Tuberculosis Flashcards
What is the name of the bacterial organism that causes tuberculosis (TB)?
Mycobacterium tuberculosis
Define mycobacterium tuberculosis
An aerobic, non-spore forming bacillus that thrives in environments where the oxygen tension is relatively high
Mycobacterium tuberculosis is often referred as:
Acid-fast bacillus (AFB) because it resists decolorization by acid alcohol after staining with basic fuschin
Is replication of mycobacterium tuberculosis fast or slow?
Slow (very slow)
How is mycobacterium tuberculosis transmitted?
Through the air by aerosolized drop nuclei
- Cough
- Sneeze
- Speak
- Sing
(T/F) - Transmission of mycobacterium tuberculosis occurs through inanimate objects too
FASLE - does not occur
Who are most at risk for tuberculosis?
- Family household contacts
- Persons living or working in enclosed environments
- People with impaired immune systems
(T/F) - During latent infection of TB, patients are infectious
FALSE - not infectious
(T/F) - During latent infection of TB, patients are positive from the tuberculin skin test (PPD)
TRUE
(T/F) - During latent infection of TB, patients are asymptomatic without radiographic evidence of infection
TRUE
(T/F) - Patient who do not receive treatment during latent TB will develop active TB
TRUE
(T/F) - High risk of active TB is in the first 5 years
FALSE - first 2 years
What are the subjective findings of TB in a patient?
- Cough
- Fatigue
- Fever
- Night sweats
- Anorexia/weight loss
- Pleuritic pain
Is the cough productive or not productive in subjective findings?
Non-productive at first then becomes productive
What are the objective findings of TB in a patient?
- Nodular infiltrates
- Positive sputum smear of AFB
- Positive PPD skin test
- Anemia
- Leukocytosis
What could cause a PPD skin test to be a false positive?
Pts with hx of bacillus of Calmette-Guerin vaccine (BCG)
What is a definitive diagnosis of TB?
- Isolate M. tuberculosis from the site of the infection
- AFB smear are best obtained in the morning
- PPD test
At least how long should AFB smear tests should be taken?
At least 3 consecutive days
(T/F) - A negative AFB smear test rules out TB
FALSE - it does not rule out TB
(T/F) - PPDs have a false negative rate of 25%
TRUE
What is the cause of false negatives in PPDs?
Anergy
Define anergy
Decreased ability to respond to antigens
If anergy is suspected in a PPD skin test, what should be done furthermore?
Control skin tests should also be placed in contralateral arm
What treatment should be given in a patient who is suspected to have high clinical suspicion of active TB?
Rifampin (RIF), Isoniazid (INH), Ethambutol (EMB), and Pyrazinamide (PZA) for 8 weeks
Which of the 4 medications that are given initially would be given for an extra 18 weeks?
RIF and INH
What is the role in therapy of INH?
Potent ability to kill rapidly multiplying organisms during the initial phase of treatment
What is the MOA of INH?
Unknown; may affect cell wall
What are some main AEs of INH?
- Hepatitis
- GI Sx of hepatitis
- Peripheral neuropathy
- CNS reactions
- Allergic reactions
- Arthritic symptoms/SLE
- Dry mouth
- Psychoses
- Hemolytic anemia
- Agranulocytosis
Who are at risk of gaining hepatitis with the use of INH?
- EtOH consumption
- > 35 yo
- IVDU
- Using other hepatoxic drugs
- Black and Hispanic women
- Postpartum women
- Liver disease
INH is a potent inhibitor of:
- CYP2C9
- CYP2C19
- CYP2E1
INH is a minimal inhibitor of:
CYP3A4
What is the role in therapy of RIF?
Activity against intracellular organisms that are usually dormant; inhibits RNA synthesis to inhibit RNA transcriptase
What are some main AEs of RIF?
- Flu-like Sx
- Elevated LFTs
- Thrombocytopenia
- Drug-induced SLE
- Fever, N/V, rash
- Acute renal failure
- Orange-red colorization
What should be avoided during the use of RIF?
