Mycobacteria Flashcards
- aerobic bacilli
- difficult to decolorize (acid-fast)
- grow slowly
Mycobacteria
Identification of Mycobacteria
- colony morphology
- colony pigmentation
- growth rate
- growth temperture
- biochemical test
decontamination and digestion agents
sodium hydroxide
N-acetyl-L-cyteine
benzalkonium chloride
oxalic acid
mycobacterial growth media
- Lowenstein-Jensen - egg-based medium
2. Middlebrook 7H10 - agar based; inhibitory to contaminants
Mycobacterial stain
- conventional stains - Ziehl-Neelsen and Kinyoun
2. fluorochrome stains - auramine and auramine-rhodamine
1 stain: carbolfuchsin
decolorizing agent: acid alcohol
counterstain: methylene blue
Ziehl-Neelsen and Kinyoun
produce pigment on exposure to light
photochromogens
produce pigment in the light or dark
Scotochromogens
no pigment produced in the light or dark
nonchromogens
produce colonies in <= 7 days
rapid growers
produce colonies in >= 7 days
slow growers
growth temperature
35-37C
- M. marinum - 30C
- M. ulcerans - 32C
- M. xenopi - 42C
Biochemical tests
- Niacin accumulation
- Nitrate reduction
- Catalase
- Tween hydrolysis
- NaCl tolerance
- Iron uptake
- Arylsulfatase
- Urease test
- Susceptibility to thiophen-2-carboxylic acid hydrazide
10 nucleic acid amplification
measures nicotinic acid w/c reacts with cyanogen bromide in the presence aniline to form a yellow compound
Niacin accumulation
- used for Enterobacteriaceae
- end product: red pigment
Nitrate reduction
measures the height of the column of bubbles when H2O2 is added
Catalase
- measures the presence of lipase
- pink color change
Tween hydrolysis
uses egg-based media w/ 5% NaCl
NaCl tolerance
determined by adding ferric ammonium citrate to the colonies and observing rusty-brown colonies (formation of iron oxide)
Iron uptake
- adds phenolphthalein to the colony/substrate mixture
- pink color
arylsulfatase
- performed and read as broth test
- urea to ammonia
- alkaline (increase in pH): red color
Urease test
determined by observing growth or no growth
Susceptibility to thiophen-2-carboxylic acid hydrazide
cutaneous infections from water exposure
M. marinum
common contaminant (tap-water bacillus)
M. gordonae
