Modeling airway persistent infection of Moraxella catarrhalis and nontypeable Haemophilus influenzae by using human in vitro models.

Non-typeable Haemophilus influenzae (NTHi) and Moraxella catarrhalis (Mcat) are two common respiratory tract pathogens often associated with acute exacerbations in Chronic Obstructive Pulmonary Disease (COPD) as well as with otitis media (OM) in children. Although there is evidence that these pathogens can adopt persistence mechanisms such as biofilm formation, the precise means through which they contribute to disease severity and chronicity remains incompletely understood, posing challenges for their effective eradication. The identification of potential vaccine candidates frequently entails the characterization of the host-pathogen interplay in vitro even though this approach is limited by the fact that conventional models do not permit long term bacterial infections. In the present work, by using air-liquid-interface (ALI) human airway in vitro models, we aimed to recreate COPD-related persistent bacterial infections. In particular, we explored an alternative use of the ALI system consisting in the assembly of an inverted epithelium grown on the basal part of a transwell membrane with the aim to enable the functionality of natural defense mechanisms such as mucociliary clearance and cellular extrusion that are usually hampered during conventional ALI infection experiments. The inversion of the epithelium did not affect tissue differentiation and considerably delayed NTHi or Mcat infection progression, allowing one to monitor host-pathogen interactions for up to three weeks. Notably, the use of these models, coupled with confocal and transmission electron microscopy, revealed unique features associated with NTHi and Mcat infection, highlighting persistence strategies including the formation of intracellular bacterial communities (IBCs) and surface-associated biofilm-like structures. Overall, this study demonstrates the possibility to perform long term host-pathogen investigations in vitro with the aim to define persistence mechanisms adopted by respiratory pathogens and individuate potential new vaccine targets.

Bactericidal activity of hexylresorcinol lozenges against oropharyngeal organisms associated with acute sore throat.

OBJECTIVE: For the majority of people with acute sore throat, over-the-counter treatments represent the primary option for symptomatic relief. This study evaluated the in vitro bactericidal activity of lozenges containing the antiseptic hexylresorcinol against five bacteria associated with acute sore throat: Staphylococcus aureus, Streptococcus pyogenes, Moraxella catarrhalis, Haemophilus influenzae and Fusobacterium necrophorum. RESULTS: Hexylresorcinol 2.4 mg lozenges were dissolved into 5 mL of artificial saliva medium. Inoculum cultures were prepared in triplicate for each test organism to give an approximate population of 108 colony-forming units (cfu)/mL. Bactericidal activity was measured by log reduction in cfu. Greater than 3log10 reductions in cfu were observed at 1 min after dissolved hexylresorcinol lozenges were added to S. aureus (log10 reduction cfu/mL ± standard deviation, 3.3 ± 0.2), M. catarrhalis (4.7 ± 0.4), H. influenzae (5.8 ± 0.4) and F. necrophorum (4.5 ± 0.2) and by 5 min for S. pyogenes (4.3 ± 0.4). Hexylresorcinol lozenges achieved a > 99.9% reduction in cfu against all tested organisms within 5 min, which is consistent with the duration for a lozenge to dissolve in the mouth. In conclusion, in vitro data indicate that hexylresorcinol lozenges offer rapid bactericidal activity against organisms implicated in acute sore throat.

Otitis media pathogens - A life entrapped in biofilm communities.

Otitis media is a group of inflammatory diseases of the middle ear with great impact on children worldwide. The most common reported bacterial pathogens are Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. Over the last years, the role of biofilms formed by otopathogens that contribute to otitis media recurrence and chronicity has been established. An improved understanding of the properties of biofilms formed by these bacteria, which factors influence them, and how these affect the host inflammatory response is important for the development of novel strategies for the treatment of otitis media. This review focuses on the biofilm nature that the most prevalent otopathogens adopt in otitis media infections. In addition, new treatment approaches targeting biofilms are highlighted.

Moraxella catarrhalis NucM is an entry nuclease involved in extracellular DNA and RNA degradation, cell competence and biofilm scaffolding.

