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53 Cards in this Set
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- Back
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Mycobacteria (shape, growth, staining, gram - or +, resistant to..) |
-Slender and rod shaped bacteria -Slow growth, poor staining and acid fastness (once stained, resistant to decolorization by acid) -gram + (but don't gram stain very well and very resistant to physical and chemical disinfectants) |
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Explain mycobacteria cell wall, and is it intracellular or extracellular? |
The cell wall is 60% lipids, including a long chain fatty acid called Mycolic acids, waxy and greasy. Intracellular |
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What are the three classifications of Mycobacteria |
1. Tubercle Bacilli complex 2. MOTT (mycobacteria other than tubercle bacilli) - does not causes TB 3. Mycobacterium Leprae (causes leprosy) |
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What are the types of Mycobacteria Tuberculosis Complex |
1. Mycobacterium tubuculosis 2. Mycobacterium Bovis (from cattle) 3. Mycobacterium Africanum 4. Mycobacterium Canettii 5. Mycobacterium Microti |
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What do they all have in common the mycobacterium tuberculosis complex? |
They all cause TB |
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What is the population of the world that is infected with TB? How many active cases? |
1/3 of the world population is infected 30 million active cases |
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How does TB spread? |
through the air. Active cases coughing can transfer it, or spitting or playing with your mouth and touching something and someone else puts there hands in there mouth |
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What if the sputum stain for acid fast bacilli for TB is negative or positive? |
If the sputum sample is positive - active TB If sputum sample is negative - non infectious for TB - quick test to see if someone with TB is contagious or not |
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Where is the TB seen more commonly? |
More common or a little higher than the normal population in First Nations, nuts, refugees, AIDS and the homeless compared to the rest of North America |
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If you have latent TB do you get sick? (tb skin test and sickness) |
if you have latent TB you can't transmit it however your TB test will be positive. You don't get sick however if you become sick, or are on chemo meds or become immunocompromised it may become activated. |
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What is the hallmark of Tuberculosis |
it is a tubercle - it is a caveating granuloma (caseating: deteriorates into a cheeselike substance. Granuloma: a chunk of reactive granuloma tissue) |
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What are the symptoms of TB? (someone who is highly infectious..) (what symptoms will you see when there is a lesion on the chest X-ray) |
Pulmonary TB is asymptomatic at first with insidious (gradual) onset of a cough. Highly infectious people may seen in good health for long periods of time Fever, weight loss and or hemoptysis (coughing up blood) usually occurs by the time there is a lesion on the chest X-ray |
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TB has a high affinity for... |
Upper lung area that is where you'll see it |
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Where does TB not go? |
Tooth Enamel |
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What is the curve of decreasing return? |
ex: if you tanked midterm and you want to get your mark up then you'll have to do 5x as much work for 20 marks up and if you want 30 marks 25x as much work. The higher aspirations the more work you have to do to move up a category The last one is the hardest (scientist would say increase funding to cure TB and get rid of the last little bit however a politician would say okay we have 98% covered lets put the funding else where. |
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In adults with pulmonary TB where is the TB |
its usually in the apical areas which has seeded via the hematogenous route (blood flow) from an often undetected primary focus in the lower lung |
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How is Extrapulmonary TB acquired and is it contagious? |
It is acquired via hematogenous seeding and is almost non contagious |
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When may Tb be reactivated if the patient is recovered? |
if the patient becomes immunocompromised
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What do you see on the chest Xray for TB? |
Thickening and infiltration (cloudy) in the apical area |
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What is the Mantoux test? |
Intradermal injection of 5 tuberculin units of PPD |
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What do you measure for the TB skin test? |
You measure induration in mm 48 hours to 72 hours later. You do not look at erythema (redness) |
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Who is considered positive for TB if its greater than or equal to 5mm? |
contact cases, immunocompromised |
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Who is considered positive for TB if the induration is greater than 10? |
People from high prevalence countries, healthcare workers, in prison or institutions |
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Who is considered positive for Tb if induration is greater than 15mm |
Anyone |
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What increases when you have two tb skin tests a few weeks apart (step 2) --> does repeated testing lead to false positive? |
Sensitivity increases NO |
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How long does it take after you have been exposed to Tb to develop a positive tb skin test?
