Lecture | Mycobacteria Flashcards
(79 cards)
1
Q
Aerobic, nonmotile, acid alcohol-fast (able to resist decolorization), slightly curved or straight bacilli
A
mycobacteria
2
Q
M.tuberculosis complex (MTBC)
A
- Mycobacterium tuberculosis
- Mycobacterium bovis,
- M. bovis Bacille Calmette- Guérin strain [BCG]
- Mycobacterium caprae, Mycobacterium
pinnipedii, Mycobacterium africanum, Mycobacterium microtii, and Mycobacterium canettii
3
Q
Nontuberculous mycobacteria are classified based on the pigment or known as
A
Runyon’s classification
4
Q
classified as Slow-growers
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Photochromagen, Scotochromogen, and Nonchromogen
5
Q
- Battey Bacillus
- In AIDS patients
A
MYCOBACTERIUM AVIUM COMPLEX
6
Q
“yellow bacillus,”
A
MYCOBACTERIUM KANSASII
7
Q
growth requirement for hemoglobin or hemin
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MYCOBACTERIUM HAEMOPHILUM
8
Q
Bairnsdale ulcer
A
MYCOBACTERIUM ULCERANS
9
Q
cultured from hot and cold water taps, hospital hot water generators and storage tanks, and other environmental sources.
A
MYCOBACTERIUM XENOPI
10
Q
disseminated disease in HIV-infected patients
A
MYCOBACTERIUM GENAVENSE
11
Q
chronic granulomatous infections involving skin and soft tissue, often called “swimming pool granuloma” or “fish tank granuloma”
A
MYCOBACTERIUM MARINUM
12
Q
“Tap-water bacillus
A
MYCOBACTERIUM GORDONAE
13
Q
etiologic agent of leprosy
A
MYCOBACTERIUM LEPRAE
14
Q
also called Hansen’s disease
A
MYCOBACTERIUM LEPRAE
15
Q
1 Lepra cells (cells that infect)
2 Not culturable;
3 Infects the nerves
A
MYCOBACTERIUM LEPRAE
16
Q
Methods for Decontamination and Digestion of Mycobacteria
A
- N acetyl-L-cysteine (NALC) and 2-4% NaOH
- Trisodium phosphate and benzalkonium
chloride (ZEPHIRAN) - Dithiothreitol and NaOH
17
Q
release mycobacteria trap in the mucin or in the cells.
A
digesting agent or 2-4% NaOH
18
Q
- 0.2-0.6 micron in diameter and 1-4 micra in length
- Highly resistant to drying (protected from sunlight)
A
MYCOBACTERIUM TUBERCULOSIS
19
Q
mycobacterium tuberculosis Putrifying sputum
A
WEEKS
20
Q
mycobacterium tuberculosis Dried sputum
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6-8 months
21
Q
Droplets of dried sputum in the air
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8-10 days
22
Q
mycobacterium tuberculosis exposed to direct sunlight, organism for culture are killed within
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2 hours
23
Q
mycobacterium tuberculosis In sputum
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20-30 hours
24
Q
Disinfection of sputum
A
24 hours in 5% phenol
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Easily killed by moist heat, boiling for 10
minutes, autoclave
mycobacterium tuberculosis
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is the initial infection. The mycobacterium is eradicated by the host cellular immune response or walled off in a granuloma in the lung.
Primary tuberculosis
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Primary tuberculosis Reactivation of latent infections can occur in immunocompromised individuals and cause
secondary tuberculosis.
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in mycobacterium tuberculosis, a disseminated infection with multiple organ involvement.
Miliary TB
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is miliary tuberculosis in the bones or spine
Pott's disease
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is used to detect MTB-infected individuals
Tuberculin skin test
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purified protein derivative (PPD) is what type of antigen
MTB antigen.
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Tuberculin skin test: positive test
hypersensitivity reaction at the injection site within 72 hours
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Fluorochrome =
Auramine & Rhodamine
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Gene Xpert =
new method
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Cultures of mycobacteria are maintained for
8 week
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Cultures of mycobacteria are Incubated at
35°C in the dark in 5%-10%
carbon dioxide
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Liquid media
10 days - Löwenstein-Jensen (LJ) agar slant
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Solid media
17 - Middlebrook 7H11 agar
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standard for Isolating mycobacteria
Löwenstein-Jensen (LJ) agar slant
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this agar contains coagulated whole eggs. glycerol, potato flour, and salts.
Löwenstein-Jensen (LJ) agar slant
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in Löwenstein-Jensen (LJ) agar slant, what is is added to inhibit the growth of contaminating bacteria.
