Moraxella catarrhalis Flashcards
What is the gram stain and morphology of Moraxella catarrhalis?
Gram-negative diplococcus
On which agar media does M. catarrhalis grow well?
Blood agar, chocolate agar, among others
How does M. catarrhalis colony morphology change after 48 hours?
- Large pink colonies
- Display hockey puck sign
Which biochemical enzymes does M. catarrhalis produce?
- Oxidase
- Catalase
- DNase
Where is M. catarrhalis exclusively recovered from?
Humans
When are M. catarrhalis colonization rates highest?
Winter months
What factors may contribute to regional differences in M. catarrhalis colonization rates?
- Living conditions
- Daycare
- Crowding
- Hygiene
- Environmental factors
- Genetics
- Host factors
What type of infections does M. catarrhalis cause?
Mucosal infections
Where does M. catarrhalis initially colonize before causing infection?
Upper respiratory tract
How does M. catarrhalis reach the middle ear in otitis media?
It travels from the nasopharynx through the eustachian tube to the middle ear
What is a key step for M. catarrhalis to initiate infection?
Adherence to the human respiratory epithelium
Surface proteins that help M. catarrhalis adhere to host cells.
Adhesins
What is the major component of M. catarrhalis’ outer membrane?
Lipooligosaccharide (LOS)
How does M. catarrhalis activate B lymphocytes?
Trough the MID/Hag protein; mitogenic for B cells
Which M. catarrhalis surface protein regulates nuclear factor kappa B and induces interleukin-8 release?
UspA2 surface protein
What does M. catarrhalis shed from its surface that interacts with respiratory epithelial cells?
Vesicles
T/F. M. catarrhalis can form a biofilm.
True
How does M. catarrhalis evade host immunity?
By binding to extracellular matrix proteins found in connective tissue
Which extracellular matrix proteins does M. catarrhalis bind to for immune evasion?
Vibronectin, fibronectin, collagen, plasminogen, and catilage oligomeric matrix protein
By what age have approximately 80% of children experienced at least one episode of acute otitis media?
By 3 years of age
What is the gold standard for determining the cause of acute otitis media?
Tympanocentesis to culture middle ear fluid
T/F. M. catarrhalis is one of the three primary bacterial causes of acute otitis media.
True
Lab technique that can improve pathogen detection in otitis media.
PCR
What findings indicate active infection in otitis media samples?
- Detection of mRNA
- Viable bacteria in biofilms
