Term
| What 5 factors determine infectiousness? |
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Definition
| intensity of exposure, infectious burden, site of infection, strain variant, host susceptibility |
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Term
|
Definition
| identify strain isolates and follow transmission |
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Term
| How does TB avoid phagocytic clearance? |
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Definition
| inhibits acidification, inhibits phago-lysosome fusion, resistant to ROS |
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Term
| TB spreads to lymph nodes at ___wks; bacteremia occurs at __ wks; CMI and DTH develop at ___ wks |
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Definition
| LNs at 2-4 wks; bacteremia at 6-8 wks; CMI and DTH at 2-8wks |
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Term
| What percentage of infected people develop primary TB? |
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Definition
|
|
Term
| What are the 2 ways a person can develop secondary TB? |
|
Definition
| reactivation or reinfection |
|
|
Term
| What are risk factors for reactivation? |
|
Definition
| HIV, advanced age, silicosis, malnutrition, diabetes |
|
|
Term
| What cells and cytokines characterize the immune response to TB? |
|
Definition
CD4, NK cells, macrophages:
CD4 --IFNg--> activate macrophages into epithelioid histiocytes, which form granulomas; macrophages --IL-12--> activate T cells, which release IFNg, TNF-a, ROS, and NOS |
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|
Term
| What characterizes the caseous center of a granuloma that inhibits bacterial growth? |
|
Definition
| low pH, low O2, avascular |
|
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Term
|
Definition
| lesion of initial site of TB infection + lymph node involvement |
|
|
Term
| What are the 3 states a granuloma can progress to? |
|
Definition
-> calcified (healed)
-> fibrosis: but this can be reactivated
-> cavitate: via liquefactive necrosis, is highly infectious |
|
|
Term
| How do primary and secondary TB differ in lung location and lymph node involvement? |
|
Definition
| primary TB: lower to middle lobes, no cavities, lymph nodes are involved // secondary TB: apical lung sites, cavities, no lymph node involvement |
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Term
|
Definition
| osteomyelitis or thoracic spine with anterior vertebral body involvement; an extrapulmonary manifestation of TB (12%) |
|
|
Term
|
Definition
| cervical lymphadenopathy, more common in children; an extrapulmonary manifestation of TB (27%) |
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Term
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Definition
| disseminated TB after primary infection; common in HIV pts; PPD+ (50%); affects eyes, liver, lung, bone, etc. |
|
|
Term
| how does HIV affect TB presentation in terms of lung involvement, lymph nodes, systemic manifestations, and PPD? |
|
Definition
| less apical involvement, fewer cavitations, more lymphadenopathy, more dissemination (bacteremia, miliary TB), negative PPD |
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Term
| what tests are used to diagnose TB and how long do they take? |
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Definition
| acid-fast smear: <1d; liquid culture: 1-3wks; culture 2-6wks; PCR: 1d // PPD is used for screening |
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Term
| What are the pros and cons of using Quantiferon as a screening tool? |
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Definition
| pro: does not give false positive in pts with BCG vaccine; con: becomes negative after TB treatment |
|
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Term
| How is the Kinyoun technique done? What organisms will stain positive? |
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Definition
| stain with carbol-fuchsin or fluorochrome, wash, counterstain with methylene blue; Mycobacterium, Nocardia, some Corynebacteria will stain positive |
|
|
Term
| What component of the bacterial cell wall allows resistance to decolorization in the presence of acid? |
|
Definition
| mycolic acid: long chain fatty acids |
|
|
Term
| What diagnostic test is best used as a measure of infectivity? |
|
Definition
| acid-fast: indicates high inoculum (10^4 bacilli/ml) |
|
|
Term
| Without treatment, what percentage of patients with TB disease die? Are persistent shedders? Are spontaneously cured? |
|
Definition
| 50% die in 5y; 30% shed; 20% spontaneously cure (if no cavitations) |
|
|
Term
| What is the treatment regimen for non-drug resistant TB? |
|
Definition
| isoniazide (INH), rifampin, and pyrazinamide for 2mo, then INH and rifampin for 4-7mo |
|
|
Term
| What methods are used to detect drug resistance and how long do they take? |
|
Definition
| culture: 2-4wks; liquid culture: 7-10d; PCR: for rifampin only, 1d |
|
|
Term
| MDR TB occurs because of [new mutations/plasmid] |
|
Definition
|
|
Term
MDR TB is defined by resistance to...
