Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Microbiology > Detection and Disinfection > Flashcards

Detection and Disinfection Flashcards

1
Q

most assays for detecting bacteria growth rely on

A

culturing bacteria and obtaining a pure culture of a single species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

diluting samples is used to

A

isolate single colonies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

dilution streaking

A

streaking bacteria from a culture on a plate
flame between each streak
rubbing bacteria off the loop and onto the plate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

pour plates

A

warm media is mixed with agar in tubes
sample is serial diluted in several tube
tube are then poured onto a petri dish

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

biochemical identification

A

once a pure culture is obtained, it can be tested for its biochemical properties
many tests are required to positively identify a bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

biochemical identification kits

A

kits can complete many biochemical tests in one sample
the pattern of positives and negatives is interpreted by software
can identify many species this way, but not all

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

MALDI-TOF MS stands for

A

Matrix-assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is MALDI-TOF MS

A

-grow bacteria on a plate
-scrape some bacteria onto a plate and add matrix (an organic acid that absorbs the laser)
-vaporize with an ultraviolet laser
-measure the mass to charge ratio of the resulting debris by the length of time it takes to reach the detector
-every bacterial species yields a specific pattern of debris
-spectrum can be matched to a database

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

how can antibodies be used as diagnostic tools

A

inoculating rabbits, mice, etc., with viral or bacterial antigens

the antibodies can be purified from blood, or produced in mass quantities recombinantly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

advantages of diagnosis by antibodies

A

highly specific
rapid
point of care testing can be done cheaply

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

limitations of antibodies

A

expensive to generate, slow to develop (months)
antigenic variation can alter epitopes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

ELISA

A

enzyme-linked immunosorbent assay

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

quantitative assay

A

the amount of colour change indicates the amount of antigen present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is ELISA

A

-well is coated with an antibody for a specific antigen
-sample is added and incubated for antigens (virus or bacteria protein) to bind to antibody
-a detection antibody is added, which is conjugated to an enzyme that can process a substrate to generate colour change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

lateral flow assay

A

COVID rapid antigen test
-liquid with sample rehydrates the reagents on the strip/pad/cassette
-capillary action wicks the samples and reagents across the Test Line (antibodies specific for antigen e.g., viral nucleoprotein)
-the negative control line has antibodies that recognize the detection antibodies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

version of lateral flow assay

A

UTIs, streptococcus A, RSV, human chorionic gonadotropin (pregnancy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

genetic detection: nucleic acid amplification test (NAAT)

A

sequence-based surveillance and diagnosis
-highly specific
-inexpensive and fast
-flexible requirement for sample quality
-easily multiplexed (many tests in parallel)
-algorithms to correlate gene presence and pathogenicity
-less susceptible to variation in sequence than antibodies (target conserved regions)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

newer assays can detect and determine

A

the sequence of all the nucleic acid in a sample
you can find things that you are not looking for and that no one has ever seen before

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

polymerase chain reaction (PCR)

A

a method to amplify specific segments of DNA into very large quantities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what was the main advance that allowed PCR

A

the discovery of thermostable polymerases from bacteria living near hydrothermal vents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

PCR requires

A

buffer
Taq Polymerase (or variant)
Template/target DNA
dNTP (ATP, CTP, GTP, TTP)
Mg2+
Primers (~20 bp) which provide specificity and a free 3’OH
thermocycler

22
Q

detecting PCR products gel electrophoresis

A

gel electrophoresis - PCR products are added to well in an agarose gel
-gel is submerged in buffer
-current is run through the gel (DNA is negatively charged, moves towards the anode (+))
-PCR products are separated by size
-DNA can be visualized using intercalating dye e.g., Ethidium Bromide, which fluoresces under UV light
-laborious and not done often anymore in clinical labs

23
Q

real time, quantitative PCR

A

-PCR is conducted with a molecule that only fluoresces when it’s bound to double-stranded DNA
-assay is run in a thermocycler that has a camera and records the amount of fluorescence in each well at the end of each cycle
-the cycle where the fluorescence reaches a certain threshold can be used to calculate the amount of starting material
-can also be used with reverse transcriptase to convert RNA into DNA before amplification

24
Q

next-generation or deep sequencing

A

-PCR methods requires primers, which requires knowledge of the sequence being amplified
-new sequencing techniques can be used to obtain the entire nucleotide sequence of a sample without primers or foreknowledge
-can diagnose unknown pathogens, discover new variants, and be used to map pandemics
-used during the SARS-CoV-2 pandemic

