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2020 CPR II Pulm Exam 2 > Lecture 1: Mycobacterium > Flashcards

Lecture 1: Mycobacterium Flashcards

1
Q

Which chronic lung disease puts people at a particularly high risk for tuberculosis?

A

Silicosis

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2
Q

Which critical mediator released from TH1 cells both in LN’s and the lung enables macrophages to contain M. tuberculosis infection?

A

IFN-γ

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3
Q

Which immune cells orchestrate the formation of granulomas and caseous necrosis seen in M. tuberculosis infection?

A

TH1

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4
Q

Macrophages activated by IFN-γ in M. tuberculosis infection differentiate into what?

A

“Epithelioid histiocytes” that aggregate to form granulomas; some may aggregate to form giant cells

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5
Q

Pt’s with RA treated with what type of drugs are at an increased risk for tuberculosis reactivation?

A

TNF antagonist

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6
Q

Which pattern of tuberculosis arises in a nonimmune host vs. previously sensitized host?

A
  • Non-immune = primary TB
  • Previously sensitized = secondary TB
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7
Q

Secondary pulmonary tuberculosis classically involves which area of the lungs?

A

APEX of one or both lungs

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8
Q

What are the systemic and pulmonary signs/sx’s associated with secondary tuberculosis?

A
  • Remittent/low-grade FEVER + WEIGHT LOSS + Night sweats
  • Fever appears late each afternoon and then subsides
  • Sputum that at first is mucoid and later purulent; variable degree of hemoptysis
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9
Q

Which laboratory diagnostic test allows for more rapid diagnosis of M. tuberculosis?

A

PCR amplification of M. tuberculosis DNA

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10
Q

What remains the gold standard for confirming diagnosis of M. tuberculosis?

A

Culture

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11
Q

Primary tuberculosis almost always begins in which organ and what is seen morphologically as sensitization develops?

A
  • Lungs –> bacilli implant in the distal airspaces of lower part of upper lobe or upper part of lower lobe
  • Gray-white inflammation w/ consolidation, know as Ghon focus –> center of focus undergoes caseous necrosis
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12
Q

Ghon complex seen in primary TB is a combination of what?

A

Parenchymal lung lesion (Ghon focus)+LN involvement

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13
Q

Cell-mediated immunity typically controls the primary TB infection leading to what morphological change in the Ghon complex, which is often followed by what radiologically detectable change?

A

Ghon complex undergoes progressive fibrosis, followed by radiologically detectable calcification (Ranke complex)

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14
Q

Which subset of pt’s do NOT form the characteristic granulomas associated with primary TB and instead have macrophages loaded with many bacilli?

A

Immunocompromised

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15
Q

What is a risk factor in HIV infected pt’s before starting HAART which increases risk for developing tuberculosis?

A

Low CD4 count

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16
Q

Systemic miliary tuberculosis is most prominent in which organs/structures?

A
  • Liver
  • Bone marrow (osteomyelitis)
  • Spleen
  • Adrenals (Addison diseas)
  • Meninges (tuberculous meningitis)
  • Kidneys (renal tuberculosis)
  • Fallopian tubes (salpingitis) and Epididymis
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17
Q

With progressive pulmonary tuberculosis, the pleural cavity is almost invariably involved, and what 3 complications may be seen here?

A
  • Pleural effusions
  • Tuberculous empyema
  • Obliterative fibrous pleuritis
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18
Q

When the vertebrae are affected by isolated tuberculosis this is known as what?

Parapsinal “cold” abscesses in these pt’s may track along tissue planes and present how clinically?

A
  • Pott disease
  • Present as abdominal or pelvic mass
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19
Q

What is the most frequent presentation of extra-pulmonary tuberculosis (aka what is most often affected)?

A

Lymphadenitis

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20
Q

How does lymphadenitis and the presentation differ in HIV-negative vs. HIV-positive pt’s with active tuberculosis?

A
  • HIV-negative = lymphadenitis tends to be unifocal and localized
  • HIV-positive = tends to be multifocal disease w/ systemic sx’s, and either pulmonary or other organ involvement
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21
Q

Granulomatous inflammation leading to ulceration of the overlying mucosa and eventually healing strictures associated with intestinal tuberculosis is most often seen in which segment of the intestine?

A

Ileum

22
Q

What is the stain, shape, motility and oxygen dependence of M. tuberculosis?

A

Weakly gram (+) rod, NON-motile, obligate aerobe

23
Q

How is TB required and what is unique about this mode of transmission?

A

Aerosolized transmission; droplets can remain suspended for hours!

24
Q

Which virulence factor of M. tuberculosis inhibits neutrophil migration and damages mitochondria; releases cachectin causing weight loss?

A

Cord factor

25
Q

Which lobes of lung involved in primary TB?

A

Middle and lower lobes

26
Q

Which virulence factor of M. tuberculosis inhibits the phagosome from fusing with the lysosome?