Moraxella catarrhalis is a host-adapted bacterial pathogen that causes otitis media and exacerbations of chronic obstructive pulmonary disease. This study characterises the conserved M. catarrhalis extracellular nuclease, a member of the ßßα metal finger family of nucleases, that we have named NucM. NucM shares conserved sequence motifs from the ßßα nuclease family, including the DRGH catalytic core and Mg2+ co-ordination site, but otherwise shares little primary sequence identity with other family members, such as the Serratia Nuc and pneumococcal EndA nucleases. NucM is secreted from the cell and digests linear and circular nucleic acid. However, it appears that a proportion of NucM is also associated with the cell membrane and acts as an entry nuclease, facilitating transformation of M. catarrhalis cells. This is the first example of a ßßα nuclease in a Gram negative bacteria that acts as an entry nuclease. In addition to its role in competence, NucM affects cell aggregation and biofilm formation by M. catarrhalis, with ΔnucM mutants having increased biofilm biomass. NucM is likely to increase the ability of cells to survive and persist in vivo, increasing the virulence of M. catarrhalis and potentially affecting the behaviour of other pathogens that co-colonise the otorhinolaryngological niche.

Persistence of Moraxella catarrhalis in Chronic Obstructive Pulmonary Disease and Regulation of the Hag/MID Adhesin.

BACKGROUND: Persistence of bacterial pathogens in the airways has profound consequences on the course and pathogenesis of chronic obstructive pulmonary disease (COPD). Patients with COPD continuously acquire and clear strains of Moraxella catarrhalis, a major pathogen in COPD. Some strains are cleared quickly and some persist for months to years. The mechanism of the variability in duration of persistence is unknown. METHODS: Guided by genome sequences of selected strains, we studied the expression of Hag/MID, hag/mid gene sequences, adherence to human cells, and autoaggregation in longitudinally collected strains of M. catarrhalis from adults with COPD. RESULTS: Twenty-eight of 30 cleared strains of M. catarrhalis expressed Hag/MID whereas 17 of 30 persistent strains expressed Hag/MID upon acquisition by patients. All persistent strains ceased expression of Hag/MID during persistence. Expression of Hag/MID in human airways was regulated by slipped-strand mispairing. Virulence-associated phenotypes (adherence to human respiratory epithelial cells and autoaggregation) paralleled Hag/MID expression in airway isolates. CONCLUSIONS: Most strains of M. catarrhalis express Hag/MID upon acquisition by adults with COPD and all persistent strains shut off expression during persistence. These observations suggest that Hag/MID is important for initial colonization by M. catarrhalis and that cessation of expression facilitates persistence in COPD airways.

The bacterial species associated with aspirated foreign bodies in children.

OBJECTIVE: Inhaled foreign bodies in children are common and may be complicated by secondary airway tract infection. The inhaled foreign body may act as carrier of infectious material and the aim of this study was to explore the bacterial species associated with aspirated foreign bodies in a cohort of children. METHODS: Retrospective case series of 34 patients who underwent rigid laryngobronchoscopy because of foreign body aspiration. Each patient had a sample taken from tracheobronchial secretions during the procedure. RESULTS: The average patient age was 31.2 months and the average hospital stay was 2.5 days. Of the foreign bodies 24 (71%) were organic in nature and 10 (29%) were non-organic. Twenty eight (82.3%) patients had mixed oropharyngeal flora organisms growth. Fifteen (44%) samples were positive for organisms other than oropharyngeal flora with the most common cultured organisms being: Streptococcus pneumonia (4/12%), Haemophilus influenza (4/12%), Moraxella catarrhalis (4/12%). Four samples (12%) grew a fungus; Candida albicans was cultured in 3 patients and Aspergillus glaucus was identified in one sample. Of the non-oropharyngeal organisms 7(47%) demonstrated antibiotic resistance with four having resistance to amoxycillin, two resistant to penicillin and one resistant to cotrimoxazole. CONCLUSION: Some children who present with aspirated foreign body may be complicated with secondary airway infection. Antibacterial treatment might be considered in some of these cases. The regimen of antibiotics should aim to cover oropharyngeal flora, S. pneumonia, H. influenza and Moraxella catarrhalis.

