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Infectious Disease > Acid-Fast Bacteria > Flashcards

Acid-Fast Bacteria Flashcards

1
Q

What is scroffula?

A

Lymphadenitis due to mycobacterium, usually M scrofulaceum.

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2
Q

A refugee child is seen for a dermatitis that has not responded to topical therapies. A Fite stain is performed on a biopsy and confirms the diangosis. What is the infection?

A

Leprosy (M. leprae)

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3
Q

What are the treatment options for a 17 year old female volunteer of the local aquiarium who has developed non-healing ulcers on her skin which have not responded to topical therapy in for the last 4 months?

A

This is Mycobacterium marinum infection.

  • Rifampin + ethambutol OR
  • Rifampin + clarithromycin
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4
Q

Which mycobacterium is associated with drinking fresh cow’s milk?

A

Mycobacterium bovis

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5
Q

A parent returns to clinic with her 4-year old who is being treated for pulmonary tuburculosis which she contracted from her grandfather. She asks you about daycare and wonders what the risk is for her child spreading the illness to other children. What should you tell her?

A

It isn’t likely. Children < 10 don’t commonly spread the disease via airborn route.

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6
Q

Primary, non-latent TB infection occurred in a 18 year old male with HIV.

  • Is it more likely he has infection in the upper or lower lobes?
  • What about reactivation TB? Is it more likely in upper or lower lobes?
A
  • More likely in lower lobes since they get more airflow.
  • More likely in upper lobes.
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7
Q

A 3 year old immigrant infant with apparently normal immune system is seen for non-productive cough and reports of wheezing, especially at night. The chest x-ray shows hilar lynphadenophathy. What infection do you suspect?

A

Tuburculosis.

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8
Q

What signs/symptoms do most children with TB present?

A

NO SYMPTOMS! Infants and adolescents, however, are more likely to have symptoms.

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9
Q

How might tuburculous pericarditis present on exam?

A

Rub or distant heart sounds.

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10
Q

What age range is more likely to develop tuburculous meningitis as a complication of untreated TB?

  • Children 6 months to 4 years
  • Children > 5 years old
  • Adolescents
  • Infants < 6 months old
  • Children 5 - 12 years old
A

Occurs in young children, 6 months to 4 years old.

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11
Q

In a child with TB meningitis, will sodium likely be low, normal, or high?

A

Low, because they often develop SIADH.

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12
Q

Which CSF profile fits best with TB meningitis?

  • Protein low, glucose low, WBC high
  • Protein high, glucose low, WBC low
  • Protein high, glucose low, WBC normal or mildly elevated
  • Protein low, glucose high, WBC high
A

Protein high, glucose low, WBC mildly elevated.

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13
Q

In TB meningitis, do you expect the CSF to have a lymphocyte or granulocyte predominance?

A

Lymphocyte predominance

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14
Q

True or False: Adolescents with pulmonary TB present like adults, with cough, fever, weakness, night sweats, and weight loss.

A

True

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15
Q

A 3 year old presents to clinic and she has risk factors for TB exosure. You are concerned about risk to follow-up regarding TB screening.

True or False? You should screen this child with Quantiferon Gold assay.

A

False. This can’t be used under age 5 because of no data regarding its use in that age group.

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16
Q

In terms of TB skin testing, you need to remember 3 different cutoff diameters. What are the three diameters upon which the guidelines are based?

A

5, 10, and 15 mm

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17
Q

In general, the three cutoffs for TB skin testing form three groups of possible positive testing. In general, how are these three cohorts described?

A

The test is positive for each cohort based on their risk factors:

  • 5 mm: positive for HIGH RISK
  • 10 mm: positive for INTERMEDIATE RISK
  • 15 mm: positive for LOW RISK
18
Q

List some risk factors that would classify a patient in the high risk group for TB infection. What measurement on skin testing would support a positive result?

A

5 mm is positive for people who:

  • Have CXR consistent with TB
  • Clinical symptoms consistent with TB
  • HIV or other cell-mediated immune dysfunction
  • Fibrotic changes on CXR consistent with TB
  • Close contacts with documented TB
  • Patients with organ transplant
  • Patients getting > 15 mg/day prednisone for > 1 month
19
Q

List some risk factors that would place someone n the moderate risk group for TB infection. What measurement in skin testing suggests a positive result?

A

10 mm is positive for:

  • Homeless
  • Recent travel or birth in a high prevalence region
  • IV drug abusers who are HIV negative
  • Prisoners
  • Health care workers
  • Nursing home patients/staff
  • Diabetics
  • People with CKD
  • Persons getting immunosuppression but < equivalent 15 mg/day prednisone
  • Children < 4
20
Q

A child 3 years of age is screened with PPD for TB. His result was 12 mm. He has not had BCG. Is this a positive result?

A

YES! Although he seems like he’d be in the low risk group (and would need to be > 15 mm) he is < 4 which makes him intermediate risk.

21
Q

Give a three-rule summary of the risk groups upon which PPD testing is based.

A
  • 5 mm for HIV, abnormal CXR, close contact, severely immunocompromised.
  • 15 mm for >= 4 and no risk factors
  • 10 mm for all the rest
22
Q

A 13 year old moved into the household 6 weeks ago of a grandparent who was just found out to have TB. TB skin test placed on the 13 year old was negative (no induration.)

