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Microbiology > Quiz 2: Lab > Flashcards

Quiz 2: Lab Flashcards

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Biology 101 flashcards
1
Q

antibiotic

A

a chemical synthesized by a microbe that will kill or inhibit other microbes

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2
Q

important producers of antibiotics

A

streptomyces, bacillus, penicillium, cephalosporium

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3
Q

tube dilution antibiotic sensitivity assay

A

a known concentration of antibiotic is diluted in a twofold tube dilution series and a drop of test organism is added to each tube to observe if good growth will occur. The antibiotic in the highest dilution tube that shows no culture growth is called the minimum inhibitory concentration (MIC).

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4
Q

kirby-bauer or disc method of determining antibiotic sensitivity

A

paper discs containing antibiotic are used to test for inhibition of bacterial growth in the vicinity of the disc on the agar plate. For standardization of the technique, a type of agar called Mueller-Hinton is used for plates. To determine if an isolate is resistant or sensitive to an antibiotic, the growth inhibition zone diameter (including disc diameter) is compaired with values produced by reference organisms of the same species on a standard table. Two antibiotics that produce the same inhibition zone diameter do diffusion rates effect results.

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5
Q

organism used for antibiotic disc assay

A

e. coli & staph. epidermidis

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6
Q

methods

A

Mueller-Hinton agar was used
Swabbing in 3 planes

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7
Q

disc assay: CAR 100

A

concentration: 100
inhibition zones:
e. coli: 2mm
s. epidermidis: 1.75mm

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8
Q

disc assay: C30

A

concentration: 30
inhibition zones:
e. coli: 2.25mm
s. epidermidis: 2.5mm

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9
Q

disc assay: Te30

A

concentration: 30
inhibition zones:
e. coli: 1.75mm
s. epidermidis: 0mm

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10
Q

disc assay: K30

A

concentration: 30
inhibition zones:
e. coli: 1mm
s. epidermidis: 1.5mm

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11
Q

What is the concentration of the antibiotic disk?

A

It is the number printed on the disc in units or micrograms

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12
Q

ADA: Did the two organisms tested show the same antibiotic sensitivity pattern? Why

A

No because bacteria reacts differently to different antibiotics
E.coli: thick peptidoglycan
S. epi: thin

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13
Q

Minimum Inhibitory Concentration (MIC)

A

least amount of antibiotic to stop bacteria

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14
Q

What is a bactericidal antibiotic?

A

antibiotic that kills microorganisms

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15
Q

What is a bacteriostatic antibiotic?

A

antibiotic that prevents growth

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16
Q

Explain the function of penicillinase

A

hydrolyzes penicillin

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17
Q

How are plasmids associated with the efficacy of antibiotic therapy?

A

They decrease the efficacy of antibiotic therapy because they introduce genes that are resistance to the antibiotics.

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18
Q

zone size interpretation chart

A

Carbenicillin (CB-100/CAR-100): disc potency: 100 ug – resistant: < 19 ; intermediate: 20-22 ; sensitive: >23
Chloramphenicol (C-30): disc potency: 30 – resistant: <12 ; intermediate: 13-17 ; sensitive: >18
Kanamycin (K-30): disc potency: 30 – resistant: <13 ; intermediate: 14-17 ; sensitive: >18
Tetracycline (Te-30): disc potency: 30 – resistant < 14 ; intermediate: 15-18 ; sensitive: >19

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19
Q

serum titer

A

the greatest dilution of serum which causes agglutination

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20
Q

acute serum

A

a sample taken from a patient at the onset of an illness

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21
Q

convalescent serum

A

a sample taken from a patient during recovery of an illness or several days after the onset

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22
Q

identification of etiological agent

A

if the microorganism being tested as an antigen results in the observation of an increase in convalescent titer at least 4 fold greater than the acute titer, it is likely to be the infectious agent

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23
Q

ATS: organism used & serums

A

sheep RBC (used as antigen)
serums:
phosphate buffered saline (PBS): 7.2 pH
NaCl: 8.77 g/Liter
KH2PO4: 5.10
Na2HPO4 7H2O: 10.50

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24
Q

What is titration measuring?

A

It is measuring the activity

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25
Q

When you are unable to measure concentration, what can you look for instead?

