Otitis Media-causing bacterium Moraxella catarrhalis, previously classified as Neisseria catarrhalis and Branhamella catarrhalis, is a Gram-negative bacterium commonly present as a normal commensal organism in the human respiratory tract.
Although it usually exists harmlessly as part of the normal flora, it has the potential to act as an opportunistic pathogen, particularly when host immunity is weakened or compromised.
It is recognized as a significant cause of several respiratory and related infections, including Otitis Media, sinusitis, ocular infections, and lower respiratory tract infections such as bronchitis and pneumonia.
These infections are most frequently observed in children and elderly individuals, who are considered more vulnerable due to developing or weakened immune defenses.
In uncommon but clinically important situations, Moraxella catarrhalis can also lead to severe invasive systemic infections, including Endocarditis and Meningitis, which may require urgent medical attention.
Taxonomy and Classification of Moraxella catarrhalis
Domain: Bacteria
Kingdom: Pseudomonadati
Phylum: Pseudomonadota
Class: Gammaproteobacteria
Order: Pseudomonadales
Family: Moraxellaceae
Genus: Moraxella
Species:Moraxella catarrhalis (M. catarrhalis)
Morphology and Microscopy of Moraxella catarrhalis
Moraxella catarrhalis is a Gram-negative coccobacillary rod-shaped bacterium that typically occurs in pairs (diplococci) and may occasionally be arranged in short chains.
The bacterial cells measure approximately 0.6–1.0 µm in diameter, making them relatively small under microscopic observation.
It is non-motile, meaning it lacks structures such as flagella required for movement.
It is non-spore-forming, so it does not produce resistant endospores for survival under harsh environmental conditions.
The organism is capsulated, possessing a protective outer capsule that contributes to its virulence by helping it evade host immune defenses.
Morphologically, Moraxella catarrhalis commonly appears as Gram-negative diplococci on Gram staining, closely resembling species of Neisseria.
Due to this close microscopic resemblance to Neisseria, initial differentiation based solely on Gram stain can be difficult, making additional biochemical and molecular identification methods essential for accurate confirmation.
Cultural and Growth Characteristics of Moraxella catarrhalis
Moraxella catarrhalis is an aerobic bacterium, meaning it requires oxygen for growth and grows well on suitable culture media under aerobic incubation conditions.
The optimum growth temperature for this organism ranges between 33°C and 35°C, which closely matches conditions of the human respiratory tract.
Its optimum pH for growth is approximately 7, indicating preference for a neutral environment.
On Nutrient Agar, Moraxella catarrhalis produces small, smooth, grayish-white, convex, and firm colonies. These colonies display the characteristic “hockey puck” appearance, meaning they can be pushed intact across the agar surface when touched with a loop.
On Blood Agar, the colonies are non-hemolytic, indicating they do not cause red blood cell lysis. They typically measure 1–3 mm in diameter and appear round, opaque, convex, and grayish-white in color.
A distinctive feature on Blood Agar is that the colonies remain intact on the agar surface and can be pushed across the medium without breaking apart, demonstrating the classic “hockey puck” phenomenon, which is an important identifying characteristic.
On Chocolate Agar, colonies appear medium-sized, smooth, moist, convex, and pinkish-brown in color, with a firm consistency.
Similar to growth on Blood Agar, colonies on Chocolate Agar also exhibit the characteristic “hockey puck” phenomenon, further aiding laboratory identification of Moraxella catarrhalis.
Biochemical and Identification Tests of Moraxella catarrhalis
Gram Staining: Negative – Moraxella catarrhalis appears as Gram-negative diplococci or coccobacillary rods, typically showing a pink/red coloration after staining.
Catalase Test: Positive – the organism produces the enzyme catalase, which breaks down hydrogen peroxide into water and oxygen, producing visible bubbling.
Oxidase Test: Positive – it contains cytochrome c oxidase, resulting in a positive oxidase reaction and helping differentiate it from many other Gram-negative bacteria.
Indole Test: Negative – Moraxella catarrhalis does not produce indole from tryptophan metabolism.
Citrate Utilization Test: Negative – the bacterium cannot utilize citrate as its sole carbon source.
Glucose Fermentation Test: Negative – it does not ferment glucose for acid production.
Sucrose Fermentation Test: Negative – no fermentation of sucrose occurs.
Lactose Fermentation Test: Negative – the organism does not metabolize lactose.
