Micro Bio > RTI's 2 > Flashcards

RTI's 2 Flashcards

(43 cards)

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1
Q

What are the causes of M. pneumoniae

A

Tracheobronchitis & Pneumonia

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2
Q

Describe the charcateristics of Tracheobronchitis

A
  1. ~ 60 - 70% of infections for M. pneumoniae
  2. Prolonged post-infectious cough
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3
Q

Describe the characteristics of Pneumonia

A
  1. Approximately 20-30% of M. pnuemoniae infections
  2. Milder disease but long duration
  3. Most common cause of atypical pneumonia
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4
Q

Describe the virulence factors of chlamydia pneumonie

A
  1. unique cell wall structure = lacks peptidoglycan = inhibits phagocytosis
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5
Q

Describe the chacterostics of Chlamydia pneumoniae

A
  1. Resembles gram-negative bacteria
    -2. ontains an outer LPS membrane
  2. Lacks peptidoglycan in its cell wall, therefore beta-lactams won’t work
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6
Q

Describe what chlamydia pneuminoa means when it come to elementary bodies (EB)

A
  1. Infective form
  2. Attach to susceptible host
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6
Q

Describe what chlamydia pneuminoa means when it come to reticulate bodies (RB)

A
  1. Divide by binary fission
  2. After division, reorganize into EB
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7
Q

Describe the charcateristoics of legionella pneumophila

A
  1. Gram negative bacilli
  2. Intracellular pathogen
  3. widespread in environment
    (soil, water, taps, showers)
  4. widespread spectrum of illness
  5. stains faintly = very easy to miss
  6. motile
  7. Fastidious, BCYE agar (buffered charcoal yeast extract agar)
  8. Asaccharolytic
  9. require L-cysteine for growth
  10. stimulated by 5% CO2
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8
Q

How do you test for Legionella

A
  1. Culture ✔
    a. Sens 80-90%
    b. Spec 100%
  2. Urinary Ag ✔
    Sens 70-80%
    Spec > 99%
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9
Q

How can you treat Legionella

A

Fluroquinolones and Macrolides (exelent alterative)

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10
Q

What is the incubation period of pertussis

A

10 days (range 4-21)

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11
Q

Describe the Catarrhal stage of pertussis

A

Duration: 1-2 weeks
Symptoms : non-specific URI Sneezing, runny nose, mild cough, low grade fever, very contagious

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12
Q

Describe the Paroxysmal stage of pertussis

A

Duration: 1-6 weeks
Symptoms: paroxysmal cough, inspiratory whoop, posttussive vomiting, cyanosis, exhaustion, leukocytosis, lymphocytosis

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13
Q

Describe the convalescent stage of pertussis

A

Duration: 2-3 weeks
Symptoms: gradually resolve, however, may return or worsen if patients acquires secondary infection

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14
Q

What is the cause of Tuberculosis

A

Mycobacterium tuberculosis = Mycobacteria

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15
Q

Describe the charcateristics of mycobacteri

A
  1. Aerobic, non-spore-forming bacilli
  2. Slowly grow in bacterial culture (1-8 weeks)
  3. Cell walls contain long chain fatty acids (mycolic acid)
  4. ~100 species of Mycobacteria
  5. BSC-3 organisms
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16
Q

What is acid fast stain also refered to

A

The Ziehl-Neelsen stain

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17
Q

what is the furpose of The Ziehl-Neelsen stain

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A
  1. to indentify acid fast bacteria
18
Q

Describe the steps of an acid fast stain

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A
  1. The slide is flooded with carbol fuchin which is then heated to dry.
  2. Slide flooded with an acid alcohol solution and then counter
    stained with methylene blue or other stain
  3. “ACID FAST” bacteria retain the carbol fuchin stain due to the mycolic acids in their cell wall
  4. ACID FAST bacteria will stain PINK/RED.
  5. counterstain with blue of green
19
Q

Who are where are theyr more TB cases

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A
  1. Nunavat
  2. Foreign-born
  3. Indigenous
20
Q

How does Tb spread and how does one catch TB

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A
  1. Spread by airborne droplets, “droplet nuclei,” 1 to 5 microns in size
  2. Droplet nuclei generated when a person with TB disease coughs, sneezes, speaks, etc
  3. TB infection occurs when a susceptible person inhales droplet nuclei containing the bacteria becomes established in the body
  4. Infective dose <10 bacilli
21
Q

What does active Tb mean

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A

Infection WITH apparent disease

22
Q

what does Latent Tb mean

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A

Infection WITHOUT apparent disease

23
Q

What is the percentage of active pulmonary Tb

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A

5% = less common

24
What is the percentage that TB bacteria remains viable for long period of time
95%
25
what is the percentage of Disseminated TB (miliaryTB). Due to: Opening of a tubercle into bronchus Erosion of a blood vessel (blood-stained sputum)
~2%
26
What is the percentage that TB bacteria may reactivate after months or years
5%
27
What does MDR TB mean
Multi drug resistant to TB
28
What are the sites of infection for TB
1. Lungs – Pulmonary TB 2. Genitourinary tract 3. Lymph nodes 4. Bones and Joints = Pott's disease 5. GI Tb 6. Meningitis 7. Skin 2-7 = Extra-pulmonary TB
29
Describe the symptoms of TB
1. sually ‘chronic’ vs acute 2. Fever 3. Sweats (drenching, night-time) 4. Weight loss 5. Focal symptoms
30
What can give you clues to diagnosisng TB
1. History of TB 2. Immuno-compromised (ie. HIV, steroids) 3. Exposure history a. Country of origin, recent travel/work b. Contact with known TB
31
What is 2 step-Tuberculin skin test used for?
Test to determine previous exposure to Tuberculo-protein.
32
Describe how to identify positive TB test
1. Induration of  10 mm with erythema 2. Induration of 5-9 mm – low level sensitization with tubercle bacilli or cross reacting NTM 3. In AIDS patients: 5 mm induration – positive test
33
What would a positive TB test indicate
1. Active disease 2. Infection by M. tuberculosis at sometime in life 3. Previous vaccination with BCG 4. Infection with strongly cross reacting NTM
34
What could cause a False Neg Tb test
1. Early TB (recently exposed = test becomes positive after 4-6 weeks of infection) 2. Miliary TB (disseminated TB, where the bacteria spread throughout the body = not react properly) 3. Immunosuppression / anergy (AIDS, pregnancy) = Conditions where the immune system is weakened
35
If the skin test is negative what can you do
Use a chest x-ray
36
What does IGRA stand for
Interferon-Gamma Release Assay
37
Name two common IGRA tests
QuantiFERON-TB and T-Spot.TB
38
Is IGRA done in vivo or in vitro?
In vitro (in the lab, using blood samples)
39
How does IGRA work?
White blood cells from an infected person are stimulated with M. tuberculosis antigens, and if the person has TB infection, the cells release interferon-gamma (IFN-γ)
40
Advantages of IGRA over TB skin test (Mantoux)?
1. More specific (less false positives) 2. Quantitative result 3. Not affected by BCG vaccination
41
What does IGRA measure?
Individual’s immune reactivity to M. tuberculosis
42
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