Mycobacteriaceae (Part I-IV)

Question 1

Where is mycobacteria found?

Answer 1

Water, soil, animals

Question 2

Are mycobateria aerobic/non-aerobic and spore-formers/non-spore formers?

Answer 2

Aerobic, non spore formers

Question 3

What is the gram stain for mycobacteria and are they slow/fast growing?

Answer 3

• Beaded gram-positive rod that is slow growing

* Note: Usually will not see on gram-stain because waxy coating

Question 4

True/False: Mycobacteria are “Acid Fast” organisms meaning they resist decolorization by acid alcohol

Answer 4

TRUE

Question 5

List two tests for mycobacteria and explain each.

Answer 5

1) Purified protein derivative (PPD)- In vivo. Shows immune response telling that patient has been exposed to mycobacteria. Delayed hypersensitivity.
2) Quantiferon-TB Gold Test: Performed on blood collected from patient measuring amount of interferon-gamma secreted by patients lymphocytes in whole blood in response to stimulated mycobacterial antigens IN VITRO. Cell-mediated response. Detection and Quantification. No false positive.

Question 6

Mycobacteria Active vs. Inactive Disease:

Answer 6

Active: Organism multiplies, patient is symptomatic and infectious.
Inactive: Organism walled-off, patient is symptom free and not infectious, screening tests WILL BE positive (TB skin test, and will remain +).

Question 7

Symptoms of active mycobacterium disease:

Answer 7

Fever, Shortness of breath, night sweats, chills, fatigue, anorexia and weight loss.

Question 8

If a tuberculosis screen is recently positive but the patient DOES NOT show indications of active disease, what would you do?

Answer 8

Perform Chest X-ray looking for active disease, still treat to prevent active disease (usually INH). See sanford pg. 117

Question 9

If a tuberculosis screen is recently positive and the patient SHOWS indications of active disease, what tests would you do?

Answer 9

1) Sputum: Smear and culture x3 first morning specimens.

2) Nucleic Acid Probes performed on Culture growth, Direct respiratory specimens (Perform on AFB smear positive sputa).

Question 10

If a tuberculosis screen is recently positive and the patient SHOWS indications of active disease, what would you do next WITH THE PATIENT?

Answer 10

Isolation: Maintained in negative-pressure isolation room until:

a) M. Tuberculosis ruled out (M. kansasii causes similar disease but not transferred person to person).
b) 2 weeks successful treatment
c) Smear negative specimens on 3 consecutive days.
d) Determined to be non-infectious by appropriate individual

Question 11

What 4 drug combination would you use with Mycobacteria and what is the length of therapy?

Answer 11

Isoniazid (INH), Rifampin (RIF), Ethambutol (ETB), Pyrazinamide (PZA). 6-9 months

Question 12

Multi-drug resistant TB is defined as what?

Answer 12

Resistant to at least 2 drugs including INH and RIF

Question 13

T/F: M. kansasii diagnosis and disease is similar to M.TB?

Answer 13

TRUE

Question 14

Extensively Drug resistant TB is defined how?

Answer 14

Resistant to at least 2 drugs including INH and RIF AND a FQ AND at least 1 of 3 second line drugs, ethambutol, pyrazinamide

Question 15

How is M. kansasii most likely acquired and how would you treat it?

Answer 15

Most likely through aspiration or local inoculation from environment. Treat at least 18 months with 3 drugs (INH, RIF, ETB).

Question 16

You have an immunocompromised patient (HIV+) patient and their CD4+ cells are <50-100mm and has symptoms of TB. What Mycobacterium species are you thinking it could be?

Answer 16

Mycobacterium avium complex

Question 17

An Acid-Fast Stain will be positive for:
A) M. tuberculosis
B) M. kansasii
C) M. avium complex
D) All the above

Answer 17

D) All the above

Question 18

When would you obtain a gastric lavage specimen for Mycobacteria?

Answer 18

When unable to obtain sputum sample. Preferred specimen for children. MUST neutralize acids in specimen.

Question 19

T/F: A fecal specimen is an acceptable culture for Mycobacteria

Answer 19

False

Question 20

Why is microscopic examination important for Mycobacteria?

Answer 20

Specimen detection important because of the slow growth rate. Purpose is to determine acid fast characteristic, detect new cases, monitor progress of disease/ treatment, criteria for patient release

Question 21

T/F: Fluorochrome stains is a screening procedure for mycobacteria that is more sensitive, but less specific than carbolfuschin stains

Answer 21

True

Question 22

Describe how you would do a blood culture for mycobacteria?

Answer 22

A) Lysis centrifugation- release intracellular mycobacteria, concentrate organisms if present.
B) OR inoculate directly to BROTH media (not to solid media)

Question 23

T/F: You should collect 3 to 5 early morning midstream or catheterized specimens if you decide to do a urine specimen for mycobacterium?

Answer 23

TRUE- Entire volume of 15mls, centrifuge to concentrate specimen

Question 24

When mycobacterial infection is suspected, which of the following specimens requires a special mycobacteria culture to be ordered to recover mycobacterial isolate as opposed to a routine bacterial culture?
A) Blood
B) Sputum
C) Urine
D) All the above

Answer 24

D) All the above

Question 25

What would mycobacterium sp. look like on a sputum direct specimen gram stain?

Answer 25

Would not show up because they do not gram stain because of waxy coating! BUT…mycobacterium are beaded gram-positive rod

Question 26

A patient has symptoms of TB and the Acid-fast Stain was reported as 3+ acid-fast bacilli seen. What does this indicate?

Answer 26

Infection of mycobacterium sp.