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
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
3
Q
What is the recommended timeframe for transporting specimens after collection?
A
Within 2 hours of collection
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.
5
Q
What additional measures can be taken for transport if needed?
A
Use special preservatives, temperature-controlled containers, or holding media
6
Q
What is boric acid commonly used for in specimen preservation?
A
Preserving urine specimens.
7
Q
Which preservative is used for stool samples intended for ova and parasite examination?
A
Polyvinyl alcohol (PVA) and buffered formalin.
8
Q
Name two common transport or holding media used for specimens.
A
Stuart’s medium and Amie’s medium.
9
Q
What is the purpose of adding charcoal to transport media?
A
To absorb fatty acids.
10
Q
What is the commonly used anticoagulant in specimen collection?
A
0.025% Sodium polyanethol sulfonate (SPS).
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.
12
Q
Which anticoagulants should not be used in specimen collection?
A
Citrate and Ethylenediaminetetraacetic acid (EDTA), among others.
13
Q
What is the recommended storage temperature for specimens in a refrigerator?
A
4°C.
14
Q
At what temperature should specimens be stored in ambient (room) conditions?
A
22°C.
15
Q
What is the storage temperature for specimens that require body temperature conditions?
A
37°C.
16
Q
What are the recommended freezer temperatures for long-term storage of specimens?
A
-20°C or -70°C.
17
Q
Which types of specimens should be stored at 4°C?
A
Urine, stool, viral specimens, sputa, swabs, and foreign devices (catheters).
18
Q
For how long can serum for serologic studies be stored at -20°C?
A
Up to 1 week.
19
Q
What is the recommended storage temperature for tissues or specimens intended for long-term storage?
A
-70°C.
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
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
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)
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
24
Q
What should be recorded immediately upon arrival of a specimen?
A
Time and date of arrival.
25
What action should be taken if a specimen arrives with multiple testing requests but insufficient specimen volume?
The microbiologist should call the clinician to prioritize the testing based on clinical need.
26
What is the initial step in processing specimens?
Performing a gross examination of the specimen.
27
What should be done if areas with blood or mucus are found during the examination?
Locate and sample these areas for culture and direct examination.
28
How can barium affect the appearance of stool?
It can cause stool to appear chalky white in color.
29
Why is it important to note the status of the specimen during gross examination?
To document characteristics such as bloody, clouded, or clotted
30
What is the purpose of direct microscopic examination
* 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
31
Which specimens are usually not performed for direct microscopic examination?
Throat, nasopharyngeal, and stool specimens
32
What is the most common stain used in bacteriology for direct microscopic examination
Gram staining
33
Name the most common direct fungal stains
-KOH, PAS (Periodic acid-Schiff),
-GMS (Grocott’s methenamine silver stain),
-Calcofluor white
34
What are the most common direct acid-fast stains?
-Auramine rhodamine,
-Ziehl-Neelsen,
-Kinyoun
35
Phases of Growth Media
-Broth
-Agar
-Biphasic medium
36
What type of medium is broth in microbiology?
liquid medium
37
How are nutrients presented in a broth medium?
How is bacterial growth indicated in a broth medium?
-Nutrients are dissolved in water
-Bacterial growth is indicated by a change in the broth’s appearance from clear to turbid.
38
What is the purpose of pH indicators in broth media?
pH indicators, such as phenol red, change color in the presence of metabolites.
39
What is thioglycollate broth and what does it indicate?
Thioglycollate broth is a semisolid medium that provides an indication of the type of organism present based on oxygen requirements.
40
What type of medium is agar and what components make up an agar medium?
Solid medium: combination of a solidifying agent added to nutrients and water
41
What is the most common solidifying agent used in agar?
Agarose
42
At what temperature does agarose melt?
Agarose melts at high temperatures, specifically above or equal to 95°C
43
At what temperature does agarose resolidify?
after the temperature falls below 50°C
44
What is a biphasic medium
consists of both liquid and solid phase
45
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.
Nutritive Media
46
Give examples of Nutritive Media
-Tryptic soy agar,
-Nutrient agar plates (for bacteria),
-Sabouraud’s dextrose agar (for fungi), as well as blood or chocolate agar.
47
It contains specific nutrients required for the growth of bacterial pathogens
Supplemental or Enrichment Medium
48
Give an example of a Supplemental or Enrichment Medium and its purpose.
