22 Tuberculosis Flashcards
What percentage of the worlds population has TB?
1/3
what percentage of those with TB infection will become sick?
5-10%
T/F Someone dies every second from TB?
False. Every 20 seconds
Where is TB most prevalent?
South western africa
In general, the US TB infection rates are falling. This was not the case in the early 90’s. why was this?
There was a peak of TB in the early 90’s because there was a peak of HIV at that time. Recall that these two diseases go hand in hand.
TB can cause meningitis in whom?
Generally children less than 5 in high TB endemic areas
T/F If left to progress, TB can infect bones, joints, nervous system, etc?
true
What is miliary TB?
a form of TB that causes wide spread dissemination of the whole body and causing small lesions. Results in multiple organ failure and is often fatal.
What are 6 major general symptoms of TB?
fever chills Night sweats weight loss Appetite loss Fatigue
what are 3 major specific symptoms of TB?
cough lasting 3 or more weeks
chest pain
coughing up blood
What is the main cause of tuberculosis?
mycobacterium tuberculosis (apparently there are others)
What is unique about the mycobacterium genus?
1) bacilli
2) High lipid content cell wall that doesn’t gram stain.
3) naturally resistant to many antibiotics
4) resistant to acids, alkalis, and dehydration
what are 2 prominant components of the thick lipid wall of mycobacterium?
1) Mycolic acid
2) Glycolipid
which pathogen is usually obtained from ingestion of raw milk, is a significant livestock pathogen, and is naturally resistant to pyrazinamide?
Mycobacterium bovis
Why is M. tuberculosis such a successful pathogen?
1) obligate human pathogen that has evolved with the human.
2) replicates slowly. (persistent)
3) master adapter. (aerobic or anaerobic, intracellular or extracellular pathogen)
If you are in contact with person with TB and get aerosolized, what are the chances you will end up with latent TB? If you have latent TB, what are the chances that it will become active TB?
10% chance infected
10% chance activation
what is essential for the growth of M. tuberculosis and granule formation?
TNF-alpha
which groups are considered high risk for TB?
1) contact with TB patients
2) migrated to USA in last 5 years
3) Travel to TB endemic areas
4) Health care workers
5) Homeless/poverty population
6) immunocompromised individuals
What factors predispose you to get TB?
1) HIV/AIDS
2) Malnutrition
3) infection with other diseases
4) Age
What are 6 ways to help diagnosis TB?
1) History of present illness
2) Tuberculin skin test
3) Acid Fast Bacilli sputum test
4) Chest X ray
5) culture the bacteria
6) Nucleic acid testing
With the TST or PPD what are you looking for?
the rise of the skin only and not the wheal.
what is TST? PPD?
TST= tuberculin skin test PPD= purified protein derivitive
How do you read the TST?
48-72 hours only
measure only induration (rise) in mm
(recall it is different for different groups)
T/F A positive TST shows active TB?
False.
1) you may not have TB just be sensitive to it from something like the BCG vaccination.
2) It can also show positive for latent TB
What are 3 things that can give you a false + TST test?
1) prior BCG vaccination
2) Exposure to NTM
3) Latent TB
what are 4 reasons for a false negative TST test?
1) Non- reactor individual
2) very recent TB infection
3) very young age (less than 6 months)
4) immunocompromized individuals
What are 2 forms of acid fast stains for mycobacterium?
1) ziehl nelsen (pink bacteria with everything else blue)
2) Flourochrome (bright bacteria with black background)
T/F 50-60% of actual TB patients show smear negative on acid fast stains?
true
If you want to grow TB on an agar you can use the middlebrook agar. To ensure that there are no other types of bacteria present, what do you do?
treat the colony with sodium hydroxide that will kill all other bacteria except for the acid fast mycobacterium.
T/F persons with latent TB are still infectious?
False. Only when they progress to the active state are they infectious.
If you have a patient that show up with TB, what other test should you always give them?
HIV testing because they frequently go hand in hand.
when doing a TB assay in the lab, why would you try to measure the patients response to INF gamma?
A high IFN gamma response would tell you that the person has had previous exposure to the pathogenic TB.
How many drugs and for how long do you treat TB?
4 drugs, 6 months
what 4 drugs are used to treat TB?
Ethambutol & isoniazid (inhibit cell wall synthesis)
Rifampin (inhibit RNA synthesis)
Pyrazinamine (PZA) target unknown
With full treatment TB has a _____% cure rate? what is the biggest problem with treating TB?
1) 95%
2) compliance
What function does the BCG vaccine have?
its protective against childhood TB and meningitis in endemic areas.
T/F Not giving the BCG vaccine such as in the USA allows you to better test for TB?
true because the BCG vaccines gives you a false positive result on the TST
what are 3 major reasons why TB is such a huge problem?
1) survives in host very well
2) can maintain with very low numbers
3) easily spread form one person to another
How does TB survive within phagocytes?
it avoids fusion with the lysosome
what are 2 major factors contributing to the current TB epidemic?
HIV/AIDS
Drug resistant TB
What is the number 1 cause of mortality in HIV infected individuals?
TB (10-30%)
what would you expect to see as far as TB signs/symptoms in a person coinfected with HIV?
Everything would be decreased or downsized because they do not have the immune system to respond normally.
T/F in a person with TB and aids you have chest X rays that look normal?
True. Even though they have TB, there is less upper lobe changes, and less granuloma formation.
T/F Sputum cultures are less reliable as well as TST in HIV patients?
true
Multi drug resistant TB is resistant to which 2 drugs?
1) isoniazid
2) rifampin
Extensively drug resistant TB is resistant to what?
Isoniazid & rifampin plus resistant to flouroquines and one other antibiotic
Primary drug resistance means?
infected with TB which was already drug resistant
Secondary drug resistance means?
drug resistance developed during treatment. This is usually because lack of compliance.
South western Africa has the highest rate of TB but yet have the lowest prevalence of drug resistant TB. why?
This is because they are not treating the cases of TB. In order to have resistance to a drug, you have to treat with that drug.
T/F It is required to report every case of TB infection?
Yes in every state.