Contact-lenses due to the colorization
RIF is an inducer of:
CYP3A4 and glucoronidation
What is the role in therapy of PZA?
Most effective against organisms in the acidic environment within the macrophages or areas of tissue necrosis; most effective within the first 2 months of treatment
What is the MOA of PZA?
Converted to pyrazinoic acid in MTB to lower the pH of the environment
What are some main AEs of PZA?
- Hepatitis
- Arthralgias
- Malaise
- N/V
What is the role in therapy of EMB?
Bacteriostatic at low doses; bactericidal at high doses; moderately effective against the fast-growing bacilli with little sterilizing activity.
Used mainly to prevent resistance
What is the MOA of EMB?
RNA synthesis
What are some main AEs of EMB?
- Optic neuritis
- Renal adjust
EMBs absorption is decreased when?
Aluminum salts are taken concomitantly
Which of the 4 medications does not have any CYP450 enzyme interactions?
PZA
What is the name and dose of the medication that should be administered with INH?
Pyridoxine 25 mg/day
Why does INH need to be taken with another medication?
To prevent peripheral neuropathy
What two ways can TB medications be administered?
- Directly observed therapy (DOT)
- Fixed dose combinations
Which administered method is preferred?
DOT
Which administered method reduces pill burden and risks of monotherapy?
Fixed dose combinations
What should be monitored during therapy?
- CBC
- LFTs
- Visual examination
- Sputum cultures and AFB smears
- Adherence
- Chest X-ray
How often should sputum cultures and AFB smears be monitored?
Initially q 2-4 weeks THEN
monthly once sputum cultures are negative THEN
one more smear and culture at the completion of therapy.
Who are candidates for latent TB treatment?
- Positive PPD skin test and/or
- Risk for reactivation of active TB
What are the preferred treatment options of TB?
- INH QD x 6 months - no DOT
OR - INH and rifapentin qweek x 3 months - DOT
Which patients should not use INH and rifapentin as a treatment option for latent TB?
- < 2 yo
- Pregnant or becoming pregnant during treatment
- HIV pts receiving antiretroviral
- Patients with latent TB with presumed resistance to INH or RIF
In elderly patients, active TB is treated how?
The same as the general population; use with caution due to AEs
In elderly patients, latent TB is treated how?
The same as the general population; but should cutoff if 15 mm or more in > 35 yo
Define MDR-TB
Resistant to RIF and INH
Define primary resistance
Patient harbors a resistant strain PRIOR to any treatment
Define acquired resistance
Gaining resistance due to:
- Noncompliance
- Inappropriate therapy
- Inadequate dosage
- Malabsorption issues
What are the treatment options for MDR-TB?
- Bedaquiline
- Fluoroquinolones
- Para-aminosalicylic acid
- Cycloserine
- Ethionamide
- Injectible agents
In HIV-patients, latent TB is treated how?
- INH QD
OR - INH and RIF
Depends on ARV therapy
In HIV-patients, active TB is treated how?
INH/RIF/PZA/EMB
If HIV-patient is on PI, how is active TB treated then?
Replace RIF to rifabutin to avoid DDIs
- INH/PZA/EMB and rifabutin
(T/F) - Fixed dose combinations is recommended for active TB in HIV-patients
FALSE - DOT is preferred
In pregnant patients, TB is treated how?
INH/RIF/EMB
(T/F) - Streptomycin should not be used in pregnant patients for TB treatment, unless no other alternative
TRUE
(T/F) -TB is an indication for terminating pregnancy
FALSE - it’s not
(T/F) - EMB should only be used in pediatrics if resistance is suspected
TRUE - it’s not used routinely b/c it’s difficult to assess visual acuity in children
(T/F) - Extrapulmonary TB or TB meningitis have a longer duration of treatment of at least 12 months
TRUE
(T/F) - Corticosteroids are prohibited for adjunctive treatment in extrapulmonary TB or TB meningitis
FASLE - it can be used
Solid organ transplant patients are treated how in latent and active TB?
Standard treatment from general population
