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WorksheetsMedical, Environmental, and Food Microbiology
Total questions: 73
Worksheet time: 1hrs 28mins
used to measure the effectiveness of antibiotics and other chemotherapeutic agents on pathogenic microorganisms.
Ames test
Antimicrobial Susceptibility Test
(Kirby-Bauer Method and E Test)
Pyrole test
Quinidine test
Kirby-Bauer test,
Disk diffusion test
standard tool for measuring the effectiveness of antimicrobics
against pathogenic microorganisms.
antimicrobic-impregnated paper disks are placed on a plate that is inoculated to form
a bacterial lawn.
As the drug moves through the agar, it establishes a concentration gradient.
If the organism is susceptible to it, a clear zone will appear around the disk where growth has been inhibited
This depends upon the sensitivity of the bacteria to the
specific antimicrobial agent and the point at which the chemical’s minimum inhibitory concentration (MIC) is reached.
zone of inhibition
minimum inhibitory
concentration (MIC)
Some drugs kill the organism and are said to be bactericidal. Other drugs are bacteriostatic; they stop growth but don’t kill the microbe.
Both statements are correct
Only one statement is correct
Neither of the statements is correct.
Mueller-Hinton agar has a pH between 7.2 and 7.4. It is poured to a depth of 4 mm in either 150 mm or 100 mm Petri dishes. The depth is not important because of its effect upon diffusion. Inoculation is made with a
broth culture diluted to match a 0.5 McFarland turbidity
standard
The first statement is incorrect
The second statement is incorrect.
All of them are incorrect
The third statement is correct
Only one statement is incorrect
Thick agar on used Muller Hinton test hasten lateral diffusion and thus produces smaller zones than plates held to the 4 mm standard.
The statement is correct
The statement is incorrect
The disks, which contain a specified amount of the
antimicrobial agent (printed on the disk) are dispensed
onto the inoculated plate and incubated at 35 +/-2°C . After 16 to 18 hours of incubation, the plates are
re-incubated and the clear zone diameters are measured.
The first statement is incorrect
Neither of the statement is correct
The second statement is correct
Only one statement is correct
Normally, the zones around each antibiotic disk will be
distinct and separate. Occasionally a synergistic effect of
two antibiotics will produce a clear area between the disks
extending beyond the perimeters of the otherwise circular zones. In this area between the zones both
antibiotics are below MIC, but bactericidal in combination
with each other.
The first statement is the only correct answer
Two of the statements given are incorrect
No statement is correct
all the three statements are correct
The E-test system for determining antibiotic sensitivity is an alternative to the Kirby-Bauer
method and has the added advantage of allowing the MIC
to be determined.
The statement is correct
The statement is incorrect.
It consists of a paper strip with a gradient of antibiotic concentrations on one surface and a printed scale on the other. After an agar plate is inoculated with a lawn of bacteria (as in the Kirby-Bauer method), the strip
is placed, antibiotic side down, on the agar surface.
Ames test
E-test
M-figure Myco test
Antibiotic resistance 0211 test
During incubation in the E-test, the antibiotic will diffuse into the agar
higher concentrations travels farther than lower concentrations
an elliptical zone of inhibition will develop.
The point at which the inhibition zone intersects the scale is the MIC, printed on the strip
All of the choices are correct
One statement is incorrect
ANTIBIOTIC SYNERGISM seen in Kirby Bauer Test
antibiotics Sulfisoxazole (G) and
Trimethoprim (TMP) have overlapping clearing area
antibiotics Sulfisoxazole (G) inhibits the effect of
Trimethoprim (TMP) causing absence of zone of inhibition
antibiotics Sulfisoxazole (G) and
Trimethoprim (TMP) forms two parallel line
is a procedure in which susceptibility to a particular antibiotic can be quantified as a Minimum Inhibitory Concentration (MIC).
