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Acid Fast Bacteria Flashcards

1
Q

Process for acid fast staining

A

Carbolfushsin (red), heat, acid alcohol, methylene blue counter stain.

Acid fast organisms are red

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2
Q

Why are HIV patients at high risk for TB?

A

Reduced cell mediated immuntiy

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3
Q

Basic description of Mycobacterium tuberculosis

A

Acid fast
Obligate aerobe
Grows slowly
Hydrophobic lipid cell wall

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4
Q

What are the virulence factors of TB?

A

1) mycolic acid / mycosides - all below are mycosides
2) cord factor (damages mitochondria, releases tumor necrosis factor)
3) sulfatides- prevent phagocytosis
4) wax d- enhances antibody formation

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5
Q

Pathogenesis of TB

A

Inhaled via lungs, survives in macrophages (facultative intracellular growth) and invades other sites

Cell mediated immunity, necrosis of lung tissue

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6
Q

Term for necrosis of lungs from tb

A

Caseous necrosis

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7
Q

How long does it take for hypersensitivity reaction in PPD test to develop

A

48 hours

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8
Q

What are the cut points for TB ppd test induration

A

5 mm- HIV positive or immunosupressed

10 mm- from high incidence country, HCP, prior incarceration, high risk medical condition (diabetes)

15 mm- all others

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9
Q

What does a positive PPD result mean?

A

Person was exposed and infected at some time in the past

Positive for active, latent, and cured

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10
Q

What may cause a false positive TB ppd?

A

Bacillus calmette-guerin (BCG) vaccine

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11
Q

What may cause a false negative PPD test?

A

Anergic patients (lack normal immune response due to steroid use, malnutrition, AIDS, etc

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12
Q

Second test for tb

A

interferon gamma release assay (IGRA)

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13
Q

What is the risk of developing TB if infected with mycobacterium tuberculosis?

A

10 %

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14
Q

Stages of tb

A

1) primary (subclinical infection in lungs
2) latent - cell mediated immunity walls off bacteria
3) secondary or reactivation TB

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15
Q

Transmission of TB

A

Aerosolized droplet nuclei from adult with pulmonary tb

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16
Q

Describe the asymptomatic primary infection of TB

A

Tubercles form in lungs (walled off bacterium) and calcify (ghon focus)

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17
Q

Calcified tubercle in middle or lower lung zone

A

Ghon focus

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18
Q

Ghon focus accompanied by perihilar lymph node calcified granulomas

A

Ghon complex

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19
Q

Who is typically effected by symptomatic primary TB?

A

Children
Elderly
Immunocompromised

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20
Q

Clinical symptoms symptomatic primary tb

A

Chest radiograph shoes enlargement if mediastinal or hilar lymph nodes, sometimes chest infiltrates

Usually resolves with formation of tubercle granulomas

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21
Q

Most common site for tuberculosis reactivation

A

Pulmonary tb

22
Q

Clinical symptoms of pulmonary tb

A

Chronic low grade fever, night sweats, weight loss, productive cough that may have blood

23
Q

Describe pleural and pericardial TB infections

A

Fluid collection around the lungs or heart

24
Q

Most common extra pulmonary tb infection

A

Lymph node infection, called scrofula

25
Another name for secondary TB if kidneys
Sterile pyuria
26
What is the disease causes by secondary TB in the skeleton?
Pott's disease
27
How can secondary TB impact the joints?
Chronic arthritis in 1 joint
28
How can secondary TB effect the CNS
Meningitis and granulomas of the brain
29
Form of secondary TB, usually in children and elderly, where tiny Millet seed shaped tubercles (granulomas) are disseminated all over the body
Military tuberculosis
30
What are the diagnostic test for tb?
Chest x-ray Sputum acid fast stain and culture Rapid molecular detection
31
Describe resistance in MDR-TB
Resistant to isoniazid and rifampin
32
What is the resistance in XDR-TB
Resistant to isoniazid and rifampin, a fluoroquinolone, and an injectable agent (like and aminoglycosides)
33
Basic description mycobacterium leprae
Acid fast rod Impossible to feel on artificial media
34
Transmission of mycobacterium leprae
Respiratory secretion or skin lessions, unknown why certain people are susceptible
35
Types of leprosy based on severity
Lepromatous leprosy (most severe) Tuberculosis leprosy Borderline leprosy
36
Expansive group of acid fast organisms that are ubiquitous in the soil and water
Nontuberculosis mycobacteria (NTM)
37
Opportunistic Nontuberculosos mycobacteria that is common in people with AIDS
Mycobacterium avium-complex (MAC)
38
CD4 Cell count typically associated with mycobacterium avium complex infections
<50 CD4 per mm^3
39
Symptoms Mycobacterium avium-complex
Fever Weight loss Diarrhea General malaise Increase in alkaline phosphatase in routine labs
40
Organism that most commonly causes NTM lung diesase
Mycobacterium avium-complex
41
In an immunocompromised host, what illness can mycobacterium avium complex cause?
1. Upper lung cavitary disease in elderly smokers 2. Middle and lower lung nodular and bronchial disease in middle aged female non-smokers 3. Lymphadenitis in children
42
What diseases can Mycobacterium kansasii cause?
1. Upper lung cavitary disease 2. Disseminated disease in immune compromised patients
43
Diseases caused by mycobacterium abcessus
1. Pulmonary disease 2. Skin, soft tissue, and bone disease
44
Diseases caused by mycobacterium fortuitum
Skin, soft tissue, and bone disease
45
What NTM is a common lab contaminant?
Mycobacterium fortuitum
46
What mycobacterium is associated with foot baths
Mycobacterium fortuitum
47
What diseases does mycobacterium chelonae cause?
1. Skin, soft tissue, bone disease 2. Disseminated disease immunocompromised 3. Keratitis associated with contact use
48
What NTM is associated with fish tanks and is usually found in fresh and salt water
Mycobacterium marinum
49
What disease does mycobacterium marinum caus
Fish tank granuloma
50
What disease does mycobacterium ulcercans cause
Buruli ulcers (progressive necrotic skin ulcerations)
51
This NTM is found in tropical rain forests
Mycobacterium ulcerans
52
This species of MAC caused two outbreaks in prosthetic valve infections And disseminated infection tied to heating and cooling units in cardiac bypass procedures
Mycobacterium chimera

Clinical Micro (12 decks)

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