Mannitol Fermentation Test: Negative – it is unable to ferment mannitol.
DNase Production Test: Positive – it produces deoxyribonuclease (DNase), an important diagnostic characteristic that assists in laboratory identification.
The combination of oxidase positivity, catalase positivity, DNase production, nitrate reduction, and absence of carbohydrate fermentation serves as a key biochemical profile for the accurate identification of Moraxella catarrhalis in clinical microbiology laboratories.
Pathogenesis and Virulence Factors of Moraxella catarrhalis
Adherence
Adherence of Moraxella catarrhalis to the host, particularly to respiratory mucosal epithelial cells, is a crucial initial step in the pathogenesis of infection.
This attachment enables the bacterium to firmly colonize the respiratory epithelium, allowing persistent survival and facilitating the development of infection.
Moraxella catarrhalis produces several adhesins that promote attachment to host cells, including:
Surface protein A family (UspA)
Human erythrocyte agglutinin/Moraxella immunoglobulin D-binding protein (Hag/MID)
Outer membrane protein CD (OMP CD)
Moraxella catarrhalis adherence protein (McaP)
Lipooligosaccharide (LOS)
These surface-associated factors strengthen bacterial attachment and enhance colonization of the respiratory tract.
Invasion
The invasive ability of Moraxella catarrhalis has been observed primarily in vitro under laboratory conditions.
This process is regulated through the expression of UspA1, LOS, and other outer membrane proteins.
Invasion enables the bacterium to resist destruction by host immune defenses and provides protection from the action of certain extracellular antibiotics.
The exact molecular mechanism of invasion remains partially understood, and additional research is required to fully clarify this process.
Biofilm Formation
Moraxella catarrhalis is capable of forming biofilms both in vitro and in vivo.
Biofilm formation enhances bacterial survival by providing protection against:
Host immune responses
Antibiotic action
Environmental stress
The virulence factors UspA and Hag/MID play major roles in regulating and promoting biofilm development.
Biofilm production contributes significantly to chronic and recurrent respiratory infections.
Immune Evasion Strategies – Complement Resistance
Moraxella catarrhalis possesses multiple mechanisms to resist complement-mediated killing by the host immune system.
The bacterium can stimulate all pathways of the human complement system, while simultaneously expressing protective surface structures that interfere with complement activity.
It binds to the host regulatory protein C4b-binding protein through UspA1 and UspA2, helping suppress complement activation.
UspA2 also binds to C3 and vitronectin, which obstructs activation of the alternative complement pathway.
These mechanisms allow the organism to survive and persist within the host.
Virulence Factors
Outer Membrane Proteins (OMPs)
Outer membrane proteins facilitate bacterial adhesion to host epithelial cells.
They promote colonization of the respiratory mucosa and contribute to persistent infection.
These proteins also play a role in immune system interaction and bacterial survival.
Human Erythrocyte Agglutinin/Moraxella Immunoglobulin D-binding Protein (Hag/MID)
Hag/MID is an important multifunctional outer membrane protein.
It mediates attachment of the bacterium to host respiratory tract cell lines.
Its expression is influenced by phase variation, which helps the bacterium adapt to changing host conditions.
It also contributes to immune modulation and immune evasion.
Lipooligosaccharide (LOS)
LOS functions as an endotoxin.
It stimulates inflammation by triggering the release of pro-inflammatory cytokines such as:
IL-1
TNF-α
This inflammatory response contributes to tissue damage and disease symptoms.
These enzymes hydrolyze β-lactam antibiotics, providing resistance to:
Penicillin
Ampicillin
Related β-lactam antibiotics
This resistance complicates treatment and necessitates careful antibiotic selection.
Complement Resistance
Complement resistance is a major virulence trait of Moraxella catarrhalis.
It enables the bacterium to evade destruction by the host complement system, promoting persistence and increasing pathogenic potential.
Epidemiology of Moraxella catarrhalis
In 1896, this bacterium was originally named Mikrokokkus catarrhalis in German and was later referred to as Micrococcus catarrhalis in English.
In 1963, Micrococcus catarrhalis was divided into two distinct species:
Neisseria catarrhalis
Neisseria cinerea
This classification was based on differences in:
Nitrate and nitrite reduction
Hydrolysis of tributyrin
In 1970, the organism was renamed Branhamella catarrhalis after phylogenetic studies showed that it differed significantly from Neisseria.