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

OBJECTIVES: We sought to understand how polymicrobial colonization varies during health, viral upper respiratory infection (URI) and acute upper respiratory bacterial infection to understand differences in infection-prone vs. non-prone patients. METHODS: Nasopharyngeal (NP) samples were collected from 74 acute otitis media (AOM) infection-prone and 754 non-prone children during 2094 healthy visits, 673 viral URI visits and 631 AOM visits. Three otopathogens Streptococcus pneumoniae (Spn), Nontypeable Haemophilus influenzae (NTHi), and Moraxella catarrhalis (Mcat) were identified by culture. RESULTS: NP colonization rates of multiple otopathogens during health were significantly lower than during viral URI, and during URI they were lower than at onset of upper respiratory bacterial infection in both AOM infection-prone and non-prone children. AOM infection-prone children had higher polymicrobial colonization rates than non-prone children during health, viral URI and AOM. Polymicrobial colonization rates of AOM infection-prone children during health were equivalent to that of non-prone children during viral URI, and during viral URI were equivalent to that of non-prone during AOM infection. Spn colonization was positively associated with NTHi and Mcat colonization during health, but negatively during AOM infection. CONCLUSION: The infection-prone patients more frequently have multiple potential bacterial pathogens in the NP than the non-prone patients. Polymicrobial interaction in the NP differs during health and at onset of infection.

Quantification of biofilm formation on silicone intranasal splints: An in vitro study.

OBJECTIVES: Biofilms are associated with persistent infections and resistant to conventional therapeutic strategies. The aim of this study was to investigate the quantity of biofilm produced on silicone intranasal splints. METHODS: Quantity of biofilm formation on silicone splints (SS) was tested on 15 strains of Staphylococcus aureus and Moraxella catarrhalis, respectively. Antimicrobial susceptibility testing was performed in accordance with European Committee on Antimicrobial Susceptibility Testing recommendations. RESULTS: All tested strains formed different amounts of biofilm on SS: 66.7% S. aureus and 93.3% M. catarrhalis were weak biofilm producers and 33.3% S. aureus and 6.7% M. catarrhalis were moderate biofilm producers. S. aureus formed significantly higher quantity of biofilm compared with M. catarrhalis (p < 0.05). Multidrug resistant S. aureus produced significantly higher amount of biofilm compared with non-multidrug resistant strains (p < 0.05). CONCLUSION: Quantity of biofilm on SS is highly dependent on bacterial species and their resistance patterns. Future studies are needed to ascertain another therapeutic option for prophylaxis prior to SS placement.

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

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

Moraxella catarrhalis induces CEACAM3-Syk-CARD9-dependent activation of human granulocytes.

The human restricted pathogen Moraxella catarrhalis is an important causal agent for exacerbations in chronic obstructive lung disease in adults. In such patients, increased numbers of granulocytes are present in the airways, which correlate with bacteria-induced exacerbations and severity of the disease. Our study investigated whether the interaction of M. catarrhalis with the human granulocyte-specific carcinoembryonic antigen-related cell adhesion molecule (CEACAM)-3 is linked to NF-κB activation, resulting in chemokine production. Granulocytes from healthy donors and NB4 cells were infected with M. catarrhalis in the presence of different inhibitors, blocking antibodies and siRNA. The supernatants were analysed by enzyme-linked immunosorbent assay for chemokines. NF-κB activation was determined using a luciferase reporter gene assay and chromatin-immunoprecipitation. We found evidence that the specific engagement of CEACAM3 by M. catarrhalis ubiquitous surface protein A1 (UspA1) results in the activation of pro-inflammatory events, such as degranulation of neutrophils, ROS production and chemokine secretion. The interaction of UspA1 with CEACAM3 induced the activation of the NF-κB pathway via Syk and the CARD9 pathway and was dependent on the phosphorylation of the CEACAM3 ITAM-like motif. These findings suggest that the CEACAM3 signalling in neutrophils is able to specifically modulate airway inflammation caused by infection with M. catarrhalis.

