Term
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Definition
Acid-fast bacteria with a thick layer of mycolic acid, few porin channels.
- M. tuberculosis - TB - respiratory infection
- MAC complex of M. avium and M. intracellulare - important in AIDS
- M. leprae - leprosy, endemic to tropics |
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Term
| What are the stages of TB? |
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Definition
- Primary - low infection dose, Mycobacterium live in alveolar macrophages
- Secondary - Tubercles expand to urt, severe respiratory Sx
- Extrapulmonary - in immunosuppressed and young kids, travels to kidney, bone, genitals.
**Tubercles - clumps of bacteria |
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Term
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Definition
- Presence in sputum or CSF
- Xray to detect tubercles
**TB test for antibody presence |
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Term
| How does a TB infection hide in the body? |
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Definition
Inside macrophages in the alveoli
Sometimes dendritic cells take bacteria to lymph nodes - leads to infection outside the lungs |
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Term
| What is the 1st line treatment for TB? |
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Definition
Isoniazid - affects mycolic acid, bacteria lose acid-fastness
**Metabolized by catalase peroxidase/katG --> acetylation of mycolic acid. Bacteria can't survive. |
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Term
| How do mycobacterium become resistant to isoniazid? |
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Definition
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Term
| What are considerations for Isoniazid dosing? |
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Definition
- Give with B6 to prevent neuropathy
- NAT2 metabolized
- SLOW NAT2 metabolizers have more parent product --> more neuropathy
- FAST NAT2 metabolizers - more metabolite = more hepatotoxicity
- The parent Isoniazid = neuropathy while the metabolite = hepatotoxicity |
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Term
| What drugs are Rifamycins? |
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Definition
- Rifampin/Rimactane - increases activity of isoniazid. Also used for CRE, Staph, Strep, N. menigitidis, and H. influenzae
- Rifabutin/Mycobutin - for MAC, well tolerated in AIDS patients
- Rifapentine/Priftin - LONG half life
- Rifamixin/Xifaxin - ONLY used for traveler's diarrhea from E. coli
**Works on DNA dependent RNA polymerase. Avoid Rifampin in HIV! |
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Term
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Definition
Ethambutol/Myambutol - blocks arabinosyl transferase
**Optic neuropathy leads to vision loss - chelation of copper |
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Term
| What other drugs can be used for TB? |
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Definition
- Pyrazinamide - inhibits mycolic acid synthesis. Liver fxn tests
- Cycloserine - Major CNS effects, an agent of last resort |
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