Malachite green
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The disadvantage of this medium is that it becomes hydrolyzed when contaminants do grow on it, and the culture must be discarded.
Löwenstein-Jensen (LJ) agar slant
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In what agar does M. tuberculosis colonies appear as cream-colored, dry, and wrinkled.
Middlebrook 7H11 agar.
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In what agar does M. tuberculosis colonies appear as rough, buff-colored colonies that appeared within 3 weeks
Löwenstein-Jensen (LJ) agar slant
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widely used medium for the isolation and antimicrobial susceptibility testing of mycobacteria. Although similar to Middlebrook 7H10 agar.
Middlebrook 7H11 agar
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Middlebrook 7H11 agar con- tains casein hydrolysates that improve the recovery of
isoni azid-resistant strains of M. tuberculosis
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M. avium strains on Middlebrook 7H11 agar can be distinguished from other M. avium-complex microorganisms, such as M. intracellulare, by their ability to grow at the temperature
45°C
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M. avium on Lowenstein Jenson agar slant. appears as a
a film after 3 to 4 weeks of incubation.
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on Lowenstein Jenson agar slant, its Colonies are buff-colored , but much smaller than M. tuberculosis
M. avium
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bacteria with smooth colony type can appear as a "sun-spot" with starlike or asteroid margins
M. avium
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bacteria with rough colony has a characteristic "lacy" appearance.
M. avium
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a photochromogen, group I of Runyon's classification
M. kansasii on Middlebrook 7H11 agar
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classical method for differentiating the mycobacteria
M. kansasii
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A characteristic feature of the photochromogens is their dependence on exposure
to light for pigment production
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colonies of this bacteria have a strong yellow color
M. kansasii
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a positive catalase reaction, reduction of nitrate to nitrite, and rapid hydrolysis of Tween 80, a detergent.
M. kansasii
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on Middlebrook 7H11 agar. This rapid grower can appear on culture media within 2 to 4 days.
M. chelonae
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M. chelonae can be distinguished from M. fortiatum because
1. does not reduce nitrates or assimilate iron
2. suceptible to polymyxin B and resistant to ciprofloxacin.
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on chocolate agar it appear as smooth, opaque colonies resembling staphylococci or yeast
M. chelonae
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Examined microscopically, the colonies appear dark and dense with smooth edges and a somewhat lighter center
Colony of M. chelonae
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on Middlebrook 7H11 agar. The rapidly growing, rough colonies are shown after 3 days of incubation.
M. fortuitum
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M. fortuitum can also grow on modified Mac- Conkey agar, without crystal violet, at temperature?
37°C
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M. fortuitum can grow on 7H11 and LJ at temperaure?
43°C
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M. fortuitum can grow in 5% NaCl at temperaure?
37°C
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The rough colonies of M. fortuitum on Löwenstein-Jensen agar are shown growing after how many days of incubation
3 days
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The rough colony of M. fortultum observed microscopically with
transmitted light
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M. gordonae colonies on Middlebrook 7H11 agar.
Yellow- orange pigmented colonies
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This species belong to the Runyon group II scotochromogens, characterized by pigmented colonies in the absence of exposure to light. Colony growth can appear in 3 weeks.
M. gordonae
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M. gordonae colonies on Löwenstein-Jensen agar.
Yellow- orange pigmented colonies as well
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Biochemical Test:
Reagent strip impregnated with substrate cyanogen halide = yellow
Niacin accumulation tests
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Biochemical Test:
1. Base on the ability to convert ferric ammonium citrate to an iron oxide
2. Reddish brown or rust colored colonies
Iron uptake test
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Biochemical Test:
1. Growth at 28°C on an egg based medium containing 5% NaCl.
2. All species of Mycobacteria are + except M. chelonae (-)
NaCl tolerance test
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Two classes of catalase test
thermolabile and thermostable
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In M. tuberculosis and M. bovis the enzymatic activity is inhibited at
68°C
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Biochemical Test:
1. solution of perhydrol 30% and Tween 80 at 10%
2. height of the column of bubbles can be measured
Catalase test
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Biochemical Test:
- detected by adding phenolphthalein to the colony/ substrate mixture and observing the formation of a pink color
Arylsulfatase test
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species positive in Arylsulfatase test
1. after three days: M. fortuitum and M. abcesuss
2. after 2 weeks : M. gastri
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Biochemical Test:
pyrazinamide is converted into pyrazinoic acid through the action of the pyrazinamidase enzyme
Pyrazinamide test
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Biochemical Test:
1. measures the presence of a lipase.
2. Hydrolysis causes a pink color change
Tween 80 hydrolysis