Haemophilus influenzae biofilm formation in chronic otitis media with effusion.

Otitis media with effusion (OME) is a highly prevalent disease in children, but the exact pathogenesis and role of bacteria are still not well understood. This study aimed to investigate the presence of otopathogenic bacteria in the middle ear effusion (MEE) and adenoid of children with chronic OME (COME), and to investigate in vivo whether these bacteria, especially Haemophilus influenzae, are organized as a biofilm in the middle ear fluid. MEE and adenoid samples were collected from 21 patients with COME. Extensive bacterial culturing and genotyping was performed on all middle ear and adenoid samples. Fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy (CLSM) was used to visualize possible biofilm structures for a selection of middle ear effusion samples. 34 MEE samples were collected from 21 patients of which 64.7 % were culture positive for bacteria and 47.0 % were culture positive for Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus and/or Streptococcus pneumoniae. All 21 adenoid samples were culture positive for one or more of these four otopathogens. H. influenzae (35.3 %) and S. pneumoniae (76.2 %) were the most frequently cultured bacteria in the MEE and adenoid samples, respectively. The same bacterial species was found in MEE and adenoid for 84.6 % of the patients and in 81.2 % of the cases where the same species was found in more than one site it involved the same bacterial genotype. FISH and CLSM demonstrated the presence of H. influenzae specific biofilm structures in five of the eight culture positive MEEs that were tested, but in none of the two culture negative MEEs. The findings in this study indicate that the adenoid acts as a reservoir for bacteria in MEE and confirms that biofilms, in at least half of the cases consisting of H. influenzae, are indeed present in the MEE of children with COME. Biofilms may thus play a crucial role in the pathogenesis of COME, which is important in the understanding of this disease and the development of potential future treatment options.

The Respiratory Pathogen Moraxella catarrhalis Targets Collagen for Maximal Adherence to Host Tissues.

UNLABELLED: Moraxella catarrhalis is a human respiratory pathogen that causes acute otitis media in children and is associated with exacerbations in patients suffering from chronic obstructive pulmonary disease (COPD). The first step in M. catarrhalis colonization is adherence to the mucosa, epithelial cells, and extracellular matrix (ECM). The objective of this study was to evaluate the role of M. catarrhalis interactions with collagens from various angles. Clinical isolates (n= 43) were tested for collagen binding, followed by a detailed analysis of protein-protein interactions using recombinantly expressed proteins.M. catarrhalis-dependent interactions with collagen produced by human lung fibroblasts and tracheal tissues were studied by utilizing confocal immunohistochemistry and high-resolution scanning electron microscopy. A mouse smoke-induced chronic obstructive pulmonary disease (COPD) model was used to estimate the adherence of M. catarrhalis in vivo. We found that all M. catarrhalis clinical isolates tested adhered to fibrillar collagen types I, II, and III and network-forming collagens IV and VI. The trimeric autotransporter adhesins ubiquitous surface protein A2(UspA2) and UspA2H were identified as major collagen-binding receptors.M. catarrhalis wild type adhered to human tracheal tissue and collagen-producing lung fibroblasts, whereas UspA2 and UspA2H deletion mutants did not. Moreover, in the COPD mouse model, bacteria devoid of UspA2 and UspA2H had a reduced level of adherence to the respiratory tract compared to the adherence of wild-type bacteria. Our data therefore suggest that theM. catarrhalisUspA2 and UspA2H-dependent interaction with collagens is highly critical for adherence in the host and, furthermore, may play an important role in the establishment of disease. IMPORTANCE: The respiratory tract pathogen Moraxella catarrhalis adheres to the host by interacting with several components, including the ECM. Collagen accounts for 30% of total body proteins, and therefore, bacterial adherence to abundant host collagens mediates bacterial persistence and colonization. In this study, we characterized previously unknown M. catarrhalis-dependent interactions with host collagens and found that the trimeric autotransporter adhesins ubiquitous surface protein A2(UspA2) and UspA2H are highly important. Our observations also suggested that collagen-mediated adherence ofM. catarrhalis is indispensable for bacterial survival in the host, as exemplified by a mouse COPD model.

