A Unique Case of Moraxella catarrhalis Meningitis Following Neurosurgical Intervention.

We present a rare case of Moraxella catarrhalis meningitis in a 51-year-old immunocompetent woman after surgical resection of a fourth ventricle ganglioma. Notably, the patient had no history of sinusitis or otitis media, which are typical predisposing factors for Moraxella infection. She developed symptoms including headache, altered mental status, and neurological deficits three days post discharge, leading to her diagnosis confirmed by cerebrospinal fluid culture. This case highlights the diagnostic challenges and management complexities of atypical meningitis post neurosurgery. The occurrence emphasizes the necessity of considering Moraxella catarrhalis in differential diagnoses, particularly following neurosurgical procedures. This instance contributes to the scarce documentation of such infections in immunocompetent adults, underscoring the importance of vigilant microbiological evaluation and tailored antimicrobial therapy in postoperative settings.

The Moraxella catarrhalis AdhC-FghA system is important for formaldehyde detoxification and protection against pulmonary clearance.

Multidrug-resistant clinical isolates of Moraxella catarrhalis have emerged, increasing the demand for the identification of new treatment and prevention strategies. A thorough understanding of how M. catarrhalis can establish an infection and respond to different stressors encountered in the host is crucial for new drug-target identification. Formaldehyde is a highly cytotoxic compound that can be produced endogenously as a by-product of metabolism and exogenously from environmental sources. Pathways responsible for formaldehyde detoxification are thus essential and are found in all domains of life. The current work investigated the role of the system consisting of the S-hydroxymethyl alcohol dehydrogenase (AdhC), a Zn-dependent class III alcohol dehydrogenase, and the S-formyl glutathione hydrolase (FghA) in the formaldehyde detoxification process in M. catarrhalis. Bioinformatics showed that the components of the system are conserved across the species and are highly similar to those of Streptococcus pneumoniae, which share the same biological niche. Isogenic mutants were constructed to study the function of the system in M. catarrhalis. A single fghA knockout mutant did not confer sensitivity to formaldehyde, while the adhC-fghA double mutant is formaldehyde-sensitive. In addition, both mutants were significantly cleared in a murine pulmonary model of infection as compared to the wild type, demonstrating the system's importance for this pathogen's virulence. The respective phenotypes were reversed upon the genetic complementation of the mutants. To date, this is the first study investigating the role of the AdhC-FghA system in formaldehyde detoxification and pathogenesis of M. catarrhalis.

Bacterial antigens and asthma: a comparative study of common respiratory pathogenic bacteria.

Objective: In a previous study we have shown that, in the presence of interleukin (IL)-33, repeated, per-nasal challenge of murine airways with Streptococcus pneumoniae (S. pneumoniae) organisms induces human asthma-like airways inflammation. It is not clear, however, whether this effect is unique or manifest in response to other common respiratory pathogens.Methods: To explore this, airways of BALB/c mice were repeatedly challenged per-nasally with formaldehyde-inactivated bacterial bodies in the presence or absence of murine recombinant IL-33. Serum concentrations of S.pneumoniae, Moraxella catarrhalis (M.catarrhalis) and Haemophilus influenzae (H.influenzae) lysates-specific IgE were measured in patients with asthma and control subjects.Results: We showed that in the presence of IL-33, repeated, per-nasal airways exposure to the bodies of these bacteria induced airways hyperresponsiveness (AHR) in the experimental mice. This was accompanied by cellular infiltration into bronchoalveolar lavage fluid (BALF), eosinophilic infiltration and mucous hypertrophy of the lung tissue, with elevated local expression of some type 2 cytokines and elevated, specific IgG and IgE in the serum. The precise characteristics of the inflammation evoked by exposure to each bacterial species were distinguishable.Conclusions: These results suggest that in the certain circumstances, inhaled or commensal bacterial body antigens of both Gram-positive (S. pneumoniae) and Gram-negative (M. catarrhalis and H. influenzae) respiratory tract bacteria may initiate type 2 inflammation typical of asthma in the airways. In addition, we demonstrated that human asthmatic patients manifest elevated serum concentrations of M.catarrhalis- and H.influenzae-specific IgE.

Formation and immunological evaluation of Moraxella catarrhalis glycoconjugates based on synthetic oligosaccharides.

