Mod 6 Fastidious Organisms Flashcards
What organism that is GNCB that only grows on chocolate agar?
Haemophilus spp (a GNCB that grows only on Chocolate agar-CA)
What are two specific respiratory pathogens that have to be requested by the Doctor in order to be cultured?
Legionella and Bordetella are specific respiratory pathogens that have to be requested by the Doctor in
order to be cultured.
What two classes are typically used for grouping Haemophilus influenza? What is the bases of the classes?
Haemophilus influenza is usually classified as non-typable or typable: typing occurs from antigens on the capsule so when there is no capsule, they are non-typable and more frequently part of the normal flora.
Types are a to f, with type b being the most aggressive (Hib).
What clincially significant pathogens are fastidious CO2 requiring pleomophic G- coccibacilli?
Haemophilus spp.
When a more virulent strain have a capsule what does that make their cultural morphology look like?
Makes the morphology appear quite wet or moist looking.
For Haemophilus on CA it appears quit wet or moist looking grey translucent colonies.
What does the presence of a polysaccharide capsule on Haemophilus spp. allow for in terms of identification techniques?
Capsule –> enables antigenic typing with specific antisera (serotypes a to f), with type b being the most common.
Which of the two Haemophilus spp. we are studying is more clinically relevant?
H. influenzae is clinically THE most relevant species, especially in the respiratory tract.
H. parainfluenzae is normal flora in this body site, so having it as a pathogen is a lot more rare, but it is important to be able to differentiate between these two species.
Why will most strains of Haemophilus spp. not grow on blood agar unless it is next to S. aureus?
Most strains will not grow on sheep BA, which contains hemin (factor X) but not NAD (factor V) that Haemophilus spp. needs. It typically needs both X and V.
If a streak of Staphylococcus aureus is inoculated onto the sheep BA, it will produce NAD as a metabolic by-product and Haemophilus will grow very close to the Staph streak.
Note: CA provides both hemin (X) and NAD (V).
What biochemical test separates Moraxella catarrhalis from Neisseria gonorrhoeae?
MUB
What media constituents in Buffered Charcoal Yeast Extract (BCYE) agar protects against the toxic effects of metabolic end-products
Charcoal
What media is used to show the difference in cultural growth requirements of Neisseria gonorrhoeae and Neisseria meningitidis?
Blood Agar
N. gonorrhoeae does not grow on BA or simple media like MH (grows on CA in CO2), and
N. meningitidis does not grow on simple medium like MH, but grows on BA and CA.
What are the atmospheric and incubation requirements for the growth of cultures for possible Legionella spp.?
Increased humidity at 35C
__________ is characterized by episodes of violent coughing followed by inspiratory “whoop” and vomiting.
Pertussis
____________ is not transmitted person to person, but rather from inhalation of aerosols or aspiration from water containing the bacterium.
Legionella pneumophila
An antibiotic incorporated into Reagan Lowe media to inhibit normal respiratory flora is:
Cephalexin, inhibits growth of normal flora from nasopharynx (e.g. Staph & Strep).
