Acid Fast Infections Flashcards
what bacteria causes TB?
mycobacterium tuberculosis
what bacteria causes leprosy?
mycobacterium leprae
Tuberculosis
risk factors for infection
5 ?lifestyle? things
- household exposure
- crowded housing (prison, immigration)
- drug use
- travel to/from endemic area
- homelessness
Tuberculosis
conditions that are risk factors for TB
5 things
- DM
- immunosuppressive conditions/meds
- chronic renal failure
- hematologic malignancies
- head/neck cancer
Tuberculosis
what does TST mean?
TB skin test
Tuberculosis
what does PPD mean? what type of test is it?
- puriified protein derivative
- TST
Tuberculosis
what is LTBI
latent TB infection
Tuberculosis
what is active TB?
when sx occur
Tuberculosis
what is reactivation TB
Active TB after LTBI
Tuberculosis
who is considered positive with induration >/= 5 mm
- HIV infection/immunosuppressed pts
- close contact to active case
- those with abnormal CXR
Tuberculosis
who is considered TST positive with induration >/= 10mm?
- children younger than 4 y/o
- Immigrants from countries w/ high incidence
- residents/employees of high risk settings (prisons, healthcare facilites, homeless shelters)
- person’s w/ conditions that increase risk of reactivation
Tuberculosis
who is positive with induration >/= 15mm?
- healthy individuals age 4 yrs and older with low likelihood of TB infection
Tuberculosis
pathophys
4 steps
- inhalation of droplets
- bacteria travels to alveoli
- infection established if bacilli are not killed by alveolar macrophages
- CMI kicks in and T-cells and macrophages surround TB in granuloma (LTBI)
Tuberculosis
Signs & Sx
Constitutional (5), resp (3)
- malaise
- anorexia
- unintentional wt loss
- fever
- night sweats
- chronic, productive cough
- blood-streaked sputum
- dyspnea (unusual unless severe infection)
Tuberculosis
what is likelihood of extra-pulm TB?
20%
can occur anywhere
Tuberculosis
what is Pott’s Disease?
TB of the vertebrae
Tuberculosis
What is scrofula
TB lymphadenitis of cervical region (think dracula biting neck)
Tuberculosis
difference in CXR between primary & reactivation TB
- primary: middle/lower lobe opacities
- reactivation: opacities in apices
Tuberculosis
what is a gohn focus?
calcified granuloma
Tuberculosis
what is a ghon complex?
ghon focus + enlarged/calcified hilar nodes
Tuberculosis
why should you be cautious with CXR/chest CT?
- they are non-specific to TB
Tuberculosis
Describe cavitary lesions
what occurs, how tb spreads to others, how it spreads internally
- necrosis progresses to wall of airway and liquid necrotic material is discharged into bronchial tree
- this is then coughed up to infect others
- if swallowed, you could have GI infection
Tuberculosis
describe miliary TB
massive dissemination of tuberculosis in lungs- many tiny widespread nodules
Tuberculosis
Dx
NOT SCREENING
- Sputum AFB smear or NAAT (3 consec samples)
- Sputum culture
Tuberculosis
Screening tests for LTBI
- TST/PPD (skin test, measure induation)
- IGRA (blood test)
Tuberculosis
which screening test will be positive in pts with hx of BCG vaccination?
TST/PPD
Tuberculosis
who should be screened for TB?
- close contacts of sx pts
- immigrants from endemic areas
- those in high risk (crowded) settings
Tuberculosis
what don’t screening tests tell us?
active vs latent infection
Tuberculosis
Managing active TB cases
measures to follow
- pt in negative pressure room
- pt isolated until 2-3 neg sputum smears/cultures
- public health involvement
Tuberculosis
Tx for active infection
- Rifampin
- Isoniazid
- Pyrazinamide
- Ethambutol
Tuberculosis
side effects to remember for tx meds
- Rifampin: red/orange secretions
- Isoniazid: peripheral neuropathy
- Pyrazinamide: uric acid stones, photosensitivity
- Ethambutol: optic neuritis
Tuberculosis
which med requires you to supplement B6?
isoniazid
Tuberculosis
Tx for LTBI
- Rifampin
- Isoniazid
Leprosy
Pathophys
- preferentially attacks Schwann cells
- leads to nerve demyelination
Leprosy
Sx
9 sx/signs
- pale/pink patches of skin
- formication (feeling of insects crawling on skin)
- erythema patches w/ sensory loss
- deformity
- paralysis
- edema
- skin ulceration
- muscle weakness
- poor eyesight
Leprosy
define paucibacillary
fiver or fewer poorly pigmented, numb skin patches
Leprosy
define multibacillary
more than five poorly pigmented, numb skin patches
Leprosy
complications
damage to what systems?
- nerve damage
- skin damage
- eye damage
- resp tract damage
Leprosy
Dx
AFB identified in skin biopsy
Leprosy
Tx for paucibacilliary vs multibacillary
- paucibacilliary: dapsone, rifampicin, clofazimine (6 mo)
- multibacillary: dapsone, rifampicin, clofazimine (12 mo)
NTM
most common cause
MAC
NTM
who is at risk?
immunodeficient pts
NTM
signs/sx
6
- chronic/productive cough (+/-) blood tinged sputum
- fatigue
- malaise
- dyspnea
- fever
- unintentional wt loss
NTM
findings on chest imaging
- nodules, cavities, bronchiectasis
NTM
components of dx
3 things
- clinical compatible sx
- lung abnormalities on imaging
- Mycobacterium spp isolated from specimen
NTM
pos result criteria for sputum cultures vs bronchial washings
- sputum cultures: 2+ pos results
- bronchial washings: 1 pos result
NTM
tx
- macrolide
- rifampin
- ethambutol