E-test
AST test
Ames test
EP 21 test
In E-test, MIC is determined by:
where the zone of inhibition intersects the scale
printed on the strip.
where the zone of inhibition wash out the scale
printed on the strip.
where the zone of inhibition forms parallel line with the scale
printed on the strip.
Effect of antibiotic vancomycin in E-test
zone formed when incubated with Methicillin-resistant Staphylococcus aureus
zone formed when incubated with E.coli
Sample collection and transport are the first steps in identifying pathogens from patients, and their importance cannot be overstated. Improper collection and transport can make microbial identification by the laboratory more difficult assuming that the sample is even usable.
The first statement is correct
The first and second statement are incorrect
Both statements are correct
Neither of the statements is correct
First and foremost, collection of patient specimens for
laboratory diagnosis requires that the site sampled has an active infection. Collection of patient specimens may involve tissue removal, collection of sputum, urine or feces, fluid aspiration, venipuncture, or a surface swab.
The first statement is incorrect
Both statements are correct
Neither of them is correct
The second statement is incorrect
The method of choice in specimen collection .
is dictated by the body region and suspected pathogen,
regardless of the patient’s normal flora, environmental
surroundings, sample taker must not contaminate the
sample.
the appropriate sampling instrument and
transport medium must be used
Proper training of medical staff in sample collection and transport is imperative, because the laboratory can do little when the sample is contaminated or is not transported properly.
Samples are frequently obtained with : Swabs
come in a variety of types—
wooden swab ,
plastic swab
metal shafts and cotton swab
Dacron swab
swab calcium alginate tips
Plastic swabs are used most often because wooden swabs
may harbor toxins that interfere with microbial growth.
The statement is correct
The statement is incorrect
We don't use swab, we use our fingers
We don't use swab, we lick the area to get a sample
Wooden swabs are used most often because plastic swabs
may harbor toxins that interfere with microbial growth.
The statement is correct
The statement is incorrect
We don't use swab to collect, we use our fingers
We don't use swab to collect, we lick the area to get a sample
Flexible wire swabs are recommended for nasopharyngeal and male urethral samples.
The statement is correct
The statement is incorrect
We don't use swab, we lick the area to get a sample
We don't use swab, we use our fingers to get a sample
Cotton tips are useful in collecting non-fastidious organisms but may contain chemicals that are inhibitory to fastidious ones.
correct
incorrect
non-micro topic
Only God knows the answer
Cotton tips are useful in collecting fastidious but may contain chemicals that are inhibitory to non-fastidious organisms
incorrect
correct
My cat knows the answer
Brain dead
Dacron tips have the widest application and may even be used for collecting viral samples.
correct
incorrect
pass
maybe
Dacron tips cannot be used for collecting viral samples.
correct
incorrect
no need for swab, lick it
Calcium alginate-tipped swabs are best used to sample for Chlamydia.
correct
incorrect
maybe
I've lost my hope
Calcium alginate-tipped swabs are should not be used to sample for Chlamydia.
incorrect
correct
My dog knows the answer
Maybe you can help me
Flow for specimen collection
the sample must be labeled with all relevant information:
patient name
sample site
date and time of collection
collector’s initials.
ID number
Which is correct regarding specimen collection and transport
The faster the sample gets to the laboratory for processing, the better.
Bacterial samples should be transported within 2 hours, if possible;
the sample probably will be useless after 24 hours.
once in the laboratory, the sample should be processed in a timely fashion.
refrigeration is acceptable for a given amount of time before processing.
Examples of transport media
Amies
Stuart’s
Cary-Blair
only one is incorrect
All are correct
What is true about Amies' transport media
a medium with a variety of chloride salts to maintain osmotic pressure.
Phosphate buffers maintain the pH
thioglycollate produces a reduced environment to minimize oxidative damage to the cells.
Some formulations contain charcoal to neutralize fatty acids and bacterial toxins.
This medium is designed to maintain the bacteria, not provide for their growth.
