Exam 2 Lecture 13 Flashcards
Mycobacteria
Many Mycobacteria are _____ organisms. They can be found in:
opportunistic; Water, soil, food (plumbing)
The most common species of Mycobacteria is:
M. tuberculosis
The genus Mycobacterium includes 2 ____ parasites, which are:
Obligate; M. tuberculosis and M. leprae
How do we organize mycobacterial human pathogens?
We organize them based on the diseases the cause (i.e. organized clinically)
What are the three categories of Mycobacterial human pathogens?
- Mycobacterium tuberculosis complex
- Mycobacterium leprae
- Nontuberculosis mycobacteria
Mycobacterium tuberculosis complex (definition and associated species)
species that cause tuberculosis; M. tuberculosis, M. bovis
Mycobacterium leprae causes:
Leprosy
Nontuberculosis mycobacteria (definition)
Any other mycobacterium that causes human disease (but not TB or leprosy)
____ ____ is an important determinant of mycobacterial disease presence and severity.
Host susceptibility (i.e. immune characteristics)
True or false: differences between strains of Mycobacteria are very important determinants of how sick the host will get and how severe the disease will be.
False (strain differences are much less important than host susceptibility)
Mycobacteria differ greatly from gram positive and gram negative species in that:
Their cell walls contain mycolic acids
Can you use a gram stain approach in Mycobacteria?
No, you use acid-fast staining
What is the acid-fast staining process?
- Stain with carbol fuschin
- Decolorize with acid-alcohol
- Counterstain with methylene blue
Mycobacteria are slow-growing and thus are ____. They can be divided further into two categories:
fastidious (also difficult to culture); slow-growing and fast growing
Mycobacteria produce distinct ____ ____ that may be used to speciate clinical isolates. However, it more useful to use ____ and ______ ____.
carotenoid pigments; PCR and biochemical tests
True or false: Mycobacteria are strict aerobes and lack anaerobic metabolic capacity.
True
Do Mycobacteria possess flagellae?
No, they are non-motile
2 factors that hinder diagnosis and lab study of Mycobacteria
- difficult to culture in vitro
2. difficult to manipulate genetically (due to lack of tools/gene knockdown)
Why does the slow-growing nature of Mycobacteria make them difficult to treat?
- may be less likely to respond to standard antibiotics
2. can develop resistance to single agents easily
What diseases can nontuberculosis mycobacteria cause?
- pulmonary disease similar to TB
- lymphadenitis
- skin and soft tissue diseases
- disseminated diseases
True or false: Mycobacteria stains strongly gram positive.
False; neither GP nor GN
Mycolic acids make up ____% of the cell wall and allows cells to be resistant to ____.
60; desiccation
Mycolic acids are anchored to the rest of the cell wall through _______.
Arabinogalactan
True or false: Mycobacteria do not contain peptidoglycan
False: they do, just small amount