[2] Rodents including rats, mice, and chinchillas have been used to study Moraxella catarrhalis with varying degrees of success.

Some individuals disagreed with this change, the rationale being that other members of the genus Moraxella are rod-shaped and rarely caused infections in humans.

[4] However, results from DNA hybridization studies and 16S rRNA sequence comparisons were used to justify inclusion of the species M. catarrhalis in the genus Moraxella.

[4] Moraxella is named after Victor Morax, a Swiss ophthalmologist who first described this genus of bacteria.

[6] The whole genome sequence of M. catarrhalis CCUG 353 type strain was deposited and published in DNA Data Bank of Japan, European Nucleotide Archive, and GenBank in 2016 under the accession number LWAH00000000.

Current estimates have M. catarrhalis as the cause of approximately 10% of all chronic obstructive pulmonary disease exacerbations, impacting millions of people each year.

[14][15] M. catarrhalis is an opportunistic pulmonary invader, and causes harm especially in patients who have compromised immune systems or any underlying chronic disease.

A microbiological evaluation of the patient (a 41-year-old male) revealed that M. catarrhalis was the cause of the disease rather than Neisseria as was previously believed.

[16] Cases of M. catarrhalis infection have been misdiagnosed as normal lung flora or disregarded due to a lack of importance in the pathogen screening at the time, contributing to the trend of infrequent reporting of M.

Likewise, respiratory debility in patients with bacteremic pneumonia caused by M. catarrhalis infection can be linked with increased rates of pharyngeal colonization, enhancement of bacterial adherence to abnormal epithelium, and increased susceptibility of pulmonary parenchyma to infection.

[12] However, a 1994 study has identified a large protein on the surface of M. catarrhalis that may serve as a target for protective antibodies.

Likewise, passive immunization of M. catarrhalis from the mice respiratory tracts also enhanced the mice's ability to clear the microbes from their lungs, which means that serum antibodies likely play a large role in the immunization and protection of the respiratory tract.

M. catarrhalis can be treated oral antibiotics including trimethoprim-sulfamethoxazole (TMP-SMX), tetracycline, fluoroquinolones, most second- and third-generation cephalosporins, erythromycin, and amoxicillin-clavulanate.

It is a significant cause of otitis media and respiratory tract infections against which a vaccine is sought.

[22] A vaccine against M. catarrhalis has been sought after to develop protective immunity in individuals that are at higher risk of infection from this bacterium, such as COPD patients.

[22] Vaccine candidates for M. catarrhalis are dependent on multiple factors, including whether the candidates are expressed on the surface of the cell, whether they are conserved across different strains of M. catarrhalis, whether they play a role in the colonization of the bacteria, or whether they cause an immune response in individuals infected.

[22] Several outer membrane proteins have been investigated for their potential role in generating a vaccine against M. catarrhalis.

Porin M35 was sequenced and found to have almost 100% conservation among isolated samples of M. catarrhalis, and produced immune responses and bacteria clearance in mice.

The outer membrane protein (OMP) profiles of different strains of M. catarrhalis are extremely similar to each other.

[13] Analyses of these OMP profiles with monoclonal antibodies (MAbs) revealed that a few proteins with similar molecular masses in the different strains have cross-reactive epitopes.

[20] Multiple M. catarrhalis proteins have been predicted or tested to contain the highly conserved leader motif for translocation and to be transported by the TAT pathway.