Finally, in 1984, based on the genetic relatedness of its 16S rRNA sequence to the genus Moraxella, it was officially classified as Moraxella catarrhalis.
Over the last 20–30 years, Moraxella catarrhalis has evolved from being considered a harmless commensal organism to being recognized as a clinically significant respiratory pathogen.
It is now an important cause of upper respiratory tract infections, particularly among:
Healthy children
Elderly individuals
Approximately 15–20% of acute otitis media cases in infants are caused by Moraxella catarrhalis.
The rate of nasopharyngeal colonization is significantly higher in infants than in adults, indicating early-life exposure and colonization.
By the age of 6 months, the colonization rate ranges between 22% and 55%, demonstrating its frequent presence during infancy.
In the United States, approximately 2–4 million severe cases of chronic obstructive pulmonary disease (COPD) exacerbations annually are associated with infection by Moraxella catarrhalis.
Various nosocomial (hospital-acquired) outbreaks involving this bacterium have been reported in both:
Adults
Children
Important risk factors associated with hospital transmission include:
Winter and spring seasons
Multi-bed hospital wards
Seasonal colonization patterns have been observed:
One study reported peak colonization during autumn and winter in healthy children
Another study identified a seasonal peak during winter and spring
These findings indicate that Moraxella catarrhalis demonstrates clear seasonal epidemiological variation.
It has also been reported that children with nasopharyngeal infection caused by Respiratory Syncytial Virus Infection are at a significantly increased risk of developing Acute Otitis Media.
This suggests that viral respiratory infections may predispose the respiratory tract to secondary bacterial infection, facilitating subsequent acute otitis media caused by Moraxella catarrhalis.
Transmission of Moraxella catarrhalis
Moraxella catarrhalis is transmitted through multiple routes, enabling its spread within both community and healthcare settings.
The primary mode of transmission is respiratory droplet spread, in which the bacterium is expelled into the air through coughing, sneezing, or even normal conversation.
During respiratory droplet transmission, infected or colonized individuals release droplets containing the bacteria, which can then be inhaled by nearby susceptible individuals.
This mode of transmission is particularly common among children, who frequently interact in close-contact environments and often have less developed hygiene practices.
Respiratory droplet transmission is especially common in close-contact settings, including households, schools, daycare facilities, and pediatric healthcare environments.
Direct contact transmission is another important route of spread for Moraxella catarrhalis.
This occurs through direct contact with contaminated hands, respiratory secretions, or contaminated surfaces (fomites) carrying the bacterium.
The organism can also spread through the transfer of oral and nasal secretions from one person to another, either directly or indirectly through shared objects.
Direct contact transmission is particularly common in daycare centers, schools, hospitals, and other crowded environments, where close physical interaction facilitates bacterial spread.
Endogenous transmission also plays a significant role in disease development.
In many healthy individuals, Moraxella catarrhalis exists harmlessly as part of the normal nasopharyngeal flora without causing symptoms.
However, under favorable conditions such as weakened immunity, concurrent viral infection, or disruption of normal mucosal defenses, the bacterium may overgrow or migrate to normally sterile anatomical sites.
When the bacterium spreads from the nasopharynx to the middle ear, it can cause Otitis Media.
If it extends into the paranasal sinuses, it may result in Sinusitis.
When it descends into the lower respiratory tract, it can cause infections such as bronchitis and pneumonia, particularly in vulnerable individuals such as young children, elderly adults, and immunocompromised patients.
Clinical Manifestations of Moraxella catarrhalis
Upper Respiratory Tract Infections
Middle Ear Infection (Otitis Media)
Moraxella catarrhalis is a common cause of middle ear infections, particularly in children.
It is one of the major bacterial pathogens associated with pediatric Otitis Media.
Clinical symptoms commonly include:
Ear pain
Fever
Irritability
Difficulty hearing
Sinus Infection (Sinusitis)
This bacterium frequently causes sinus infections, especially in:
Children
Adults with weakened immune systems
Infection results from bacterial colonization and inflammation of the paranasal sinuses.
Common symptoms include:
Greenish-yellow nasal discharge
Facial pressure or pain
Persistent nasal congestion and discharge
Pharyngitis
Pharyngitis caused by Moraxella catarrhalis is comparatively less common.
It involves inflammation of the pharyngeal tissues.