Published work has shown that glycoconjugate vaccines, based on truncated detoxified lipopolysaccharides from Moraxella catarrhalis attached through their reducing end to a carrier protein, gave good protection for all three serotypes A, B, and C in mice immunisation experiments. The (from the non-reducing end) truncated LPS structures were obtained from bacterial glycosyl transferase knock-out mutants and contained the de-esterified Lipid A, two Kdo residues and five glucose moieties. This work describes the chemical synthesis of the same outer Moraxella LPS structures, spacer-equipped and further truncated from the reducing end, i.e., without the Lipid A part and containing four or five glucose moieties or four glucose moieties and one Kdo residue, and their subsequent conjugation to a carrier protein via a five­carbon bifunctional spacer to form glycoconjugates. Immunisation experiments both in mice and rabbits of these gave a good antibody response, being 2-7 times that of pre-immune sera. However, the sera produced only recognized the immunizing glycan immunogens and failed to bind to native LPS or whole bacterial cells. Comparative molecular modelling of three alternative antigens shows that an additional (2 â†’ 4)-linked Kdo residue, not present in the synthetic structures, has a significant impact on the shape and volume of the molecule, with implications for antigen binding and cross-reactivity.

Stress-Tolerant Dormant Bacterial Forms: Biological and Ultrastructural Properties of Moraxella catarrhalis and Kocuria rhizophila.

Dormant forms of causative agents of healthcare-acquired infections Moraxella catarrhalis and Kocuria rhizophila have been obtained. Dormant forms cells retained viability during long-term storage (≈107 CFU/ml after 2 months) under provocative conditions (lack of nutrient sources; temperature 20°C, oxygen access) were characterized by heat resistance, and acquired special ultrastructural organization typical of dormant forms (compacted nucleoid, thickened cell wall). They were also capable of forming alternative phenotypes (dominant and small colony variants) in a new cycle of germination in a fresh medium. These results demonstrate that the dormant forms can be responsible both for survival in the environment and persistence in the host organism.

Inhibiting F-Actin Polymerization Impairs the Internalization of Moraxella catarrhalis.

Moraxella catarrhalis, a commensal in the human nasopharynx, plays a significant role in the acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Its pathogenicity involves adherence to respiratory epithelial cells, leading to infection through a macropinocytosis-like mechanism. Previous investigations highlighted the diverse abilities of M. catarrhalis isolates with different phenotypes to adhere to and invade respiratory epithelial cells. This study used a murine COPD model and in vitro experiments to explore the factors influencing the pathogenicity of distinct phenotypes of M. catarrhalis. Transcriptome sequencing suggested a potential association between actin cytoskeleton regulation and the infection of lung epithelial cells by M. catarrhalis with different phenotypes. Electron microscopy and Western blot analyses revealed a decrease in filamentous actin (F-actin) expression upon infection with various M. catarrhalis phenotypes. Inhibition of actin polymerization indicated the involvement of F-actin dynamics in M. catarrhalis internalization, distinguishing it from the adhesion process. Notably, hindering F-actin polymerization impaired the internalization of M. catarrhalis. These findings contribute vital theoretical insights for developing preventive strategies and individualized clinical treatments for AECOPD patients infected with M. catarrhalis. The study underscores the importance of understanding the nuanced interactions between M. catarrhalis phenotypes and host lung epithelial cells, offering valuable implications for the management of AECOPD infections.

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.

TLR2 regulates Moraxella catarrhalis adhesion to and invasion into alveolar epithelial cells and mediates inflammatory responses.

