Bacteriology Media Flashcards
0
Q
What is a blood agar plate selective for?
A
Nothing, blood agar is nonselective.
1
Q
What does BAP stand for?
A
Blood Agar Plate
2
Q
What is a blood agar plate used for?
A
Determination of hemolytic reactions. Cultivation of microorganisms.
3
Q
What is in a BAP?
A
5% sheep red blood cells
4
Q
What does BBE stand for?
A
Bacteroides Bile Esculin
5
Q
What is BBE selective for?
A
Bacteroides fragilis group
6
Q
What does BBE differentiate?
A
Bacteroides fragilis group
7
Q
What is in a BBE plate?
A
OC bile (gall), esculin, ferric ammonium citrate, hemin, vitamin K, gentamicin in casein and soybean agar.
8
Q
What is esculin?
A
A glycoside hydrolysed into esculatin and glucose by certain bacteria, particularly enterococci and listeria.
9
Q
Why is ferric ammonium citrate included in an agar plate?
A
Ferric citrates react with esculatin to form a dark black iron salt.
10
Q
What is hemin?
A
A substance necessary for the growth of anaerobic bacteria. Chemically, protoporphyrin IX with an iron chloride (FeCl) ion. Related to heme B.
11
Q
Why include vitamin K in agar medium?
A
It is a nutrient required by many anaerobic bacteria.
12
Q
What is gentamicin?
A
An aminoglycoside antibiotic that prevents growth of most gram negative bacteria.
13
Q
What does BCYE stand for?
A
Buffered Charcoal Yeast Extract
14
Q
What is BCYE selective for?
A
Legionella subspecies
15
Q
What is in BYCE media?
A
Ferric pyrophosphate, L-cysteine, charcoal, ACES buffer, yeast extract
16
Q
Why is oxgall used in a medium?
A
Oxgall inhibits the growth of many gram positive bacteria
17
Q
Why is ferric pyrophosphate included in a medium?
A
Ferric pyrophosphate provides iron for the growth of bacteria.
18
Q
Why is L-cysteine included in a medium?
A
L-cysteine is an amino acid necessary for the growth of anaerobes such as legionella subspecies. It helps maintain reduced O2 environment.
19
Q
Why is charcoal included in a medium?
A
To decompose hydrogen peroxide, a toxic metabolic product of certain bacteria, including Legionella.
20
Q
What is ACES for?
A
A common biochemical buffer to maintain a neutral pH, generally between 6.1 and 7.5.
21
Q
Why include yeast extract in a medium?
A
To provide nutrients (nitrogen, carbon, vitamins) to growing bacteria.
22
Q
What does BCYE/PAC stand for?
A
Buffered Carbon Yeast Extract / Polymixin, Anisomycin, Cefamandole
23
Q
What is BYCE/PAC used for?
A
Selective growth of Legionella subspecies.
24
What is polymixin B?
An antibiotic that kills most gram negative bacilli.
25
What is anisomycin?
An antifungal agent that works through inhibiting protein synthesis.
26
What is cefamandole?
A cephalosporin antibiotic used to suppress the growth of unwanted microbes
27
What does BG stand for?
Bordet-Gengou, an agar named for the microbiologists who were first to isolate bordetella.
28
What is BG media used for?
To select Bordetella subspecies.
29
What is in BG agar?
Starch, potato infusion, glycerol, 20-30% sheep blood, methicillin or cephalexin.
30
Why does BG agar contain starch?
To absorb fatty acids from mucus or the collection swab so that they do not inhibit growth.
31
Why is potato infusion used in a medium?
To provide nitrogen and vitamins.
32
Why is glycerol included in a medium?
It is a carbon source.
33
Why does BG media have sheep blood in it?
To provide extra nutrients to Bordetella.
34
What is methicillin?
A penicillin class beta-lactam antibiotic.
35
What is cefalexin?
A cephalosporin antibiotic
36
What does BHI stand for?
Brain Heart Infusion
37
What is BHI medium used for?
It is enriched to allow cultivation of yeasts, molds, and some fastidious bacteria.
38
What is in BHI media?