A

Sulfatides

27
Q

A person with a postive PPD skin test is considered to have what?

A

Latent TB

28
Q

A positive PPD skin test is defined as what?

A

Area of induration (hardness) that is greater than a pre-defined size after 48 hours!

29
Q

A positive PPD skin test will be present in which 3 situations?

A
  • Pt with active infection
  • Pt with latent infection
  • Pt who was cured of their infection
30
Q

What is the BCG vaccine made from and why is it given; why you should be weary about it when giving a PPD test for TB?

A
  • Made from M. bovis
  • Given in high prevelnace areas for prevention of severe forms of disseminated TB in children
  • May cause a false (+) PPD test
31
Q

What is anergy and what may it be caused by?

A
  • Anergic = lack normal immune response due to..

- Steroid use, malnutrition, AIDS, etc.

32
Q

If the typical healing by fibrosis and/or calcification seen with primary TB does not occur and instead progresses to primary progressive TB what are 3 patterns of injury which may be seen?

A
  • Primary caseous pneumonia
  • Tuberculosis bronchopneumonia –> 2’ to bronchogenic spread
  • Miliary tuberculosis –> 2’ to hematogenous spread
33
Q

What is the common CXR finding for secondary TB?

A

APICAL and posterior segment involvement, pulmonary cavitation present

34
Q

What is another name for the PPD test?

A

Mantoux skin test

35
Q

In which 4 situations will an induration of ≥5mm be considered a positive PPD test?

A
  • HIV
  • Close contact w/ actively infected person
  • CXR w/ fibrotic changes consistent w/ TB
  • Immunosuppression (TNF-alpha inhibitors, chronic glucocorticoids, chemotherapy, and organ transplant)
36
Q

What are 4 situations where an induration of ≥10mm is considered a positive result from a PPD test?

A
  • Pt w/ clinical conditions that ↑ risk of reactivation: silicosis, DM, chronic renal failure w/ dialysis, malginancies, malnourished, IV drug abuse
  • Children <4
  • From country of high prevalence
  • Residents/employees in high risk setting: jail, healthcare, mycobacterium labs, homeless shelters
37
Q

What are 4 causes of false positive PPD tests?

A
  • Previous BCG vaccine
  • Infections w/ nontuberculosis mycobacterium
  • Incorrect administration of TST
  • Incorrect interpretation
38
Q

What are 6 causes of false negative PPD test?

A
  • Anergy
  • Recent TB exposure (not enough time to generate response)
  • Age <6 months
  • Very old TB
  • Recent live virus vaccine for infxn w/ virus (measles, chicken pox)
  • Overwhelming TB infection
39
Q

What is the initial staining used to screen for M. tuberculosis?

A
  • Initial screen = Auramine-rhodamine stain (utilizes fluorescent microscopy)
40
Q

Which 2 stains are confirmatory for TB?

A
  • Ziehl-Neelsen stain
  • Kinyon stain
41
Q

XDR-TB (aka extremely drug resistant) is defined as resistance to what?

A
  • Isoniazid
  • Rifampin
  • a Fluoroquinolone
  • An injectable agent (such as an aminoglycoside)
42
Q

What is the most common cause of fever of unknown origin in AIDS patients?

A

Mycobacterium Avium Complex (MAC)

43
Q

How does mycobacterium avium complex present in AIDS patients?

A

Disseminated infection w/ fever, weight loss, hepatitis, and diarrhea

44
Q

Which 2 immunocompetent patient populations may be affected by mycobacterium avium complex and what is seen in each?

A
  • Upper lung cavitary disease in elderly smokers
  • Middle and lower lung nodular and bronchiectatic disease in middle-aged female non-smokers
45
Q

Which virulence factor of M. tuberculosis is used for Fe2+ acquisition?

A

Siderophore

46
Q

Which drug is added to TB regimen for drug resistant forms?

A

Streptomycin

47
Q

What is the most common extrapulmonary manifestation of M. tuberculosis?

A

Lymphadenitis –> Scrofula

48
Q

If a pt showing no signs of pulmonary TB receives a PPD test with induration of 12mm and has a hx of BCG vaccination; what is the next best step in management of this pt?

A

Interferon-gamma release assay

49
Q

What are 2 lab findings of the aspirate taken from a pleural effusion caused by TB; what stage of TB infection are pleural effusions most commonly associated with?

A
  • Adenosine deaminase and IFN-gamma
  • Associated with primary progressive TB
50
Q

Mycobacterium kansasii is most commonly seen in whom; is endemic in which areas of the US?

A
  • Older pt’s with underlying lung disease or long term smokers
  • M>>W
  • Endemic: Midwest and SW United States
51
Q

What is the tx and duration for Mycobacterium kansasii?

A

Rifampin + isoniazid + ethambutol for at least 18 months!!!

2020 CPR II Pulm Exam 2 (28 decks)

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