  • When should he be tested again?
  • The result of the second test was 7 mm. Is this a positive result?
A
  • 10-12 weeks after first exposure
  • YES. It only need to be > 5 mm.
23
Q

How long after initial exposure to TB should a patient who had close contact be tested?

A

10-12 weeks after first close contact exposure.

24
Q

An IV drug user has HIV. His TB skin test will be considered positive at what diameter?

A

5 mm.

25
Q

An adolescent IV drug user who does not have HIV has a PPD measured at 5 mm. Should he be treated for latent TBI?

A

No, because in this case he is intermediate risk since he does not have HIV. For him, it needs to be > 10 mm.

26
Q

How do you interpret PPD testing in a patient who has had BCG vaccination?

A

The latest recommendations say to ignore the immunization and use the same cutoffs as for everyone else.

27
Q

In an asymptomatic patient with POSITIVE PPD, what is the workup?

A
  • CXR
  • sputum or morning gastric aspirate (if too young for sputum sample) x 3 for AFB culture, stain, PCR.
28
Q

An 8 year old and his 3 year old sister with no special risk factors for TB were tested with PPD.

  • What constitutes a positive result for each?
  • What would the next testing be for each?
A
  • Positive result:
    • For him, >= 15 mm
    • For her, >= 10 mm (since she is < 4)
  • Further testing:
    • The same for both except for the younger, she may not be able to provide sputum and thus you could do AM gastric aspirate.
29
Q

True or False? A patient with positive PPD is suspected of LTBI. Regardless of age, s/he should be treated for latent TBI even if further workup is negative.

A

True, treat all positive TSTs for latent TB regardless of status.

30
Q

What is the optimal treatment duration for LTBI? What is the treatment of choice?

A
  • 9 months
  • Isoniazide 10-15 mg/kg/day, max 300 mg/day
31
Q

Regardless of PPD test result, certain children who have had close contact with an active TB person should get treated. What are these risk factors?

A
  • < 4 years old
  • immunocompromised (i.e. HIV)
32
Q

Regarding LTBI treatment:

  • What is the duration of treatment?
  • When should the patient be retested?
  • How long should treatment be extended if repeat testing is positive?
A
  • 9 months
  • 8-10 weeks
  • 9 more months
33
Q

A 9 year old lives in a household with another person who had active TB. This person routinely cares for the child after school.

  • What PPD criteria would you consider a positive result?
  • What would trigger treatment of the child for LTBI?
  • If the adult’s TB is resistant to isoniazide, with what drug should the 9 year old be treated? For how long?
A
  • 5 mm since he has close contact with a documented case.
  • Doesn’t matter the result of the PPD. Because he had close contact, treat… regardless of PPD testing.
  • Rifampin, but for 6 months, not 9.
34
Q

Of the following drugs, which constitute the 4-drug regimen for treatment of active TB? The 3-drug regimen?

  • Ethambutol
  • Streptomycin
  • Doxycycline
  • Pyridoxine
  • Pyrazinamide
  • Rifampin
  • Indomethacin
  • Isoniazid
  • Erythromycin
A
  • 4 drug: Ethambutol or streptomycin, rifampin, pyrazinamide, isoniazid
  • 3 drug: skip ethambutol or streptomycin, but keep rifampin, pyrazinamide, isoniazid.
35
Q

You have diagnosed a 7 year old with active TB infection.

  • What are the four drugs in the treatment cocktail?
  • For how long do you treat with these drugs?
  • What do you do after that?
A
  • Ethambutol or streptomycin PLUS rifampin, isoniazid, pyrazinamide
  • 2 months
  • 4 months of INH and rifampin
36
Q

You have properly treated and 17 year old with HIV for active TB with the 4-drug cocktail. He is on protease inhibitors for his HIV infection.

  • How long did you treat initially?
  • What drugs do you give in the next phase?
  • How long does the next phase last?
A
  • 2 months, same as with any case.
  • Give INH + rifabutin instead of rifampin because of the protease inhibitor.
  • Treat for 4 more months, same as with any case.
37
Q

In some patients, you might need to supplement which vitamin due to the effects of INH?

A

B6 (pyridoxine)

38
Q

What should you councel a 15 year old female taking OCP while taking rifampin for TB infection?

A

Use another birth control method because OCP may become ineffective due to sped-up metabolism.

39
Q

True or False? All patients taking INH should have routine LFT monitoring.

A

FALSE. Only test those who are sympomatic.

40
Q

One of the four drugs used in active TB treatment can cause changes in vision. Which is it? What is the usual first symptom?

A
  • Ethambutol
  • Decrease in color perception
41
Q

An 8 year old taking 4-drug therapy for active TB experiences vertigo and ataxia. Which drug is likely the culprit?

A

Streptomycin

42
Q

A 10 year old has a lung abscess that has been very difficult to treat. Aspiration on acid-fast staining showed weakly acid-fast bacteria that were beaded in some cases, branching and filamentous in others.

  • What bacteria do you suspect?
  • What drugs are often used to treat this?
A
  • Nocardia
  • Bactrim (high dose) plus other drugs including:
    • Amikacin + ceftriaxone
    • Amikacin + imipenem

Infectious Disease (11 decks)

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