Mycobacteria (complete) Flashcards
What are the structures of an acid fast cell wall
- peptidoglycolipids
- Arabinogalactan
- PIM (phosphatidyl-inositol mannosides)
What are the 3 main mycobacterial diseases in humans
Tuberculosis
Leprosy
Buruli Ulcer
what is the estimate for the portion of the worlds population that is infected with TB
1/3 of the worlds population
What bacteria causes TB
mycobacterium tuberculosis
What is the cell wall component in the virulent strains of M. Tuberculosis that is necessary to cause disease
cord factor
What are the three types of TB
- Primary TB
- Secondary TB
- Disseminated TB
What is primary TB
initial infection with M. Tuberculosis
what is secondary TB
reestablishment of an active infection after a period of dormancy. a tubercle from primary TB ruptures and spreads again
what is disseminated TB
This is when infection spreads throughout the body
What two things reduced the incidence of TB in the US
pasteurization of milk and the isolation of patients in sanatoriums
who is at high risk for TB
those in contact with infected patients and those with immunodeficiencies (HIV)
How is TB diagnosed
by stethoscope, X-rays, skin tests using PPD, culturing
and an ACID FAST STAIN OF SPUTUM
what does a TB skin test identify
individuals with previous exposure to M. Tuberculosis by the presence of a hard red, swelling at the test site
What does a chest X-ray do for TB diagnosis
it identifies individuals with active TB
What easy is TB treatment, and what is used
it is difficult with common antimicrobials because the bacteria grow slowely and live in macrophages, but months of combination therapy is used to treat the disease
what are MDR TB strains
Multi drug resistant TB strains, are at least resistant to INH and rifampin
how are MDR TB strains treated
with cipro and kanamycin for up to 2 years (100 x more expensive)
What are XDR TB strains
Extensively drug resistant TB strains (INH, rifampin, fluoroquinone and one of the second line drugs)
how is TB prevented
prophylactic use of antibacterial drugs for those who went from negative to positive on the skin test and those exposed to active TB
vaccine (BCG) more effective for kids, used in countries where TB is common
What are MOTTs
mycobacterium other than tuberculosis
What are common MOTTs
- Mycobacterium avium complex (MAC)
- Mycobacterium Kansasii
- Mycobacterium fortuitum
- Mycobacterium Marinum
- Mycobacterium Scrofulaceum
what happens with mycobacterial infections in AIDS patients
mycobacterium avium-intracellulare is the most common amongst AIDS patients, they affect almost every organ and cause massive organ failure.
how easily are mycobacterial infections in AIDS patients to treat
very difficult do to the disseminated nature of the infection
What is the bacteria that causes leprosy
mycobacterium leprae
how easily in mycobacterium leprae grown
hard, it has never been grown in cell-free culture
how is leprosy transmitted
person to person contact, or a break in the skin
What are the two forms of leprosy
Tuberculoid leprosy
lepromatous leprosy
What is tuberculoid leprosy
- high cell-mediated response
- Low antibody
- nonprogressive disease, loss of sensation in skin regions
What is lepromatous leprosy
- low cell-mediated response
- High antibody
- gradual tissue destruction
- loss of facial features, digits, and other structures
what are the only two places mycobacterium leprae can be cultivated
footpads of mice, bellies of 9-banded armadillos
how is leprosy diagnosed
loss of sensation in skin lesions (tuberculous leprosy)
disfigurement (lepromatous leprosy)
how is leprosy treated
dapsone and rifampin for 6 mo. (tuberculoid)
dapsone, rifampin, and clofazimine for 2 years dapsone for 10 years
what is the mycobacterium that causes beruli ulcers
mycobacterium ulcerans
where is mycobacterium ulcerans foudn
slow moving water
how does mycobacterium ulcerans enter the body
through skin abraisions
does mycobacterium ulcerans grow intracellularly or extracellularly
extracellularly
what is the toxin make by mycobacterium ulcerans
mycolactone, a polyketide (lipid)
what does mycolactone (beruli ulcer toxin) do
destroys subcutaneous tissue, and is a powerful immune suppressing agent
what is the main visible symptom of a beruli ulcer
when the subcutaneous tissue has been destroyed by mycolactone, the skin on top dies and sloughs off producing a clean ulcer
how is a beruli ulcer treated
there is no reliable drug therapy, the infected skin must be removed and replaced with a skin graft
