deck_5760688 Flashcards
___ have nearly impermeable cell walls made up of mycolic acids
mycobacterium
> 60% of the cell wall of mycobacteria is lipid, which does what?
shields and thus prevents many drugs from accessing the cell membrane
describe how mycobacterial defenses make it exceptionally difficult for antimicrobials to do their jobs
- they have very thick, hydrophobic cell walls rich in mycolic acid
- efflux pumps
- some species can hid inside host cells
what are two key mycobacterium-related diseases?
mycobacterium tuberculosis (TB) and mycobacterium leprae (hansen’s disease or leprosy)
describe mycobacterium tubercosis (TB)
9 million new cases of TB and 2 million deaths annually
what bacteria has the following characteristics?
- hansen’s disease, leprosy
- 2 million new cases worldwide
- the bacteria grow better in areas with cooler body temperatures closer to skin surfaces (ex. extremities)
mycobacterium leprae
in 1882, TB killed ___ out of every ___ people living in the US and Europe
1/7
among infectious diseases, TB remains the ___ leading killer of adults in the world, with ___ million TB-related deaths annually
- 2nd
* 2 million
what is used to test for tuberculosis?
mantoux tuberculin skin test (TST)
with latent/asymptomatic primary TB infections, there will be no active disease, but a ___ TST
positive
what is the preventative treatment for latent/asymptomatic primary TB?
- initiate immediately
* prophylactic treatment of choice is isoniazid for 9 months
what type of infection is described by the following:usually in lungs, but can effect other organs; dyspnea, fever, productive cough and night sweats for >2 months; upper lobe consolidation on chest x-ray; acid fast bacilli on sputum test, positive TST
overt/active primary TB
the following is the treatment of choice for what type of tuberculosis?
- 2 months treatment with combination of ribampin + isoniazid + pyrazinamide + ethambutol (R+I+P+E)
- followed by 4 months with rifampin + isoniazid
- “2 with 4, then 4 with 2”
overt/active primary tuberculosis
describe the treatment of overt/active primary tuberculosis when it is an intracellular organism
- treat with RIPE for 12 months + azithromycin (macrolide) restrict use of pyrazinamide to only the 1st 2 months
- hepatotoxic
secondary, reactivated (resistant) TB is of greater risk in what patients?
HIV-positive, immunosuppressed, or other “high risk” patients
describe the secondary TB “rule of 5’s”
- otherwise healthy patients infected with mycobacterium tuberculosis have a 5% risk of reactivation in the first 2 years and then a 5% lifetime risk of reactivation
- high risk patients have a 5%+5% risk of reactivation per year
T or Fsecondary tuberculosis can only reactivate in the lungs
falseit can reactivate in a variety of different locations
the following is the treatment of choice for what type of tuberculosis? RIPES
- 2 months treatment with combination of rifampin, isoniazid, pyrazinamide, and ethambutol, PLUS STREPTOMYCIN
- followed by 4 months treatment with isoniazid and firampin (2 with 5, then 4 with 2)
secondary TB
what can be done in cases of secondary TB where drug resistance is a problem?
second line drugs can be added to overcome drug resistance
what are 7 tuberculosis drugs?
- streptomycin - aminoglycoside
- azithromycin - macrolide
- rifampin - nucleic acid synthesis inhibitor
- isoniazid
- pyrazinamide
- ethambutol
- bedaquiline
what is the clinical use of isoniazid (INH)?
- drug of choice for prophylaxis of mycobacterium tuberculosis
- also effective in combo against active TB
what is the mechanism of isoniazids?
decreases mycolic acid synthesis