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BACTERIOLOGY > B4.5 NONTUBERCULOUS MYCOBACTERIA > Flashcards

B4.5 NONTUBERCULOUS MYCOBACTERIA Flashcards

1
Q

What are other names for Nontuberculous Mycobacteria (NTM)?

A

Atypical Mycobacteria,
Mycobacteria Other Than Tubercle Bacillus (MOTT),
Anonymous,
Unclassified,
Unknown,
Tuberculoid,
Environmental, or
Opportunistic.

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2
Q

Where are NTMs commonly found, and how do they infect individuals?

A

Found in the environment.

Can colonize the skin, respiratory tract, and gastrointestinal tract of healthy individuals

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3
Q

What is the typical clinical presentation of NTM infections?

A

Chronic pulmonary disease resembling TB.

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4
Q

Are NTMs transmissible from person to person?

A

No, NTMs are non-transmissible between individuals.

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5
Q

How are NTMs classified in the Runyon system

A

By growth rate and colonial pigmentation into four groups.

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6
Q

What are the two growth rates used in the Runyon classification?

A

Slow growers.
Rapid growers.

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7
Q

They produce pigment when exposed to light.

in the Runyon classification

A

photochromogens

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8
Q

PHOTOCHROMOGEN SPP

A

Mycobacterium kansasii
Mycobacterium marinum

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9
Q

known as the Yellow Bacillus

A

Mycobacterium kansasii

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10
Q

Produces yellow pigment with prolonged light exposure

A

Mycobacterium kansasii

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11
Q

What is the clinical significance of M. kansasii?

A

Pulmonary: Chronic cavitary lesions.
Extrapulmonary: Lymphadenitis, skin, soft tissue, and joint infections.

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12
Q

Cultural characteristics of M. kansasii colonies?

A

Grows on Middlebrook 7H10 agar.

Colonies are slow-growing, smooth to rough, with wavy edges and dark centers.

Prolonged light exposure: Dark red β-carotene crystals on colony surfaces.

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13
Q

Biochemical test results for M. kansasii?

A

Catalase: Strongly positive (>45 mm in semiquantitative test).

Tween 80 hydrolysis: Positive (3 days).

Nitrate reduction: Positive.

Niacin: Negative.

Pyrazinamidase production: Positive.

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14
Q

Microscopic appearance of M. kansasii?

A

Long rods with distinct crossbanding.

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15
Q

What is the environmental association and clinical presentation of M. marinum?

A

Environment: Found in fish and aquariums.

Disease: Swimming pool granuloma, tender red or blue-red subcutaneous nodules on elbows, knees, toes, or fingers.

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16
Q

Optimal growth temperature and culture characteristics for M. marinum?

A

Grows best at 28–32°C.

Egg-based medium: Smooth to rough and wrinkled.

Middlebrook 7H10/7H11 agar: Smooth colonies

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17
Q

Biochemical test results for M. marinum?

A

Tween 80 hydrolysis: Positive.
Weakly catalase: Positive.
Niacin: Negative.
Urease: Positive.
Pyrazinamidase: Positive

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18
Q

Drug susceptibility and resistance of M. marinum?

A

Susceptible: Rifampin and ethambutol.
Resistant: Isoniazid and pyrazinamide.
Intermediate: Streptomycin.

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19
Q

Microscopic appearance of M. marinum?

A

Moderately long to long rods with crossbarring.

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20
Q

They produce yellow to orange pigment regardless of light exposure.

A

Scotochromogens

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21
Q

What disease is primarily associated with M. scrofulaceum?

A

Cervical lymphadenitis in children

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22
Q

Cultural characteristics of M. scrofulaceum

A

Slow-grower (4–6 weeks).
Grows at 25–37°C.
Smooth colonies with dense centers, light yellow to orange pigment

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23
Q

Microscopic appearance of M. scrofulaceum?

A

Uniformly stained, acid-fast, medium to long rods.

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24
Q

Biochemical test results for M. scrofulaceum

A

Tween 80 hydrolysis: Negative.
Urease: Positive.
Catalase: Positive (>45 mm).

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25
Q

Drug resistance of M. scrofulaceum?

A

Resistant to isoniazid, streptomycin, ethambutol, and p-aminosalicylic acid.

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26
Q

What diseases are associated with M. szulgai?

A

Pulmonary disease similar to TB.
Extrapulmonary: Lymphadenitis and bursitis

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27
Q

Cultural characteristics of M. szulgai?

At 37°C

A

Yellow to orange pigment in the absence of light, intensifies with light exposure

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28
Q

Cultural characteristics of M. szulgai?

