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Microbiology > Bacteriology Exam 10 (AFB) > Flashcards

Bacteriology Exam 10 (AFB) Flashcards

1
Q

What are known to be the smallest self-replicating organisms in nature?

A

Mollicutes: Mycoplasma and ureaplasma sp. (previously known to be viruses, but are not self-replicating)

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2
Q

What is M. pneumoniae, M. hominis, and U. urealyticum known to cause?

A

M. pneumoniae: walking pneumonia
M. hominis: UTIs
U. urealyticum: UTIs

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3
Q

T/F: Mycoplasma and Ureaplasma are lacking a cell wall.

A

True!

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4
Q

What antibiotics are mycoplasma and ureaplasma intrinsically resistant to and why?

A

Beta-lactams because they lack a cell wall, so there is a lack of target.

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5
Q

Most mycoplasma and ureaplasma are slow growing and highly fastidious. What are the exceptions?

A

M. hominis is rapid growing
M. pneumonia is aerobic

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6
Q

Can mycoplasma and ureaplasma be gram stained? Why?

A

No, they have no peptidoglycan wall.

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7
Q

T/F: Mycoplasma and ureaplasma are susceptible to heat and drying agents.

A

True

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8
Q

What is M. pneumoniae associated with when causing infections? What community of people?

A

Bronchitis, pharyngitis, or primary atypical walking pneumonia. It is a non-seasonal infection that infects young, healthier people and is more community-acquired. (Causes 50% of all confined population pneumonia such as in military, prisons, or schools).

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9
Q

What can M. pneumoniae be co-infectious with?

A

Neisseria meningitidis in infants and neonates

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10
Q

What is M. hominis and U. urealyticum associated with when causing infections? In what community of people ?

A

Both the causative agent of UTIs in immunocompromised people, frequently associated with asymptomatic sexually active people

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11
Q

T/F: M. hominis is NEVER considered normal flora.

A

False, it is located in the lower genitourinary system of 50% of healthy adults.

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12
Q

U. urealyticum is commonly isolated from ________ and ________ infants.

A

Premature and low birth weight

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13
Q

What are the special sample collection/processing procedures for Mycoplasma and Ureaplasma?

A

Lack of cell wall so extremely sensitive to heat and drying.
Transport media = SP4, Shepard’s 10B broth, or 2SP.
Must use dacron/rayon swabs, no calcium alginate or wooden swabs with cotton tips

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14
Q

What do M. hominis and U. urealyticum need in the media to grow?

A

Cholesterol (SP4, Shephard’s 10B broth, or 2SP)

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15
Q

What is the only mycoplasma to grow on BAP and CHOC?

A

M. hominis

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16
Q

How is M. pneumoniae typically diagnosed?

A

By a four-fold titer increase of antibodies

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17
Q

What does SP4 provide for the growth of M. hominis and M. pneumoniae?

A

Glucose and arginine

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18
Q

What organism gives a fried egg appearance when put onto a glass slide and stained with Dienes or methylene blue?

A

M. hominis

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19
Q

What organism is most likely if media is acidified from metabolism of glucose to create a yellow pigment, if it is slow growing?

A

M. pneumoniae

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20
Q

What organism is most likely if media pH is raised due to arginine utilization, turning the media to a orange/red color, and occurs in <24 hours?

A

U. urealyticum

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21
Q

What organism is most likely if media pH is raised due to arginine utilization, turning the media to a orange/red color, and occurs >24 hours, but less than 72 hours?

A

M. hominis

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22
Q

Treatment for mycoplasma and ureaplasma (what can you treat with, what can you not treat with)

A

Cannot treat with beta lactams, SXT, or rifampin
They are susceptible to tetracycline, fluoroquinolones, and some macrolides

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23
Q

What is a big difference between mycoplasma/ureaplasma and mycobacteria?

A

Mycobacteria have a cell wall, unlike mycoplasma and ureaplasma.

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24
Q

Why must you acid fast stain mycobacteria?

