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23 Cards in this Set
- Front
- Back
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transmission of M. tuberculosis |
-spread by droplet nuclei -expelled when person w infectious TB coughs, sneezes, or speaks -persons w (+) smears are highly infectious -transmission occurs from person w active infectious TB disease (not latent TB infection) |
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common sites of TB disease |
lungs (most common - need O2 to replicate) pleura CNS lymphatic system genitourinary systems bones and joints disseminated (miliary TB) |
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pathogenesis of tB |
-inhale droplet nuceli which dissemintates to lung -ingested by macrophages, T lymphocytes activated & produce more reactive lymphocytes -macrophages form granulomas to contain organisms and activated lymphocytes begin to destroy the MTB-containing macrophages. Dissemination is halted and bacteria within granulomas have avoided detection by lysis (LATENT TB INFECTION) -if immune system can't keep bacilli under control, rapidly divide in lung and may spread via blood to organs w high blood flow (ACTIVE TB) |
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conditions that increase risk of progression to TB disease |
CXR suggestive of previous TB HIV infection substance abuse cancer diabetes mellitus malnutrition prolonged CS therapy other immunosuppressive therapy |
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TB skin test (TST) |
-inject intradermally 0.1mL of 5TU PPD tuberculin -produce wheal 6mm to 10mm diameter -read in 48-72h -read the induration, not the redness around |
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factors that affect TB skin test |
BCG Vaccine Infection w other mycobacteria (PPD can't distinguis from other types of mycobacteria) Anergy -pts who have dysfxnal immune system so don't react to skin test (HIV, elderly, critically ill, malnourished, chronic immunosuppressive therapy) -place control of candida, mumps, tetanus, or trichophyton on other arm |
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Interferon Gamma Release Assay (TB) |
-detects pts who have been INFECTED (exposed) but doesn't determine if they have ACTIVE DISEASE -blood test (not skin testing) -high sensitivity and specificity -eg Quantiferon Gold or T-SPOT |
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Treatment of Latent TB infection |
1st: isoniazid 300mg po daily x 9mth
2nd: can use rifampin 600mg po daily x 4mth
can be given twice-weekly if directly observed |
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symptoms of active TB disease |
fever chills night sweats appetite loss weight loss easy fatigability cough chest pain hemoptysis |
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chest radiograph in active TB |
abnormalities often seen in apical segment of upper lobe or superior segments of lower lobe |
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smear examination in active TB |
obtain 3 sputum specimens for smear examination and culture -results available within 24h -with Tx, bacteria load decrease within 2 wk -some pts may take up to 4 mths to clear |
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cultures in active TB |
-use to confirm diagnosis -culture all specimens, even if smear negative -results in 6-12wk -susceptibility testing on initial isolate |
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first-line antituberculosis drugs |
isoniazid rifampin pyrazinamide ethambutol |
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second line antiberculosis drugs |
streptomycin cycloserine p-Aminosalicylic acid ethionamide amikacin/kanamycin capreomycin levofloxacin/moxifloxacin/gatifloxacin |
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treatment regimen for active TB |
initial phase: -standard 4 drug regimens (INH, RIF, PZA, ETM) for 2mth continuation phase: -additional 4mth -if sensitive to all 4, only continue with INH and RIF -give drugs daily, bid, or 3x/wk |
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directly observed therapy (DOT) for TB |
-healthcare worker watches pts swallow each dose of medication -consider DOT for all pts -should be used with all intermittent regimens -can lead to decrease in relapse and drug resistance |
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monitoring parameters for TB |
for efficacy: -resolution of Sn & Sx, physical exam parameters, diagnostic parameters (AFB and culture, CXR) -want to see resolution at 2mth and 6mth mark
for safety: -ADRs -CBC, platelets, BUN, AST, ALT, visual exam, peripheral -at baseline and every mth until end of Tx |
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ethambutol ADRs |
eye damage -blurred or changed vision -changed colour vision (reversible when d/c ethambutol) |
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isoniazid ADRs |
hepatitis
peripheral neuropathy (tingling sensation in hands/feet) |
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pyrazinamide ADRs |
hepatitis
gastrointestinal intolerance (upset stomach, vomiting, lack of appetite
arthralgia/arthritis (joint aches and gout (rare)) |
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Rifampin ADRs |
hepatitis
thrombocytopenia -easy bruising -slow blood clotting
GI intolerance (upset stomach)
drug interactions (eg birth control pills, methadone tx) |
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hepatitis symptoms |
hepatitis (diabetic, alcoholic at higher risk of liver toxicity) -abdominal pain -abnormal LFTs -fatigue -lack of appetitie -nausea/vomiting -yellowish skin or eyes -dark urine |
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streptomycin ADRs |
ear damage -balance problems -hearing loss -ringing in the ears
kidney damage -abnormal kidney function test |