At 22°C

A

Nonpigmented or buff in darkness; yellow to orange pigment with light exposure

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29
Q

M. szulgai Grows on what media and characteristics

A

egg-based media with smooth and rough colonies

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30
Q

Microscopic appearance of M. szulgai?

A

Medium to long rods with some cross-barring

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31
Q

Biochemical test results for M. szulgai?

A

Slow hydrolysis of Tween 80.
Nitrate reduction: Positive.
Unable to grow in the presence of 5% NaCl

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32
Q

It commonly contaminates tap water, often found in rinsed sputum samples and bacteriologic smears.

A

M. gordonae

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33
Q

M. gordonae aka

A

Tap Water Bacillus

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34
Q

Cultural characteristics of M. gordonae?

A

Smooth colonies.
Yellow-orange pigment

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35
Q

Biochemical test results for M. gordonae?

A

Tween 80 hydrolysis: Positive.
Heat-stable catalase: Positive.
Nitrate reduction: Negative.

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36
Q

What species are classified under Nonphotochromogens (Runyon Group III)?

A

Mycobacterium avium Complex (MAC)
Mycobacterium genavense
Mycobacterium gastri
Mycobacterium haemophilum
Mycobacterium malmoense
Mycobacterium simiae
Mycobacterium ulcerans
Mycobacterium xenopi
Mycobacterium terrae Complex

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37
Q

What are the species in the M. avium complex?

A

M. avium
M. intracellulare

38
Q

What disease is caused by M. avium subspecies paratuberculosis?

A

Johne’s disease (chronic diarrhea in ruminants).

39
Q

Biochemical test results for M. avium complex?

A

Heat-stable catalase: Positive.
T2H (2 µg/mL): Positive.
Niacin: Negative.
Nitrate reduction: Negative.
Tween 80 hydrolysis: Negative.
Tellurite reduction: Positive (within 3 days).

40
Q

Cultural requirements for M. avium subspecies paratuberculosis?

A

Requires mycobactin-supplemented media for growth

41
Q

What infections are caused by M. genavense

A

Disseminated infections in AIDS patients.
Enteritis and genital/soft tissue infections.

42
Q

Biochemical test results for M. genavense?

A

Heat-stable catalase: Positive.
Pyrazinamidase: Positive.
Urease: Positive.

43
Q

Known as the “J Bacillus,” rapidly hydrolyzes Tween 80, and is catalase-negative at 68°C.

A

M. gastri

44
Q

Requires hemoglobin or hemin for growth on CHOC agar or LJ medium with 2% ferric ammonium citrate.

A

M. haemophilum

45
Q

Optimal growth temperature of M. haemophilum?

A

28°C to 32°C

46
Q

What is the drug susceptibility pattern of M. malmoense?

A

Resistant to: Isoniazid, streptomycin, p-aminosalicylic acid, rifampin.
Susceptible to: Ethambutol and cycloserine.

47
Q

Biochemical test results for M. malmoense?

A

Niacin accumulation: Negative.
Nitrate reduction: Negative.
Tween 80 hydrolysis: Positive.
Heat-stable catalase: Positive.

48
Q

What is the primary source of M. simiae strains?

A

Originally isolated from monkey lymph nodes

49
Q

Biochemical test results for M. simiae?

A

Niacin accumulation: Positive.
Nitrate reduction: Negative.
Heat-stable catalase: Positive.
Slow hydrolysis of Tween 80.

50
Q

What disease is caused by M. ulcerans?

A

Buruli ulcer (severe, painless skin ulcers).

51
Q

Optimal growth temperature of M. ulcerans?

A

30°C to 33°C.

52
Q

Biochemical test results for M. ulcerans?

A

Heat-stable catalase: Positive.
Inert in most other conventional tests.

53
Q

What is the characteristic appearance of M. xenopi colonies on cornmeal agar?

A

Bird’s nest appearance with stick-like projections.

54
Q

Optimal growth temperature of M. xenopi?

A

42°C (fails to grow at 25°C).

55
Q

Drug susceptibility of M. xenopi?

A

Susceptible: Quinolones (e.g., ciprofloxacin, ofloxacin).
Resistant: Ethambutol.

56
Q

What species are included in the M. terrae complex?

A

M. terrae (Radish Bacillus).
M. triviale (V Bacillus).
M. nonchromogenicum.

57
Q

Biochemical test results for the M. terrae complex?

A

Tween 80 hydrolysis: Positive.
Heat-stable catalase: Positive.
Growth in 5% NaCl: M. triviale only.

58
Q

Cultural characteristics of M. terrae complex?

A

M. terrae: Smooth.
M. triviale: Rough and dry.
M. nonchromogenicum: Smooth to rough, white to buff.

59
Q

What is the general habitat of NTM rapid growers?

A

Found in dust, soil, and water systems.