A

Due to mycolic acid in cell wall, resistant to alcohols and hydrophobic

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25
Q

General characteristics of acid-fast bacilli

A

Non-motile, non-spore forming rods, high lipid content in cell wall (mycolic acid), slow growing

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26
Q

What is the PPD test?

A

TB test that injects antigen intradermally and read 48 hours later to see if there is a raised firm area of 10mm or more. If there is, you have had TB

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27
Q

What is the Quantiferon Gold test?

A

Blood test to determine if you have TB antibodies

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28
Q

What do you use to emulsify a mycobacterium sample?

A

NaOH - decontaminant (kills non-mycobacterial organisms)
NALC - decongestant (liquifies sputum)

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29
Q

MGIT and LJ agar - solid or liquid

A

MGIT - liquid
LJ agar - solid

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30
Q

What respiratory specimens are acceptable to identify mycobacterium?

A

Sputum, bronchial wash, bronchial brush, BAL, leukens trap

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31
Q

What type of specimen may be collected for children under 3 with pulmonary TB?

A

Gastric aspirate - must be neutralized immediately because stomach acid could destroy bacteria.

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32
Q

What specimens could be acceptable for detection of mycobacterium, although rare?

A

Urine, stool, tissue/body fluids, and blood cultures

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33
Q

What does an acid fast stain look like?

A

Blue background, red mycolic acid

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34
Q

What AFB stain will have a black background with bright orange mycobacterium used for screening?

A

Auramine-Rhodamine fluorochrome

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35
Q

What is the difference between the Ziehl-Neelson and Kinyoun stain for AFB?

A

Ziehl-Neelson - apply heat
Kinyoun stain - cold stain

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36
Q

What agar is egg-based and contains malachite green to suppress gram positive bacteria?

A

Lowenstein Jensen (LJ agar) solid media

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37
Q

What is “Gruft”?

A

LJ agar with antibiotic

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38
Q

What agar for mycobacterium are solid-based?

A

LJ agar, middlebrook 7H10 and 7H11, and Mitchison’s selective 7H11

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39
Q

What agar for mycobacterium are liquid based?

A

Middlebrook 7H9 and Dubos Tween Albumin, MGIT tube (rapid ID)

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40
Q

What mycobacterium grows best at 42C?

A

M. xenopi

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41
Q

How long are mycobacterium incubated? What is considered a rapid grower vs a slow grower?

A

8 weeks;
Growth >7 days = slow grower
Growth <7 days = rapid grower

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42
Q

What is a photochromogen?

A

Produce bright yellow pigment ONLY after exposure to UV light

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43
Q

What is a scotochromogen?

A

Produce bright yellow pigment regardless if in light or dark

44
Q

What is a non-photochromogen?

A

Does not produce bright yellow pigment at all (Buff)

45
Q

What pigment formation category is Runyon group I? What species are included?

A

Photochromogens - M. kansasii, M. marinum, M. simiae

46
Q

What pigment formation category is Runyon group II? What species are included?

A

Scotochromogens - M. scrofulaceum, M. szulgai, M. gordonae

47
Q

What pigment formation category is Runyon group III? What species are included?

A

Non-chromagens (MAC) - M. avium, M. intracellularae, M. ulcerans

48
Q

What category is Runyon group IV? What species are included?

A

Rapid growers - M. fortiuitum, M. chelonae

49
Q

T/F: The Runyon groups categorize all mycobacterium.

A

False; only non-tubercular mycobacterium

50
Q

What mycobacterium is one of the only niacin positive organism? What does this mean?

A

M. tuberculosis is niacin positive; because it cannot convert free niacin to niacin ribonucleotide, so niacin accumulates and creates a YELLOW color.

51
Q

What does a positive niacin test look like? What organism could this be?

A

Yellow pigment; M. tuberculosis

52
Q

What mycobacterium is positive for nitrate reduction? Negative? What color would this be?

