Tuberculosis

Question 1

define primary TB infection

Answer 1

first infection by TB

Question 2

define active TB infection

Answer 2

evidence of TB s/s

can occur from a reactivation of previous latent infection or a progression from primary infection

Question 3

define non-respiratory (extrapulmonary/miliary) TB

Answer 3

occurs when the TB infection has spread hematologically into other body systems

mostly occurs in immunocompromised individuals (DM and HIV) or young <15Y or old >65Y

Question 4

what bacteria causes TB?

Answer 4

mycobacterium tuberculosis

Question 5

what are some ddx for TB?

Answer 5

• pneumonia
• malignancy
• non-TB mycobacterium
• fungal infection (histoplasmosis)
• sarcoidosis: inflammatory disease that results in the formation of inappropriate granulomas

Question 6

tell me about the epidemiology of TB

Answer 6

most common in developing countries

cases in developed countries are typically due to recent arrivals from TB endemic zones, healthcare workers, HIV+ indiv or immunocompromised indiv

Question 7

what are general risk factors for TB

Answer 7

1. substance abuse: smoker/illicit drugs or a heavy drinker
2. close contacts: ppl who live or work in a community with high rates of TB or visiting countries w/ high rates of TB
3. occupational: mining or construction workers
4. comorbidities: HIV/AIDS, silicosis (lung disease), LT kidney disease, cancer, DM, immunodeficiency disorders, malnutrition/underweight, heme malignancy
5. immunosuppressive medications: chemo, meds post-transplant, meds for RA or SLE

Question 8

tell me about one virulence factor that mycobacterium tuberculosis uses

Answer 8

↑ mycolic acid in the bacteria cell wall → difficult for phagocytosis

Question 9

how is TB transmitted from person to person?

Answer 9

airborne ➔ coughs, speaks, or sings ➔ TB into the air ➔ people nearby may breathe in these bacteria and become infected

Question 10

what does the disease progression/timeline look like?

Answer 10

exposure ➔ primary infection ➔ normally becomes a latent TB infection ➔ weeks, months, or years ➔ active TB w/ reactivation

Question 11

how do you screen for TB?

Answer 11

Purified protein derivative (PPD) intradermal skin test (tuberculin test)
- measure induration with 48-72h
*false positive if prev immunized by BCG vaccine
*doesn’t differentiate between latent and active disease

interferon gamma release assay: blood test
*doesn’t have false positives for BCG vaccine

Question 12

what happens once you screen positive for TB?

Answer 12

diagnostic imaging
- CXR

Question 13

how do you definitively dx TB?

Answer 13

sputum analysis and culture
- acid fast bacteria smear, mycobacterial culture, and NAAT

if sputum not possible, consider bronchoscopy

Question 14

what bloodwork would you also consider doing for a confirmed TB pt?

Answer 14

1. HIV testing – immunocompromised state will impact tx response and potential symptom development
2. liver enzymes: ALT/ALP – for medication regimen as meds are hepatotoxic
3. electrolytes

Question 15

how do you medically treat active TB?

Answer 15

R.I.P.E.S

Rifampin
Isoniazid
Pyrazinamide
Ethambutol/streptomycin

Question 16

what recommendations would you tell the pt if they had active TB?

Answer 16

compulsory isolation until sputum negative for TB

required because the mode of transmission of TB; can be spread via airborne droplets

Question 17

what is latent TB?

Answer 17

no clinical, bacteriological, or radiographic evidence of TB

Question 18

how do you treat latent TB?

Answer 18

isoniazid for 9M
correct for potential vitamin B deficieicny which can cause peripheral neuropathy

Question 19

pathophys for TB primary infection

Answer 19

1. airborne droplets ➔ airway
2. land in the midlung zone
3. alveolar macrophages ➔ engulf the bacteria
4. bacterial immune system evasion by stopping lysosome and vacuole fusion
5. bacteria survives and proliferates in the cell
6. local infection
7. granuloma formation around the TB infected cell via T helper cells and macrophages
8. caseous necrosis ➔ Ghon focus
9. Ghon focus overtime undergoes fibrosis and calcifies ➔ Ranke complexes ➔ loses lung parenchymal function
10. if there is hilar lymph node involvement ➔ Ghon focus (in lung) + lymph nodes) = Ghon complex
11. mycobacteria are contained but can stay dormant ➔ latent TB
12. change in immune system ➔ reactivate TB ➔ secondary TB
13. TB most likely seen as opacities and cavities in lung apices
14. can also disseminate to other systems via lymph nodes ➔ extrapulmonary/miliary TB

Question 20

what is a Ghon focus?

Answer 20

dead tissue inside granuloma

Question 21

what is a Ghon complex

Answer 21

a ghon focus with hilar lymph node involvement

Question 22

what are Ranke complexes?

Answer 22

Ranke complex is seen in ‘healed’ primary pulmonary tuberculosis and is a later manifestation of the Ghon complex which is fibrosed and calcified

Question 23

what does Ghon complex tell us about stage of TB?

Answer 23

latent stage bc can still have dormant bacteria in the lung

Question 24

what does Ranke complex tell us about stage of TB?

Answer 24

tells us the TB has resolved

Question 25

how does someone with primary TB usually present?

Answer 25

may be asymptomatic or have mild flu-like illness

• chronic cough, hemoptysis, wt loss, low grade fever, and night sweats

Question 26

how does someone with secondary pulmonary TB present?

Answer 26

usually in the immunocompromised pt

consistutional s/s: fever, chills, night sweats, fatigue, anorexia, wt loss, and pleuritic chest pain

cough, purulent sputum and hemoptysis

crepitations - crackling and rattling

Question 27

what does extra-pulmonary/miliary/disseminated TB look like?

Answer 27

when TB spreads to other tissues

common organs:
- kidneys – sterile pyuria
- meninges – meningitis
- vertebral – POTT disease
- adrenal – Addison’s disease
- liver - hepatitis
- joints - mycobacterial arthritis
- long bones - osteomyelitis

Question 28

is TB a public health reportable disease?

Answer 28

yes

pt consent not required to report