Tuberculosis

Question 1

what is the risk of starting a anti TNF alpha inhibitor?

Answer 1

reactivates TB

Question 2

How to test for active pulmonary TB?

Answer 2

induced sputum tested for AFB.

Question 3

Quantiferon Gold will be positive for life? True/false

Answer 3

true. so not helpful for determining if someone has active dx.

Question 4

treatment options for latent TB infection

Answer 4

isoniazide and rifapentine weekly for 3 months under DOT (not recommended for HIV pt)

isoniazid monotherapy for 6-9 months (give them pyridoxine (Vitamin B6) to prevent neuropathy from isoniazid)

rifampin for 4 months.

No need for baseline or monthly monotring of LFTs unless at risk for hepatotoxicity (HIV infection, chronic Hep B or C or ETOH use, pregnancy or other concurrent hepatotoxic drugs or underlying liver dx)

Question 5

pyridoxine is also known as

Answer 5

B6 vitamin supplement. Give this in pts on isoniazid to prevent peripheral neuropathy. Also higher risk for B6 deficiency are those with DM2, uremia, ETOH, malnutrition and HIV, pregnancy and epilepsy

Question 6

Major side effects of isoniazid therapy

Answer 6

vitamin b6 deficiency

neuropathy

hepatitis - stop drinking ETOH and check LFTs every 3 months

Question 7

When to stop isoniazid due to LFT side effects

Answer 7

check LFTs q3months and stop if serum transaminase levels are >3 times the normal limit in symptomatic pts and >5 times normal limit in asymptomatic pts

Question 8

who needs to get sputum samples for acid fast stain?

Answer 8

pts with concern for TB and they have respiratory symptoms OR chest XR symptoms concerning for active TB

Question 9

Tuberculin skin test (TST) is positive at >5mm when they are

Answer 9

close contacts of known TB case.

10 mm cut off is used for recent immigrants from endemic areas, IVDA, residents, employees of high risk settings and those at risk for TB reactivation (glucosteroids and leukemia and ESRD)

Question 10

what does a positive TST mean?

Answer 10

it means exposure and doesn’t need to be repeated. close contacts who have negative initial TST should have repeat TST done at 8-12 weeks.

Question 11

pts to treat if PPD or TST induration is >5mm

Answer 11

HIV positive pts recent contacts of known TB case nodular or fibrotic changes on CXR consistent with previously healed TB organ transplant recipient or other immunosuppressed pt

Question 12

pts to treat if PPD or TST induration is >10mm

Answer 12

recent immigrants from endemic areas, IVDA, residents, employees of high risk settings (prisons, SNF, hosptials and homeless shelters) and those at risk for TB reactivation (DM2, glucosteroids and leukemia and ESRD, chronic malabsorption syndromes) kids<4 yrs and those exposed to adults in high risk categories

Question 13

pts to treat if PPD or TST induration is >15mm

Answer 13

all the above plus healthy individuals

Question 14

those who have been exposed to the highly infectious pulmonary TB should get a

Answer 14

TST within a week of exposure. If negative it doesn’t mean they don’t have it; it means they need repeat TST in 8-12 weeks.

Question 15

is there a window period from infection/exposure to detectable PPD skin test?

Answer 15

yes. it’s about 2-12 weeks and so CDC recommend retesting exposed individuals again with a repeat TST test 8-152 weeks after exposure for those who have a negative TST initially

Question 16

what to do after someone has a positive TST?

Answer 16

need a CXR and symptom review to clarify if they have active pulmonary TB

Question 17

how long does it take for a interferon gamma release assay to turn positive after exposure

Answer 17

there’s also a window period and it takes about 4-6 weeks

Question 18

are interferon gamma release assays (IGRAs) affected by the BCG vaccine?

Answer 18

no they are not affected by this. TST can be affected by BCG vaccine.

Question 19

positive test TST criteria?

Answer 19

>10 mm increase within a 2 year period

Question 20

Prophylaxis of TB in HIV positive pts

Answer 20

Question 21

side effects of rifampin

Answer 21

hyperuricemia
discolored body fluids
hepatitis

rifampin and rifapentine also can cause drug interactions

Question 22

clinical manifestations of a TB infection:

Answer 22

fever,

weight loss,

productive cough (blood tinged sometimes)

anorexia, malaise

pleuritic chest pain

Question 23

Latent TB is defined as:

Answer 23

positive TST or IGRA with no clinical or radiographic manifestation of active TB

Question 24

When do we prefer to do a IGRA (quantiferon gold) test over a TST?

Answer 24

when pt is <5 years old

older pts who are likely to have M tb

low to intermediate risk of dx progression

history of BCG (bacillus Calmette Guerin) vaccination

or unlikely to return to have TST result read.