Symptoms generally include:
Sore throat
Mild fever
Lower Respiratory Tract Infections
Bronchitis
Bronchitis caused by Moraxella catarrhalis occurs particularly in:
Adults with underlying lung disease
Hospitalized patients
It is commonly associated with bacterial exacerbation of pre-existing respiratory conditions.
Symptoms include:
Productive cough
Wheezing
Chest discomfort
Pneumonia
Moraxella catarrhalis can cause Pneumonia, particularly in:
Elderly individual
Patients with Chronic Obstructive Pulmonary Disease
The infection may become severe if not treated promptly.
Common symptoms include:
Fever
Dyspnea (shortness of breath)
Productive cough
Chronic Respiratory Disease
Moraxella catarrhalis is strongly associated with exacerbations of chronic respiratory diseases, particularly Chronic Obstructive Pulmonary Disease.
Symptoms include:
Persistent coughing
Wheezing
Excess mucus production
Chest tightness
Shortness of breath
Difficulty breathing
These conditions may progressively worsen over time.
Severe exacerbations can result in serious complications and, in some cases, may be life-threatening.
Pink Eye (Conjunctivitis)
The bacterium can infect the outer membrane of the eye, resulting in Conjunctivitis, commonly known as pink eye.
This infection is observed most frequently in:
Newborns
Young children
It causes redness, irritation, and discharge from the affected eye.
Meningitis
In very rare cases, Moraxella catarrhalis may cause Meningitis, particularly in newborns.
This condition involves inflammation of the protective membranes surrounding the brain and spinal cord.
It requires immediate medical attention due to its potentially life-threatening nature.
Bacteremia
Bacteremia caused by Moraxella catarrhalis is extremely rare.
It is usually reported in immunocompromised individuals or patients with severe underlying illnesses.
Clinical manifestations include:
Fever
Chills
Systemic signs of infection
If untreated, it may progress to severe systemic complications.
Laboratory Diagnosis of Moraxella catarrhalis
Sample Collection
The type of clinical specimen collected depends on the site of infection suspected in the patient.
For middle ear infections, particularly Otitis Media, the preferred specimen is ear discharge.
In cases of Sinusitis, nasal discharge or sinus secretions are collected for laboratory analysis.
For lower respiratory tract infections, including bronchitis and Pneumonia, the recommended sample is sputum.
In suspected cases of bacteremia, blood samples are collected for blood culture and microbiological examination.
Microscopy
During microscopic examination using Gram staining, Moraxella catarrhalis appears as Gram-negative diplococci arranged in pairs, closely resembling species of Neisseria.
Because of this close resemblance to Neisseria, additional cultural and biochemical tests are necessary for accurate identification.
Culture
For culture, the organism is inoculated onto suitable culture media and incubated under aerobic conditions at a temperature of 35–37°C for 18–24 hours.
On Nutrient Agar, colonies appear:
Small
Smooth
Grayish-white
Convex
Firm in consistency
Colonies on Nutrient Agar also demonstrate the characteristic “hockey puck” appearance, meaning they can be pushed intact across the agar surface without disintegrating.
On Blood Agar, colonies are:
Non-hemolytic
Approximately 1–3 mm in size
Round
Opaque
Convex
Grayish-white in color
Colonies on Blood Agar remain intact over the surface of the medium and exhibit the classic “hockey puck phenomenon”, which is an important identifying feature of Moraxella catarrhalis.
On Chocolate Agar, colonies appear:
Medium-sized
Smooth
Pinkish-brown
Moist
Convex
Firm in consistency
Colonies on Chocolate Agar also demonstrate the characteristic firm hockey puck consistency.
Biochemical Tests
Following culture, isolated colonies are subjected to a series of biochemical tests for confirmation and identification.
The organism shows the following biochemical characteristics:
Gram staining: Negative
Catalase test: Positive
Oxidase test: Positive
Indole test: Negative
Citrate utilization test: Negative
Glucose fermentation test: Negative
Sucrose fermentation test: Negative
Lactose fermentation test: Negative
Mannitol fermentation test: Negative
Nitrate reduction test: Positive
DNase production test: Positive
The combination of oxidase positivity, catalase positivity, nitrate reduction, DNase production, and lack of carbohydrate fermentation is highly useful in differentiating Moraxella catarrhalis from other Gram-negative respiratory bacteria.