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4-6 weeks |
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Who can get a periodically a false negative tb skin test? |
Someone with advanced tuberculosis |
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What vaccine was given to infants in some countries and what did it do? |
the BCG vaccine is given to infants in some countries and that caused a positive test for only a few years |
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If an adult got a positive test what should it not be ascribed or related to? |
BCG vaccine. Everyone with a positive gets treated like they have TB. |
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What is the Igra blood test? What are the differences between tb and idea tests |
it is the same thing almost as a tb skin test; however, it is more specific and sensitive and is not influenced by the BCG vaccine and doesn't react with non tuberculosis (whereas tb skin test might). Also igra is not covered |
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What is MOTT? |
mycobacterium other than tubercle bacilli |
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Who normally gets MOTT? |
mainly people who are immunocompromised |
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How are MOTT usually acquired? |
Through the enivronment |
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Where does MOTT usually colonize? |
the respiratory tract without causing disease therefore the interpretation of cultures are difficult. |
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What can MOTT cause? |
local lymphadenitis, bone and joint or skin/soft tissue infections |
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What is essential for containment of mycobacterium? (who is at most risk) |
T cell immunity (therefore AIDs sufferers are at most risk for severe disease) |
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What is Mycobacterium Leprae? |
it causes leprosy (aka hansons disease) |
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What does mycobacterium leprae cause ( |
chronic infection of the skin* and peripheral nerves and nasal mucosa only in leproamatous leprosy - when the bacteria enters the peripheral nerves it causes anesthesia of the fingers and peripheries therefore less careful. |
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What are the peripheral nerves infiltrated with? |
Peripheral nerves are infiltrated with acid fast bacilli and they become tender and palpable. |
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Why later on during leprosy do you get sensory deficiency? |
this results from the infamous loss of digits through trauma |
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What are symptoms of lepromatous |
may exhibit leonine facies which can progress to hideous deformities and also nasal mucosal infection |
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Where is leprosy most common? |
Brazil, south Saharan Africa |
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What does a Th1 response(CD4 cells help macrophages - brisk cellular immunity result in in terms of leprosy? |
results in tuberculoid (pacuibacillary) leprosy. Mild form of leprosy |
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What does a Th2 response (CD4 cells help B cells -poor cellular immunity) result in |
it results In lepromatous (multibacillary) leprosy more severe form Causes severe facial abnormalities |
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What are some symptoms of leprosy? |
Hypopigmented or reddish skin lesions with definite loss of sensation Involvement of peripheral nerves (thickening and loss of sensation) |
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What if your skin smear is positive for acid fast bacilli If leprosy treatable? |
then you have leprosy Yes, renders the patient non contagious quickly, therefore institutionalization is unnecessary |
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How does leprosy spread? |
respiratory recreations, but only about 5% of contacts develop the disease.
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What is the incubation period for leprosy? Does the disease progress slow or fast? |
1-30 years Slow progression |
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Where is the most common places where leprosy is ? |
equatorial distribution endemic foci is mainly in Texas, Louisiana, Hawaii, subsaharan Africa, Brazil |
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What is the world wide occurrence of leprosy? |
12-20 million cases |
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How do you diagnose Leprosy? |
skin biopsy remains the main diagnostic of choice |
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How do you treat Leprosy? |
paucibacillary - 6 months rifampin 600mg + Dapsone 100mg po od. Multibacillary: extend to 1 year and add clofazimine 50mg PO od + 300 mg once a month od= once a day |
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Whats Mycobacterium marinum? |
symptom - fish tank granuloma
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