Download Moraxella catarrhalis

N. Patel F2013
Moraxella catarrhalis
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Large, Gram-negative diplococcus
Fastidious, nonmotile, aerobic
Psuedomonadales; Gammaproteobacteria
Human pathogen
– Infects upper respiratory tract
– Can also cause infections in ear, eye, CNS,
and joints
– Third most common cause of otitis media
and sinusitis in children
– Immunocompromised hosts (HIV/AIDS
patients) are susceptible
http://www.bacteriainphotos.com/light%20microscopy%20of
%20bacteria/Moraxella%20catarrhalis%20microscopy.jpg
• Enters via the nasopharynx
• Can be cultured on blood or chocolate
agar plates
http://www.f8i.org/bacteria/moraxella-catarrhalis/
N. Patel F2013
Moraxella catarrhalis
• Attaches to host cells and infects using Trimeric
Autotransporter Adhesins (TAA) such as UspA1
and A2 proteins
– Anchor inserts into outer membrane
– Passenger domain passes through membrane
into host extracellular environment
– Head domain adheres to host elements (collagen,
fibronectin, etc.)
https://figures.boundless.com/11965/full/taabasic1.jpeg
• Possible virulence factor is lipooligosaccharide
– Transferrin and lactoferrin receptors on surface
help sequester iron from host, and may also
serve as virulence factors
• Endotoxin similar to those found in Neisseria
• Some strains have fimbriae or pili for adhesion
• Can be treated with antibiotics
– Fluoroquinolones and erythromycin are effective
– Currently no vaccine
– Nearly all strains produce beta-lactamase
• Lends resistance to penicillin and ampicillin
http://mmbr.asm.org/content/73/3/389/F3.large.jpg