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Respiratory > EXAM #2: MYCOBATERIA INFECTIONS > Flashcards

EXAM #2: MYCOBATERIA INFECTIONS Flashcards

1
Q

Where are nontuberculous mycobacteria found? How are they transmitted?

A

NTM are found ubiquitously in soil and water; they are transmitted via inhalation

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2
Q

List the nontuberculous mycobacteria.

A

Mycobacterium avium complex (MAC)
Mycobacterium kansasii
Mycobacterium marinum
Mycobacterium scrofulaceum

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3
Q

What does MAC infection refer to?

A

Infection caused by:

1) Mycobacterium avium
2) Mycobacterium intracellulare

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4
Q

What specific patient population is at risk for MAC infection?

A

HIV patients with CD4 count less than 50

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5
Q

How is MAC infection differentiated from TB?

A

MAC is distinguished from TB by the presence of:

1) Anemia
2) Elevated alkaline phosphatase
3) Elevated lactate dehydrogenase

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6
Q

What is the regimen for MAC prophylaxis? When is this started? What about MAC treatment?

A

Prophylaxis= CD4 count less than 50
- Azithromycin or clarithromycin (macrolides)

Treatment
- Azithromycin or clarithromycin (macrolides) + ethambutol

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7
Q

What clinical symptoms are caused by M. kansasii transmitted? How is it transmitted?

A
  • M. kansasii causes sx. indistinguishable from TB
  • Transmitted via tap water in affected cities (Kansas)

*Note that CXR will be like typical TB with cavitation

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8
Q

What is the clinical presentation of M. marinum? Where is it commonly found?

A
  • M. marinum causes papules or ulcers in a lymphocutaneous pattern
  • Water sources associated with aquarium cleaners, fisherman, and seafood handlers
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9
Q

What is the mnemonic to remember the agents commonly used to treat NTM?

A

MARIE

  • Macrolides
  • Aminoglycosides
  • Rifamycins
  • Isoniazid
  • Ethambutol
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10
Q

Worldwide, what are the two most common causes of death from an infectious disease?

A

1) HIV

2) TB

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11
Q

What caused the increased TB prevalence that started in 1985-1986?

A

HIV epidemic

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12
Q

What are the high risk setting for acquiring TB? Geographically, where are the highest rates of TB infection?

A

High risk=

1) Prisons
2) Hospital
3) Homeless shelters

Geographically=

1) Sub-Saharan Africa
2) India
3) Southeast Asia/ Indonesia

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13
Q

How is TB transmitted?

A

Inhalation of droplet nuclei i.e. airborne particles

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14
Q

What are the three possible consequences of inhaling TB droplet nuclei?

A

1) Clearance w/out infection
2) Primary TB
3) Secondary TB

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15
Q

What is Primary TB?

A

TB infection arising from initial infection/ early progression

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16
Q

What is Secondary TB?

A

Reactivation of latent/contained TB

  • Primary infection years prior gets contained by immune system
  • Altered immune system–> development of symtoms
17
Q

How is Primary TB described on CXR?

A

“Ghon Complex”

  • Spread of TB to lymphatics
  • Regional lymphadenopathy= complex
18
Q

If symptomatic, what clinical symptoms are associated with primary TB?

A

1) Fever

2) Chest pain with pleural effusion

19
Q

What is the typical disease course of primary TB?

A

1) 90% become asymptomatic–infection contained but not eradicated (latent TB)
2) 10% progress to develop infection

20
Q

How is latent TB diagnosed?

A

1) Positive TB skin test
- “Mantoux technique”
2) Interferon gamma release assay (IGRA)

Note that steroid use, malnutrition, and an immunocompromised state can lead to a false negative test

21
Q

How are the results of a PPD skin test documented?

A

mm of INDURATION (thickening of the skin) not erythema

This will be a test question

22
Q

If a patient has a positive TB skin test IGRA, what does this mean?

A

LATENT TB infection, NOT active disease

23
Q

What is the important distinction between the PPD skin test and IGRA with regards to the BCG vaccine?

A

IGRA will NOT be affected by the IGRA

*PPD will be positive if the patient has had BCG vaccine

24
Q

What should you do if a patient has a positive PPD skin test?

A

1) Measure induration

2) Risk stratify to determine if test is positive

25
Q

What is indicated when a patient has a positive PPD test?

A

Prophylactic therapy w/ Isoniazid 300mg x 9 months

*Plus pyridoxine (B6)

26
Q

What medical conditions are considered high risk for TB?

A

1) Silicosis
2) DM
3) Chronic renal failure
4) Gastrectomy/ jejunoileal bypass
5) Weight loss
6) Children under 4 y/o

27
Q

What are the classic symptoms of active TB?

A

1) Cough
2) Fever
3) Night sweats/chills
3) Hemoptysis
4) Weight loss

28
Q

What are the general principles of TB therapy?

A

1) At least 2x drugs
2) Always use appropriate doses
3) Drug must be taken regularly
4) Long duration therapy

29
Q

What drugs are used for the induction phase of TB treatment? How long is this phase of treatment?

A

RIPE

R= Rifampin 
I= Isoniazid 
P= Pyrazinamide 
E= Ethambutol

*First 2x months of therapy

30
Q

If the patient has negative sputum cultures and a negative CXR after the first two months of treatment, what do you do?

A

Stop Pyrazinamide and Ethambutol

31
Q

What drugs are used for the continuation phase of treatment in TB? How long is this phase of treatment?

A

1) INH
2) Rifampin

4-7 months

32
Q

What do you do in a patient that is sputum positive and/or has a positive CXR after the first two months of therapy?

A

1) Continuation of induction therapy

2) Consider drug resistance

33
Q

What is the definition of Multidrug Resistant TB (MDR-TB)?

A

Lab confirmed resistance to INH and RIF

34
Q

What is diagnostic for active TB?

A

Positive sputum culture

35
Q

What is scrofula?

A

Mycobacterial cervical lymphadenitis

*This is a lymphadenitis of the cervical lymph nodes that usually appears as a chronic painless mass in the neck

36
Q

What is Pott’s Disease?

A

Skeletal infection with M. tuberculosis, esp. involving the spine

37
Q

What is a Ranke complex?

A

Ghon complex that has undergone fibrosis and calcification

38
Q

What stain is used to diagnose tuberulous meningitis? Where is this normally located?

A

Ziehl-Neelsen stain

*Granulomas are found at the base of the skull

39
Q

What is the most common organ to be involved with systemic spread of TB? What is the result?

A

Kidney, resulting in sterile pyuria

Respiratory (35 decks)

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