Lecture 25 Flashcards
actinobacteria 1: Mycobacteria
Describe the progression of TB in the human body
- infection enters the lung
- body builds a barrier (tubercle) around the bacteria to contain them [latent stage]
- the bacteria break out of the tubercles [primary/pulmonary TB]
- the bacteria spread out from lungs through the blood to areas including the bones and lymphatic system [extrapulmonary TB]
What is rifater?
a pill to treat TB
contains:
isonizid
rifampin
pyrazinamide
used during empiric initial treatment, and once it is discovered that the TB strain is susceptible to antibiotics
How many latent cases of TB in the world? In the USA?
- 1/3 of the world has latent TB
- 15 million people in the USA have latent TB
Describe how to interpret the results of a mantaux test
5-10-15 scale (positive means TB exposure)
<5mm is negative for everyone
5-9mm is a positive for:
- immunocompromised patients (AIDS)
- people who live with someone with TB
- people with healed TB
10-14mm is a positive for:
- people who are foreign born
- IV drug users
- residents in a long term care facility
- severe diabetics
15mm is a positive for everyone
What form of TB do x-rays test for?
if the TB has become cavitary (very large tubercles)
How can you get a false positive with a skin test for TB?
if the patient has been vaccinated against TB before
Your strain of TB is found to be susceptible, and you have 0 risk factors.
What is your course of treatment? How long does it take?
- 2 months of rifater (which includes the original month from empiric initial treatment)
- this is followed by rifimate (INH and rifampin) for 4 months
- treatment takes 6 months
What is the etiology of TB? (include all 4 species)
Mycobacterium is the genus
- M. tuberculosis
- M. bovis
- M. kansasii (MOTTS)
- M. aviam (MOTTS)
At what age does a negative result on the mantaux test become a bad thing and why?
if you are over 40 and especially over 60
because you should have antibodies against TB, but since you don’t you are more susceptible to infection
Your strain of TB is found to be susceptible, and you have only 1 risk factor. What is your course of treatment? How long does it take?
- 2 months of rifater (which includes the original month from empiric initial treatment)
- this is followed by rifimate (INH and rifampin) for 4 months
- treatment takes 6 months
What is XDR TB resistant to?
- INH
- rifampin
- fluroquinolone (such as ciprofloxacin)
- and any injectable aminoglycocide (such as amikacin, capreomycin, kanamycin)
Which tests diagnose active TB?
- sputum smear
- culture
What is DOT?
- directly observe therapy you watch the patient take their medications to ensure compliance
- has a higher cure rate than just relying on the patient
Describe the mycobacterium (growth medium, colony morphology, gram staining)
- gram non reactive (b/c of waxy coating)
- Stain with acid fast
- grow on lowenstein jensen (colonies will look dry, crumbly)
What is the defining characteristic of miliary TB?
skin lesions that look like millet seeds
How many active cases of TB in the world each year? In the USA?
8.8 million in the world
13,000 in the USA
What is the incubation period of TB?
6 months
How can you diagnose TB? (4)
- sputum (spit) smear
- taking a culture
- x-ray
- skin tests
Describe the mantaux test including what it intails and what a result looks like
- inject purified protein derivitave (PPD) just under the skin
- after 3 days a bump/erythma at the injection site occurs (in all cases)
- the diameter of the erythma determines if the test is positive or negative
- determines if someone has been exposed to TB
What are some methods of prevention of TB?
- quarantine of the infected
- education for the infected
- INH as a chemopropylaxis
- BCG vaccine (more effective in children)
Which skin test for TB is preferred?
mantaux test
How many TB deaths each year in the world? In the USA?
1.5 million deaths worldwide
2,000 deaths in the USA
What happens if after 4 months of treatment with rifater and rifampin you still test positive?
your treatment is not working, possibly due to resistance
it needs to be switched to something else
What is the treatment for MDR and XDR TB?
4-7 drugs that the strain is susceptable to
treatment is for 18-24 months
culture is taken once a month to check for progress
