Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Lab Tech 2 > Microbiology > Flashcards

Microbiology Flashcards

1
Q

Eukaryotic

A

contains genetic material within a membrane (nucleus)

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

Prokaryotic

A

genetic material but does not have a nuclear membrane

Ex. Bacteria

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

presumptive identification

A

your “best guess” on what is growing

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

gram stain

A

Primary stain - usually crystal violet
Mordant (fixes dyes to the cell wall) - Gram’s iodine solution
Decolorizer - 95% ethanol or acetone
Counterstain - basic fuchsin or safranin

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

gram positive

A

60-90% peptidoglycans in cell wall

Retain violet-iodine because of high # of peptidoglycans.

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

gram negative

A

10-20% peptidoglycans in the cell wall.

Lose crystal-violet w/ decolorizer and stains pink because low # of peptidoglycans.

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

gram variable

A

Gram variable implies that the bacteria will stain both purple and pink - but have all the same morphology (not the same as a mixed colony, where you can have cocci and bacilli together)

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

what causes gram variability

A 
excessive decolorization 
overly thick smear
excessive heat fixation
old cultures
poor quality stain (most commonly mordant - Gram’s iodine - being exposed to light
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Potassium Hydroxide Test (KOH Test)

A

determines true gram status

Loopful of 3% KOH solution is placed on slide
Generous quantity of surface growth removed from culture and transferred to drop of KOH
Specimen stirred with loop the lifted gently and slowly. Gram positive bacteria mixture will remain homogenous and doesn’t lift with loop. Gram negative bacteria will develop mucoid appearance and produce a sticky strand when lifted.

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

Ziehl-Neelsen stain

A

Primarily used to ID acid-fast organisms of Mycobacterium and Nocardia species. 3 part stain:

Primary Stain - RED
Acid-alcohol decolorizer
Counterstain - BLUE
Air dry - heat-fix - flood the slide with RED heat it until it steams - cool for 5 mins - rinse with tap water - acid alcohol decolorizer for 1-2 minutes (if negative, washed the RED away - if an acid-fast bacteria, it keeps the RED) - counterstain with blue - rinse - dry - examine
Acid-fast = red
Non-acid fast = blue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Giemsa stain

A

Used to detect spirochetes and rickettsiae as well as to demonstrate the capsule of Bacillus anthracis and the morphology of Dermatophilus congolensis

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

Baccili

A

Shaped like rods/cylinders

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

Cocci

A

Spherical cells

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

Spirochetes

A

Usually occur singly and can be subdivided into loose spirals, tight spirals, and comma-shaped spirals

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

pleomorphic

A

Shapes ranging from cocci to rods

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

arrangements

A
  1. Single - Spirilla & most Bacilli
  2. Pairs - Streptococcus pneumoniae (diplococcus)
  3. Chains - Short/Long Streptococcus spp.
  4. Tetrads - “quads”
  5. Clusters - Staphylococcus aureus (grapelike)
  6. Palisades - “Chinese letter” pattern Corynebacterium spp
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

spores

A

Some genera of bacteria produce endospores. Resistant to heat, desiccation, chemicals and radiation. Location in cells helps classify.

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

Obligate aerobes

A

Bacteria that require oxygen to survive.

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

obligate anaerobes

A

Bacteria that are killed in the presence of oxygen or those with growth that is inhibited in the presence of oxygen.

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

Facultative anaerobes

A

Organisms that can survive in the absence of oxygen, but their growth is limited.

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

Microaerophilic

A

Bacteria that prefer reduced oxygen tension.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Capnophilic

A

Bacteria that require high levels of carbon dioxide.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Fastidious microbes

A

picky eaters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

general purpose media

A

Isolation of a wide variety of bacteria.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

enriched media

A

Contains nutrients required to support the growth of a wide variety of bacteria - Meets the requirements of fastidious pathogens.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

selective media

A

Allows certain types of bacteria to grow and inhibit growth of others.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

differential media

A

Biochemical reaction to differentiate closely related organisms or groups of bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

enrichment media

A

Favors the growth of a particular type/group of organisms.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

transport media

A

Keeps the sample as close as possible to its original state.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

blood agar

A

Is an enriched medium, used to grow a wide variety of bacteria and a differential medium based on hemolysis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

hemolysis

A

Alpha Hemolysis- Partial hemolysis
Beta Hemolysis - Complete hemolysis, creates a clear zone around the colony.
Gamma Hemolysis - Hemolysis that produces no change in the appearance of the medium and around colonies.
Delta Hemolysis - Double zone hemolysis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

MacConkey agar

A

Is a selective (only grows Gram -) and differential medium (lactose fermenting = pink and non-lactose fermenting = no color change).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

EMB eosin methylene blue

A

Is a selective and differential medium used to isolate fecal coliforms -
Allows some gram positive bacteria to grow. Escheria coli and Klebsiella pneumoniae = metallic green colonies

34
Q

Thioglycollate broth

A

Is an enrichment broth used to determine oxygen requirements of microorganisms.