A

M. tuberculosis is positive for nitrate reduction, creating a purple/red color, and M. bovis is negative (colorless).

53
Q

Explain the nitrate reduction test

A

Add sulfanilamide to nitrate broth.
Red color = positive (nitrate was reduced)
Colorless = inconclusive, move to next step
Add zinc dust
Red color = negative (nitrate still present)
Colorless = positive (nitrate reduced to nitrite)

54
Q

What organisms are negative/positive for the heat stable catalase test?

A

Negative = M. tuberculosis
Strong positive >45 mm = M. kansasii
Variable positive <45 mm = other mycobacteria

55
Q

What organisms are positive for Arylsulfatase? What color is positive?

A

Positive is red
Rapid growers that are positive = M. fortuitum and M. chelonae
Slow growers that are positive = M. marinum and M. szulgai

56
Q

What agar can be used for rapid growing mycobacterium?

A

MAC without crystal violet

57
Q

Positive color for iron uptake test

A

Brown

58
Q

What organisms are included in the M. tuberculosis complex?

A

**M. tuberculosis, **M. bovis, M. africanum, M. microti, M. canettii

59
Q

What disease states does M. tuberculosis cause?

A

Primary, reactivation, or extrapulomary tuberculosis; formation of granulomas in lungs

60
Q

What are important biochemicals/characteristics for the identification of M. tuberculosis?

A

Niacin positive
Nitrate positive
Heat stable catalase negative
Non-photo chromogen
Slow growing buff colonies
Growth at 35-37 ONLY
Cording

61
Q

Treatment for M. tuberculosis

A

3 or more drugs over a 9 month period; often prescribed with b12 vitamins for liver health

62
Q

What causes MDR-TB?

A

Can be caused by resistance and noncompliance of medication

63
Q

What is the recommended susceptibility testing for TB?

A

Isoniazid, Rifampin, Ethambutol, and Streptomycin

64
Q

What does M. bovis cauase?

A

TB in animals that can be transmitted to humans after the ingestion of contaminated milk (intestinal TB) can be pulmonary and resembles M. tuberculosis

65
Q

What is the live attenuated strain of M. bovis?

A

Bacilli-Calmette-Guerin (BCG) immunization for tuberculosis

66
Q

Biochemical reactions that aid in the identification of M. bovis

A

Non-photochromogen
Niacin negative
Nitrate negative
Slow growing

67
Q

What diseases does M. kansasii cause?

A

Chronic pulmonary disease, extrapulmonary disease, disseminated infections (rare)

68
Q

Notable features/biochemicals for M. kansasii

A
  • Photochromogen
  • Exhibits cording
  • Niacin negative
  • > 45mm bubbles for heat stable catalase
  • Slow growing smooth to rough
  • Grows best at 37C
69
Q

Notable features/biochemicals for M. marinum

A

Slow growing
Photochromogen
Grows at 28-32C

70
Q

What is the site of infection and disease states for M. marinum?

A
  • Causes disease in fish, isolated from salt/freshwater aquariums
  • Can cause cutaneous infections associated with water (Swimming Pool Granuloma)
  • would be isolated from a wound bc limited to the skin
71
Q

Notable characteristics about M. simiae

A
  • Isolated from monkeys
  • Causes rare infections in people with lung damage (rare in US except Texas)
  • Photochromogen
  • Short coccobacilli
72
Q

What diseases can M. gordonae cause and where are they acquired from?

A

Acquired from contaminated drinking water, called “tap water bacillus”
- Can cause meningitis, synovitis, cutaneous lesions, pulmonary disease

73
Q

Notable characteristics of M. gordonae

A

Scotochromogen
Yellow-orange colonies
Slow growing in 10-14 days at 22-37C

74
Q

What diseases does M. scrofulaceum cause?