Molecular Methods (PCR)
Advanced laboratories may use Polymerase Chain Reaction (PCR) and other molecular diagnostic techniques for the rapid and accurate identification of Moraxella catarrhalis.
Molecular methods provide improved sensitivity and specificity, especially in cases where culture results are inconclusive or when rapid diagnosis is required.
Treatments of Moraxella catarrhalis
First-line Antibiotics
Amoxicillin-clavulanic acid is commonly used as a first-line treatment, with a typical dosage of 625 mg three times daily for 14 days.
Trimethoprim-sulfamethoxazole may also be used for susceptible infections caused by Moraxella catarrhalis.
Macrolide antibiotics, particularly Azithromycin, are effective alternatives, especially in patients allergic to penicillin.
Extended-spectrum cephalosporins, such as Cefixime, are also commonly prescribed for respiratory tract infections caused by this organism.
Selection of antibiotics should ideally be guided by:
Clinical severity
Local resistance patterns
Patient age and medical history
Antibiotic susceptibility testing when available
Alternative Antibiotics
Clarithromycin may be administered at a dose of 500 mg twice daily for 14 days.
Doxycycline can be used at a dose of 100 mg twice daily for 14 days, particularly in adults.
Ciprofloxacin may be prescribed at doses of 500 mg or 750 mg twice daily for 14 days, especially in severe lower respiratory tract infections.
Alternative antibiotics are generally considered in:
Drug-resistant infections
Penicillin allergy
Severe respiratory disease
Failure of first-line therapy
Supportive Treatment
Proper and adequate hydration is important to maintain fluid balance and assist recovery.
Adequate rest helps improve immune function and supports healing.
Analgesics and antipyretics, such as Ibuprofen, may be used to reduce:
Fever
Pain
Inflammation
General discomfort
Supportive care is particularly important in children, elderly individuals, and patients with chronic respiratory diseases.
Prevention and Control of Moraxella catarrhalis
Regular handwashing with soap and water is essential to reduce transmission.
The use of hand sanitizers while outside or in crowded places further helps minimize bacterial spread.
Individuals should avoid touching the:
Nose
Mouth
Eyes
with unclean hands, as these are common entry points for infection.
Proper respiratory hygiene should be practiced by:
Covering the mouth and nose while coughing or sneezing
Using tissues or the elbow rather than bare hands
Close contact with infected individuals should be avoided whenever possible.
Wearing masks in crowded or high-risk environments can reduce respiratory droplet transmission.
Proper sterilization and disinfection of surfaces and objects touched by infected individuals are important infection-control measures.
Extra precautions should be taken for:
Children
Elderly individuals
Patients with Chronic Obstructive Pulmonary Disease
Prompt and appropriate antibiotic therapy should be initiated to effectively treat infections and reduce complications.
Proper management of underlying respiratory conditions such as:
Chronic Obstructive Pulmonary Disease
Asthma
can help reduce susceptibility to severe infection.
Early diagnosis and treatment of upper respiratory tract infections may help prevent progression to more serious complications such as bronchitis or pneumonia.
Antimicrobial Resistance of Moraxella catarrhalis
Before the mid-1970s, Moraxella catarrhalis was considered a non-β-lactamase-producing bacterium, and infections caused by it were generally susceptible to β-lactam antibiotics.
Over time, however, β-lactamase-producing strains became widespread and are now considered ubiquitous worldwide.
The major β-lactamases associated with antimicrobial resistance in Moraxella catarrhalis include:
BRO-1
BRO-2
BRO-3
These β-lactamases are closely associated with resistant strains and are structurally different from many other β-lactamases, including TEM-type β-lactamases.
The genes responsible for β-lactamase production are mainly located chromosomally on conjugative transposons, which facilitate the spread of resistance genes between bacteria.
In addition to chromosomal localization, the presence of plasmids and transfer of β-lactamase determinants have also been reported.
β-lactamase-producing strains of Moraxella catarrhalis show resistance to several commonly used β-lactam antibiotics, including:
Amoxicillin
Penicillin
Ampicillin
Resistance to amoxicillin has been associated with Minimum Inhibitory Concentration (MIC) values ranging from 16–64 mg/L, indicating markedly reduced susceptibility.
These resistant strains also demonstrate decreased susceptibility to several cephalosporins, including cefuroxime, with MIC values ranging from 16–128 mg/L.
