Celine - Moraxella Flashcards
What is the most important species of Moraxella
Moraxella catarrhalis
Write about where M. catarrhalis is found
Opportunistic pathogen
Commensal in nasopharynx
High carriage rate in children
opportunistic pathogen in children and elderly
What infections are caused by M. catarrhalis
(4)
Otitis media in children
Sinusitis in children
Pneumonia in elderly
Bronchitis in elderly
What specimens is M. catarrhalis found in
Ear swabs/effusion
Sputum
Write about the day 1 isolation of Moraxella
Not fastidious
Doesn’t require enriched culture of CO2
But usually isolated on Blood and chocolate agar, to allow isolation of more fastidious pathogens which may be present
Write about the colonial morphology of M. catarrhalis
1-2 mm white
Hockey puck
Pushable
Gram-negative diplococci which may resist decolorisation
Oxidase positive
Catalase positive
How does M. catarrhalis appear on the gram stain
Gram-negative diplococci which may resist decolorisation
How do you remember the characteristics of moraxella?
(7)
GONOCC
Gram negative bean-shaped large diplococci
Obligative aerobe
Non motile
Oxidase positive
Catalase positive
Not fastidious -> does not require CO2 blood or serum
What day 2 confirmatory tests are carried out for Moraxella?
(4)
Biochemical (TAXO sugars)
DN’ase
Growth
Tributyrin hydrolysis (Catarrhalis disc test)
How can you identify N. catarrhalis using the TAXO sugars
Non-differential identification
i.e. will not oxidise any of the TAXO sugars
Is M. catarrhalis DN’ase positive or negative
DN’ase positive
How can you identify Moraxella based on it’s growth
Not fastidious (allows us to distinguish from Neissera)
Grows on nutrient agar
Grows at 22 degrees celsius
What is the tributyrin hydrolysis test
(6)
A discriminatory test for M. catarrhalis
Catarrhalis disc test
Organism produces butyrate esterase which hydrolyses tributyrin to release indoxyl which reacts with oxygen to turn blue-green
Rub test colony on disk and observe for a blue/green colour within 2 minutes
M. catarrhalis is positive for tributyrin hydrolysis
Neisser is negative