A

Cervical lymphadenitis in children (infected cervical lymph nodes)
- Pulmonary with skin lesions

75
Q

Growth of M. scrofulaceum

A

Scotochromogen
Yellow-orange colonies in 4-6 wks at 25-37C

76
Q

Growth of M. xenopi

A

OPTIMAL GROWTH 42C
NO GROWTH 25C
Slow growth 37C
Non-photochromogen with “birds nest morphology”

77
Q

Epidemiology/Diseases caused by M. xenopi

A

Found in hot water taps and birds, causes rare slow progressing pulmonary infections

78
Q

What diseases does M. szulgai cause?

A

Pulmonary diseases, lymphadenitis, BURSITIS (inflammation of joints)

79
Q

Identification of M. szulgai (growth)

A

Scotochromogen at 37C
Photochromogen at 22C

80
Q

What is the most common NTM causing tuberculosis in the US?

A

M. avium complex (MAC)

81
Q

What is included in the MAC?

A

M. avium, M. intracellulare

82
Q

Where is MAC acquired (site)?

A

Environmental sources (soil, water, house dust)

83
Q

What infections does MAC cause?

A

Pulmonary TB, systemic TB (HIV), and cervical lymphadenitis in children

84
Q

What does MAC look like in lymph node biopsy (notable feature)?

A

AFB inside of macrophages

85
Q

Growth of MAC

A

Non-chromogen
Slow growing smooth colonies that turn yellow with age
Growth at 37C

86
Q

What diseases can the M. terrae complex cause?

A

Septic arthritis, synovitis –> affects joints

87
Q

Where is M. terrae complex acquired from (site)?

A

Soil, vegetables

88
Q

What diseases does M. haemophilum cause and in what group?

A

Immunocompromised; causes swellings/ulcers/abscesses, draining fistulas and joint disease in Bone Marrow transplant patient

89
Q

Growth of M. haemophilum

A

Requires hemin for growth
Grows at 28-32C
No growth at 37C
Non-chromogenic

90
Q

What does M. ulcerans cause?

A

Painful nodule after trauma that develops into an ulcer

91
Q

Growth of M. ulcerans

A

Grows 30-33C
NG at 37C
Little growth at 25C
Nonchromogenic; slow growing
Smooth to rough buff colonies

92
Q

What are “rapid growers”

A

Growth in less than 7 days

93
Q

where is M. fortuitum found?

A

Soil, dust water

94
Q

What diseases does M. fortuitum cause?

A

Skin and soft tissue infections in catheter/IV/injection sites

95
Q

M. chelonae infections

A

Disseminated cutaenous infections (similar to M. fortuitum

96
Q

What organism is M. abscessus closely related to?

A

M. chelonae

97
Q

Where is M. abscessus found and what disease state may it cause?

A

Tap water; may cause lung disease, otitis media, or disseminated cutaneous infections

98
Q

What disease does M. leprae cause?

A

Hansens disease/Leprosy

99
Q

What part of the body does Leprosy/Hansen disease affect?

A

Skin, mucous membranes, and peripheral nerves. May cause tuberculoid leprosy or lepromatous leprosy

100
Q

Diagnosis for M. leprosy

A

Demonstrate acid fast bacilli on skin biopsy
Inoculate mouse foot pads to demonstrate disease (major swelling)

101
Q

M. genavense

A

Causes disseminated infections in HIV patients; only recovered from liquid media

102
Q

Where is Nocardia found and what infections may it cause?

A

Environmental organism found in soil/plants
May cause pulmonary infections after inhalation in immunocompromised patients
Causes cutaneous infection (thorn, splinter) may present the same as a fungal infection

103
Q

Smell of Nocardia

A

Earthy

104
Q

What medias will Nocardia grow on?

A

BCYE, regular media, Thayer Martin

105
Q

ID of Nocardia

A

Beaded, branching GPRs that are partially acid fast, chalky orange-tan to reddish colonies, aerial hyphae may be visible under dissecting microscope

106
Q

Treatment for Nocardia

A

Drainage and surgery; Sulfonamides

107
Q

Unique features of Rhodococcus equi

A

Has salmon pink mucoid colonies
Soil organism

Microbiology (24 decks)

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