributed throughout the biofilms, with a unique pattern that was dependent on temperature, time in culture, and position within the maturing biofilm. Tfp expression was required for the formation of the characteristic tower structures of NTHI biofilms and was significantly upregulated in NTHI biofilms formed at 34°C versus 37°C. This increase correlated with significantly greater twitching motility at 34°C than at 37°C. Treatment with antisera targeting the major subunit of Tfp (PilA) significantly inhibited NTHI biofilm formation at both temperatures, confirming the importance of this critical adhesin in biofilm formation. Additionally, treatment of preestablished biofilms with antisera against PilA significantly decreased biofilm biomass and mean thickness at both temperatures. These results demonstrated a pivotal role for Tfp in NTHI biofilm formation and stability at the temperature of the hNP, and they underscore the utility of PilA as a vaccine candidate for treatment and/or prevention of NTHI biofilm-associated diseases.

IMPORTANCE

NTHI is an important cause of chronic respiratory tract infections, including otitis media, chronic rhinosinusitis, and exacerbations of chronic obstructive pulmonary disease and cystic fibrosis. The chronic and recurrent nature of these diseases is attributed to the presence of bacterial biofilms, which are highly resistant to antimicrobials. We characterized NTHI biofilm growth and expression of PilA, the major subunit of the Tfp, at the temperature of the hNP, which is the commensal habitat of NTHI. Our results expand the current understanding of the role of Tfp during biofilm formation and maturation at the temperature of both the hNP and the middle ear, and they strengthen support for PilA as a vaccine candidate for the prevention and treatment of NTHI biofilm-associated diseases.

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.