Moraxella catarrhalis decreases antiviral innate immune responses by down-regulation of TLR3 via inhibition of p53 in human bronchial epithelial cells.

Chronic obstructive pulmonary disease (COPD) is complicated by infectious exacerbations with acute worsening of respiratory symptoms. Coinfections of bacterial and viral pathogens are associated with more severe exacerbations. Moraxella catarrhalis is one of the most frequent lower respiratory tract pathogens detected in COPD. We therefore studied the impact of M. catarrhalis on the antiviral innate immune response that is mediated via TLR3 and p53. Molecular interactions between M. catarrhalis and normal human bronchial epithelial (NHBE) cells as well as Beas-2B cells were studied using flow cytometry, quantitative PCR analysis, chromatin immunoprecipitation, RNA interference, and ELISA. M. catarrhalis induces a significant down-regulation of TLR3 in human bronchial epithelial cells. In M. catarrhalis-infected cells, expression of p53 was decreased. We detected a reduced binding of p53 to the tlr3 promoter, resulting in reduced TLR3 gene transcription. M. catarrhalis diminished the TLR3-dependent secretion of IFN-ß, IFN-λ, and chemokine (C-X-C motif) ligand 8. In addition in M. catarrhalis infected cells, expression of rhinovirus type 1A RNA was increased compared with uninfected cells. M. catarrhalis reduces antiviral defense functions of bronchial epithelial cells, which may increase susceptibility to viral infections.-Heinrich, A., Haarmann, H., Zahradnik, S., Frenzel, K., Schreiber, F., Klassert, T. E., Heyl, K. A., Endres, A.-S., Schmidtke, M., Hofmann, J., Slevogt, H. Moraxella catarrhalis decreases antiviral innate immune responses by down-regulation of TLR3 via inhibition of p53 in human bronchial epithelial cells.

Involvement of Staphylococcus aureus and Moraxella catarrhalis in Japanese cedar pollinosis.

BACKGROUND AND OBJECTIVE: From mid February to the end of March, each year ∼30% of Japanese have Japanese cedar pollinosis. Moreover, 10-50% of patients with this pollinosis exhibit nasal manifestations in the preseason. These patients have a predominance of neutrophils but not eosinophils in nasal swabs and high carriage of Staphylococcus aureus. We hypothesized that S. aureus or other bacteria and associated neutrophilia were involved in preseasonal symptoms. METHODS: Cytology and bacterial colony growth were assessed in nasal swabs in the groups of asymptomatic patients in the preseason (PreAsP) (n = 53) and symptomatic patients in the preseason (PreSyP) (n = 60), and in group of symptomatic patients in season (InSyP) (n = 72). RESULTS: In the preseason, high neutrophilia was present in only 20% of the PreAsP group but in 47% of the PreSyP group (p < 0.01). Nasal carriage of S. aureus in the PreAsP and PreSyP groups were 79%, 75%, respectively, whereas, for Moraxella catarrhalis, these were 9% versus 25% (PreAsP versus PreSyP group; p < 0.05). In patients with positive results for S. aureus and M. catarrhalis, the degrees of neutrophilia (-, ±, +, 2+, 3+) in the PreSyP group were larger than in the PreAsP groups (p < 0.01). In the PreSyP group, the magnitude of neutrophilia was greater (p < 0.05) in subgroups with more colonies of S. aureus than in subgroups with fewer colonies. CONCLUSION: Nasal symptoms in the preseason are associated with neutrophilia and nasal colonization with S. aureus and M. catarrhalis. Patients with symptoms in the preseason had improved symptom scores when given prophylactic treatment early in season but had more-severe symptom scores late in season than asymptomatic patients in the preseason. Neutrophil-associated tissue damage related to bacterial colonization may underlie these associations.