A

Instead, look for the activity AKA the titer of an antibody

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26
Q

Why are we unable to measure concentration for antibodies?

A

We cannot measure the concentration because we have antibodies for many things

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27
Q

ATS: explain the methods for the experiment

A
  1. placed PBS in each of the 9 tubes
  2. place 1 ml of the serum(aby) in position 1
  3. place .5 of serum in tube 2 which is one to two dilution
  4. take .5 from tube 2 and put in tube 3 this is one to four dilution
  5. continue two-fold dilution for all tubes and discard 0.5 ml from last tube
  6. add 0.5 of washed cells (sheep red blood cells -> antigen) to all 10 tubes
  7. incubate
  8. determine the titer
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28
Q

ATS: incubation standards

A

incubate the rack in 37 C for 1 hour

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29
Q

ATS: results

A

tubes 1-6: positive for agglutination
tubes 7-10: negative for agglutination
10 is control
tube number 6 (1/32) is the serum titer: tube number 6 is the last tube to show agglutination

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30
Q

What is serum titer normally?

A

1/16 or 1/32

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31
Q

What is agglutination?

A

When antigen combines with its antibodies causing clumping of cells

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32
Q

What happens in agglutination reaction when there is an excess of antibodies and what is it called?

A

Called prozone
Agglutination will not occur
Antibodies will bind to antigens univalently instead of multivalently
Antibodies that bind univalently cant crosslink one antigen to another

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33
Q

What occurs in agglutination when there is excess of antigens and what is it called

A

Agglutination will not occur
Called post-zone
Not enough aby and too many ag
No crossbridging

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34
Q

What is required for agglutination reaction to work optimally?

A

Specific ratio of aby:ag

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35
Q

AST: test question

A

antibodies cross between blood cells; network gets so big and falls out/agglutinates

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36
Q

How does an antibody affect a germ/bacteria?

A
  1. aby doesnt kill
  2. aby just signals
  3. wbc comes to kill
  4. complement binds and starts series of rxns
  5. complement proteins put holes in cell membrane
  6. water rushes into cell -> hemolysis
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37
Q

What creature makes the best complement?

A

guinea pig

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38
Q

What is the titer of someone who is vaccinated?

A

100

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39
Q

major illnesses caused by staphylococci

A

boils, scalded skin syndrome, toxic shock syndrome, food poisoning (staphylococcus aureus)

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40
Q

major diseases caused by streptococci

A

contagious skin disease, sore throat, rheumatic fever, glomerulonephritis (streptococcus pyogenes: the flesh eating bacteria); Pneumonia (streptococcus pneumoniae)

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41
Q

beta-hemolysis in staphylococci

A

this activity produces the lysis of red blood cells in agar plate medium. Blood agar is prepared by mixing 5% sterile defibrinated sheep blood with a nutritional blood agar that has been cooled to about 45 degree C after autoclaving. The medium is then dispensed into tubes or plates

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42
Q

hemolysis in streptococci

A

lysis of red blood cells in agar (beta-hemolysis), conversion of red blood cells to green (alpha-hemolysis), no effect on blood cells (gamma-hemolysis)

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43
Q

selective medium

A

medium to prevent growth of some species but permitting others to thrive

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44
Q

differential medium

A

medium that enables the investigator to distinguish one species from another. This is usually done through use of a chemical reaction which causes the color of the medium or colonies to change

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45
Q

BCGPC: organisms used

A

s. aureus
s. epidermidis
s. pyogenes
s. pneumoniae
s. fecalis
g. tetragena

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46
Q

BCGPC: major types of test media

A

for staph: mannitol salt, 110 agar, citrated rabbit plasma
for strep: bile esculin agar, taxos A disc, taxos P disc
agar slant: s. aureus (pathogen), s. epidermidis(normal flora), and s. faecalis (normal flora)
broth culture: gaffkya tetragena (normal flora)

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47
Q

BCGPC: What is the most dangerous organism?