25
for use on fomites
disinfection sanitization sterilization
26
for use on living tissue
antisepsis degerming aseptic
27
disinfection
reduces or destroys microbial load of an inanimate item through application of heat or antimicrobial chemical cleaning surfaces like lab benches, clinical surfaces and bathrooms chlorine black, phenols (Lysol), glutaraldehyde
28
sanitization
reduces microbial load of an inanimate item to safe public health levels through application of heat or antimicrobial chemicals commercial dishwashing of eating utensils, cleaning public restrooms detergents containing phosphates, industrial strength cleaners
29
sterilization
completely eliminates all vegetative cells, endospores, and viruses from an inanimate item preparation of surgical equipment and of needles used for injection pressurized steam, chemicals, radiation
30
antisepsis
reduces microbial load on skin or tissue through application of an antimicrobial chemical cleaning skin broken due to injury, cleaning skin before surgery boric acid, isopropyl alcohol, hydrogen peroxide, iodine
31
degerming
reduces microbial load on skin or tissue through gentle to firm scrubbing and the use of mild chemicals handwashing soap, alcohol swap
32
aspetic
an environment or procedure free of pathogenic contaminants surgical field, handwashing, flame in a lab
33
how do you kill or inactivate a microbe
physical methods: heat, filtration, desiccation, salt, radiation, refrigeration chemical methods: damage the physical structure of the viruses, parasites, and viral particles
34
effectiveness of killing or inactivating a microbe depends on
-population size -population composition -access of the agent to the microbe -concentration of the agent -duration of exposure -local environment
35
most resistant to most susceptible microbes
prions bacterial endospores cysts of Cryptosporidium mycobacteria cysts of other protozoa small nonenveloped viruses active-stage protozoa fungal spores most gram-negative bacteria vegetative fungi large nonenveloped viruses most gram-positive bacteria enveloped viruses
36
microbial populations are not killed ______, they die ______
instantly exponentially
37
decimal reduction time
the amount of time to kill 90% of organisms at a given temperature
38
what is the pressure canner temperature
121 degree C
39
autoclaves
-generate high pressure saturated steam to sterilize equipment or solutions -maintain a temperature of 121C at 15 psi for 15 minutes to eliminate spores -indicator tape can be used to demonstrate that chamber reached the needed temperature for enough time
40
sterility indicators
spore test after autoclaving, flexible vial is squeezed to break ampule and release medium onto spore strip yellow = not sterile red = sterile
41
methods of physical control of bacteria
dry heat sterilization: 160C, 2-3 hrs pasteurization: 63C, 30 min or 72C, 15s, only reduce bacterial population, spores and some bacteria are still present refrigeration: <4C, only stop/slow growth; many bacteria still viable, viral particles stabilized, freezing can kill some bacteria salt: creates hypertonic solution, drawing water out of bacteria desiccation: completely drying out a surface will kill bacteria, but not spores radiation: causes damage to DNA, UV lamps sterilizes surfaces or water, ionizing radiation used to sterilize sutures or syringes filtration: bacteria are >1 um, filtering with a 0.2 um or 0.1 um filter excludes most bacteria and many virus particles, useful for solutions that cannot be heated, important for control of pathogens in air
42
HEPA filters in biological safety cabinets
High-Efficiency Particulate Arresting air filters remove 99.97% of all particles greater than 0.3 um from the air that passes through -laminar flow of air prevents aerosol from leaving the cabinet through the front -required to work with most pathogens in a lab
43
N-95s
remove at least 95% of particles greater than 0.3 um from the air that passes through -must be properly fitted -not effective against smaller particles
44
surgical masks only
block droplets and spit they do not filter out small particles that can contain viruses
45
generally, chemical control of microorganisms involves
substances that denature proteins or disrupt the plasma membrane
46
chemical methods of disinfection
phenols alcohols halogens heavy metals quaternary ammonium compounds
47
phenols or phenolics
original surgical soap, Lysol -disinfectant -denatures proteins, disrupts cell membranes -remains active on surfaces -smell bad and can cause skin irritation
48
alcohols
isopropanol, ethanol -disinfectant and antiseptic -denatures proteins, dissolves cell membranes -evaporate quickly
49
halogens
iodine and chlorine -disinfectant (chlorine) or antiseptic (iodine) -oxidizing cellular material, likely denature proteins -e.g., Bleach (sodium hypochlorite) and Betadine (Povidone-iodine)
50
heavy metals
copper, silver, arsenic -complex with and inactivate or denatures proteins -copper handles, or water jugs can limit bacteria growth -e.g., 1% Silver nitrate solution for eye gonorrhea
51
quaternary ammonium compounds (quats)
cationic detergents -disinfectant -denatures proteins, disrupts cell membranes

Microbiology (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions