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65 Cards in this Set
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characteristics of all Mycobacterium species |
acid fast bacilli
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main component of cell wall |
mycolic acid |
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specimens |
lower respiratory gastric secretions urine tissue, CSF, blood skin |
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lower respiratory specimen |
sputum, bronchoaveolar lavage, bronchial washing first morning is the best collect over several days induced sputum |
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when to use bronchoscopy |
-if pt cannot cough up enough sputum -if an induced sputum cannot be obtained |
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gastric secretions specimen |
use if cannot get a lower respiratory specimen (kids) 1st morning is the best neutralize immediately bc acids brought up will kill bacteria usually use sodium carbonate to neutralize |
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urine specimen |
1st morning is the best |
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skin specimen |
use only if certain species are suspected |
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processing specimens, use caution |
BSL 3 negative air flow room biological safety cabinet gowns, gloves, respirator skin test every 6 months |
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acid fast for direct smears |
Kinyoun- cold method Ziehl-Neelsen- hot method |
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Fluorescent for direct smears |
auramine auramine-rhodamine increased sensitivity |
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how to process gastric/sputum specimens |
1-NALC n-acetyl-L-cysteine to digest mucus 2-NaOH to decontaminate specimen 3-neutralize after 15 mins 4-centrifuge to concentrate specimen alternate: trisodium phosphate + benzalkonium chloride 5- culture! |
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how to process urine specimen |
concentrate |
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Mycobacterium culture |
use solid & liquid media Lowenstein-Jensen Middlebrook Petragnani Can add antibiotics but need to run non-selective parallel automated detection systems |
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Lowenstein-Jensen agar |
for Mycobacterium egg-based Good for TB malachite green: bactericidal, makes it selective |
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Middlebrook media |
clear agar-based not selective 2 types: 7H10 and 7H11 (the more selective one) |
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Petragnani media |
for heavily contaminated specimens, highly selective |
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incubation of media |
temp: skin 30 C, others: 37 increased CO2 up to 8 wks before calling it TB grows in 3-5 wks in solid media some intracellular bacteria take 6-8 wks to grow |
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initial tests once growth on media: |
check acid-fastness check colonial morphology if unpigmented, expose to light for 1 hr and reincubate record time it took to grow
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Mycobacterium complex consists of |
M. tuberculosis (most common) M. bovis M. africanum M. canettii M. caprae M. microti M. pinnipedii |
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Mycobacterium tuberculosis |
causes tuberculosis (TB) only contagious AFB cording of AFB is common see a lot in people with immunosuppression |
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transmission: |
can lie latent for a very long time droplets causes pulmonary TB |
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AFB and transmission |
machrophages phagocytize AFB but cannot kill them reproduce & infect new macrophages--> lasts several weeks--> no symptoms--> inflammation--> macrophages surround site of infection--> tubercle--> collagen deposited--> necrosis of tissue/ center liquefies and fills with air |
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secondary/ reactive TB |
when tubercle ruptures |
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TB symptoms |
chronic cough low-grade fever weight loss |
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Latent TB Infection (LTBI) |
inactive, contained tubercle bacilli in the body TST/blood test: usually + chest x-ray: normal sputum smear/culture: - symptoms: no infectious: no Case of TB: no |
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TB Disease (in the lungs) |
active, multiplying tubercle bacilli in the body TST/blood test: usually + chest x-ray: abnormal sputum smear/culture: may be + symptoms: cough, fever, weight loss infectious: yes, often before treatment case of TB: yes |
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Sites of TB disease (Miliary TB) |
bacilli commonly found in: brain, larynx, lymph node, bone, pleura, lung, kidney, spine |
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methods to screen of TB |
skin tests: mantous or tine chest x-ray IGRA: interferon gamma release assays, blood test |
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IGRA Principle |
measure pt's immune rxn to M. tuberculosis detects release of interferon-gamma (IFN-y) from WBC in heprainized whole bld when incubated with 2 TB proteins ELISA test |