Amies has carbon source and nitrogen source to provide optimum growth for the bacteria
correct
incorrect
pass
I am too tired to analyze
swab transport media that contains a plastic shaft with a polyurethane tip.
tube with the maroon cap
tube with the yellow cap
tube with the green cap
polyurethane tip is nontoxic to microorganisms, no transport medium is necessary.
correct
incorrect
go to the next question
eye doe knot noe
The red cap double swab has a rayon tip.
correct
incorrect
maybe
PRC knows it
The tube to the left contains Stuart’s Liquid Transport medium, a nonnutritious, buffered medium that keeps the sample moist.
true
false
maybe
pass
The tube to the left contains Stuart’s Liquid Transport medium, a nutritious, buffered medium that keeps the sample moist.
true
false
The tube to the left contains Stuart’s Liquid Transport medium, a nonnutritious, buffered medium that keeps the sample dry.
true
false
The orange-capped swab has a regular aluminum wire
with a Dacron tip.
True
false
The orange-capped swab has a regular chromium wire
with a Dacron tip.
TRUE
FALSE
The orange-capped swab has a regular aluminum wire
with a Ronielle tip.
TRUE
FALSE
asa
The green-capped swab has a soft aluminum wire
with a Dacron tip.
TRUE
FALSE
maybe
The green-capped swab has a hard aluminum wire
with a Dacron tip.
TRUE
FALSE
Most transport media support the growth of aerobic bacteria
TRUE
FALSE
maybe
Most transport tubes are for transport of aerobic organisms.
TRUE
FALSE
Transport of anaerobes requires a special container that
produces anaerobic conditions inside when the swab is inserted. A color indicator is used as a control to assure that the inside is anaerobic
Both are correct
Neither is correct
only one is correct
TRANSPORT SYSTEM FOR ANAEROBES
The sample is taken and inserted into the tube, where it breaks open a vial that produces anaerobic conditions.
A color indicator turns pink if oxygen is present, making the sample useless.
Both are correct
Neither is correct
The RODACTM Plate
Environmental Sampling:
Forensic Sampling:
Water sampling
Aeronautic sampling
RODACTM
(Replicate Organism Detection and Count-
ing) plate
(Replicate Organization Detection and Count-
ing) plate
(Reptile Organism Detection and Count-
ing) plate
(Replicate Organ Detection and Count-
ing) plate
used to monitor contamination of surfaces in food preparation, veterinary, pharmaceutical, and medical
settings.
The RODACTM Plate
The RODAK TM Plate
The RODACGLOBE Plate
The RODAXTM Plate
can be used to assess the efficiency of decontamination of a surface by taking a sample with different plates before and after decontamination.
RODACTM Plate
RODATM Plate
RADACTM Plate
RIDACTM Plate
RODACTM Plate Principle
the medium is poured to produce a convex surface extending above the edge of the plate allowing support of the lid above the agar without touching it.
the sterile plate may be opened and pressed on a
surface to be sampled.
Most are 65 mm in diameter, which
is smaller than standard-sized 100 mm Petri dishes.
The smaller size makes it easier to apply uniform pressure across the entire plate when taking the sample.
the base is marked in sixteen 1 cm squares, allowing an estimate of cell density on the surface
Role of Polysorbate 80 and Lecithin in RODACTM Plate
counteract the effect of residual disinfectant.
counteract the effect of microbial toxin.
counteract the effect of infection.
AGAR plate used in RODACTM Plate
TrypticaseTM Soy Agar-- general media
5% sheep blood agar-- fastidious organisms
Sabouraud Dextrose Agar--monitoring yeast and mold contamination.
Sabouraud Dextrose Agar- Neisseria and Mycoplasma
The acceptable amount of growth on a RODACTM
plate is determined by the surface being sampled. It stands to reason that a surgical area would have a lower limit of acceptability than a food preparation area.
