Mycobacterial Infections Flashcards Preview

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Flashcards in Mycobacterial Infections Deck (60):
1

What are the bacteria that cause typical TB? (7) Which two are the main organisms that cause TB?

**M. TB**
M. Bovis
**M. Africanum**
M. Microti
M. Canetti
M. Caprae
M. Pinnipedii

2

What is atypical TB?

Non-TB mycobacteria that grow slowly

3

What are the two bacteria that comprise the MAC complex?

M. Avium
M. intracellulare

4

What is the natural source of non-TB bacteria?

Water sources

5

Progressive lung disease with non-TB bacteria usually occurs in whom?

In patients with underlying bronchiectasis or COPD

6

What are the two distinct forms of MAC?

Fibrocavitary disease
Fibronodular disease

7

What is the fibrocavitary disease seen with the MAC complex infection? In whom is it seen? How does it appear on CXR?

TB-like disease with Cavitary lesions. Seen in older male smokers with COPD.

Usually upper lobe predominance on x-ray.

8

What is the fibronodular disease seen with the MAC complex infection? In whom is it seen? How does it appear on CXR?

TB like disease seen in nonsmoking women over 50 yo, and without underlying lung disease

Diffuse interstitial infiltrates and bronchiectasis

9

What is the natural source of M. Kansasii? How does this present?

Water (tap water in endemic cities)

TB cavitary lesions with chest pain, cough, hemoptysis and night sweats

10

true or false: the drugs used to treat atypical TB are the same as typical TB, making culturing them clinically insignificant

false--different drugs

11

Who usually gets fast growing atypical TB infections? Are cavitations more or less common?

White, middle aged females
Usually infiltrates--rarely cavitary lesions

12

True or false: there is no other test besides a culture to differentiate TB from non TB

True

13

True and false: the ssx of atypical TB are the same as usual TB

True

14

What is the treatment for atypical TB (3)? How long?

Macrolide + rifampin + ethambutol

12-18 months

15

What is the most common infectious cause of death worldwide? #2?

1 = HIV
2 = TB

16

What fraction of the world's population is infected with TB?

1/3

17

Where in the world are the highest rates of infection with TB?

Sub-saharan africa
Islands of southeast Asia

18

What are the three possible consequences of TB droplet inhalation? What is the most common?

-Immediately cleared without issue
-immediate onset of disease
-Latent infection with reactivation years later**

19

True or false: most patients with exposure to TB clear it without issue

True

20

True or false: in patients who are infected with TB, most of the time is is contained

true

21

What is primary TB?

When initial infection with TB is not controlled by local defenses and spreads to regional lymph nodes

22

What is a Ghon complex?

Localized Lymphadenopathy in the lung that is caused by tuberculosis.The lesions consist of a calcified focus of infection and an associated lymph node

23

Why are the cavitary lesions with TB usually seen in the apices of the lung?

Most aerated area of the lung

24

What happens with TB infection if the cell mediated immunity is inadequate?

Hematogenous spread, causing active disease. Becomes infectious.

25

What is the pleuritic chest pain with TB usually associated with?

Pleural effusion

26

What fractions of patients with primary TB have the usual ssx?

1/3

27

What are the CXR findings of active TB? (3)

Hilar LAD
Perihilar infiltrates
Effusion

28

What percent of patients with primary TB become asymptomatic?

90%

29

What is the most frequent source of infection with TB?

latent TB

30

Patients with non-active TB remain asymptomatic until when?

Until cell mediated immunity is compromised

31

true or false: a positive TB skin tests indicates an active infection

False--just been exposed.

32

True or false: as long as the cell mediated immunity remains intact, patients with latent TB are not a hazard to anyone else

True

33

What is involved with the TB skin test?

Cell mediated immunity to the PPD of TB

34

What is measured with the Quantiferon gold test?

IFM-gamma

35

How is the mantoux skin test performed?

Intradermal injection of 0.1 mL of PPD

36

How are the results of a TB skin test documented?

mm of induration--NOT erythema--perpendicular to the long axis of the forearm

37

How long after infection will a skin test show a positive result for TB?

several weeks

38

What may cause a false-negative TB skin test?

Impaired cellular immunity

39

What are the factors that indicates a positive TB skin test with more than 5 mm of induration? (3)

-HIV infection (immunosuppressed)
-Close contact with contagious case
-Abnormal CXR findings

40

What are the factors that indicates a positive TB skin test with more than 10 mm of induration? (3)

- Lung or kidney disease
- children under 4
-Foreign
-high risk setting

41

What are the factors that indicates a positive TB skin test with more than 15 mm of induration?

Healthy individuals unlikely to get TB

42

What does the quantiferon gold test involve?

T cell release of IFN in response to the antigen specific M. TB

43

Can the Quantiferon gold test determine if the infection is active or latent?

No

44

What are the tests for patients who had the BCG infection?

Quantiferon TB gold
T. spot assay

45

What is the specificity of the Quantiferon gold test?

95%

46

true or false: TB abx should be given to anyone, regardless of age, if they have a positive TB skin test

true

47

What is the treatment for TB?

Isoniazid x9 months
Rifampin
Ethambutol
Pyrazinamide

48

What are the high risk conditions for getting TB? (4)

-Silicosis
-DM
-CKD
-Gastrectomy

49

What are the characteristics of the fever associated with TB?

Diurnal
Progressively worsens

50

When does dyspnea occur in TB infections?

With significant parenchymal involvement

51

If pleuritic chest pain is present with TB, what does this indicate?

Pleural involvement

52

What is the usual dose of isoniazid for TB?

900 mg

53

What are the general principles of drug therapy for TB?

use at least two drugs that have documented activity

54

What is the alternative to rifampin therapy if a patient is taking other drugs metabolized by p450 enzymes

Rifabutin

55

What is the main adverse effect of rifampin?

Orange excretions

56

What is the major adverse effect of ethambutol?

Loss of color vision

57

What are the two phases of TB treatment?

-4 drugs x8 weeks
-INH and RIF for an additional 4-7 months

58

What are the three alternative schedules for the first phase of treatment for TB?

-8 weeks daily
-daily x2 weeks, then BID for weeks
-3 times weekly for 6 weeks

59

What is the definition of multidrug resistant TB?

Lab confirmed resistance to INH and rifampin

60

What is the way to diagnose active TB?

Sputum culture