35
Q

Mueller-Hinton Agar

A

Is a general purpose medium used for culture and sensitivity (susceptibility) testing of rapid growth bacteria.

36
Q

culture incubation

A

Plates should be incubated at 37°C.

37
Q

incubate upside down

A

To lessen contamination risk from airborne particles landing on them and to prevent water condensation

38
Q

temperature

A

· Mesophiles- grow in moderate temperature.
· Psychrophiles- grow at a lower temperature.
· Thermophiles- grow in a higher temperature

39
Q

bacteria produce

A

Binary fission

40
Q

4 phases of growth for bacteria

A

Initial/Lag phase - Adjust to the environment.
Exponential - Increase in number of living bacterial cells, until space is used up or wastes accumulate.
The stationary phase - Plateau in number of living bacterial cells.
The death/final phase - Exponential decrease of living cells (spores are produced at this stage in sporulating species).

41
Q

motility tests

A

wet prep
hanging drop
motility media

42
Q

brownian movement

A

The random motion of particle as a result of collisions with surrounding gaseous molecules

43
Q

why use motility test

A

If organisms are nonmotile on microscopic examination.

44
Q

Catalase Test

A

Used to determine whether a gram-positive cocci is a staphylococci or streptococci

Positive- Bubbles after adding 3% hydrogen peroxide to slide. (staphylococci)

Negative- No bubbles. (streptococci)

45
Q

Coagulase Test

A

This test is done to differentiate among coagulase-positive Staphylococcus aureus, Staphylococcus pseudointermedius and coagulase-

negative Staphylococcus (e.g. Staphylococcus epidermidis or Staphylococcus saprophyticus)

46
Q

slide coagulase

A

Commercially available. Detects surface-bound coagulase or clumping factor.
Mix a loopful of staphylococci from a colony in a drop of water/saline solution to yield a thick suspension. Add a drop of fresh rabbit/human plasma and stirred with a sterile loop. Clumping within 5-20 seconds indicates a positive reaction.

47
Q

tube coagulase

A

Uses lyophilized plasma that has been diluted according to the manufacturer’s directions. Inoculate a loopful and culture with noninhibitory medium, such as blood agar. It is incubated at 37°C and read hourly for 4 hours.
Positive- Clot formation. (Staphylococcus aureus)
Negative- No clot formation. Note: If test results remain negative, the sample is incubated again for 24 hours and then read. (non-pathogenic Staphylococcus spp.)

48
Q

why coagulase test

A

Catalase-positive, gram-positive cocci

Which enzyme coagulates plasma? Coagulase

49
Q

oxidase activity

A

The oxidase test identifies organisms that produce the enzyme cytochrome oxidase. Escherichia coli vs Pseudomonas aeruginosa

Positive = PURPLE - Microorganisms are oxidase positive when the color changes to purple within 15 to 30 seconds. Pseudomonas aeuriginosa

Negative- = No color change Escherichia coli

50
Q

common bacteria

A

Streptococcus spp. = Gram positive cocci- catalase negative
Staphylococcus epidermidis = Gram positive cocci - catalase positive - coagulase negative
Staphylococcus aureus “golden staph”= Gram positive cocci - catalase positive - coagulase positive
Pseudomonas aeruginosa = Gram negative bacilli - oxidase positive
Escherichia coli = Gram negative bacilli - oxidase negative

51
Q

acid production for glucose

A

A tube of 1% glucose in peptone broth that contains a pH indicator is inoculated and incubated for 24-48 hrs at 37℃.

For fastidious organisms- appx. 5 drops sterile serum should be added to the peptone water medium, or growth may not occur.

52
Q

California mastitis test

A

Helps confirm the presence of subclinical mastitis. By using milk, a reagent, and a paddle

53
Q

staining milk

A

Prepare a thin smear of mastitic milk. The smear is heat fixed and stained with gram stain or methylene blue.

54
Q

agar diffusion method

A

Most commonly performed sensitivity test. Uses paper disks impregnated with antibiotics. Quantitative tests measure inhibitory zones to estimate antimicrobial sensitivity. (FDA method, Kirby-Bauer, International Collaborative Study methods)

55
Q

Kirby-Bauer Method

A

Most commonly used method. Uses paper disks impregnated with antimicrobials. Quantitative and requires the measurement of ZOI, which gives an estimate of susceptibility.