Moraxella catarrhalis is a major cause of chronic obstructive pulmonary disease. Toll-like receptor 2 (TLR2) plays an important role in the inflammatory response in host respiratory epithelial cells. M. catarrhalis induces an inflammatory immune response in respiratory epithelial cells that is mostly dependent on TLR2. However, the mechanisms by which this pathogen adheres to and invades the respiratory epithelium are not well understood. The present study aimed to reveal the role of TLR2 in M. catarrhalis adhesion to and invasion into alveolar epithelial cells, using molecular techniques. Pretreatment with the TLR2 inhibitor TLR2-IN-C29 enhanced M. catarrhalis adhesion to A549 cells but reduced its invasion, whereas the agonist Pam3CSK4 reduced both M. catarrhalis adhesion and invasion into A549 cells. Similarly, M. catarrhalis 73-OR strain adhesion and invasion were significantly reduced in TLR2-/- A549 cells. Moreover, the lung clearance rate of the 73-OR strain was significantly higher in TLR2-/- C57/BL6J mice than in wild-type (WT) mice. Histological analysis showed that inflammatory responses were milder in TLR2-/- C57/BL6J mice than in WT mice, which was confirmed by a decrease in cytokine levels in TLR2-/- C57/BL6J mice. Overall, these results indicate that TLR2 promoted M. catarrhalis adhesion and invasion of A549 cells and lung tissues and mediated inflammatory responses in infected lungs. This study provides important insights into the development of potential therapeutic strategies against M. catarrhalis and TLR2-induced inflammatory responses.

Exploring the microbial landscape: uncovering the pathogens associated with community-acquired pneumonia in hospitalized patients.

Objectives: This study aimed to investigate the etiology, clinical features, and outcomes of community-acquired pneumonia (CAP) in adults. Understanding the causative pathogens is essential for effective treatment and prevention. Design: Between 2016-2018, 518 hospitalized adults with CAP and 241 controls without symptoms were prospectively enrolled. Urine samples were collected for pneumococcal urinary antigen tests and nasopharyngeal swabs for viral and bacterial analysis, combined with routine diagnostic care. Results: Among the included CAP patients, Streptococcus pneumoniae was the most common pathogen, detected in 28% of patients, followed by Haemophilus influenzae in 16%. Viruses were identified in 28%, and concurrent viruses and bacteria were detected in 15%. There was no difference in mortality, length of stay, or symptoms at hospitalization when comparing patients with bacterial, viral, or mixed etiologies. Among the control subjects without respiratory symptoms, S. pneumoniae, H. influenzae, or Moraxella catarrhalis were detected in 5-7%, and viruses in 7%. Conclusion: Streptococcus pneumoniae emerged as the predominant cause of CAP, followed closely by viruses and H. influenzae. Intriguingly, symptoms and outcome were similar regardless of etiology. These findings highlight the complexity of this respiratory infection and emphasize the importance of comprehensive diagnostic and treatment strategies.Clinical Trial Registration: ClinicalTrials.gov, identifier [NCT03606135].

Ex-vivo RNA expression analysis of vaccine candidate genes in COPD sputum samples.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a lung disease characterised by airflow-limiting inflammation and mucus production. Acute exacerbations are a major cause of COPD-related morbidity and mortality and are mostly associated with bacterial or viral infections. A vaccine targeting non-typeable Haemophilus influenzae (NTHi) and Moraxella catarrhalis (Mcat), the main bacteria associated with exacerbations, was tested in a Phase 2 trial. We assessed "ex-vivo" expression of vaccine candidate and housekeeping genes pd, pe, pilA, gapA, ompP6 of NTHi, and uspA2, parE, polA of Mcat in sputum samples of COPD patients and determined whether expression of the vaccine candidate genes pd, pe, pilA (NTHi) and uspA2 (Mcat) differed between stable and exacerbation samples. METHODS: A single-centre, prospective, observational cohort study was conducted where 123 COPD patients were seen on enrolment, followed monthly for 2 years, and reviewed after onset of acute exacerbations. We selected 69 patients with sputum samples positive for NTHi or Mcat by PCR during at least one stable and one exacerbation visit. mRNA was isolated from the sputum, and expression of NTHi and Mcat genes was analysed with RT-PCR. Statistical analyses compared mRNA concentrations between stable and exacerbation samples and in relationship to COPD severity and exacerbation frequency. RESULTS: The vaccine candidate genes were variably expressed in sputum samples, suggesting they are expressed in the lung. Absolute and relative expression of all NTHi vaccine candidate genes and Mcat uspA2 were similar between exacerbation and stable samples. Expression of pd and pilA was slightly associated with the number of exacerbations in the year before enrolment, and uspA2 with the disease severity status at enrolment. CONCLUSIONS: The NTHi-Mcat vaccine candidate genes were expressed in sputum samples, and each gene had a specific level of expression. No statistically significant differences in gene expression were detectable between stable and exacerbation samples. However, the history of COPD exacerbations was slightly associated with the expression of pd, pilA and uspA2. Trial registration NCT01360398 ( https://www. CLINICALTRIALS: gov ).

Leveraging the human microbiota to target bacterial respiratory pathogens: new paths toward an expanded antimicrobial armamentarium.

Acute respiratory infections are the most frequent infections across the lifespan and are the leading infectious cause of death among children globally. Bacterial respiratory infections are routinely treated with antibiotics, nearly all of which are derived from microbial natural products. Unfortunately, antibiotic-resistant bacteria are an increasingly frequent cause of respiratory infections, and there are few new antibiotics in development that target these pathogens. In the article by Stubbendieck et al., the authors identified Rothia species that demonstrate in vitro and ex vivo growth inhibition of the respiratory pathobiont Moraxella catarrhalis. The authors present experiments suggesting that this activity is mediated at least in part through the secretion of a novel peptidoglycan endopeptidase that targets the M. catarrhalis cell wall. In this commentary, we discuss these findings in the context of the urgent threat of antimicrobial resistance and highlight the promise of the human respiratory microbiota as a source of novel biotherapeutics.

Haemophilus influenzae and Moraxella catarrhalis in sputum of severe asthma with inflammasome and neutrophil activation.

BACKGROUND: Because of altered airway microbiome in asthma, we analysed the bacterial species in sputum of patients with severe asthma. METHODS: Whole genome sequencing was performed on induced sputum from non-smoking (SAn) and current or ex-smoker (SAs/ex) severe asthma patients, mild/moderate asthma (MMA) and healthy controls (HC). Data were analysed by asthma severity, inflammatory status and transcriptome-associated clusters (TACs). RESULTS: α-diversity at the species level was lower in SAn and SAs/ex, with an increase in Haemophilus influenzae and Moraxella catarrhalis, and Haemophilus influenzae and Tropheryma whipplei, respectively, compared to HC. In neutrophilic asthma, there was greater abundance of Haemophilus influenzae and Moraxella catarrhalis and in eosinophilic asthma, Tropheryma whipplei was increased. There was a reduction in α-diversity in TAC1 and TAC2 that expressed high levels of Haemophilus influenzae and Tropheryma whipplei, and Haemophilus influenzae and Moraxella catarrhalis, respectively, compared to HC. Sputum neutrophils correlated positively with Moraxella catarrhalis and negatively with Prevotella, Neisseria and Veillonella species and Haemophilus parainfluenzae. Sputum eosinophils correlated positively with Tropheryma whipplei which correlated with pack-years of smoking. α- and ß-diversities were stable at one year. CONCLUSIONS: Haemophilus influenzae and Moraxella catarrhalis were more abundant in severe neutrophilic asthma and TAC2 linked to inflammasome and neutrophil activation, while Haemophilus influenzae and Tropheryma whipplei were highest in SAs/ex and in TAC1 associated with highest expression of IL-13 type 2 and ILC2 signatures with the abundance of Tropheryma whipplei correlating positively with sputum eosinophils. Whether these bacterial species drive the inflammatory response in asthma needs evaluation.

The Direct Anti-Virulence but Not Bactericidal Activity of Human Neutrophil Elastase against Moraxella catarrhalis.

Neutrophil elastase (NE) contributes to innate antibacterial defense at both the intracellular (phagocytosis) and extracellular (degranulation, NETosis) levels. Moraxella catarrhalis, a human respiratory pathogen, can exist in an inflammatory milieu which contains NE. No data are available on the action of NE against M. catarrhalis or on the counteraction of NE-dependent host defenses by this pathogen. Using time-kill assays we found that bacteria are able to survive and replicate in the presence of NE. Transmission electron microscopy and flow cytometry studies with NE-treated bacteria revealed that while NE admittedly destabilizes the outer membrane leaflet, it does not cause cytoplasmic membrane rupture, suggesting that the enzyme does not target components that are essential for cell integrity. Using LC-MS/MS spectroscopy we determined that NE cleaved at least three virulent surface proteins in outer membrane vesicles (OMVs) of M. catarrhalis, including OMP CD, McaP, and TbpA. The cleavage of OMP CD contributes to the significant decrease in resistance to serum complement in the complement-resistant strain Mc6. The cleavage of McaP did not cause any sensitization to erythromycin nor did NE disturb its drug action. Identifying NE as a novel but subtle anti-virulence agent together with its extracellularly not-efficient bactericidal activity against M. catarrhalis may facilitate the pathogen's existence in the airways under inflammation.

Rothia from the Human Nose Inhibit Moraxella catarrhalis Colonization with a Secreted Peptidoglycan Endopeptidase.

Moraxella catarrhalis is found almost exclusively within the human respiratory tract. This pathobiont is associated with ear infections and the development of respiratory illnesses, including allergies and asthma. Given the limited ecological distribution of M. catarrhalis, we hypothesized that we could leverage the nasal microbiomes of healthy children without M. catarrhalis to identify bacteria that may represent potential sources of therapeutics. Rothia was more abundant in the noses of healthy children compared to children with cold symptoms and M. catarrhalis. We cultured Rothia from nasal samples and determined that most isolates of Rothia dentocariosa and "Rothia similmucilaginosa" were able to fully inhibit the growth of M. catarrhalis in vitro, whereas isolates of Rothia aeria varied in their ability to inhibit M. catarrhalis. Using comparative genomics and proteomics, we identified a putative peptidoglycan hydrolase called secreted antigen A (SagA). This protein was present at higher relative abundance in the secreted proteomes of R. dentocariosa and R. similmucilaginosa than in those from non-inhibitory R. aeria, suggesting that it may be involved in M. catarrhalis inhibition. We produced SagA from R. similmucilaginosa in Escherichia coli and confirmed its ability to degrade M. catarrhalis peptidoglycan and inhibit its growth. We then demonstrated that R. aeria and R. similmucilaginosa reduced M. catarrhalis levels in an air-liquid interface culture model of the respiratory epithelium. Together, our results suggest that Rothia restricts M. catarrhalis colonization of the human respiratory tract in vivo. IMPORTANCE Moraxella catarrhalis is a pathobiont of the respiratory tract, responsible for ear infections in children and wheezing illnesses in children and adults with chronic respiratory diseases. Detection of M. catarrhalis during wheezing episodes in early life is associated with the development of persistent asthma. There are currently no effective vaccines for M. catarrhalis, and most clinical isolates are resistant to the commonly prescribed antibiotics amoxicillin and penicillin. Given the limited niche of M. catarrhalis, we hypothesized that other nasal bacteria have evolved mechanisms to compete against M. catarrhalis. We found that Rothia are associated with the nasal microbiomes of healthy children without Moraxella. Next, we demonstrated that Rothia inhibit M. catarrhalis in vitro and on airway cells. We identified an enzyme produced by Rothia called SagA that degrades M. catarrhalis peptidoglycan and inhibits its growth. We suggest that Rothia or SagA could be developed as highly specific therapeutics against M. catarrhalis.

An integrated complete-genome sequencing and systems biology approach to predict antimicrobial resistance genes in the virulent bacterial strains of Moraxella catarrhalis.

Moraxella catarrhalis is a symbiotic as well as mucosal infection-causing bacterium unique to humans. Currently, it is considered as one of the leading factors of acute middle ear infection in children. As M. catarrhalis is resistant to multiple drugs, the treatment is unsuccessful; therefore, innovative and forward-thinking approaches are required to combat the problem of antimicrobial resistance (AMR). To better comprehend the numerous processes that lead to antibiotic resistance in M. catarrhalis, we have adopted a computational method in this study. From the NCBI-Genome database, we investigated 12 strains of M. catarrhalis. We explored the interaction network comprising 74 antimicrobial-resistant genes found by analyzing M. catarrhalis bacterial strains. Moreover, to elucidate the molecular mechanism of the AMR system, clustering and the functional enrichment analysis were assessed employing AMR gene interactions networks. According to the findings of our assessment, the majority of the genes in the network were involved in antibiotic inactivation; antibiotic target replacement, alteration and antibiotic efflux pump processes. They exhibit resistance to several antibiotics, such as isoniazid, ethionamide, cycloserine, fosfomycin, triclosan, etc. Additionally, rpoB, atpA, fusA, groEL and rpoL have the highest frequency of relevant interactors in the interaction network and are therefore regarded as the hub nodes. These genes can be exploited to create novel medications by serving as possible therapeutic targets. Finally, we believe that our findings could be useful to advance knowledge of the AMR system present in M. catarrhalis.