Calf brains, beef heart, peptones, glucose, NaCl, disodium phosphate, 5-10% sheep blood.
39
Why does BHI media contain bovine heart and brains and peptones?
As nutrients for fastidious bacteria, molds, or yeasts.
40
Why does a media contain glucose?
As a carbon source
41
Why does BHI media contain sodium chloride?
Enterococci can grow in the presence of NaCl but streptococci and other bacteria cannot. Also it helps maintain osmolarity.
42
Why does BHI media contain disodium phosphate?
To buffer the media around 7.4
43
What does BHI/GC stand for?
Brain Heart infusion with gentamicin and chloramphenicol.
44
What is chloramphenicol?
A broad spectrum antibiotic
45
What is BHI/GC used for?
Isolating fungi.
46
Why include chloramphenicol in a medium?
It inhibits most gram positive and negative bacteria.
47
What does BHI/GCC stand for?
Brain Heart Infusion with gentamicin, chloramphenicol, and cycloheximide.
48
What is cycloheximide?
An antimicrobial that inhibits protein synthesis in eukaryotic cells. Molds and yeasts do no grow.
49
What is BHI/GCC used for?
Cultivating fungi, usually respiratory.
50
What is campy agar used for?
Selecting campylobacter subspecies.
51
What is in campy agar?
Antibiotics. Could be colistin, cephalothin, vancomycin, amphotericin B, and/or trimethoprim.
52
What is colistin?
A polymixin antibiotic, also called polymixin E. It is effective against gram negative bacteria
53
What is cephalothin?
A cephalosporin class beta lactam antibiotic.
54
What is vancomycin?
A glycopeptide antibiotic effective against gram positive bacteria.
55
What is amphotericin B?
A polyene antifungal.
56
What is trimethoprim?
A bacteriostatic antibiotic.
57
How does campy agar select for campylobacter?
The particular combination of antibiotics will inhibit the growth of other microbes from stool samples.
58
What is CDC/Brucella agar used for?
Isolating obligate and facultative anaerobes.
59
What is in CDC/Brucella agar?
Sheep RBCs, hemin, vitamin K, L-cysteine.
60
What is chocolate agar used for?
Growing most bacteria.
61
What species require chocolate agar for growth?
Haemophilius and some Neisseria.
62
What is in chocolate agar?
Lysed RBCs, factor X, factor V, vitamin K, isovitalex.
63
Why are lysed RBCs used in chocolate agar?
Certain fastidious bacteria require substances that are in blood, but cannot use intact cells. Later turned out to include hemin and NAD. The lysing process denatures an enzyme in sheep blood that inactivated NAD.
64
What is factor X?
A factor in lysed red blood cells that certain bacteria need. Later called hemin.
65
What is factor V?
A substance in lysed red blood cells needed by certain bacteria. Later discovered to be NAD.
66
What is isovitalex?
An enrichment product proprietary to Becton-Dickinson.
67
What is ChromAgar?
Proprietary agars that turn colors to indicate the activity of certain enzymes or other indicators of specific bacteria.
68
How is ChromAgar Candida used?
To isolate and make presumptive identification of Candida subspecies. C. albicans turns the agar green, C. krusei pink, and C. tropicalis blue.
69
What is in ChromAgar Candida?
Peptones, glucose, chloramphenicol, chromogenic mix.
70
Why are peptones included in a medium?
Nutrients for bacteria.
71
What type of agar contains a chromogenic mix?
ChromAgar
72
What dies CIN stand for?
Cefsulodin Irgasan Novobiocin
73
What is CIN media used for?
To selectively culture Yersinia subspecies and Aeromonas subspecies.
74
What is in CIN media?
Digested animal tissue, gelatin, sodium pyruvate, sodium deoxycholate, cefsulodin, Irgasan, Novobiocin, beef extract, yeast extract.
75
Why include digested animal tissue, gelatin, yeast extract, and beef extract in CIN media?
Nutrients. Amino acids and nitrogen
76
Why include sodium pyruvate in a media?
Both a carbon source and an energy source.
77
Why include sodium deoxycholate in a medium?
