Moraxella are commensals of mucosal surfaces and occasionally they cause opportunistic infections.

They are fastidious organisms.

Moraxella catarrhalis is the major pathogenic organism found in Moraxella species.

They are the commensals of upper respiratory tract.

They causes upper and lower respiratory tract infections, mainly in immune-compromised patients and in the patients with chronic obstructive pulmonary diseases.

In Moraxella many features are similar to the features of Neisseriae.

Moraxella causes otitis media, sinusitis, bronchitis, pneumonia and bronchitis.

These diseases mainly found in humans and transmission is occurred by respiratory aerosol.

Gram stained smears prepared by sputum are examined for the identification of this infection.

Large number of Gram-negative coccobacilli can be seen under microscope.

They mainly found as pairs. These organism can be seen among pus cells in sputum smears. In wet smears Moraxella are non-motile.   


Sputum is cultured on media for the isolation of organism.

They are incubated overnight at 37 °C in 5% carbon dioxide.

On blood agar and chocolate agar, Moraxella produce dry colonies. They are grey white color colonies.

They produce circular, rough, convex colonies which are brittle and that can be easily lifted off from the medium by using a wire loop (They give push able colonies).

Biochemical Identification

Colonies are catalase positive, strongly oxidase positive.

Some Moraxella ferment sugars and some Moraxella do not ferment sugars.

To differentiate Moraxella from Neisseria tributyrin test (Butyrate esterase test) is useful. Butyrate esterase test and deoxyribonuclease test are positive for these organisms.

Growth on nutrient agar at 22°C is another different characteristic of Moraxella. However, M. catarrhalis may not grow in these conditions. Many strains produce β-lactamase.  


For β-lactamase producing organisms, Trimethoprim-sulfamethoxazole or amoxicillinclavulanate are useful for the treatment.

Cephalosporins, Tetracyclines, Macrolides and Fluoroquinolones are also effective for the treatment. 


No vaccine is available for the prevention of the infections caused by Moraxella. However, vaccines are under development.

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