SPECIMEN MANAGEMENT Flashcards

1
Q

True or false:
Appropriate collection technique : acute (early) phase of an illness

A

True

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2
Q

How soon should specimens be collected for viral infections?

A

Within 2-3 days

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3
Q

When should specimens be collected in relation to starting antimicrobials, antifungals, or antiviral medications?

A

Before these medications are started

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4
Q

How soon should specimens be transported after collection?

A

Within 2 hours of collection

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5
Q

What are the requirements for specimen containers during transport?

A

Containers must be:
leak-proof and transported within sealable
plastic bags with a separate section for paperwork

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6
Q

What label should be marked on specimen transport bags?

A

biohazard label

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7
Q

What additional measures might be required for transporting specimens?

A

Use of special preservatives, temperature-controlled conditions, or holding media

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8
Q

What preservative is used for urine specimens?

A

boric acid

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9
Q

Which preservatives are used for stool specimens intended for ova and parasite examination?

A

Polyvinyl alcohol (PVA) and buffered formalin

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10
Q

What are common transport or holding media for specimens?

A

Stuart’s medium and Amie’s medium

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11
Q

Why is charcoal added to some transport media?

A

TO ABSORB FATTY ACID

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12
Q

What anticoagulant is commonly used for specimen preservation?

A

0.025% Sodium polyanethol sulfonate (SPS)

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13
Q

Which anticoagulant is used for viral cultures

A

Heparin

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14
Q

True or false:
Citrate and EDTA can e used for specimen preservation

A

false

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15
Q

What is the recommended temperature for storing specimens in a refrigerator?

A

4°C

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16
Q

At what temperature should specimens be stored at ambient (room) temperature?

A

22°C

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17
Q

What is the storage temperature for specimens requiring body temperature conditions?

A

37°C

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18
Q

What are the recommended freezer temperatures for storing specimens?

A

-20°C or -70°C

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19
Q

What types of specimens are typically stored at 4°C?

A

Urine
Stool
Viral specimens
Sputum
swabs
foreign devices (catheters)

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20
Q

How long can serum for serologic studies be stored at -20°C?

A

1 week

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21
Q

What temperature is recommended for long-term storage of tissues or specimens?

A

-70°C

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22
Q

True or False:
Rejection criteria include specimens where information on the label does not match the request or the specimen is unlabeled.

A

True

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23
Q

True or False:
Specimens transported at improper temperatures may be rejected.

A

True

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24
Q

True or False:
Specimens not transported in the proper medium may be rejected.

A

True

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25
Q

True or False:
Insufficient quantity of specimens can lead to rejection.

A

True

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26
Q

True or False: Leaking specimens may be rejected.

A

True

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27
Q

True or False:
Specimens with transport times exceeding 2 hours post-collection or those not properly preserved may be rejected.

A

True

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28
Q

True or False:
Specimens received in a fixative like formalin, which kills microorganisms, may be rejected.

A

True

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29
Q

True or False: Specimens received for anaerobic culture from sites known to have anaerobes as part of the microbiota (e.g., vagina, mouth) may be rejected.

A

True

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30
Q

True or False:
Dried specimens are generally acceptable for processing.

A

False

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31
Q

True or False:
Specimens that would produce information of questionable medical value upon processing, such as Foley catheter tips, may be rejected.

A

True

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32
Q

According to processing guidelines, which specimens should be given priority when multiple specimens arrive simultaneously?

A

CSF, tissue, blood, and sterile body fluids

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33
Q

What action should be taken upon the arrival of a specimen in the laboratory?

A

Record the time and date of specimen receipt

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34
Q

What should a microbiologist do if a specimen arrives with multiple test requests but there is insufficient specimen volume to perform all tests?

A

Call the clinician to prioritize the testing

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35
Q

What is the initial step in processing specimens according to guidelines?

A

Perform a gross examination of the specimen

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36
Q

What characteristic of stool should be noted, which may indicate the presence of barium?

A

chalky white color

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37
Q

What aspect of the specimen’s status should be noted during gross examination?

A

Whether it is bloody, clouded, or clotted

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38
Q

What is the purpose of direct microscopic examination of a specimen?

A

To assess the quality of the specimen

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39
Q

True or False: Direct microscopic examination is commonly performed on throat, nasopharyngeal, or stool specimens.

A

False (Usually not performed on these types of specimens)

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40
Q

What is the most common staining method used in bacteriology for direct microscopic examination?

A

Gram staining

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41
Q

What are some common stains used for direct fungal examination?

A

1.KOH (Potassium hydroxide)
2. PAS (Periodic acid-Schiff)
3.GMS (Grocott’s methenamine silver stain)
4. calcofluor white

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42
Q

What are examples of common stains used for direct acid-fast staining?

A

1.Auramine rhodamine
2. Ziehl-Neelsen
3. Kinyoun

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43
Q

It is a liquid medium where nutrients are dissolved in water, and bacterial growth is indicated by a change from clear to turbid appearance.

A

Broth medium

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44
Q

example of pH indicator used in broth medium

A

phenol red

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45
Q

what indicator used in broth medium where They change color in the presence of metabolites, indicating bacterial activity.

A

pH indicator

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46
Q

It is a semisolid medium that provides an indication of the type of organism present based on oxygen requirements.

A

Thioglycollate broth

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47
Q

How are pH indicators such as phenol red used in broth medium?

A

They change color in the presence of metabolites

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48
Q

What is the purpose of thioglycollate broth in microbiological media?

A

provides an indication of the type of organism present based on oxygen requirements.

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49
Q

a solid medium used to solidify nutrients and water to support bacterial growth.

A

Agar

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50
Q

Most common solidifyng agent in agar

A

Agarose

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51
Q

Agarose melts at high temperatures (___°C) but resolidifies when the temperature falls below __°C.

A

High temp - >95 C
Low temp - below 50 C

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52
Q

What type of growth medium combines both liquid and solid phases?

A

Biphasic medium

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53
Q

How can the growth of bacteria in broth medium be detected?

A

By observing a change in the broth’s appearance from clear to turbid, indicating bacterial growth.

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54
Q

what culture media: contain nutrients that support the growth of most nonfastidious organisms and are nonselective but differential.

A

Nutritive media

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55
Q

Name 3 examples of nutritive media used for bacterial and fungal growth.

A

1.tryptic soy agar (bacteria)
2.nutrient agar plates for bacteria,
3. Sabouraud’s dextrose agar for fungi, as well as blood or chocolate agar.

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56
Q

These culture media contain specific nutrients needed for the growth of bacterial pathogens

A

supplemental or enrichment media

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57
Q

Culture media: Buffered charcoal-yeast extract (BCYE) for Legionella pneumophila.

A

Supplemental or Enrichment Medium

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58
Q

Culture media: They are specialized to enhance the growth of organisms present in low numbers, like anaerobes or those affected by antimicrobial therapy.

A

Enrichment broth

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59
Q

Culture media: Back up broth

A

Enrichment broth

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60
Q

What is an example of an enrichment broth used for anaerobic cultures?

A
  1. Thioglycollate broth (anaerobes)
  2. Brain heart infusion broth (BHIB)
  3. Tryptic soy broth (TSB)
  4. Gram negative broth
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61
Q

What is the purpose of LIM broth (Todd Hewitt broth with colistin and nalidixic acid)?

A

It is used for selective enrichment of organisms such as Streptococcus pneumoniae.

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62
Q

How do selective media distinguish between groups of organisms?

A

By incorporating antimicrobials, dyes, or alcohol to support the growth of one group of organisms while inhibiting another.

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63
Q

What antimicrobial agent is used in MacConkey agar to inhibit gram-positive organisms?

A

Crystal violet

64
Q

It contains colistin and nalidixic acid, which inhibit the growth of gram-negative organisms.

A

Columbia agar

65
Q

Columbia agar contains?

A

Colistin and nalidixic acid

66
Q

True or false:
Selective media can also be differential media

A

True

67
Q

Culture media: They employ specific factors that allow colonies of one bacterial species or type to exhibit certain metabolic or culture characteristics.

A

Differential media

68
Q

What characteristic of MacConkey agar allows it to differentiate between bacteria?

A

It differentiates between gram-negative bacteria based on their ability to ferment lactose.

69
Q

It differentiates between gram-negative bacteria based on their ability to ferment lactose.

A

MacConkey agar

70
Q

What type of medium is Brain-heart Infusion (BHI)?

A

It can be either a broth or agar medium

71
Q

True or False: BHI only without blood

A

False (both with and without blood)

72
Q

What carbohydrate does Brain-heart Infusion (BHI) contain

A

dextrose

73
Q

Culture media: It is often used for culturing patient blood samples to detect bacterial infections.

A

BHI broth

74
Q

Culture media: Baacterial Susceptibility

A

Brain heart Infusion

75
Q

What components are essential for Chocolate Agar to support the growth of organisms like Neisseria gonorrhoeae and Haemophilus spp.?

A

1.Hemoglobin
2. hemin (X factor),
3. nicotinamide adenine dinucleotide (NAD, V factor),

which are released during lysis.

76
Q

Chocolate Agar to support the growth of organisms like

A

Neisseria gonorrhoeae and Haemophilus spp

77
Q

True or false: Neisseria gonorrhoeae and Haemophilus spp groows on sheep blood agar

A

False (neither)

78
Q

Why do Neisseria gonorrhoeae and Haemophilus spp. not grow on sheep blood agar but thrive on Chocolate Agar?

A

Because Chocolate Agar provides specific growth factors like hemin and NAD that are not present in sheep blood agar.

79
Q

What are the main components of Columbia CNA agar with blood?

A

It consists of Columbia agar base supplemented with 3 peptone sources and 5% defibrinated sheep blood.

80
Q

It differentiates based on hemolytic reactions, which can indicate the ability of bacteria to break down red blood cells.

A

Columbia CNA with blood

81
Q

CNA means

A

Colistin and nalidixic acid

82
Q

It is a selective broth used for cultivating gastrointestinal pathogens from stool specimens and rectal swabs.

A

Gram negative broth

83
Q

What selective components are present in Gram-Negative Broth?

A
  1. Sodium citrate,
  2. sodium deoxycholate (bile salt),
  3. mannitol as the primary carbon source.
84
Q

serves as the primary carbon source, supporting the growth of targeted gastrointestinal pathogens in the medium.

A

Mannitol

85
Q

What carbohydrates are included in Hektoen Enteric Agar, and what is their purpose?

A

Lactose, sucrose, and salicin, which help differentiate bacteria based on their ability to ferment these sugars.

86
Q

How does Hektoen Enteric Agar detect hydrogen sulfide (H2S) production?

A

It contains ferric ammonium citrate, which reacts with H2S to form a black precipitate.

87
Q

Hektoen enteric (HE) agar is a medium that relies on the use of ________for selective inhibition

A

bile salts

88
Q

What is the primary dye used in MacConkey Agar, and what is its role?

A

Crystal violet, which inhibits the growth of Gram-positive bacteria.

89
Q

How does MacConkey Agar differentiate between lactose-fermenting and non-lactose-fermenting bacteria?

A

It uses a pH indicator, neutral red, which turns pink when lactose is fermented, indicating acid production.

90
Q

What pH indicator is used in Hektoen Enteric Agar?

A

Bromthymol blue.

91
Q

What type of medium is Hektoen Enteric Agar classified as?

A

Differentail medium

(not sure if also selective)

92
Q

What specific carbohydrate is used in MacConkey Agar to differentiate bacterial colonies?

A

lactose

93
Q

What is Phenylethyl Alcohol Agar (PEA) primarily used for?

A

provide nutrients for common gram (+) cocci

94
Q

What component in PEA inhibits gram-negative bacteria?

A

Phenylethyl alcohol

95
Q

What type of agar is Phenylethyl Alcohol Agar based on?

A

Sheep blood agar

96
Q

Which common gram-positive cocci are supported by PEA?

A

Enterococci, streptococci, and staphylococci.

97
Q

Why should PEA not be used for interpreting hemolysis?

A

The phenylethyl alcohol can interfere with the appearance of hemolysis, making it unreliable for such assessments.

98
Q

What is the primary purpose of adding phenylethyl alcohol to the agar?

A

To inhibit the growth of gram-negative bacteria.

99
Q

What type of bacteria does Sheep Blood Agar support the growth of?

A

All but the most fastidious clinically significant bacteria.

100
Q

What are the primary components of Sheep Blood Agar?

A

Tryptones
soybean protein digest, sodium chloride,
agar,
5% sheep blood

101
Q

What does the soybean protein digest provide in Sheep Blood Agar?

A

It contains natural carbohydrates and additional nutrients.

102
Q

What are the three types of hemolysis that can be interpreted on Sheep Blood Agar?

A

Alpha hemolysis (partial, greenish discoloration), beta hemolysis (complete, clear zone), and gamma hemolysis (no hemolysis).

103
Q

What hemolysis : A greenish discoloration around the colonies

A

Alpha

104
Q

What type of medium is Modified Thayer-Martin Agar?

A

It is an enrichment and selective medium.

105
Q

What is the enrichment component in Modified Thayer-Martin Agar?

A

Chocolatized blood.

106
Q

What are the antibiotics included in Modified Thayer-Martin Agar and their targets?

A

Colistin: Inhibits gram-negative bacteria (excluding Neisseria species).

Vancomycin: Inhibits gram-positive bacteria.

Nystatin: Inhibits yeast.

Trimethoprim: Inhibits Proteus species.

107
Q

Why is Modified Thayer -Martin Agar is also a selective medium

A

due to the antibiotics

108
Q

What distinguishes Martin-Lewis Agar from Modified Thayer-Martin Agar?

A

Martin-Lewis Agar uses asamycin instead of nystatin and includes a higher concentration of vancomycin.

109
Q

What type of medium is Thioglycollate Broth?

A

It is an enrichment broth or semisolid medium.

110
Q

What components in Thioglycollate Broth provide essential nutrients for bacterial growth?

A

Casein, yeast and beef extracts, and vitamins.

111
Q

It is an oxidation-reduction indicator that changes color in the presence of oxygen in Thioglycollate Broth

A

resazurin

112
Q

What additional nutrients can be found in modified Thioglycollate Broth?

A

Dextrose, vitamin K, and hemin.

113
Q

It prevent convection currents from carrying atmospheric oxygen, maintaining anaerobic conditions Thioglycollate Broth

A

0.075% agar

114
Q

What is the function of thioglycolic acid in Thioglycollate Broth?

A

It acts as a reducing agent to create and maintain an anaerobic environment.

115
Q

What type of medium is Xylose-Lysine Deoxycholate (XLD) Agar?

A

It is a selective and differential medium for Shigella and Salmonella

116
Q

What components in XLD Agar inhibit the growth of gram-positive bacteria?

A

Salt and sodium deoxycholate.

117
Q

It is a pH indicator that changes color based on the fermentation of carbohydrates in XLD agar

A

phenol red

118
Q

Which carbohydrates are present in XLD Agar?

A

Lactose, xylose, and sucrose.

119
Q

XLD agar : Initially yellow due to xylose fermentation, then red after lysine decarboxylation, and black if hydrogen sulfide is produced.

A

Salmonella

120
Q

XLD agar: Red colonies as it does not ferment xylose or decarboxylate lysine, and does not produce hydrogen sulfide.

A

Shigella

121
Q

What type of medium is Eosin Methylene Blue (EMB) Agar?

A

It is a selective and differential medium for gram-negative enteric bacilli.

122
Q

What carbohydrate is present in EMB Agar?

A

lactose

123
Q

What are the indicators in EMB Agar?

A

Eosin Y and methylene blue.

124
Q

How do lactose fermenters appear on EMB Agar?

A

They produce dark colonies with a green metallic sheen.

E.g E.coli

125
Q

How do non-lactose fermenters appear on EMB Agar?

A

They form colorless or light pink colonies.

Ex.
Salmonella and shigella

126
Q

What type of medium is Salmonella-Shigella Agar?

A

selective

127
Q

What inhibitor is used in Salmonella-Shigella Agar?

A

Brilliant green

128
Q

What carbohydrate is present in Salmonella-Shigella Agar?

A

lactose

129
Q

What is the indicator in Salmonella-Shigella Agar?

A

netral red

130
Q

They are used to detect hydrogen sulfide production, resulting in black centers in colonies of hydrogen sulfide-producing bacteria in Salmonella-shigella agar

A

Ferric citrate and sodium citrate

131
Q

What type of medium is Thiosulfate Citrate-Bile Salts (TCBS) Agar?

A

It is a selective and differential medium for Vibrio species.

132
Q

What indicator is used in TCBS Agar?

A

Bromthymol blue. (based on fermentation of SUCROSE)

133
Q

What are the main nutrient components in TCBS Agar?

A

Yeast extracts,
bile salts,
citrate,
sucrose,
ferric citrate,
sodium thiosulfate.

134
Q

How does Thiosulfate citrate-bile salts Agar differentiate Vibrio species?

A

Through the fermentation of sucrose and the production of hydrogen sulfide, which changes the color of the medium.

135
Q

What type of medium is Trypticase Soy Broth (TSB)?

A

It is an all-purpose enrichment broth.

136
Q

what broth: It can support the growth of many fastidious and nonfastidious bacteria.

A

Trypticase soy broth

137
Q

Its purpose is It is used for subculturing various bacteria from primary agar plates.

A

Trypticase soy broth

138
Q

What type of bacteria uses oxygen as the terminal electron acceptor and grows well in room air?

A

Aerobic bacteria

139
Q

What type of bacteria finds oxygen inhibitory or lethal?

A

Anaerobic

140
Q

What term describes bacteria that can grow in the presence or absence of oxygen?

A

Facultative anaerobic bacteria.

141
Q

What type of bacteria cannot grow in the absence of oxygen?

A

Strictly aerobic bacteria.

142
Q

What type of bacteria grows only in low levels of oxygen (approximately 20% or less)?

A

Microaerophilic or microaerobic bacteria.

143
Q

What term describes bacteria that grow slowly and poorly in the presence of oxygen?

A

Aerotolerant bacteria.

144
Q

What type of bacteria grows best with higher carbon dioxide concentrations (5-10%)?

A

Capnophilic bacteria.

145
Q

Capnophilic bacteria grows best with higher oxygen concentrations.
With a percentage range of.

A

5-10%

146
Q

What temperature range is similar to those of internal human host tissues and organs, ideal for most bacterial growth?

A

35-37°C.

147
Q

Which bacteria require cold enrichment for optimal growth, and what temperature range does this entail?

A

Listeria monocytogenes and Yersinia enterocolitica; 4-43°C.

148
Q

What pH range is near neutral and ideal for bacterial growth?

A

6.5-7.5.

149
Q

How does increased atmospheric humidity affect the growth of certain bacterial species?

A

It enhances their growth.

150
Q

What is the ideal incubation temperature for fungi?

A

28-30°C. (room temp)

151
Q

At what temperature should bacteria, viruses, and acid-fast bacillus be incubated?

A

35-37°C.

152
Q

What is the typical oxygen concentration and carbon dioxide for aerobes during incubation?

A

21% oxygen in ambient air.
0.03% of carbon dioxide

153
Q

What type of environment is required for anaerobes during incubation?

A

An environment with 5%-10% hydrogen, 5-10% carbon dioxide, 80-90% nitrogen, and 0% oxygen, using an anaerobe jar, bags, or chambers

154
Q

What concentration of carbon dioxide and oxygen do capnophiles (e.g., H. influenzae and N. gonorrheae) require?

A

Increased concentrations of 5-10% carbon dioxide and approximately 15% oxygen.

155
Q

How can increased carbon dioxide and reduced oxygen be achieved for capnophiles?

A

Using candle jars (3% carbon dioxide), carbon dioxide incubators, chamber jars, or bags.

156
Q

What conditions are necessary for microaerophiles (e.g., C. jejuni, H. pylori) during incubation?

A

Reduced oxygen (5-10%) and increased carbon dioxide (8-10%).