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state exam > tb > Flashcards

tb Flashcards

1
Q

urine

A

40 ml

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2
Q

commonly used methods for processing

A 
nalc-naoh
ztsp
2-4% naoh (petroff's)
sputolysin
cpc
oxalic acid
sulfuric acid
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3
Q

ideal digestant:decontaminant

A

luquify mucoid specimen
kill most of normal flora
gentle enough to not harm mycobacteria

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4
Q

nalc

A

mucolytic agent, decreases concentration of naoh
must be used within 24 hr
0.5-2.0 % depending on consistency of sputum

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5
Q

naoh

A

decontaminating agent, 1%

increase concentration rather than lengthen exposure if continuously contaminated

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6
Q

sodium citrate

A

stabilizing effect on nalc

chelates heavy metals

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7
Q

phosphate buffer

A

stops reaction

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8
Q

0.2% ablumin

A

buffereing agent, helps sediment adhere

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9
Q

z-tsp

A

trisodium phosphate- liquefies sputus

zephirin- kills contaminants must mused be washed

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10
Q

petroff

A

naoh is decontaminant and digestant
exposure time is critical
50-60% of tb may be killed
level 1 labs- quick smear

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11
Q

spurtolysin

A

dithiothreitol plus 2% nacl

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12
Q

cpc-nacl

A

cpc (cetylpyridinium chloride)- quarternary ammonium compound
bacteriostatic
mycobacteria vialbe up to 8 days (transit)

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13
Q

oxalic acid

A

repeat contaminated with pseudomonas

longer exposure time

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14
Q

sulfuric acid

A

consistently yield contaminated cultures when processed with alkaline,
urine or other thin watery body fluids

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15
Q

nalc-naoh procedure

A 
equal volume of digestant to specimen
vortex, inc. 15 min
add pbs to stop
centrifuge and pour off
add albumin and indicator and neutralize with hcl
inoculate 0.1 to solid and 0.5 to liquid
make smear, dry and heat fix
stain with auramine
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16
Q

other organisms with mycolic acid

A

nocardia, rhodococcus, tsukamurella, actionmyces, gordonia

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17
Q

Ideal Media

A

should support the growth of mycobacteria and inhibit the growth of contaminating organisms
support the growth of few viable organisms
aloow pigment production
allow drug susc to be performed
be economical and simple to prepare

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18
Q

Media QC

A

CLIA specifications

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19
Q

Media for Mycobacteria

A

Agar-based (LJ), Egg-based (7H10, 7H11), liquid (MGIT)

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20
Q

Egg-based

A 
contains egg, potato flour and glycerol
sterilized by inspissation
non-selective 
LJ- pereferred- malachite green
ATS- easily overgrown, sterile site use
Petragnani-higher concentration of malachite green, inhibits some atypical mycobacteria, useful for high contamination specimens
21
Q

Egg-based selective

A

Gruft- malachite green, penicillin, nalidixic acid
may inhibit growth of atypical
enhances growth of MAC
Mycobactosel- contains malachite green, cyclohexamide, lincoymycin, nalidixic acid

22
Q

Adv. egg based

A

photochromogenicity, long shelf life, less contamination, supports growth

23
Q

Disadv. egg-based

A

contamiatnio affects entire slant, not good for susceptibility, media is opaque

24
Q

Agar based- non-selective

A

7H10- malachite green, defined salts, vitamins and co-factors
OADC- oleic acid, albumin, dextrose, catalase
7H11- 7H10 blus glycerol & casein hydrolysate

25
Q

Agar based- selective

A 
Middle broth 7H11 selective plus PACT
Polymyxin B (+)
Amphotericin B
Carbenicillin (pseudomonas)
Trimethoprim lactate (-)
26
Q

Adv. agar based

A 
colony morphology
mixed cultures
susceptibility
early detection
less contamination
27
Q

Disadv. Agar-based

A 
plated media can dry out
need CO2 permeablebags
exposure to light is inhibitory
short shelf-life
preparation requires great care
28
Q

Liquid media

A 
early detection
some contain surfactant tween 80
7H9
dubos tween
albumin broth
bactec 12B
29
Q

Bactect 12B

A

contains casein hydrolysate, catalase and 14C-labeled substrate (palmitic acid)
PANTA
minimum GI=10
radioactive carbon is produced, detected quantitatively, rate and amount of 14CO2 directly proportional to growth

30
Q

PANTA

A

polymyxin B, amphotericin B, nalidixic acid, trimethoprim, azlocillin

31
Q

Bactec Adv.

A

Early detection, use for susc, automated, increased sensitivity due to large inculum and liquid medium

32
Q

Bactec Disadv.

A 
use of radioactive material
expensive instrument
cannot examine colony morpholy
possible cross-contamination
uses sharp needle
33
Q

Septicheck biphasic media

A

detection of m. haemophilum
7H9 with 20% CO2
bottles are inverted periodically after inoculation until colonies are seen or growth observed in broth

34
Q

MGIT-

A

mycobacterial growth indicator tube

35
Q

MGIT detection

A

fluorescent compound is embedded in silicon, initially large amount of 02, as O2 gets consumed stops quenching
CONTAMINATION RATE IS HIGHER THAN BACTEC

36
Q

Time to detect growth

A

2-8 weeks

37
Q

Difco ESP-Myco

A

automated instrument that detects pressure changes as a result of O2 consumption

38
Q

MB System

A

automated, liquid-based media with a CO2 sensor at bottom of the vial

39
Q

Incubation conditions

A

37 C- incubate second set for skin and soft tissue lesion at 30 C (m. haemophilum, m. ulcerans, m. marinum)
incubate in dark
obligate aerobes but 5-10% stimulate better grwoth

40
Q

reading

A

mycobacterial growth in liquid can usually be detected within a week
liquid media are read daily or twice weekly
automated systems detect growth on a continuous basis, positives removed, smears made, and further testing is performed

41
Q

Leprosy

A 
Mycobacterium leprae
humans only
incubation 3 months to 40 years
doesn't grow in aritifical culture media
grows in mouse footpad or armadillos
42
Q

Leprosy epidemiology

A

nearly eradicated

90% of cases- brazil, Madagascar, Nepal, tansania, mozambique

43
Q

Leprosy transmission

A

not highly infectious
transmission among household contact
shed from nasal mucosa
humans are the reservoir

44
Q

M. leprae

A

obligate intracellular AFB
prefers cooler temp
pleomorphic
may be fragment, ovoid, or granular

45
Q

Leprosy clinical

A

chronic granulomatous disease

anastheitic skin lesion- lose feeling in affected area

46
Q

Leprosy AFB smear

A

skin lesion is the specimen of choice
nose blow smears
mucous membranes

47
Q

Diagnosis

A

cannot be cultured

diagnosis based on finding AFB on smears (skin lesions, nasal mucosa) and clinical manifestation

48
Q

Leprosy Transmission

A

prolonged exposure or close contact
inhlation of bacilli- spreads from respiratory tract to other sites, may also be transmitted by ingestion, abraded skin, or contaminated bedding/clothes
bacteria viable several days

state exam (9 decks)

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