Term
| what are other names for TB used historically? who first isolated the organism responsible? |
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Definition
| TB has also been called the "white plague" and "consumption". koch was the dr who discovered it and it wasn't until the 1940s-50s that the first effective drugs were developed |
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Term
| what is the rate of TB infection worldwide? in the US? |
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Definition
| 1 in 3 humans are infected w/TB worldwide but the rate of TB infection in the US is droppping |
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Term
| what are the risk factors for TB? |
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Definition
| immune suppression, occupational (HCW, prison guard), substance abuse (EtOH), diabetes, malnutrition, poor medical care, and location |
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Term
| what is the relative risk of TB infection in HIV pts? diabetes? |
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Definition
| HIV: 100-300x, diabetes: 2-4 |
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Term
| what characterizes mycobacterium tuberculosis? |
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Definition
| it is rod shaped, aerobic, slow growing, it can have multi-organ effects, genetically dynamic (can develop resistance to antibx), highly-lipid cell wall and stains red acid fast (ziehl-neelsen) |
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Term
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Definition
| aerosolized droplet (<1-5 micrometers) transmission (cough, sneezing, speaking, singing). a cough contains 3000 droplets and <10 droplets can initiate infection |
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Term
| what does the likelihood of transmission increase with? |
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Definition
| the number of organisms expelled, the concentration of organisms, the length exposure in breathing contaminated air, and the immune status of the exposed individual |
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Term
| what % of people exposed to TB will not become infected? |
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Definition
| 70% of people exposed to TB will not become infected and will spontaneously heal within 6 mos |
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Term
| what % of people infected with TB develop latent infections? |
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Definition
|
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Term
| what % of people who develop latent TB develop active TB disease at some point later on? |
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Definition
|
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Term
| what is the immune response to TB infection? |
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Definition
| the droplets are engulfed by the lung dendritic cells and macrophages which upon phagocytosis begin to form granulomas. granulomas (tubercules) are the hallmark protective immune mechanism of the host, creating a low O2, low pH environment |
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Term
| what cytokines are released by T cells which activate macrophages in the immune system's response to TB? |
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Definition
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Term
| what are the signs and symptoms of TB? |
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Definition
| weight loss/anorexia, fever/chills/night sweats, fatigue, cough > 3 wks, hemoptysis, and chest pain. *Hx establishes a high index of suspicion* |
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Term
| what if seen in a physical exam would be indicative of TB? |
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Definition
| cachexia, fever, lymphadenopathy, hepatosplenomegaly, tachycardia/friction rub, hypoxia/rales/decreased breath sounds/dullness to percussion/egophony/decreased tactile fremitus |
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Term
| what are the most common extrapulmonary TB disease sites? |
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Definition
| meningitis of the CNS, scrofula of the cervical lymphatics (matted calcific lymphadenopathy), TB pleurisy of the pleura, (disseminated)miliary TB, pott's disease of the bones and joints of the spine, urogenital TB of the genito-urinary system |
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Term
| since TB is one of the "great masqueraders" what should be in the ddx for it? |
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Definition
| TB, asthma, influenza, EtOH/drug abuse, asbestosis, aspergillosis, bronchitis, histoplasmosis, pneumothorax, non-TB mycobacterium, silicosis, pneumonia, ARDS, lung neoplasms, HIV/AIDS, alpha-1 antitrypsin, lung abscess, pleural effusion, bronchiolitis, wegeners |
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Term
| what is the initial diagnostic work-up for TB? |
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Definition
| CXR, tuberculin skin test/IFN-gamma release blood test, serial sputum smears and cx, and opt-out HIV testing |
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Term
| what is the use of an NAA sputum smear? |
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Definition
| the nucleic acid amplification can look directly for TB nucleic acid in a sputum smear, rather than having to wait for the cx. it is pretty fast ~48 hrs |
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Term
| what characterizes microscopy for acid-fast bacteria as method of diagnosing TB? |
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Definition
| this only takes about a day, but a negative microscopy for acid-fast bacteria does not r/o TB |
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Term
| how long does it take to cx TB from a specimen? ID the TB? check drug susceptibility? check second-line drug susceptibility? |
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Definition
| cx: ~14 days, ID TB: ~21 days, drug susceptibility: ~30 days, second-line drug susceptibility: ~4 wks |
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Term
| what is the PPD skin test? |
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Definition
| the purified protein derivative (PPD), tuberculin skin test or mantoux method is an intradermally injected TB purified protein - which if the pt has a hypersensitivity rxn to, indicates a previous exposure to TB (or BCG vaccination) |
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Term
| how is a PPD result interpreted if the pt has a 15 mm induration? (*exam question*) |
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Definition
| if the the induration (diameter of bump - not erythema) is measured 15 mm+ and the pt has no risk factors. |
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Term
| how is a PPD result interpreted if the pt has a 10 mm induration? (apply this for the most part) (*exam question*) |
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Definition
| 10 mm+ is positive if the pt has some risk factors: recent immigrant from a high prevalence country, IVDA, a high risk occupation (prisons/jails, nursing homes/other long term facilities for the elderly, hospitals/other health care facilities, residential facilities for patients with AIDS, homeless shelters), high risk clinical conditions (silicosis, DM, CRF, some hematologic disorders (leukemia/lymphoma), other specific malignancies (carcinomas of the head, neck, lung), weight loss of > 10% of ideal body weight, gastrectomy and jejunoileal bypass), and children younger than 4 yrs or those exposed to high risk adults |