A

s. pyogenes

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48
Q

BCGPC: gram stain results

A

S. aureus: gram positive, coccus, cluster
S. epidermidis: gram positive, coccus, cluster
S. faecalis: gram positive, coccus, chain
G. tetragena: gram positive, coccus, tetrad

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49
Q

BCGPC: catalase reaction

A

S. aureus: +
S. epidermidis: +
S. faecalis: -
G. tetragena: -

50
Q

BCGPC: staphylococci

A

S. aureus: positive for all tests (hemolysis on blood agar, mannitol fermentation, gelatinase, coagulase)
S. epidermidis: negative for all tests(hemolysis on blood agar, mannitol fermentation, gelatinase, coagulase)

51
Q

BCGPC: bile esculin azide agar

A

s. faecalis: good growth and blackening of medium
g. tetragena: no growth

52
Q

Under the microscope, how can staphylococcus be differentiated from gaffkya tetragena?

A

Staph has grape-like clusters and g. tetragena is in tetrad

53
Q

What is the chemical reaction mediated by the enzyme catalase?

A

2H2O2 > O2 + 2H2O
hydrogen peroxide to water and oxygen

54
Q

What simple test can differentiate staph from strep?

A

catalase

55
Q

Describe the mechanism by which staphylococcal coagulase causes plasma to clot?

A

conversion of fibrinogen to fibrin
-s. aureus produces bound & free coagulase (bound directly to fibrinogen)

56
Q

major intestinal diseases

A

typhoid (salmonella typhi), dysentery (shigella dysenteriae), cholera (vibrio cholerae), travelers diarrhea (escherichia coli)

57
Q

enterobacteria

A

gram-negative rods that are frequently found in the intestinal tract

58
Q

facultative anaerobe

A

a bacterium that can grow in the anaerobic intestinal tract but also in the presence of oxygen

59
Q

selective medium

A

medium to prevent growth of some species but permitting others to thrive

60
Q

differential medium

A

medium that enables the investigator to distinguish one species from another. This is usually done through use of a chemical reaction which causes the color of the medium or colonies to change

61
Q

macconkey agar

A

lactose fermenting organisms produce red colonies on this plate medium. Gram-positive bacteria are inhibited. The ingredients include lactose, bile salts and neutral red (pH indicator)

62
Q

XLD

A

organisms that ferment the constituent carbohydrates produce yellow or red colonies on this plate medium. If lysine decarboxylase is produced colonies are red. Colonies may be black if H2S is produced. The medium contains xylose, lactose, sucrose, phenol red (pH indicator), bile salts, lysine, and ferric ammonium citrate (H2S detection)

63
Q

TSI

A

triple sugar iron agar is used in the form of a slant tube. If an organism can use lactose or sucrose, the entire tube will turn yellow (acid). Gas may push the agar up the tube or form large bubbles. If only glucose is used, the base (butt) of the agar slant will turn yellow but the slant itself will remain red. An organism that produces H2S will cause the formation of a black pigment in the tube. Besides the sugars, the medium containts phenol red (pH indicator) and iron salts (H2S)

64
Q

Simmons Citrate

A

this medium will turn blue if inoculated organism can use citrate. The medium includes citrate and thymol blue (pH indicator) and is prepared as an agar slant.

65
Q

urea agar

A

organisms that can break down urea can be recognized by changing the color of this medium. Phenol red is used as an indicator.

66
Q

iron Agar

A

this medium is for the detection of H2S produced by some species

67
Q

Fermentation Broth

A

this is a test to determine if an organism can use a specific carbohydrate. The broth includes phenol red to test for acid produced from the carbohydrate.
A tiny inverted tube (durham tube) is present to assay production of gas

68
Q

Decarboxylase Broth

A

this medium can detect the ability to produce decarbyoxylases by a color change of the tube

69
Q

Motility Medium

A

if growth spreads from a straight vertical stab line of inoculation, the bacterium may be motile

70
Q

enterotube II

A

this is a multiple test medium made by Roche diagnostics that can assay for several qualities at once

71
Q

organisms used for biochemical characterization of enteric bacteria

A

e. coli
klebsiella pneumoniae
proteus vulgaris
pseudomonas aeruginosa

72
Q

Try to describe in one or two sentences the basis behind identifying the species of a gram-negative rod

A
73
Q

Why must the tube media be inoculated with a pure strain?