Moraxella catarrhalis-produced nitric oxide has dual roles in pathogenicity and clearance of infection in bacterial-host cell co-cultures.

In humans, the free radical nitric oxide (NO) is a concentration-dependent multifunctional signaling or toxic molecule that modulates various physiological and pathological processes, and innate immunity against bacterial infections. Because the expression of bacterial genes encoding nitrite reductase (AniA) and NO reductase (NorB) is highly upregulated in biofilms in vitro, it is important to investigate whether bacterial NO-metabolism might subvert host NO signaling and play pathogenic roles during infection. The Moraxella catarrhalis AniA and NorB directly function in production and reduction of NO. Using M. catarrhalis-human bronchial epithelial cell (HBEC) co-cultures, we recently reported AniA/nitrite-dependent cytotoxic effects on HBECs, including altered protein profiles of HBECs and induced HBEC apoptosis, suggesting bacterial nitrite reduction likely dysregulates host cell gene expression. To further clarify whether nitrite reduction-derived NO or nitrite-dependent stimulation of bacterial growth was responsible for adverse effects on HBECs, we monitored bacterial nitrite reduction, levels of NO in co-cultures and resulted dynamic effects on HBEC proliferation and bacterial viability. This study demonstrated that M. catarrhalis nitrite reduction-derived NO was responsible for observed adverse effects on HBECs at mid-to-late stages of infection. More importantly, our data showed that while nitrite promoted bacterial growth and biofilm formation at early hours of infection, nitrite reduction-derived NO was toxic towards M. catarrhalis in maturing biofilms, suggesting nitrite reduction-derived NO might be a possible dualistic mechanism by which M. catarrhalis promotes diseases and spontaneous resolutions.

Common Cell Shape Evolution of Two Nasopharyngeal Pathogens.

Respiratory infectious diseases are the third cause of worldwide death. The nasopharynx is the portal of entry and the ecological niche of many microorganisms, of which some are pathogenic to humans, such as Neisseria meningitidis and Moraxella catarrhalis. These microbes possess several surface structures that interact with the actors of the innate immune system. In our attempt to understand the past evolution of these bacteria and their adaption to the nasopharynx, we first studied differences in cell wall structure, one of the strongest immune-modulators. We were able to show that a modification of peptidoglycan (PG) composition (increased proportion of pentapeptides) and a cell shape change from rod to cocci had been selected for along the past evolution of N. meningitidis. Using genomic comparison across species, we correlated the emergence of the new cell shape (cocci) with the deletion, from the genome of N. meningitidis ancestor, of only one gene: yacF. Moreover, the reconstruction of this genetic deletion in a bacterium harboring the ancestral version of the locus together with the analysis of the PG structure, suggest that this gene is coordinating the transition from cell elongation to cell division. Accompanying the loss of yacF, the elongation machinery was also lost by several of the descendants leading to the change in the PG structure observed in N. meningitidis. Finally, the same evolution was observed for the ancestor of M. catarrhalis. This suggests a strong selection of these genetic events during the colonization of the nasopharynx. This selection may have been forced by the requirement of evolving permissive interaction with the immune system, the need to reduce the cellular surface exposed to immune attacks without reducing the intracellular storage capacity, or the necessity to better compete for adhesion to target cells.

Long-term survival of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis as isolates and in nasopharyngeal specimens in frozen STGG storage medium.

We evaluated survival in WHO-recommended STGG storage medium of bacteria causing respiratory-tract infection. Streptococcus pneumoniae and Moraxella catarrhalis survived as single and mixed isolates stored at -70°C for 12.5 years, but Haemophilus influenzae less than 4 years. All the bacteria survived in the nasopharyngeal specimens at -70°C for 11 years.

Bactericidal, opsonophagocytic and anti-adhesive effectiveness of cross-reactive antibodies against Moraxella catarrhalis.