Epidemiological studies have shown increasing resistance rates over time in different regions of the world.
In Europe, resistance rates increased from approximately 70% in 1992 to 82% in 1993.
In the United States, resistance rates also showed a slight increase, rising from approximately 85% to 92%.
Despite the widespread occurrence of β-lactam resistance, significant resistance against macrolide antibiotics has generally not been observed.
Studies conducted in countries such as Spain reported even lower resistance rates to macrolides.
Similarly, remarkable resistance to fluoroquinolone antibiotics has not commonly been reported in Moraxella catarrhalis.
Continuous monitoring of antimicrobial susceptibility patterns is important because increasing antimicrobial resistance may complicate the treatment of respiratory infections caused by this bacterium.
Conclusion
Moraxella catarrhalis is a Gram-negative diplococcus that commonly colonizes the human upper respiratory tract as part of the normal microbial flora, particularly in children.
Although it usually remains harmless in healthy individuals, it can behave as an opportunistic pathogen under favorable conditions.
The bacterium is an important cause of several respiratory infections, including:
Otitis Media
Sinusitis
Bronchitis
Pneumonia
These infections occur most commonly in:
Children
Elderly individuals
Patients with underlying respiratory diseases such as Chronic Obstructive Pulmonary Disease
The pathogenicity of Moraxella catarrhalis is mainly associated with several virulence mechanisms, including:
Adhesion to respiratory epithelial cells
Biofilm formation
Complement resistance
Production of β-lactamase enzymes
These factors contribute to:
Persistent colonization
Immune evasion
Survival within the host
Development of antimicrobial resistance
Due to its increasing clinical importance as a respiratory pathogen, proper prevention and management strategies are essential.
The impact of infections caused by Moraxella catarrhalis can be reduced through:
Good personal hygiene
Early and accurate diagnosis
Effective infection control measures
Prompt and appropriate treatment of respiratory tract infections.
References
Government of Canada – Pathogen Safety Data Sheet: Moraxella spp.
Public Health Agency of Canada. (2011). Pathogen safety data sheet: Infectious substances—Moraxella spp. Government of Canada.
Clinical Microbiology Reviews – Moraxella catarrhalis: From Emerging to Established Pathogen
C. M. Verduin, C. Hol, A. Fleer, H. van Dijk, & A. van Belkum (2002). Moraxella catarrhalis: From emerging to established pathogen. Clinical Microbiology Reviews, 15(1), 125–144.
Swiss Medical Weekly – Molecular Pathogenesis of Moraxella catarrhalis Infections in Children
S. Bernhard, V. Spaniol, & C. Aebi (2012). Molecular pathogenesis of infections caused by Moraxella catarrhalis in children. Swiss Medical Weekly, 142, w13694.
Royal College of Pathologists – Identification of Moraxella Species and Morphologically Similar Organisms
Public Health England. (2015). UK Standards for Microbiology Investigations: ID 11i3 – Identification of Moraxella species and morphologically similar organisms. Royal College of Pathologists.
ResearchGate – Biochemical Characteristics of Moraxella catarrhalis
A. Farajzadeh Sheikh, M. Feghhi, M. Torabipour, M. Saki, & H. Veisi (2020). Biochemical characteristics of Moraxella catarrhalis isolated from conjunctival swab [Table]. ResearchGate.
MechPath – Moraxella catarrhalis Overview
MechPath. (2021, November 16). Moraxella catarrhalis.
Healthline – Moraxella catarrhalis: Infection, Causes, Symptoms, and Treatment
M. Dix (2019, January 30). Moraxella catarrhalis: Infection, causes, symptoms, and treatment. Healthline.
University of Southampton Repository – The Epidemiology of Moraxella catarrhalis
D. E. Morris (2022). The epidemiology of Moraxella catarrhalis (Doctoral thesis, University of Southampton). University of Southampton Institutional Repository.
DrOracle – Treatment Options for Moraxella catarrhalis Infections
DrOracle. (2025, March 18). What are the treatment options for Moraxella catarrhalis infections?
Medical News Today – Moraxella catarrhalis: Linked Conditions, Treatment, and Prevention
A. Bell (2020, May 6). Moraxella catarrhalis: Linked conditions, treatment, and prevention. Medical News Today.
%20Formation,%20Delivery%20Mechanism,%20Microfluidic%20Mixing%20&%20Therapeutic%20Applications.png)