A
74
Q

phage

A

this is a virus that infects bacteria

75
Q

plaque

A

infective center (clear area) caused by phage on lawn of bacteria on a plate. It contains thousands of new phage. In this area the bacteria have been killled

76
Q

plaque forming unit (PFU)

A

a phage particle that is capable of forming a plaque on a lawn of bacteria

77
Q

methods the measure virus concentration

A

phage titration or plaque assay, routine test dilution (RTD), electron microscopy (EM), hemagglutinin titration, dose to infect 50% of subjects (ID50), dose to kill 50% of subjects (LD50)

78
Q

PT: organism used

A

e. coli

79
Q

remember for test

A

maximum is 10^11

80
Q

ideal plaque count

A

30-300

81
Q

What degree is agar melted at for phage titration experiment?

A

45 degrees C

82
Q

For phage titration how do tubes get intubated?

A

36 degrees C for 20 minutes

83
Q

For phage titration how to plates get intubated?

A

Upright position at 37 degrees C for 18-24 hours

84
Q

Do you think every phage particle makes a plaque and why?

A

No, a cell infected by two phages makes 1 plaque because the phage grows as the cell grows
Some viruses and cells are dead

85
Q

Why do the plaques stop growing?

A

There are mutants and they are no longer affected by the virus

86
Q

Why can’t you see any plaques on zero dilution?

A

Plaques that overlap do not have a borders

87
Q

What are those colonies on the zero dilution plate?

A

A few cells are resistant to infection

88
Q

What does color change in the tube indicated?

A

positive inoculation

89
Q

mycology

A

study of fungi

90
Q

hypha

A

a filament of fungal cells

91
Q

mycelium

A

mass of fungal hyphae

92
Q

yeast

A

single celled fungi

93
Q

pseudohyphae

A

short hyphal filaments consisting of rapidly dividing yeast cells

94
Q

conidia

A

spores that develop on conidiophore

95
Q

conidiophore

A

modified hypha for spore production in some fungi

96
Q

fruiting body

A

large complex structure in some fungi to make spores

97
Q

bud

A

offspring of yeast attached to parent cells

98
Q

dimorphism

A

a characteristic of some fungi to exist in a yeast or hyphal phase depending on temperatiure

99
Q

germ tube test

A

yeast cells of candida may produce short projections (germ tube) after inoculation into albumin and incubation for a few hours at 37 C

100
Q

lacto-phenol cotton blue stain

A

a general purpose stain for examination of fungi

101
Q

sabouraud dextrose agar

A

general purpose stain for the examination of fungi

102
Q

aspergillus

A

a saprobe that can cause opportunistic infections of the lungs

103
Q

candida albicans

A

a commensal organism that can be found on the skin, in the mouth, and in the genitourinary tract and causes opportunistic infections

104
Q

basidiomycotina

A

group of fungi that includes edible mushrooms

105
Q

mycology: organisms used

A

candida albicans grown at room temperature
candida albicans grown at 37 degrees C
apergillus nidulands grown at room temperature

106
Q

mycology: structures from the specimens

A

hypha
mycelium
bud
conidia
conidiophore
pseudohyphae
germ tube
yeast cell

107
Q

mycology: structures from the mushroom

A

cap
gills
ring
stipe
basidium
hymenium

108
Q

what is the etiological agents and what are the major characteristics for each of the following diseases?

A

tinea corporis
histoplasmosis
coccidiodomycosis

109
Q

parasite

A

an organism that lives on another to its detriment

110
Q

trophozoite

A

adult vegetative form of a protozoan

111
Q

cyst

A

small inactive state of protozoan

112
Q

proglottid

A

a segment of tapeworm

113
Q

entamoebba histolytica

A

pathogenic amoeba that causes severe dysentery and hepatic infection

114
Q

giardis lamblia

A

flagellate that is a cause of weakness, abdominal pain and diarrhea

115
Q

balantidium coli

A

ciliate that causes diarrhea, nausea, and vomiting

116
Q

taenia saginata

A

beef tapeworm that inhabits the small intestine and is associated with weight loss and abdominal pain

117
Q

enterbius vermicularis

A

pinworm (roundworm) that inhabits the colon and causes itching

118
Q

fasciola hepatica

A

liver fluke that infects the bile ducts

119
Q

parasitology: parasites examined

A

entamoeba histolytica
giardia lamblia
balantidium coli
taenia saginata (proglottid)
enterobius vemicularis (adult)
enterobius vermicularis (eggs)
fasciola hepatica

120
Q

how do human beings become infected with the above organism?

A

Microbiology (6 decks)

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