Both are correct
Neither is correct
only one is correct
the agar extends above the edges of the plate to allow contact with the surface to be sampled.
RODACTM PLATE
RODACTM PLATUE
RODACTM PLANT
Describe theTHE RODACTM PLATE
RODACTM plates are 65 mm in diameter.
A grid of 16 squares is molded into the base,
each with an area of 1 cm2.
Colonies growing in the grid can be counted
and an average number of CFU per cm2 of surface can be determined.
Interpretation of RODACTM Plate Colony Counts
"Good"
Colilert®* Method
Water test
Environmental test
Aeronautic testing
Forensic testing
Generally used to detect E. coli
Alert®* Method
Mentilert®* Method
Colilert®* Method
Robert®* Method
Colilert®* Method
reagent contains nutrients and salts which favor the
growth of coliforms and inhibit the growth of noncoliforms.
contains the indicator nutrients, o-Nitrophenyl--D-
Galactopyranoside (ONPG) and 4-Methylumbelliferyl--D-Glucuronide (MUG).
The test is conducted by adding
Colilert® reagent to a nonfluorescing bottle containing a
100 mL sample of drinking water.
The sample is incubated
at 35°C for 24–28 hours and then compared to the control.
All coliforms ferment lactose using the enzyme-galactosidase. ONPG is an artificial substrate of the
same enzyme and, when hydrolyzed, produces the yellow
compound o-Nitrophenol.
Both are correct
Neither is correct
only one is correct
Interpretation of Colilert®* Method
If the test bottle is as yellow or more yellow than the control, the first portion of the test is positive and reported as “total coliforms present.”
Yellow color means presence of E.coli
Both are correct
Only one is correct
True about water testing
MUG acts as a substrate for the E. coli enzyme
-glucuronidase, from which a fluorescent compound is
produced.
A positive MUG result produces fluorescence when viewed under an ultraviolet lamp .
If the test bottle fluorescence is equal to or greater than that of the control, the presence of E. coli has been confirmed.
This portion of the test is reported as “E. coli present.”
A sample that is not as yellow and does not fluoresce is considered negative and is reported as “total coliforms absent” and “E. coli absent.”
Colilert ONPG
has (o-Nitrophenyl-D-Galactopyranoside) test for total coliforms.
(4-Methylumbelliferyl--D-Glucuronide) test for Escherichia coli seen under a UV Lamp.
COLILERT® MUG
has (4-Methylumbelliferyl--D-Glucuronide) test for Escherichia coli seen under a UV Lamp.
(o-Nitrophenyl-D-Galactopyranoside) test for total coliforms.
Describe Membrane Filter Technique
used to identify the presence of fecal coliforms in water. ex: Escherichia coli, Klebsiella pneumoniae, and Enterobacter aerogenes,
a water sample is
drawn through a special porous membrane designed to
trap microorganisms larger than 0.45 μm.
After filtering the water sample, the membrane (filter) is applied to the surface of plated Endo Agar and incubated for 24 hours
Endo Agar is a selective medium use in Membrane filter that encourages Gram-
negative bacterial growth and inhibits Gram-positive
growth. Endo Agar contains lactose for fermentation and a dye to indicate changes in pH.
Both are correct
Neither of them is correct
only one is correct
In Membrane filter technique, Because of their vigorous lactose fermentation resulting in acid and aldehyde formation, coliform colonies typically appear red and/or mucoid with a gold or green metallic sheen. Noncoliform bacteria (including several dangerous pathogens) tend to be pale pink, colorless, or the color of the medium.
only one is correct
Both are correct
Neither of them is correct
Membrane Filter technique is interpreted as
“coliform colonies/100 mL”
“coliform colonies/100 uL”
“coliform colonies/100 dL”
“coliform colonies/100 L”
Calculate:
Coliform counted: 100
Volume of original sample: 10mL
Potable water contains less than one(1) coliform per 100 milliliters of sample.
TRUE
FALSE
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