Lab Practical Exam Review Flashcards
(101 cards)
1
Q
bacterial spores require temperatures above __ for destruction
A
100°C
2
Q
bacterial vegetative cells are killed at temperatures of ___ to ___ in __ minutes
A
60°C, 70°C, 10
3
Q
fungi can be killed at __ to __
A
50 to 60°C
4
Q
fungal spores require __ to __ in __ minutes for destruction
A
70°, 80°, 10
5
Q
- test for hemolysis of colonies
- primarily to distinguish staphylococci and streptococci
A
blood agar plates
6
Q
- tests for staphylococci
- differential for S. aureus versus avirulent staphylococci
A
mannitol salt agar
7
Q
- used for neisseria and haemophilus bacteria
- neisseria develop pink/purple coloration after oxidase test (addition of p-aminodimethylaniline oxalate)
- requires CO2
A
chocolate agar
8
Q
- demonstrates presence of diptheroids (corynebacteria)
- tellurite ions diffuse into bacteria and reduce to tellurium metal which preceipitates
A
Mueller-Hinton tellurite agar
9
Q
blood agar, mannitol salt agar, chocolate agar, mueller-hinton tellurite agar
A
plates for throat microbiota
10
Q
- detects yeasts and molds
- yeasts will be glistening and pigmented or not
- molds will appear fuzzy or powdery
- requires 25°C first
A
sabouraud agar
11
Q
blood agar, mannitol salt agar, sabouraud agar
A
plates for skin microbiota
12
Q
- differential test to determine S. aureus
- converts fibrinogen to fibrin forming a clot
A
coagulase
13
Q
- enzyme that degrades DNA; addition of toluidine blue makes pink halo
- differential for S. aureus
A
DNase
14
Q
- golden colored colonies
- produces coagulase
- produces DNase
- beta hemolytic
A
S. aureus
15
Q
resistant to novobiocin
A
S. saprophyticus
16
Q
gram-positive cocci including pathogenic and generally non-pathogenic strains
A
streptococci
17
Q
sole member of the Lancefield group A streptococci often referred to as GAS, or group A strep
- beta hemolysis
- susceptible to bacitracin
A
S. pyogenes
18
Q
most common cause of life-threatening neonatal sepsis; S. agalactiae
A
group B streptococci (GBS)
19
Q
- hemolysis
- bacitracin test
- CAMP test
A
tests to identify human streptococcal pathogens
20
Q
bacitracin antibiotic susceptibility; GAS is susceptible
A
bacitracin test
21
Q
GBS make a peptide that interacts beta hemolysins of S. aureus causing increased hemolysis
A
CAMP test (peptide)
22
Q
- isolation of distinct colonies
- determine purity of culture
A
streak plate (4 quadrant streak or T-(3) streak)
23
Q
- aseptic technique
- labeling
- ability to isolate individual colonies
A
steps for a streak plate
24
Q
Enterococcus faecalis
Staphylococcus aureus
Bacillus cereus
A
gram-positive bacteria
25
Escherichia coli
Klebsiella aerogenes
Proteus vulgaris
Pseudomonas aeruginosa
Alcaligenes faecalis
gram-negative bacteria
26
primary stain; stains everything strongly in acid-fast stain
carbolfuchsin
27
counter-stain for acid fast staining (non-acid fast cells)
methylene blue
28
used for decolorization for acid-fast staining; removes stain from non acid-fast cells
acid alcohol
29
- Schaeffer-Fulton method
- uses primary stain malachite green to visualize cells
spore stain
30
stains cells weakly, steam forces stain into spores; spore retains stain while other bacterial cells lose it
malachite green
31
counterstain for spore stain
safranin
32
spores are resistant to __
decolorization
33
genus for spore stains
bacillus and clostridium
34
- selective for gram-negative enterics
- differential for coliforms
- uses lactose and neutral red pH indicator
MacConkey Agar
35
bacteria exhibit red/pink coloration on their surface on MacConkey Agar
lactose fermenters/coliforms
36
no change on MacConkey Agar; colonies appear uncolored or same color as medium
non-lactose fermenters/pathogens
37
bile salts and crystal violet; inhibit G+ growth
selective reasoning for MacConkey Agar
38
MacConkey Agar-
produces acid by-products from lactose fermentation, which turn the medium surrounding the colony red in the presence of neutral red indicator dye
E. coli
39
MacConkey Agar-
does not ferment lactose but does grow on the plate
P. aeruginosa
40
MacConkey Agar-
does not grow in the presence of bile salts and crystal violet, both of which inhibit the growth of gram-positive bacteria
S. epidermidis
41
selective for staphylococcus and differential for S. aureus
mannitol salt agar species
42
high salt concentration (7.5% NaCl)
why mannitol salt agar is selective for staphyloccocus
43
the carbohydrate, mannitol, is fermented by S. aureus resulting in acidic end product which turn the phenol red indicator yellow around growth
why mannitol salt agar is differential for S. aureus
44
-selective for fastidious bacteria; streptococcus pathogens
-differential for S. pneumoniae, S. pyogenes, and non-pathogenic bacteria (based on hemolysis)
blood agar
45
hemolysis
lysis of RBCs
46
alpha hemolysis on blood agar; partial clearing and green halo around bacterial colonies
streptococcus pneumoniae
47
beta hemolysis on blood agar; complete zone of clearing around colonies
streptococcus pyogenes
48
gamma hemolysis on blood agar; no clearing and no color change
non-pathogenic bacteria
49
-selective for gram-negative enterics (enterobacteriaceae)
-fecal coliform bacteria
-differential for coliforms vs. non-coliforms
Eosin-Methylene Blue (EMB) Agar
50
eosin and methylene blue dyes inhibit growth of most G+ organisms