XDR TB is defined by resistance to... |
|
Definition
MDR TB: rifampin, INH
XDR: rifampin, INH, fluoroquinolones + kanamycin, amikacin, OR capreomycin |
|
|
Term
| What is the best way to prevent MDR/XDR TB? |
|
Definition
| DOT--effective but expensive |
|
|
Term
|
Definition
| live, attenuated M. bovis; provides ~5y protection |
|
|
Term
| prophylactic INH is indicated for... |
|
Definition
| high risk populations: recent converts, pts with silicosis, fibrotic CXRs, ESRD, HIV, diabetics |
|
|
Term
| What defines a positive PPD? |
|
Definition
| >5mm in HIV pts, >10mm in high risk populations (diabetics, underserved, ESRD, healthcare workers, etc.), >15mm for general population |
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|
Term
| hepatotoxicity from TB treatment is most frequent in __ |
|
Definition
|
|
Term
|
Definition
| repeated PPD testing can boost latent anti-TB activity, appearing to be a "recent converter" |
|
|
Term
| What institutional controls are used to control TB spread? |
|
Definition
| negative pressure room, N-95 masks |
|
|
Term
| M. leprae is grown in ___ |
|
Definition
| mouse foot pad or armadillo |
|
|
Term
| pathogenesis and clinical presentation of tuberculoid leprosy |
|
Definition
| TT: anesthetic skin plaques, peripheral nerve swelling, many granulomas, lepromin skin test+; no limb loss; Th1 (CMI, IL-12, IFNg) |
|
|
Term
| pathogenesis and clinical presentation of lepromatous leprosy (LL) |
|
Definition
| LL: skin lesions, limb loss, neuropathies, leonine facies, lepromin skin test (-); Th2 (Ab, IL-4, IL-10) |
|
|
Term
|
Definition
TT: dapsone, rifampin
LL: dapsone, rifampin, clofazamine |
|
|
Term
| AE of LL tx (rifampin, dapsone, and clofazamine) |
|
Definition
| erythema nodosum leprosum; tx with prednisone or thalidomide |
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Term
|
Definition
|
|
Term
| typical demographic of MAI |
|
Definition
| older male with hx of TB, bronchiectasis or COPD; or thin middle-aged female with no underlying disease except scoliosis |
|
|
Term
| CT shows "tree-in-bud"; dx? |
|
Definition
|
|
Term
| what are the 2 clinical presentations of MAI characterized by? |
|
Definition
1. TB-like: cavitations
2. disseminated MAI: HIV pts; disseminates to liver, bone, small bowel; scrofula; poorly formed granulomas |
|
|
Term
|
Definition
| macrolides+rifampin+ethambutol indefinitely or 1-2y for lung disease |
|
|
Term
| when is prophylaxis for MAI indicated? |
|
Definition
|
|
Term
| brain abscesses, no granulomas; tx with sulfa drugs; dx? |
|
Definition
|
|
Term
| Gram+, aerobic, weakly AFB-positive, thin filamentous branched rods |
|
Definition
|
|
Term
| Gram+, not acid fast, anaerobic; clumps of branched filaments |
|
Definition
|
|
Term
| pt has IUD; biopsy shows yellow sulfur granules; bug? |
|
Definition
|
|
Term
| "lumpy jaw" that looks like tumors; tx with penicillin; dx? |
|
Definition
|
|
Term
1. necrotizing, suppurative, nongranulomatous lesions in lung and CNS; bug?
2. suppurative, fibrotic, nongranulomatous lesions in neck and abdomen; bug? |
|
Definition
1. Nocardia
2. Actinomyces |
|
|
Term
| prophylaxis regimens for MAI |
|
Definition
| 1x/day rifabutin, 2x/day clarithromycin, or weekly azithromycin |
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