Buffered charcoal-yeast extract (BCYE) contains L-cysteine and other nutrients for the growth of Legionella pneumophilia.
49
What is an Enrichment Broth and is used for?
-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.
50
Give examples of Enrichment Broths
-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).
51
support the growth of one group of organisms but not another by adding antimicrobials, dyes, or alcohol.
Selective Media
52
contains crystal violet, which inhibits gram-positive organisms
MacConkey agar
53
contains colistin and nalidixic acid, which inhibit gram-negative organisms.
Columbia agar
54
Can Selective Media also be Differential Media? If so, how?
Yes, Selective Media can also be Differential Media if they differentiate between groups of organisms in addition to their inhibitory activity.
55
employ factors that allow colonies of one bacterial species or type to exhibit certain metabolic or culture characteristics.
Differential Media
56
differentiates between gram-negative bacteria that can ferment lactose and those that cannot.
MacConkey agar
57
What phases of growth media can Brain-heart Infusion (BHI) be found in?
broth or agar
58
Does Brain-heart Infusion can be prepared with or without blood? T or F
T
59
What carbohydrate does Brain-heart Infusion typically contain?
contains dextrose, which serves as a readily accessible source of energy.
60
is often used as a major component of media designed for culturing patient’s blood for bacterial growth.
BHI broth
61
Assess bacterial susceptibility
Brain-heart Infusion
62
What are the essential components of Chocolate Agar?
-Hemoglobin,
-Hemin (X factor),
-And nicotinamide adenine dinucleotide (NAD, V factor), which are released during lysis.
63
Which organisms specifically benefit from Chocolate Agar?
Neisseria gonorrhoeae and Haemophilus spp. neither grow well on sheep blood agar
64
What are the components of Columbia CNA with Blood?
contains a Columbia agar base with 3 peptone sources and 5% defibrinated sheep blood.
65
Differentiates bacterial colonies based on their hemolytic reactions
Columbia CNA with Blood
66
CNA stands for
colistin and nalidixic acid
67
What type of broth is Gram-Negative Broth?
selective broth
68
For what purpose is Gram-Negative Broth
cultivation of gastrointestinal pathogens from stool specimens and rectal swabs.
69
Gram-Negative Broth contains?
-Sodium citrate,
-Sodium deoxycholate (bile salt)
70
Mannitol serves as ?
primary carbon source in Gram-Negative Broth
71
What are the components that make up Hektoen Enteric Agar?
-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
Hektoen enteric agar is not a differential medium. T or F
F; it is indeed differential medium
73
What components are included in MacConkey Agar
o Dye: crystal violet
o pH indicator: neutral red
o Carbohydrate: lactose
74
What is the composition of Phenylethyl Alcohol Agar (PEA)?
sheep blood agar with phenylethyl alcohol, which inhibits the growth of gram-negative bacteria.
75
which types of bacteria does Phenylethyl Alcohol Agar (PEA) provide nutrients?
provides nutrients for common gram-positive cocci, such as enterococci, streptococci, and staphylococci.
76
should not be used for the interpretation of hemolysis
Phenylethyl Alcohol Agar
77
Supports growth for all but the most fastidious clinically significant bacteria
Sheep Blood Agar
78
Sheep Blood Agar contains?
-tryptones (protein source),
-soybean protein digest (which contains natural carbohydrate),
-sodium chloride,
-agar,
-5% sheep blood.
79
Interpret hemolysis
Sheep Blood Agar
80
serves as both an enrichment (chocolatized blood) and selective medium (antibiotics)
Modified Thayer-Martin Agar
81
What antibiotics are included in Modified Thayer-Martin Agar and their purpose?
-Colistin: inhibits gram-negative bacteria
-Vancomycin: inhibits gram-positive bacteria.
-Nystatin: inhibits yeast.
-Trimethoprim: inhibits Proteus species.
82
Similar to Thayer-Martin Agar, but with higher vancomycin concentration and the addition of asamycin (nystatin).
Martin-Lewis agar
83
What components enhance the growth of most organisms in Thioglycollate broth?
Casein, yeast and beef extracts, and vitamins
84
an enrichment broth or semisolid media
Thioglycollate broth
85
Which compound serves as the oxidation-reduction indicator in Thioglycollate broth?