why EMB agar is selective for gram-negative enterics
51
lactose and the eosin and methylene blue dyes
what makes EMB agar differential for coliforms vs. non-coliforms
52
thick, mucoid purple/pink colonies due to decreased pH from lactose fermentation
lactose fermenters/coliforms on EMB agar
53
Escherichia, Klebsiella, Serratia, Citrobacter
examples of lactose fermenters/coliforms
54
colonies are blue-black with a metallic green sheen due to a large quantity of acid made by lactose fermentation that precipitates the dyes onto the colony surface
E. coli on EMB agar
55
on EMB agar- no change, colorless colonies- may appear purple due to the color of the medium
non-lactose fermenters/pathogens on EMB agar
56
Salmonella, Shigella, Yersinia
examples of non-lactose fermenters/pathogens on EMB agar
57
fails to grow in the presence of eosin and methylene blue
S. epidermidis
58
able to carry out limited fermentation of the sugars in EMB agar, turning the methylene blue indicator red and imparting a pink color to the colonies
K. aerogenes
59
peptone, lactose, sucrose
sugars in EMB agar
60
circular bacterial morphology
cocci
61
rod bacterial morphology
baccili
62
2 cocci together
ex- streptococcus pneumoniae, enterooccus
diplococci
63
cocci ex- staphylococcus aureus
cocci clusters
64
cocci ex- streptococcus pyogenes
cocci chains
65
bacilli ex- salmonella typhi (looks like tails off of rod)
flagellate rods
66
bacilli ex- bacillus anthracis (multiple rods next to one another)
bacilli chains
67
bacilli ex- clostridium botulinum (contain endospore)
spore formers
68
spiral ex- treponema pallidum (normal squiggle)
spirochaetes
69
sprial ex- helicobacter pylori (squiggle with tails)
spirilla
70
spiral ex- vibrio cholera (curved rod with tail)
vibrios
71
obligate aerobes, obligate anaerobes, facultative anaerobes, microaerophiles, aerotolerant anaerobes
five classes oxygen metabolism among microorganisms
72
growth only at the top of the tube, closest to oxygen saturation
obligate aerobes
73
growth only at the bottoms of the tube, closest to aerobic bottom zone
obligate anaerobes
74
growth throughout entire tube but more concentrated at the top near oxygen saturation
facultative anaerobes
75
growth only at the bottom portions of the TOP oxygen layer
microaerophile
76
even growth throughout entire tube
aerotolerant anaerobe
77
(colony count on agar plate) / (total dilution of tube used to make plate for colony x amount plated)
OR
number of colonies on plate x reciprocal of dilution of sample
the standard formula for dilutions and spread plates
78
- product of decarboxylation of certain amino acids
- hydrolyzed to ammonia and carbon dioxide by bacteria containing enzyme urease
urea/urease test
79
differentiate enteric bacteria on their ability to hydrolyze urea with the enzyme urease (rapid/weak/none)
reason for differentiation in urease test
80
-only nutrient source- trace 0.0001% of yeast extract
-contains buffers strong enough to inhibit alkalization of the medium
-exception --> rapid urease-positive organisms
urea broth
81
Proteus vulgaris
-turns hot pink for positive result
organism for urease test
82
simmon's citrate agar slant
medium for citrate utilization test
83
differentiates enteric organisms on their ability to use citrate as a sole carbon source using the enzyme citrase
citrate utilization test
84
indicator for citrate utilization test;
turns from green to blue in a basic pH to indicate a positive result
acid-base indicator Bromthymol blue
85
conversion of ammonium phosphate to ammonia and ammonia hydroxide
reason for alkaline pH in positive citrate utilization test
86
defined medium containing sodium citrate as the sole carbon source and the ammonium ion as the sole nitrogen source
simmon's citrate agar
87
utilization of peptone rather than the sugar in carbohydrate fermentation
alkaline metabolic product; color change to a dark pinkish-redish
88
purpose is to differentiate among microorganisms that enzymatically transform different milk substrates (lactose, casein) into varied metabolic end products
litmus milks reactions
89
pink medium for litmus milk
presence of lactic acid from lactose fermentation
90
oxidized litmus
purple litmus color
90
reduced litmus
white litmus color
90
indicates proteolysis for litmus reactions
yellow/clearish liquid
91
indicated elevated pH due to deamination
purple band at the top of yellow liquid for litmus reaction
92
yellowish semisolid bottom medium in litmus reaction
curd formation
93
blue top of medium for litmus reaction
alkaline conditions
94
alkaline conditions for litmus reaction
purple or blue litmus
95
positive presumptive test for LTB broth
indicates that coliforms are present in the water sample
96
-selective using bile salts
-lactose for fermentation
-positive is both turbid and gas production
(for coliform test in water sample)
BGLB selective medium
97
-streak a lawn (horizontal and vertical) of bacteria using sterile cotton swab saturated in culture
-divide plate into 6 labeled quadrants for disinfectant type
-sterilize tweezers to place dipped disk in quadrants
-look for zone of inhibition
(not quantitative because of varying amounts of chemical on disks)
Disinfectants: agar plate sensitivity method steps
98
selectable marker genes in plasmid
amp^r and gfp
99
able to grow on plates containing ampicillin and should express GFP
cells containing the plasmid
