Moraxella catarrhalis - MegaMicro

Go to content

Main menu:

Moraxella catarrhalis

Microbiology > Bacteriology > Gram-negative bacteria > Gram Negative Cocci
1.       Structure
a.       Gram-negative diplococcus (about 2 um)
b.      No capsule
c.       Non-motile
d.      Non-spore forming

2.       Pathobiology:
a.       Aerobic bacteria
b.      Has LOS (lipooligosaccharide)
c.       Produces beta-lactamase
d.      Binds to respiratory epithelium and to ECM components via pili and outer membrane proteins (ex. UspA1 on bacteria binds to CEACAM1 on human epithelia). This enables invasion of host epithelial cells and formation of micro colonies and biofilms.

3.       Epidemiology
a.       Can be isolated from sputum
b.      Found in nasopharynx of children (more often than adults); more often seen during winter months
c.       Found only in humans
d.      Transmitted by respiratory aerosol

4.       Laboratory diagnosis
a.       Resembles cocci of the genus Neisseria
b.      Catalase positive
c.       Oxidase positive
d.      Blood agar- colonies are “nonhemolytic, round, opaque, convex, greyish-white”

5.       Disease manifestations
a.       Bacteremia – seen often in febrile children with underlying immune dysfunction and URI
b.      Causes local infections – ex. Otitis media, sinusitis,  laryngitis, bronchopneumonia – primarily in children
c.       More rare – systemic infections ex. Asmeningitis, endocarditis
d.      In older patients with compromised immune system (COPD)– will present as lower respiratory tract infections  - bronchitis and pneumonia

6.       Therapy
a.       Can treat with cotrimoxazole, erythromycin, sulfadimidine, tetracycline
b.      Often resistant to penicillin, ampicillin, amoxicillin, trimethoprim

7.       Prevention and control
a.       Potential target for vaccine due to large molecular weight surface protein expression
Related concepts
1.       Moraxella catarrhalis
2.       Gram-negative
3.       Aerobic
4.           Neisseria
Copyright 2016. All rights reserved.
Back to content | Back to main menu