60
Q

What is the mode of transmission (MOT) for NTM rapid growers?

A

Inoculation into skin and subcutaneous tissues through trauma, injections, surgery, or animal contact.

61
Q

What is the culture characteristic of NTM rapid growers?

A

Produce colonies on solid media within 7 days.

62
Q

What are the microscopy features of NTM rapid growers?

A

Weakly Gram-positive rods resembling diphtheroids.

63
Q

What species are classified under NTM rapid growers?

A

Mycobacterium abscessus subsp. abscessus
Mycobacterium chelonae
Mycobacterium fortuitum
Mycobacterium smegmatis

64
Q

What is the notable feature of Mycobacterium chelonae infections?

A

Causes disseminated cutaneous infections in immunocompromised patients

65
Q

What are the culture characteristics of Mycobacterium chelonae?

A

Rough or smooth, nonpigmented to buff colonies within 3 to 5 days at 37°C.

66
Q

What is the biochemical test profile of Mycobacterium chelonae?

A

3-day arylsulfatase test (+)
Nitrate reduction (-)
Growth on MacConkey agar without crystal violet.

67
Q

What infections are associated with Mycobacterium abscessus subsp. abscessus?

A

Chronic lung disease, otitis media, disseminated cutaneous infections, and cystic fibrosis-related infections.

68
Q

What is the culture characteristic of Mycobacterium fortuitum?

A

Rough or smooth, nonpigmented, creamy white, or buff colonies within 3 to 5 days at 37°C.

69
Q

What is the notable feature of Mycobacterium smegmatis on culture?

A

Produces rough, wrinkled colonies that are nonpigmented or creamy white to buff or pink

70
Q

What biochemical test distinguishes Mycobacterium fortuitum from

A

Positive for nitrate reduction and 3-day arylsulfatase test.

71
Q

What is the microscopy feature of Mycobacterium smegmatis?

A

Long and tapered or short rods with irregular acid-fastness and sometimes Y-shaped branching.

72
Q

Noncultivable Nontuberculous Mycobacteria

A

Mycobacterium leprae

73
Q

What is the causative agent of leprosy?

A

Mycobacterium leprae

74
Q

What is another name for leprosy?

A

Hansen’s disease

75
Q

What is the cellular arrangement of Mycobacterium leprae in tissues?

A

Parallel or palisade arrangement known as “cigar packets.”

76
Q

What enzyme is present in Mycobacterium leprae that differentiates it from other mycobacteria?

A

Phenolase

77
Q

What are the two stable forms of leprosy?

A

Tuberculoid (TT)
Lepromatous (LL)

78
Q

Skin lesions with nerve involvement leading to loss of sensation
Effective cell-mediated immune (CMI) response

A

tuberculoid leprosy

79
Q

Progressive, symmetric nerve damage and skin lesions
No effective cell-mediated immune (CMI) response

A

lepromatous leprosy

80
Q

What is the treatment for lepromatous leprosy?

A

Diaminodiphenyl sulfone (dapsone), clofazimine, and rifampin

81
Q

What is the treatment for tuberculoid leprosy?

A

Dapsone and rifampin

82
Q

What is the mode of transmission (MOT) for Mycobacterium leprae?

A

Contact with nasal secretions or ulcer exudates of patients with lepromatous leprosy
Major portal of entry: respiratory tract

83
Q

What is the pathogenesis of Mycobacterium leprae?

A

Obligate intracellular bacteria with a strong predilection for nerves, multiplying slowly within mononuclear phagocytes.

84
Q

What are the five clinical forms of leprosy?

A

Tuberculoid (TT), Borderline Tuberculoid (BT), Borderline (BB), Borderline Lepromatous (BL), and Lepromatous (LL)

85
Q

What test is used to detect immune response in leprosy?

A

Lepromin test

86
Q

What are the two types of lepromin reactions?

A

Early Fernandez Reaction: Induration appears in 24–48 hours.
Late Mitsuda Reaction: Indurate nodule appears after 3–4 weeks

87
Q

What are the specimens used for diagnosing Mycobacterium leprae?

A

Nasal mucosal smear and skin snips from eyebrows and other sites

88
Q

Can Mycobacterium leprae be cultured on artificial media?

A

No, it is non-culturable on artificial media.

89
Q

What are the experimental methods to grow Mycobacterium leprae?

A

Footpads of mice (30°C)
Armadillos

90
Q

What is the optimal growth temperature for Mycobacterium leprae?

A

30°C

91
Q

What are the acid-fast staining indices for Mycobacterium leprae?

A

Bacteriologic Index (BI): Number of organisms per OIF
Morphologic Index (MI): Number of solid-staining cells per 100 bacilli examined

92
Q
A

BACTERIOLOGY (31 decks)

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