Resazurin
86
Name the substances used to modify the basic formula of Thioglycollate broth.
dextrose, vitamin K, hemin
87
What percentage of agar is typically used in Thioglycollate broth, and what purpose does it serve?
0.075% agar ;prevents convection currents from carrying atmospheric oxygen
88
What compound acts as the reducing agent in Thioglycollate broth?
Thioglycolic acid
89
Is Xylose-Lysine Deoxycholate Agar selective, differential, or both? And which bacterial pathogens is it used to differentiate?
Both selective and differential, specifically for the isolation and differentiation of Shigella and Salmonella species.
90
Xylose-Lysine Deoxycholate Agar contains
salt and sodium deoxycholate
91
Xylose-Lysine Deoxycholate (XLD) Agar indicator?
phenol red
92
Name the three carbohydrates present in Xylose-Lysine Deoxycholate Agar.
lactose, xylose, and sucrose
93
Which carbohydrate is present in EMB Agar?
lactose
94
EMB stands for
Eosin Methylene Blue (EMB) Agar
95
Name the two indicators used in EMB Agar.
Eosin Y and methylene blue
96
What is the primary purpose of EMB Agar? What type of enteric bacilli does it differentiate?
Differentiation of lactose and non-lactose fermenting enteric bacilli
97
What is the inhibitor used in Salmonella-Shigella Agar?
Brilliant green
98
Which carbohydrate is present in Salmonella-Shigella Agar?
lactose
99
Name the indicator used in Salmonella-Shigella Agar
neutral red
100
What are the two compounds included in the Salmonella-Shigella Agar
ferric citrate and sodium citrate
101
Which bacterial pathogens is SS Agar selective for?
Salmonella and some Shigella spp.
102
What indicator is used in TCBS Agar?
bromothymol blue
103
Composition present in TCBS Agar
Yeast extracts
Bile salts
Citrate
Sucrose
Ferric citrate
Sodium thiosulfate
104
What type of bacteria is TCBS Agar selective and differential for?
Vibrio spp
105
TCBS stands for
Thiosulfate Citrate-Bile Salts Agar
106
Which types of bacteria can TSB support the growth of?
many fastidious and nonfastidious bacteria
107
an All-purpose enrichment broth
Trypticase Soy Broth (TSB)
108
When is TSB commonly used?
Used for subculturing various bacteria from primary agar plates
109
Enumerate the Environmental Requirements
Oxygen and Carbon Dioxide Availability
Temperature
pH
Moisture
110
enumerate all the Oxygen and Carbon Dioxide Availability
Aerobic
Anaerobic
Facultative anaerobic
Strictly aerobic
Microaerophilic or microaerobic
Aerotolerant
Capnophilic
111
grows best with higher oxygen concentrations (5-10%)
Capnophilic
112
grow slowly and poorly in the presence of oxygen
Aerotolerant
113
grow only in low levels of oxygen (approximately 20% or less)
Microaerophilic or microaerobic
114
cannot grow in the absence of oxygen
Strictly aerobic
115
grow in the presence or absence of oxygen
Facultative anaerobic
116
oxygen is inhibitory or lethal
Anaerobic
117
uses oxygen as the terminal electron acceptor and grow well in room air
Aerobic
117
What is the optimal temperature range for most bacteria?
35-37°C (similar to that found in internal human host tissues and organs)
117
Which bacteria can grow at lower temperatures, between 4°C and 43°C?
Listeria monocytogenes and Yersinia enterocolitica
118
Increased atmospheric humidity enhances the growth of certain bacterial species
Moisture
119
Neutral pH range?
6.5-7.5
120
Incubation temperature (Fungi)
28-30°C
121
Incubation temperature (Bacteria, Viruses, and Acid-Fast Bacillus)
35-37°C
122
These bacteria grow in ambient air.
Oxygen availability: 21%.
Carbon dioxide level: 0.03%.
Aerobes
123
cannot grow in the presence of oxygen.
Anaerobes
124
Identify:
5%-10% hydrogen.
5%-10% carbon dioxide.
80-90% nitrogen.
0% oxygen.
Anaerobe
125
What are the incubation conditions required for anaerobic bacteria?
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
What are capnophiles and what are their specific growth requirements?
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
What are microaerophiles and what are their specific growth requirements?
Microaerophiles such as Campylobacter jejuni and Helicobacter pylori grow under :
-reduced oxygen conditions (5-10%)
-increased carbon dioxide levels (8-10%).