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Term
| how is a PPD result interpreted if the pt has a 5 mm induration? (*exam question*) |
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Definition
| *5 mm is positive if the pt is HIV+*, had recent contact with a TB+ pt, past TB+ CXR, organ transplant, or immunosuppressed on chronic steroid therapy |
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Term
| what are the problems/disadvantages of the PPD skin test? |
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Definition
| it requires a f/u, and there can be false positives (BCG-vaccinated or other mycobacterial infections) and false negatives (anergic, immune suppressed individuals) |
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Term
| what is quanti-feron gold? what are the advantages/disadvantages? |
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Definition
| a blood test for the presence of IFN-gamma, where a blood sample from the pt is mixed w/TB protein and the level of IFN-gamma is measured. advantages: no reader bias, 24 hr results, no BCG rxn, no amnestic response. disadvantages: doesn't work w/immunosuppressed pts, children or predict who will develop active TB |
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Term
| what would be seen radiographically in TB pts? |
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Definition
| airspace consolidation (typically uper lobe), infiltrates, cavitations, volume loss, pleural effusions (ipsilateral to TB), linear opacities, nodules, hilar adenopathy, ghon/ranke complexes |
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Term
| what is the difference between a ghon and ranke complex? |
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Definition
| a ghon lesion is a parenchymal abnormality sometimes with some calcific flecks w/in it, if it involves a lymph node: ghon complex, and a ranke complex is basically a more healed ghon complex |
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Term
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Definition
| an old method for fighting TB: remove upper ribs, causing the lung to collapse some, pushing O2 out of the cavities, causing TB to become quiescent |
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Term
| when TB heals what is left behind? |
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Definition
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Term
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Definition
| putting ping pong balls in the apical portions of TB pts lungs in order to block the TB's O2 supply |
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Term
| what is the definite way to diagnose active pulmonary TB? |
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Definition
| + acid fast bacterial smear and + cx |
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Term
| what needs to happen upon TB dx? |
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Definition
| the disease need to be reported as it is a public health threat |
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Term
| what are the major first line drugs used against TB? |
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Definition
| isoniazid (inhibits cell wall synthesis), rifampin (inhibits RNA synthesis), pyrazinamide (disrupts the plasma membrane/energy metabolism), rifapentine, and ethambutol (inhibits cell wall synthesis) |
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Term
| what is the main ADR for isoniazid? |
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Definition
|
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Term
| what are ADRs for rifampin? |
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Definition
| hepatoxicity, orange urine, and diminished efficacy of oral conraceptives |
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Term
| what are ADRs for pyrazinamide? |
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Definition
| hyperuricemia, which can precipitate into gout in those predisposed |
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Term
| what are ADRs for ethambutol? |
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Definition
| ocular toxicity, specifically optical neuritis |
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Term
| *what are the active INH sensitive TB tx dosages for a 70 kg pt?* (*exam question*) |
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Definition
isonazid: 300 mg
rifampin: 600 mg
pyrazinamide: 1500 mg
ethambutol: 1200 mg (all PO daily) use these 4 drugs for 2 mos, then stop pyrazinamide and ethambutol and continue isoniazid and rifampin for 4-7 more months |
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Term
| what is the DOTS program? |
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Definition
| directly observed treatment short course for possibly non-compliant TB pts, which has been successful globally. |
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Term
| what characterizes a pt with a latent TB infection? are they treated? |
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Definition
| a positive PPT, negative CXR, asymptomatic, non-contagious, and a progression risk greatest in the first 2 yrs after infection. isoniazid is used most commonly to prophylax these pts depending on certain clinical scenarios. |
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Term
| what is the recommendation for INH prophylaxis for PPD+ pts? (*exam question*) |
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Definition
| <35: consider for all pts, >35: consider for recent converters (w/in 2 yrs), close contact of active case, HIV+, IVDA, medical condition that increases risk. (people under 35 are at a lower risk for hepatoxicity) |
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Term
| what % of HIV+ pts convert to active TB? how is this combination treated? |
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Definition
| 30% of HIV+ pts convert to active TB, and this combination is treated with chemotherapy |
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Term
| what is the standard latent TB infection tx? (*exam question*) |
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Definition
| isoniazid 300 mg PO daily for 6-9 mos, follow LFTs, and the pt must abstain from EtOH (pt must be motivated and compliant w/medication) |
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Term
| what is the definition of multi-drug resistant TB? how is this treated differently? |
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Definition
| TB resistant to RIF and INH (4% of all cases globally). lung resection combined with anti-TB chemo is the tx for this. |
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Term
| what is the definition of extensively drug resistant TB? |
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Definition
| this is TB resistant to INH, RIF plus any quinolone plus at least one injectable second-line agent (5% of all MDR TB) |
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Term
| what are the primary methods of TB prevention? |
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Definition
| reduce risk factors and BCG vaccination (attenuated mycobacterium bovis ) |
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Term
| what are the secondary methods of TB prevention? |
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Definition
| identification/isolation of active cases, tx, look for 3 consecutive negative AFB sputum smears and evaluate risk to household contacts |
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Term
| what is the cornerstone of anti-TB efforts? |
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Definition
| timely case identification and tx |
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