It is a mild detergent that inhibits growth of gram positive bacteria.
78
What is Irgasan?
An antiseptic that inhibits the growth of gram positive bacteria.
79
What is Novobiocin?
An aminocoumarin antibiotic particularly effective against staphylococcus.
80
What does CNA stand for?
Colistin Nalidixic Acid
81
What is CNA media used for?
To select gram positive bacteria from a sample.
82
What is Columbia agar?
A general purpose medium for growing fastidious bacteria.
83
What is in CNA media?
Columbia agar, Nalidixic acid, colistin, blood
84
Why include Nalidixic acid in a medium?
In the right concentration, it inhibits DNA synthesis in gram negative bacteria.
85
What does CT stand for?
Cysteine Tellurite Blood Agar
86
What is CT agar used for?
To cultivate Corynebacterium diphtheriae.
87
What is in CT media?
Heart infusion, potassium Tellurite, l-cysteine and rabbit blood.
88
Why include tellurite in a medium?
C. diphtheriae reduces it, producing a black color.
89
Why use rabbit blood in a medium
Sheep blood is usually preferred, but it breaks down its own NAD. Rabbit blood does this much less. Certain bacteria want to use the NAD in the media.
90
What does HE stand for?
Hektoen enteric
91
What is hektoen enteric agar used for?
Screening for salmonella or shigella subspecies in samples that have a mixed population.
92
What is in hektoen enteric agar?
Bile salts, ferric ammonium citrate, bromthymol blue, lactose, sucrose, salicin, sodium thiosulfate.
93
Why include bile or bile salts in a medium?
To inhibit growth of gram positive bacteria.
94
Why include ferric ammonium citrate in HE media?
As a source of iron which forms a black precipitate with hydrogen sulfide (H2S)
95
Why include bromthymol blue in HE media?
It turns yellow in acid pH such as that produced by sugar fermentation. It turns blue in alkaline pH such as that produced by shigella or salmonella metabolizing peptones.
96
What is the function of sucrose, lactose, and salicin in Hektoen agar?
Enteric bacteria that can use these sugars will acidify the media and it will turn yellow. Yellow means the colony is neither Shigella nor Salmonella.
97
Why is there sodium thiosulfate in a medium?
As a source of sulfur for bacteria to turn into hydrogen sulfide.
98
What does IMA stand for?
Inhibitory mold agar.
99
What is IMA used for?
Isolating pathogenic fungi other that dermatophytes.
100
What is a dermatophyte?
A fungus that infects the skin.
101
Why not use IMA to identify dermatophytes?
Because dermatophytes are slower to grow and any other fungi will overwhelm them on IMA
102
What is in IMA?
Digests of animal tissue and casein, yeast extract, dextrin, starch, glucose, salts, chloramphenicol.
103
Why is there so much dextrin and glucose in IMA?
Too much sugar inhibits the growth of bacteria.
104
What is Todd-Hewitt broth used for?
Cultivating streptococci and other fastidious bacteria.
105
What is in Todd-Hewitt broth?
Heart infusion, peptones, dextrose, NaCl and buffers.
106
What is Lim broth?
Todd-Hewitt broth plus yeast extract, colistin and nalidixic acid.
107
What is Lim broth used for?
Isolating group B streptococci
108
What does LKV stand for?
Laked Kanamycin Vancomycin Blood agar
109
What is LKV used for?
Recovery of anaerobic gram negative bacteria, especially bacteroides and prevotella species.
110
What is in LKV media?
Casein and soybean agar, kanamycin, vancomycin, vitamin K1, and lysed sheep blood.
111
What is kanamycin?
An amino glycoside antibiotic effective against gram negative bacteria and some gram positive.
112
Why is blood laked or lysed in a medium?
To make hemoglobin and other nutrient available.
113
What does LOE stand for?
Loeffler medium
114
What is Loeffler medium used for?
Isolating Cornyebacterium diphtheria.
115
What is in Loeffler medium?
Animal tissue digest, heart infusion, beef serum, egg, glucose.
116
What is MacConkey agar used for?
Isolating gram negative bacteria and determining positive or negative lactose fermentation.
117
What is in MacConkey agar?
Peptones, bile salt, crystal violet, lactose, neutral red.
118
Why is crystal violet included in a medium?
To inhibit the growth of gram negative bacteria.
119
What is neutral red?
An indicator that turns red in acid and yellow in base.
120
Why is sorbitol sometimes added to MacConkey agar?
To detect E. coli 0157:H7 strain. This strain usually cannot feet sorbitol, unlike other strains.
121
What does MTM stand for?
Modified Thayer Martin
122
What is MTM used for?
Isolating pathogenic Neisseria subspecies.
123
What is in MTM agar?
Blood, hemoglobin, supplements, vancomycin, colistin, nystatin, trimethoprim.
124
What is nystatin?
An antifungal.
125
What is Mycosel used for?
Isolating molds from skin, hair, and nail specimens.
126
What is in Mycosel?
Soybean meal, glucose, cyclohexamide, chloramphenicol.
127
What does PEA stand for?
Phenyl ethyl alcohol agar
128
What is PEA used for?
Selecting gram positive bacteria, inhibiting gram negatives.
129
What is in PEA?
Casein and soybean agar, phenyl ethyl alcohol, blood
130
Why is phenyl ethyl alcohol included in a medium?
To inhibit gram negative, facultative anaerobic bacteria.
131
What does RL stand for?
Reagan Lowe agar
132
What is RL agar used for?
Isolation of Bordetella subspecies.
133
What is in RL agar ?
Charcoal, horse blood, niacin, cephalexin.
134
Why is niacin included in a medium?
A vitamin necessary for growth, particularly of Bordetella.
135
What does SABDEX stand for?
Sabourad Dextrose agar.
136
What is SABDEX used for?
Isolation of saprophytic and pathogenic fungi.
137
What is in SABDEX?
Dextrose and pH adjusters
138
What is SXT agar used for?
Selecting group A strep.
139
What is in SXT agar?
Sulfamethoxazole trimethoprim.
140
Why include Sulfamethoxazole trimethoprim in a medium?
A sulfonamide antibiotic to inhibit streptococci other than group a, and other bacteria.
141
What does TCBS stand for?
Thiosulfate Citrate Bile Sucrose
142
What is TCBS used for?
It is selective and differential for Vibrio subspecies.
143
What is in TCBS?
Bile salts, ferric ammonium citrate, sodium citrate, bromthymol blue, casein, yeast extract, sucrose.
144
What role does thiosulfate play in TCBS agar?
First, it makes a reduced atmosphere that Vibrio subspecies thrive in. Second, it is a source of sulphur to identify H2S producing bacteria. These are not Vibrio.
145
What does sodium cholate do in an agar?
Provide an alkaline environment. Certain species like Vibrio prefer it.
146
What is thioglycolate broth used for?
To recover aerobic and anaerobic bacteria in samples with very low counts. It can also help determine the aerotolerance of bacteria, depending on where in a tube the colonies grow.
147
What is in thioglycolate broth?
Casein, glucose, yeast extract, cysteine, hemin, vitamin k, sodium thioglycolate.
148
What is sodium thioglycolate.?
A reducing agent that lowers the oxygen content of a medium.
149
What is Tinsdale agar used for?
Isolating Cornyebacterium diphtheria
150
What is in Tinsdale agar?
Peptones, salt, yeast extract, L-cysteine, potassium tellurite, serum
151
What does TSA stand for?
Trypticase Soy Agar
152
What is TSA used for?
A general purpose growth medium.
153
What is V agar used for?
It is selective for G. vaginalis.
154
What is in V agar?
Human blood.
155
How does V agar identify G. vaginalis?
G. vaginalis is hemolytic on human blood, but not on sheep blood.
156
What does XLD stand for?
Xylose Lysine Deoxycholate.
157
What is XLD medium used for?
Selection and differentiation of salmonella and shigella subspecies.
158
What is in XLD medium?
Sodium deoxycholate, sodium thiosulfate, ferric ammonium citrate, phenol red
159
What is phenol red?
An indicator that is yellow in acid and pink in base environments.