Immunogenicity and safety of the non-typable Haemophilus influenzae-Moraxella catarrhalis (NTHi-Mcat) vaccine administered following the recombinant zoster vaccine versus administration alone: Results from a randomized, phase 2a, non-inferiority trial.

A candidate AS01-adjuvanted vaccine containing four surface proteins from non-typable Haemophilus influenzae and Moraxella catarrhalis (NTHi-Mcat) has been developed to help prevent exacerbations of chronic obstructive pulmonary disease (COPD). Sequential administration of different vaccines containing the same AS01-adjuvant system could lead to immune interference. We compared administration of NTHi-Mcat following AS01-adjuvanted recombinant zoster vaccine (RZV) versus NTHi-Mcat alone. This phase 2a, open-label trial (NCT03894969) randomized healthy current or former smokers (50-80 years) without COPD to administration of NTHi-Mcat at 1, 3 or 6 months after RZV or to NTHi-Mcat alone (2-dose for both vaccines). Primary outcome was non-inferiority of the humoral immune response to NTHi-Mcat administered 1 month after RZV versus NTHi-Mcat alone, evaluated by specific antibody geometric mean concentration (GMC) ratio with 95% confidence intervals (CIs). The per-protocol set included 411 participants. Primary objective was met; lower limit of the 95%CI for the GMC ratio above 0.667 for all four vaccine antigens, 1 month after the second NTHi-Mcat dose. NTHi-Mcat induced similar immune response regardless of whether administered alone or 1, 3 or 6 months following RZV. Safety and reactogenicity profiles were acceptable; adverse event frequency was similar among study groups. Injection site pain was the most common symptom. No new safety concerns were identified. The study demonstrated non-inferiority of the immune response elicited by NTHi-Mcat administered sequentially to RZV versus NTHi-Mcat alone, indicating no immune interference. Starting from 1 month, no specific interval is required between RZV and NTHi-Mcat containing the same AS01-adjuvant system components in different quantities.

Colonization Rate and Associated Factors of Non-Pathogenic Neisseria Species, and Moraxella catarrhalis Among Healthy School Children in Gondar, Northwest Ethiopia.

Background: Although commensal Neisseria species inhabiting mucosal surfaces in the upper respiratory tract (URT) are rarely associated with infections, their presence in the area has been linked to the development of immunity against N. meningitidis and the source of antibiotic resistance determinants in pathogenic species. M. catarrhalis in the oropharynx of children is also a predisposing factor for otitis media. As a result, determining the oropharyngeal carriage rate of these commensal species and associated factors among healthy schoolchildren is substantial. Materials and Methods: This community-based cross-sectional study was conducted in Gondar, Northwest Ethiopia, from January to April 2019. A multi-stage and simple random sampling technique were used to select schools and participants, respectively. A total of 524 oropharyngeal swabs were collected using cotton swabs. Modified Thayer-Martin media was used for primary bacterial isolation, and battery of biochemical tests was performed to identify species. For frequencies, descriptive statistics were computed and the logistic regression model was used to see the relationship between dependent and independent variables. Results: A total of 524 healthy schoolchildren with a mean age of 12.2 ± 2.74 years participated in this study. The overall oropharyngeal carriage rate was 21.8% (114/524). Of these, N. meningitidis, N. lactamica, N. sicca, and M. catarrhalis were identified in 53 (46.5%), 14 (12.3%), 11 (9.6%), and 36 (31.6%) children, respectively. The culture positivity rate was higher at a younger age, which was 8.1%, 11.3%, and 14.9% in ages between 15-18, 11-14, and 7-10, respectively. The oropharyngeal carriage was significantly associated with the number of students per class (>40). Conclusion: There is a higher proportion of carriers of commensal N. lactamica and M. catarrhalis in Gondar town schoolchildren. The oropharyngeal carriage rate was associated with a crowded classroom. The characterization of non-pathogenic Neisseria species and M. catarrhalis in the study area can support the diagnosis of patients suspected of having N. meningitis infections.