Question 25

in which cases or clinical scenarios are IGRA better than using a TST to tell if they have TB?

Answer 25

BCG (bacillus Calmette Guerin) vaccination and non tuberculous mycobacterium infection.

IGRAs have less cross reactivity and sensitization with BCG (bacillus Calmette Guerin) vaccination whereas TST will show a bump or induration

IGRAS have less cross reactivity and sensitization by non tuberculous mycobacterium

Question 26

how to diagnose some with active TB infection?

Answer 26

All suspected people must get AFB smear microscopy

Testing three samples is recommended because can have both false negative and false positive

Need to get expectorated sputum (preferred over BAL) and needs 5-10 ml _at least 8 hrs apar_t with one early morning specimen.

Gold standard is - culture of MTB - liquid or solid cultures which return in 2-4 weeks (as opposed to traditional 8-10 weeks)

If sputum smear is positive for AFB, then need to get NAAT or nucleic acid amplification testing - which detects PCR of TB in sputum. PPV of NAAT on a smear positive sputum is 95%

Question 27

Gold standard of active TB infection

Answer 27

Gold standard = culture of MTB - liquid or solid cultures which return in 2-4 weeks (as opposed to traditional 8-10 weeks)

Question 28

importance of getting NAAT testing for TB and how it all fits in to diagnosis of TB.

Answer 28

three expectorated sputums 8 hrs apart with one early morning sputum for AFB smear microscopy

If sputum smear is positive for AFB, then need to get NAAT or nucleic acid amplification testing - which detects PCR of TB in sputum. PPV of NAAT on a smear positive sputum is 95%

If negative smear, NAAT can be positive in 65% of cases

NOTE a negative NAAT doesn’t exclude TB - can confirm presence of TB in 50-80% of time on AFB negative smear, culture positive specimens.

NAAT also can help detect for rifampin resistance.

gold standard diagnosis : culture of AFB.

Question 29

histopathology of TB is

Answer 29

caseating granulomas which are suggestive but not exclusive to or diagnostic of TB.

can get blood cultures of TB.

Question 30

Pregnant women who have latent TB should get

Answer 30

should delay or defer therapy until after delivery unless the pt is at high risk for developing active infection due to immunocompromise (HIV)

Question 31

Treatment of active TB infection

Answer 31

1st line agents: isoniazid, rifampin, pyrazinamide, ethambutol

• from multidrug resistant and extensively drug resistant TB

needs 6-9 months of treatment (4 drugs given daily for 2 months then can get isoniazid plus rifampin daily for 4 months)

Direct observed thearpy is needed

recheck sputum samples at 1 month and 2 months to look for efficacy.

Question 32

what must be checked prior to starting TB treatment for active TB infection?

Answer 32

check CBC, LFTs, hepatitis serology and clinical assessment.

Question 33

Drug resistant TB is:

Answer 33

isoniazid resistant TB- isoniazid, rifampin, ethambutol can be given 6 months but some experts recommend adding a fluoroquinolone

isoniazid and rifampin resistant MDR-TB (multi drug resistant) - FIVE drug regimen depneding on isolate susceptbility for 4 months followed by four drug regimen for 12-18 months

Question 34

HIV and TB

Answer 34

TREAT TB infection first before HIV….can layer in ART to avoid IRIS.

ART should be started within 2 weeks (after starting TB meds) with CD4<50

start ART by 8 to 12 weeks (after starting TB meds) with CD4 >50 or more

exception is HIV positive pts with TB meningitis then ART should not be started during first 8 weeks of TB therapy regardless of CD4 count due to increased morbidity because of IRIS.

Question 35

when are active TB pts safe and no longer contagious (ok to remove the airborne precautions)

Answer 35

• needs to be on appropriate TB meds for 2 weeks
• clinical improvement of signs and symptoms
• 3 negative sputum smears collectived at least 8 hours apart with one being an early morning specimen

Pts with negative smears are less contagious even if they still have infection.

Question 36

what to do with someone who is on chemotherapy and getting immunosuppressants and has been living with a someone who has acute TB infection (with cavitary lesion)?

Answer 36

High risk pts for TB infection are those that include (duration of space of contact with infected indvidual as well as degree of symtpoms especially the presence of cavitation of X-Ray).

These include HIV pts, chemotherapy pts, immunosuppressed (TNF alpha agents)

get a TST in those who haven’t gotten BCG vaccine. If they got BCG vaccine get interferon gamma release assay.

In the meantime treat with isoniazid and pyridoxine

there is a window period of 8-10 weeks after exposure where TST and quantiferon is negative. Negative test at 8 and 10 weeks ok to stop treatment.