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Micro Test 2 > Mycobateriacae- Part I > Flashcards

Mycobateriacae- Part I Flashcards

1
Q

Where is mycobacteriacae found?

A

water, soil, and animals.

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2
Q

Describe mycobac

A

they are aerobic, non spore forming
slow growing
gram stain= beaded gram positive rod
It has a high lipid content (difficult to pick up on aniline dyes and will NOT be seen on a gram stain)

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3
Q

What is “Acid fast”?

A

organisms resist decolorization by acid alcohol. It distinguhes other mycobateria from each other.

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4
Q

What do mycobacteria require for growth?

A

prefer CO2 for cell growth, optimal temp is 35-37, and range = 2 days to 8 weeks to grow

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5
Q

Why is safety so important to handling mycobacteria?

A

Serious nature of mycobacterial disease (particularly TB), health care workers are at risk fit for contracting TB, MINIMAL CHANCE OF INFECTIONS WHEN PROPER PRECAUTIONS ARE USED.

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6
Q

Describe specimen collection?

A

sterile disposable container, collect before antibiotic therapy, deliver promptly to lab, refrigerate if delay in delivery, SWABS NOT ACCEPTABLE IN MOST LABS

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7
Q

What can you use for specimen types for mycobacteria?

A

Respiratory, Urine, Gastric Lavage, Feces (not acceptable), Wound drainage, Blood, Body fluids, Tissues

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8
Q

How much sputum needs to be collected for a sample?

A

recommend minimum of 3 to 5 EARLY MORNING specimens on consecutive days because there is irregular and intermittent release of mycobacteria into bronchial lumen. THERE SHOULD BE NO POOLED SPECIMENS

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9
Q

Describe urine specimens

A

3-5 early morning midstream or catheterized specimens. Centrifuge to concentrate specimen.

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10
Q

When do you get a gastric lavage specimen?

A

When you are unable to obtain a sputum sample. Preferred specimen for children. However, you need to neutrilize the acid in the specimen.

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11
Q

What specimen is unacceptable for mycobacteria

A

Feces

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12
Q

For specimens from aspirated wound cultures…

A

swabs NOT acceptable

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13
Q

What is the method for collecting specimens for blood cultures?

A

lysis centrifugation or inoculating directly to broth media

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14
Q

For sterile body fluids…

A

STERILITY MUST BE STRICTLY MAINTAINED! For CSF, large volumes are needed. (tissues must stay sterile too!)

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15
Q

What is added to tissue specimans?

A

saline–helps avoid dehydration. You grind up the tissue to help release the organisms

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16
Q

What is a fluorochrome stain? (auramine O)

A

primary stain: fluorescent dyes

counter stain: potassium permanganate. It will appear gold against a black background.

17
Q

What are the +/- of using a flurochrome stain?

A

+: more sensitive than carbolfuchsin stains, examine on lower magnification.

-: rapid growing mycobacteria do not stain, less specific

18
Q

What are Carbolfuschins tains?

A

primary stain: carbolfuschin
counter stain: methylene blue
AFB will appear red and backround will be blue

19
Q

What are the +/- of using a Carbolfuschin stain?

A

+: more specific than fluroescent stain, stains all mycobacteria

-: longer exam time, less sensitive

20
Q

How do you interpret smears?

A

observe over 300 oil immersion fields. Look for mycobacteria, other organisms will stain partially acid fast.

21
Q

Microscopic eval: correlation with culture results

A

Extensive disease: good correlation

minimal/less advanced: less correlation

22
Q

What are the causative agents of tuberculosis?

A 
myobacterium tuberculosis (humans)
myobacterium bovis (cattle)
mybacterium africanum

they have an increase rate of infections, and multidrug resistance

23
Q

What is the most common cause of tuberculosis?

A

myobacterium tuberculosis, it is primarily a lung disease.

24
Q

What is a myobacterium tuberculosis active disease dependent on?

A

cellular immunity, amount of exposure, virulence of strain

25
Q

How does infection of myobacterium tuberculosis take place?

A
  1. inhalation of organisms
  2. reach aveoli
  3. immune response is initiated (organism can be walled-off)
26
Q

myobacterium tuberculosis: Active vs Inactive

A

Inactive disease:

  • organism is walled off
  • patient is symptom free and not infectious
  • screening tests will be positive (once a test is pos, it will always be pos)

Active:

  • organism multiples
  • patient is symptomatic AND infectious
27
Q

What are the symptoms of myobacterium tuberculosis: Active?

A

fever, SOB, night sweats, chills, fatigue, anorexia and weight loss.

28
Q

Where are the most common places for a disseminated disease to go to?

A

spleen, liver, bone marrow, kidney

29
Q

Three basic strategies are critical to prevention and control of TB:

A
  1. ID and completely treat person with active TB
  2. Finding and evaluating persons who have had contact with TB patients, possibly treatment. (contact investigations)
  3. screening populations at high risk for TB to locate persons infected with TB and giving therapy.
30
Q

What are myobacterium tuberculosis screen tests?

A

PPD or TST: in vivo, delayed hypersensitivity

QFT-G: in vitro, performed on blood collected from the patient. its cell-mediated response with blood.

31
Q

How many patient visits does QFT-G vs TST take?

A

1 vs 2

32
Q

What happens if someone recently screen positive for myobacterium tuberculosis?

A

1.Perform CXR for active disease (if no active, then still treat.
2. Active TB suspected
sputum: smear and culture X3
Nucleic Acid Probes performed on: culture growth, direct respiratory specimens

33
Q

TB-> What is the lab diagnosis?

A

Acid-fast stain, nucleic acid probes, sputum culture–> susceptiblity testing.

PCP is verbally informed at any stage of the process when smear/culture is positive.

34
Q

How should a patient be isolated?

A

patient isolated in a negative-pressure room until…

  • M. tuberculosis is ruled out
  • 2 weeks of successful treatment
  • smear negative specimens on 3 successive days
  • determined to be non-infectious by appropriate individual
35
Q

Active TB drug therapy:

A

Isoniazid, Rifampin, Ethambuton, Prazinamide. Length of therapy is around 6-9 months.

36
Q

Multidrug resistant TB:

A

resistant to at least 2 drugs including INH and RIF

37
Q

Extensively resistant TB:

A
  • resistant to at least 2 drugs including INH and RIF
  • a FQ
  • at least one of 1 of the 3 second-line
  • Ethambutol
  • Pyrazinamide
38
Q

What do you give for latent TB?

A

Isoniazid (and B6–but thats from med!!)

Micro Test 2 (4 decks)

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