56
Q

minimum inhibitory concentration

A

Lowest concentration of the specific antimicrobial that can inhibit the growth of a given bacteria

57
Q

antimicrobial disks

A

It is paper with known concentrations of antibiotics

58
Q

direct sensitivity testing

A

Application of undiluted samples directly to Mueller Hinton plate. Not as precise as indirect testing, reasonable results when only one organism present

59
Q

zone of inhibition

A

area of no bacterial growth around an inhibitory disk that indicates some sensitivity of the particular organism to an antimicrobial.

60
Q

reading ZOI

A

Should be read after a constant period, most satisfactorily after overnight incubation - 18 to 24 hours. Rapid results may be read after 6 to 8 hours of incubation. The diameter of each inhibition zone is measured from the underside of the plate using calipers, a transparent ruler, or template. Zones are measured and recorded to the nearest millimeter.
Note: For Mueller-Hinton agar with blood, the zone size must be read from the top surface, with the lid of the plate removed.

61
Q

heterotrophs

A

Digest complex organic material (plant/animal) food internally - enzymes. May be Parasitic or Saprophytic.

62
Q

parasitic

A

Cause harm to the plant/animal host it is using for food

63
Q

saphrophytic

A

Feed on dead/dying material - These are the fungi you see on fallen trees.

64
Q

yeast

A

Single-celled and reproduces by budding.

65
Q

hyphae

A

Multicellular fungal organism - Microscopic feeding form

66
Q

mycelium

A

Large branched webbings. Composed of hyphae

67
Q

Sabouraud Dextrose

A

DTM commonly found in most clinics, contains an indicator that turns red if dermatophytes are present

68
Q

collect dermatophytes

A

Pluck: To pull hair out along with the fungus with forceps/tweezer.

  1. Tooth brush: Obtain a new toothbrush. Brush suspected lesion for 1 to 2 minutes.
69
Q

lactophenol cotton blue

A

ID fungal organisms

70
Q

Microsporum canis

A

Little boats with pointed ends.

71
Q

Microsporum gypseum

A

Little boats with blunted ends.

72
Q

Trichophyton mentagrophytes

A

Little coffins with circular friends

73
Q

dermatophyte testing

A

Wood’s lamp: warm up light for 5 minutes. Infected hairs will glow in a dark room using fluorescence light.

Dermatophyte test medium (DTM): Culture media will turn red in the presence of most dermatophytes.

Rapid sporulation medium (RSM)/ Enhanced 
sporulation medium (ESM): Culture media will turn Teal in the presence of most dermatophytes.
What color does a positive result for DTM yield? Red
If the color change occurs, is that 100% positive? No.  Confirm with microscopic examination.
74
Q

non dermatophytes

A

Bismuth-Glucose-Glycine-Yeast (Biggy), Blood agar or Sabouraud dextrose agar

75
Q

microscopic evaluation of fungi

A

Collect mycelium from media with sticky side of clear cellophane (Scotch) tape, place a strip of lactophenol cotton blue (or methylene blue from DiffQuik) onto a slide and place the tape onto the stain - examine on 10x and 40x for specific spores (tells you the organism)

76
Q

send out viral samples

A

Check with the diagnostic laboratory for a preferred sample and necessary transport medium.

77
Q

cell culture

A

need living cells to grow and replicate, Animal’s cells grown in vitro, continuous cell lines and single cell type. Fetal kidney, embryonic trachea, skin from lab animals. Inoculated into primary culture from the same species from which specimen was taken.

78
Q

Immunologic and Molecular Diagnostics Examination

A

Definitive ID requires serologic procedures, in-house tests for viral pathogens, Molecular testing, PCR also used to ID pathogens.
Viruses are often present in nasal or pharyngeal secretions in early stage of URI (Upper Respiratory Infection). Mucosal scrapings rather than swabs of the secretions should be taken. Viral diseases are often complicated by pathogenic bacteria (secondary infections), which can turn into a mild viral infection into a serious disease

79
Q

histopathology

A

For viral samples – thin tissue sections placed in 10% formalin – no freezing – may also do 2x2 inch cubes that contain normal and abnormal tissue

80
Q

submission virus samples

A

refrigerated at 4°C. Why? Viral titers decrease as temperature increases.

  1. If delivered within 24 hours, what do you do? Pack with coolant packs or ice in polystyrene-insulated carton for shipment
  2. If over 24 hours, what do you do? Snap freeze at -70°C and ship on dry ice. However, suspected parainfluenza and influenza viruses being shipped are best preserved at -20°C.
  3. Small tissue pieces, fecal material, or mucus preserved in vials filled with 50% glycol and stored at 4° C
  4. Scanning electron microscopy
    a. Fixative- 10% buffered neutral formalin added to sample at maximum fixative-to-sample ratio 1:1.
  5. Urine samples
    a. 5 mL in sterile container
    b. Chilled within 24 hours or frozen

Lab Tech 2 (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions