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MTAP FIRST SEM 2024-2025 > MICROBIOLOGY-SPECIMEN MANAGEMENT > Flashcards

MICROBIOLOGY-SPECIMEN MANAGEMENT Flashcards

1
Q

Appropriate Collection Techniques

A
  • Acute (early) phase of an illness
  • Within 2-3 days for viral infections
  • Before antimicrobials, antifungals, or antiviral medications are started
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2
Q

How should specimen containers be prepared for transport?

A

leak-proof; transported within sealable, leak-proof, plastic bags with a separate section for paperwork

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3
Q

What is the recommended timeframe for transporting specimens after collection?

A

Within 2 hours of collection

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4
Q

What labeling is required on transport bags containing specimens?

A

They should be marked with a biohazard label to indicate potential biological hazards.

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5
Q

What additional measures can be taken for transport if needed?

A

Use special preservatives, temperature-controlled containers, or holding media

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6
Q

What is boric acid commonly used for in specimen preservation?

A

Preserving urine specimens.

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7
Q

Which preservative is used for stool samples intended for ova and parasite examination?

A

Polyvinyl alcohol (PVA) and buffered formalin.

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8
Q

Name two common transport or holding media used for specimens.

A

Stuart’s medium and Amie’s medium.

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9
Q

What is the purpose of adding charcoal to transport media?

A

To absorb fatty acids.

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10
Q

What is the commonly used anticoagulant in specimen collection?

A

0.025% Sodium polyanethol sulfonate (SPS).

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11
Q

For which type of cultures is Heparin often used as an anticoagulant?

A

Viral cultures, although it may inhibit the growth of gram-positive bacteria and yeast.

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12
Q

Which anticoagulants should not be used in specimen collection?

A

Citrate and Ethylenediaminetetraacetic acid (EDTA), among others.

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13
Q

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

A

4°C.

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14
Q

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

A

22°C.

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15
Q

What is the storage temperature for specimens that require body temperature conditions?

A

37°C.

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16
Q

What are the recommended freezer temperatures for long-term storage of specimens?

A

-20°C or -70°C.

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17
Q

Which types of specimens should be stored at 4°C?

A

Urine, stool, viral specimens, sputa, swabs, and foreign devices (catheters).

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18
Q

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

A

Up to 1 week.

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19
Q

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

A

-70°C.

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20
Q

SPECIMEN LABELING

A
  • Patient’s name
  • Identifying number (hospital or
    sample number)
  • Birth date
  • Date and time of collection
  • Source
  • Initials of the individual who
    collected the sample
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21
Q

Specimen Requisition

A
  • Patient’s name
  • Hospital identification number
  • Age and DOB
  • Sex
  • Collection date and time
  • Ordering physician
  • Exact nature and source of the
    specimen
  • Diagnosis
  • Current antimicrobial therapy
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22
Q

Give atleast 3 of Rejection of Unacceptable Specimens

A
  • Information on the label does not match the request or the specimen is not labeled at all
  • Specimen has been transported at the improper temperature
  • Specimen has not been transported in the proper medium
  • Insufficient quantity of specimens
  • Specimen is leaking
  • Transport time is more than 2 hours post collection or specimen was not preserved
  • Specimen was received in a fixative (formalin), which kills any microorganisms present
  • The specimen has been received for anaerobic culture from a site known to have anaerobes as part of the microbiota (vagina, mouth)
  • The specimen is dried
  • Processing of specimen would produce information of questionable medical value (Foley catheter tip)
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23
Q

When multiple specimens arrive at the same time, priority should be given to those that are
most critical:

A

CSF, tissue, blood, and sterile body fluids

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24
Q

What should be recorded immediately upon arrival of a specimen?

A

Time and date of arrival.

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25
Q

What action should be taken if a specimen arrives with multiple testing requests but insufficient specimen volume?

A

The microbiologist should call the clinician to prioritize the testing based on clinical need.

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26
Q

What is the initial step in processing specimens?

A

Performing a gross examination of the specimen.

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27
Q

What should be done if areas with blood or mucus are found during the examination?

A

Locate and sample these areas for culture and direct examination.

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28
Q

How can barium affect the appearance of stool?

A

It can cause stool to appear chalky white in color.

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29
Q

Why is it important to note the status of the specimen during gross examination?

A

To document characteristics such as bloody, clouded, or clotted

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30
Q

What is the purpose of direct microscopic examination

A
  • Assess the quality of the specimen
  • Can give an early indication of what may be wrong with the patient
  • Workup on the specimen can be guided by comparing what grows in culture to what was seen on the original smear
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31
Q

Which specimens are usually not performed for direct microscopic examination?

A

Throat, nasopharyngeal, and stool specimens

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32
Q

What is the most common stain used in bacteriology for direct microscopic examination

A

Gram staining

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33
Q

Name the most common direct fungal stains

A

-KOH, PAS (Periodic acid-Schiff),
-GMS (Grocott’s methenamine silver stain),
-Calcofluor white

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34
Q

What are the most common direct acid-fast stains?

A

-Auramine rhodamine,
-Ziehl-Neelsen,
-Kinyoun

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35
Q

Phases of Growth Media

A

-Broth
-Agar
-Biphasic medium

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36
Q

What type of medium is broth in microbiology?

A

liquid medium

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37
Q

How are nutrients presented in a broth medium?

How is bacterial growth indicated in a broth medium?

A

-Nutrients are dissolved in water

-Bacterial growth is indicated by a change in the broth’s appearance from clear to turbid.

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38
Q

What is the purpose of pH indicators in broth media?

A

pH indicators, such as phenol red, change color in the presence of metabolites.

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39
Q

What is thioglycollate broth and what does it indicate?

A

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

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40
Q

What type of medium is agar and what components make up an agar medium?

A

Solid medium: combination of a solidifying agent added to nutrients and water

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41
Q

What is the most common solidifying agent used in agar?

A

Agarose

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42
Q

At what temperature does agarose melt?

A

Agarose melts at high temperatures, specifically above or equal to 95°C

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43
Q

At what temperature does agarose resolidify?

A

after the temperature falls below 50°C

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44
Q

What is a biphasic medium

A

consists of both liquid and solid phase

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45
Q

contain nutrients that support the growth of most nonfastidious organisms and support the growth of a wide range of microorganisms.

They are considered nonselective and differential.

A

Nutritive Media

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46
Q

Give examples of Nutritive Media

A

-Tryptic soy agar,
-Nutrient agar plates (for bacteria),
-Sabouraud’s dextrose agar (for fungi), as well as blood or chocolate agar.

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47
Q

It contains specific nutrients required for the growth of bacterial pathogens

A

Supplemental or Enrichment Medium

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48
Q

Give an example of a Supplemental or Enrichment Medium and its purpose.

A

Buffered charcoal-yeast extract (BCYE) contains L-cysteine and other nutrients for the growth of Legionella pneumophilia.

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49
Q

What is an Enrichment Broth and is used for?

A

-It is a specialized broth used to enhance the growth of organisms present in low numbers
-To detect anaerobes in aerobic culture or organisms that may be damaged by previous or concurrent antimicrobial therapy.

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50
Q

Give examples of Enrichment Broths

A

-Thioglycollate broth (anaerobes),
-Brain-heart infusion broth (BHIB),
-Tryptic soy broth (TSB),
-LIM (Todd Hewitt broth with colistin and nalidixic acid),
-Gram-negative broth (for enteric gram-negative organisms).

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51
Q

support the growth of one group of organisms but not another by adding antimicrobials, dyes, or alcohol.

A

Selective Media

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52
Q

contains crystal violet, which inhibits gram-positive organisms

A

MacConkey agar

53
Q

contains colistin and nalidixic acid, which inhibit gram-negative organisms.

A

Columbia agar

54
Q

Can Selective Media also be Differential Media? If so, how?

A

Yes, Selective Media can also be Differential Media if they differentiate between groups of organisms in addition to their inhibitory activity.

55
Q

employ factors that allow colonies of one bacterial species or type to exhibit certain metabolic or culture characteristics.

A

Differential Media

56
Q

differentiates between gram-negative bacteria that can ferment lactose and those that cannot.

A

MacConkey agar

57
Q

What phases of growth media can Brain-heart Infusion (BHI) be found in?

A

broth or agar

58
Q

Does Brain-heart Infusion can be prepared with or without blood? T or F

A

T

59
Q

What carbohydrate does Brain-heart Infusion typically contain?

A

contains dextrose, which serves as a readily accessible source of energy.

60
Q

is often used as a major component of media designed for culturing patient’s blood for bacterial growth.

A

BHI broth

61
Q

Assess bacterial susceptibility

A

Brain-heart Infusion

62
Q

What are the essential components of Chocolate Agar?

A

-Hemoglobin,
-Hemin (X factor),
-And nicotinamide adenine dinucleotide (NAD, V factor), which are released during lysis.

63
Q

Which organisms specifically benefit from Chocolate Agar?

A

Neisseria gonorrhoeae and Haemophilus spp. neither grow well on sheep blood agar

64
Q

What are the components of Columbia CNA with Blood?

A

contains a Columbia agar base with 3 peptone sources and 5% defibrinated sheep blood.

65
Q

Differentiates bacterial colonies based on their hemolytic reactions

A

Columbia CNA with Blood

66
Q

CNA stands for

A

colistin and nalidixic acid

67
Q

What type of broth is Gram-Negative Broth?

A

selective broth

68
Q

For what purpose is Gram-Negative Broth

A

cultivation of gastrointestinal pathogens from stool specimens and rectal swabs.

69
Q

Gram-Negative Broth contains?

A

-Sodium citrate,
-Sodium deoxycholate (bile salt)

70
Q

Mannitol serves as ?

A

primary carbon source in Gram-Negative Broth

71
Q

What are the components that make up Hektoen Enteric Agar?

A

-Bile salts,

  • Dye (bromothymol blue as a pH indicator and acid fuchsin),

-Carbohydrates (lactose, sucrose, and salicin),

-Ferric ammonium citrate for the detection of hydrogen sulfide (H2S).

72
Q

Hektoen enteric agar is not a differential medium. T or F

A

F; it is indeed differential medium

73
Q

What components are included in MacConkey Agar

A

o Dye: crystal violet
o pH indicator: neutral red
o Carbohydrate: lactose

74
Q

What is the composition of Phenylethyl Alcohol Agar (PEA)?

A

sheep blood agar with phenylethyl alcohol, which inhibits the growth of gram-negative bacteria.

75
Q

which types of bacteria does Phenylethyl Alcohol Agar (PEA) provide nutrients?

A

provides nutrients for common gram-positive cocci, such as enterococci, streptococci, and staphylococci.

76
Q

should not be used for the interpretation of hemolysis

A

Phenylethyl Alcohol Agar

77
Q

Supports growth for all but the most fastidious clinically significant bacteria

A

Sheep Blood Agar

78
Q

Sheep Blood Agar contains?

A

-tryptones (protein source),
-soybean protein digest (which contains natural carbohydrate),
-sodium chloride,
-agar,
-5% sheep blood.

79
Q

Interpret hemolysis

A

Sheep Blood Agar

80
Q

serves as both an enrichment (chocolatized blood) and selective medium (antibiotics)

A

Modified Thayer-Martin Agar

81
Q

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

A

-Colistin: inhibits gram-negative bacteria
-Vancomycin: inhibits gram-positive bacteria.
-Nystatin: inhibits yeast.
-Trimethoprim: inhibits Proteus species.

82
Q

Similar to Thayer-Martin Agar, but with higher vancomycin concentration and the addition of asamycin (nystatin).

A

Martin-Lewis agar

83
Q

What components enhance the growth of most organisms in Thioglycollate broth?

A

Casein, yeast and beef extracts, and vitamins

84
Q

an enrichment broth or semisolid media

A

Thioglycollate broth

85
Q

Which compound serves as the oxidation-reduction indicator in Thioglycollate broth?

A

Resazurin

86
Q

Name the substances used to modify the basic formula of Thioglycollate broth.

A

dextrose, vitamin K, hemin

87
Q

What percentage of agar is typically used in Thioglycollate broth, and what purpose does it serve?

A

0.075% agar ;prevents convection currents from carrying atmospheric oxygen

88
Q

What compound acts as the reducing agent in Thioglycollate broth?

A

Thioglycolic acid

89
Q

Is Xylose-Lysine Deoxycholate Agar selective, differential, or both? And which bacterial pathogens is it used to differentiate?

A

Both selective and differential, specifically for the isolation and differentiation of Shigella and Salmonella species.

90
Q

Xylose-Lysine Deoxycholate Agar contains

A

salt and sodium deoxycholate

91
Q

Xylose-Lysine Deoxycholate (XLD) Agar indicator?

A

phenol red

92
Q

Name the three carbohydrates present in Xylose-Lysine Deoxycholate Agar.

A

lactose, xylose, and sucrose

93
Q

Which carbohydrate is present in EMB Agar?

A

lactose

94
Q

EMB stands for

A

Eosin Methylene Blue (EMB) Agar

95
Q

Name the two indicators used in EMB Agar.

A

Eosin Y and methylene blue

96
Q

What is the primary purpose of EMB Agar? What type of enteric bacilli does it differentiate?

A

Differentiation of lactose and non-lactose fermenting enteric bacilli

97
Q

What is the inhibitor used in Salmonella-Shigella Agar?

A

Brilliant green

98
Q

Which carbohydrate is present in Salmonella-Shigella Agar?

A

lactose

99
Q

Name the indicator used in Salmonella-Shigella Agar

A

neutral red

100
Q

What are the two compounds included in the Salmonella-Shigella Agar

A

ferric citrate and sodium citrate

101
Q

Which bacterial pathogens is SS Agar selective for?

A

Salmonella and some Shigella spp.

102
Q

What indicator is used in TCBS Agar?

A

bromothymol blue

103
Q

Composition present in TCBS Agar

A

Yeast extracts
Bile salts
Citrate
Sucrose
Ferric citrate
Sodium thiosulfate

104
Q

What type of bacteria is TCBS Agar selective and differential for?

A

Vibrio spp

105
Q

TCBS stands for

A

Thiosulfate Citrate-Bile Salts Agar

106
Q

Which types of bacteria can TSB support the growth of?

A

many fastidious and nonfastidious bacteria

107
Q

an All-purpose enrichment broth

A

Trypticase Soy Broth (TSB)

108
Q

When is TSB commonly used?

A

Used for subculturing various bacteria from primary agar plates

109
Q

Enumerate the Environmental Requirements

A

Oxygen and Carbon Dioxide Availability
Temperature
pH
Moisture

110
Q

enumerate all the Oxygen and Carbon Dioxide Availability

A

Aerobic
Anaerobic
Facultative anaerobic
Strictly aerobic
Microaerophilic or microaerobic
Aerotolerant
Capnophilic

111
Q

grows best with higher oxygen concentrations (5-10%)

A

Capnophilic

112
Q

grow slowly and poorly in the presence of oxygen

A

Aerotolerant

113
Q

grow only in low levels of oxygen (approximately 20% or less)

A

Microaerophilic or microaerobic

114
Q

cannot grow in the absence of oxygen

A

Strictly aerobic

115
Q

grow in the presence or absence of oxygen

A

Facultative anaerobic

116
Q

oxygen is inhibitory or lethal

A

Anaerobic

117
Q

uses oxygen as the terminal electron acceptor and grow well in room air

A

Aerobic

117
Q

What is the optimal temperature range for most bacteria?

A

35-37°C (similar to that found in internal human host tissues and organs)

117
Q

Which bacteria can grow at lower temperatures, between 4°C and 43°C?

A

Listeria monocytogenes and Yersinia enterocolitica

118
Q

Increased atmospheric humidity enhances the growth of certain bacterial species

A

Moisture

119
Q

Neutral pH range?

A

6.5-7.5

120
Q

Incubation temperature (Fungi)

A

28-30°C

121
Q

Incubation temperature (Bacteria, Viruses, and Acid-Fast Bacillus)

A

35-37°C

122
Q

These bacteria grow in ambient air.
Oxygen availability: 21%.
Carbon dioxide level: 0.03%.

A

Aerobes

123
Q

cannot grow in the presence of oxygen.

A

Anaerobes

124
Q

Identify:

5%-10% hydrogen.
5%-10% carbon dioxide.
80-90% nitrogen.
0% oxygen.

A

Anaerobe

125
Q

What are the incubation conditions required for anaerobic bacteria?

A

They require anaerobic conditions provided by anaerobe jars, bags, or chambers, typically containing

5%-10% hydrogen.
5%-10% carbon dioxide.
80-90% nitrogen.
0% oxygen.

126
Q

What are capnophiles and what are their specific growth requirements?

A

Capnophiles such as Haemophilus influenzae and Neisseria gonorrhoeae require increased concentrations of:

-5-10% carbon dioxide
-approximately 15% oxygen

These conditions can be achieved by :

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

127
Q

What are microaerophiles and what are their specific growth requirements?

A

Microaerophiles such as Campylobacter jejuni and Helicobacter pylori grow under :

-reduced oxygen conditions (5-10%)
-increased carbon dioxide levels (8-10%).

MTAP FIRST SEM 2024-2025 (15 decks)

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