Moraxella catarrhalis is a human-restricted significant respiratory tract pathogen. The bacteria accounts for 15-20% of cases of otitis media in children and is an important causative agent of infectious exacerbations of chronic obstructive pulmonary disease in adults. The acquisition of new M. catarrhalis strains plays a central role in the pathogenesis of both mentioned disorders. The antibody-dependent immune response to this pathogen is critical for its effective elimination. Thus, the knowledge about the protective threshold of cross-reactive antibodies with defined functionality seems to be important. The complex analysis of broad-spectrum effectiveness of cross-reactive antibodies against M. catarrhalis has never been performed. The goal of the present study was to demonstrate and compare the bactericidal, opsonophagocytic and blocking function of cross-reacting antibodies produced in response to this bacterium or purified outer membrane proteins incorporated in Zwittergent-based micelles. The multivalent immunogens were used in order to better mimic the natural response of the host. The demonstrated broad-spectrum effectiveness of cross-reactive antibodies in pathogen eradication or inhibition strongly indicates that this pool of antibodies by recognition of pivotal shared M. catarrhalis surface epitopes seems to be an essential additional source to control host-microbe interaction.

Staphylococcus aureus is a major pathogen in severe acute bacterial rhinosinusitis.

PURPOSE: The purpose of this study was to investigate the epidemiology and microbiology of severe acute bacterial rhinosinusitis in patients admitted to a Danish tertiary hospital. METHODS: A retrospective study was performed including all cases of acute rhinosinusitis admitted to the ENT-department of Aarhus University Hospital, in the period 2001 to 2011. RESULTS: In total, 143 cases of acute rhinosinusitis were identified of which 51% were children. The most prevalent bacterial strains were Staphylococcus aureus followed by group A streptococcus, Haemophilus influenzae and Streptococcus pneumonia. Morexella catarrhalis was only rarely cultured. Anerobes were not assessed routinely. Of all patients, 47.8% presented with orbital complications and 2.1% developed intracranial complications. Patients infected with group A streptococcus had significantly higher leukocyte and neutrophil counts than other patients. All cultured S. aureus were resistant to penicillin, but sensitive to methicillin. CONCLUSION: Our results imply that S. aureus and group A streptococcus are important pathogens in severe and complex cases of ABRS, in addition to the accepted pathogens S. pneumoniae and H. influenzae. On the contrary M. catarrhalis appears less significant. These findings have important implications regarding the selection of relevant treatment strategy in secondary care, which may currently be underestimating the role of S. aureus.

Residence of Streptococcus pneumoniae and Moraxella catarrhalis within polymicrobial biofilm promotes antibiotic resistance and bacterial persistence in vivo.

Otitis media (OM) is an extremely common pediatric ailment caused by opportunists that reside within the nasopharynx. Inflammation within the upper airway can promote ascension of these opportunists into the middle ear chamber. OM can be chronic/recurrent in nature, and a wealth of data indicates that in these cases, the bacteria persist within biofilms. Epidemiological data demonstrate that most cases of OM are polymicrobial, which may have significant impact on antibiotic resistance. In this study, we used in vitro biofilm assays and rodent infection models to examine the impact of polymicrobial infection with Moraxella catarrhalis and Streptococcus pneumoniae (pneumococcus) on biofilm resistance to antibiotic treatment and persistence in vivo. Consistent with prior work, M. catarrhalis conferred beta-lactamase-dependent passive protection from beta-lactam killing to pneumococci within polymicrobial biofilms. Moreover, pneumococci increased resistance of M. catarrhalis to macrolide killing in polymicrobial biofilms. However, pneumococci increased colonization in vivo by M. catarrhalis in a quorum signal-dependent manner. We also found that co-infection with M. catarrhalis affects middle ear ascension of pneumococci in both mice and chinchillas. Therefore, we conclude that residence of M. catarrhalis and pneumococci within the same biofilm community significantly impacts resistance to antibiotic treatment and bacterial persistence in vivo.