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2 proteins used in IGRA |
ESAT-6: early secretory antigenic target CFP-10: culture filtrated protein |
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uses for IGRAs |
detect LTBI and active infetion for pts that won't return for TST reading for pts who received BCG |
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CDC testing recommendations |
Test pulmonary specimens for M. tb AFB smear culture for 1-8 weeks; 1 liquid and 1 solid media at least 1 specimen tested with NAAT for M. tb |
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cautions regarding NAAT |
a single - NAAT cannot excluded TB especially when there is moderate-high suspicion of TB do not use for non-respirator specimen or if pt is already being treated |
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cultures: |
use to confirm diagnosis of TB culture all specimens, even if smear is - results in 4-14 days liquid medium systems used |
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reporting TB |
Report of Verified Case of Tuberculosis (RVCT) |
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treatment for TB |
2 lines of drugs |
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first-line of drugs |
Isoniazid (INH) Rifampin (RIF) Pyrazinamide (PZA) Ethambutol (EMB) Rifapentine |
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problems with 2nd |
less effective more toxic more expensive less available less convenient require longer duration of treatment |
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Drug Resistant TB |
MDR TB XDR TB |
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what is MDR TB resistant to? |
Isoniazoid Rifampin possibly other 1st line drugs |
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MDR TB |
Multiple drug resistant TB (MDR TB) 2/3 of cases in Russia, China, India |
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XDR TB |
extreme drug resistant TB
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what is XDR TB resistant to? |
Isoniazid and Rifampin possibly other 1st line drugs Fluoroquinolones at least 1 2nd line injectable drug |
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DOT |
directly observed therapy |
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TB pts must be: |
in isolation until evidence of TB - need 3 - AFB smears to rule out TB confirmed TB needs evidence of response to treatment:symptom improvement, AFB smear - |
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Mycobacterium bovis |
rare in US BCG vaccine: Bacillus Calmette-Guerin Found in cattle Get TB like symptoms |
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Nontuberculous Mycobacteria (Runyon's Groups) |
photochromogens scotochromognes non-chromogens rapid growers |
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photochromogens |
develop yellow-orange pigment only when exposed to light for only 1 hr M. kansasii M. marinum |
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Mycobacterium kansasii |
chronic TB-like illness photochromogens |
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Mycobacterium marinum |
"swimming pool granuloma" grows at room temp 30-33 C photochromogens |
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scotochromogens |
produce pigment in the dark M. scofulaceum M. gordonae |
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Mycobacterium scofulaceum |
causes Scofula in neck, infection of lymph nodes in neck high drug resistance scotochromogens |
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Mycobacterium gordonae |
tap water scotochromogen rarely pathogenic can interfere with stains if you use tap water to rinse stains |
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non-chromogens |
M. avium complex (MAC) M. ulcerans M. haemophilum |
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Mycobacterium avium complex |
MAC M. avium-intracellulare complex disseminates to skin, intestine, liver, bone marrow 50% of non TB isolates are this high drug resistance |
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Mycobacterium ulcerans |
skin buruli ulcer |
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Mycobacterium haemophilum |
skin with immunocompromised pts |
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other non-chromogens |
M. branderi M. celatum M. conspicuum M. gastri M. genavense M. heidelbergense M. malmoense M. shimoidei M. simiae M. triplex M. xenopi |
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rapid growers |
grow within 7 days M. fortuitum complex (see the most)
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Mycobacterium fortuitum complex |
rapid grower soft tissue and bone nail & skin infections: assoc. with nail salons not contagious, found in soil, water, non-pasturized milk |
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other rapid growers |
M. abscessus M. chelonae M. immunogenum M. peregrinum M. smegmatis |
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Leprosy |
found in leper cells humans are the only host for M. legrae lepromatous and tuberculoid |
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Lab Dx of Leprosy |
AFB in vivo growth only: armadillis and pads of mouse feet elimination of other Mycobacterium species to ID incubation period: 2-30 yrs Lepromatous form-skin Tuberuloid form- nerve |
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Mycobacterium paratuberculosis |
Crohn's disease |