Portage Learning: Microbiology Module 5
UPDATED ACTUAL Exam Questions and
CORRECT Answers
Define the concept of universal precautions. - CORRECT ANSWER - Universal
precautions means any and all samples, whether known or unknown, are to be treated as
potentially hazardous (or pathogenic) materials.
What would a researcher be certain to note while analyzing a microbial sample? - CORRECT
ANSWER - 1. Size and shape
2. Any observable motility
3. Gram status (positive or negative)
4. The presence of any chemical reactions
5. Changes in color localized to the organism or the surrounding media
6. Capture (or draw) images of any of the characteristics described above
Which non-selective yet differential agar plate should be used if a Streptococcus sample is
suspected? - CORRECT ANSWER - A BAP (blood agar plate) would be the quickest way
to identify and classify a potential streptococcus microbe based on its hemolytic properties.
What disease can result if a patient with streptococcal pharyngitis goes untreated? - CORRECT
ANSWER - Rheumatic fever occurs in approximately 3% of untreated cases of
streptococcal pharyngitis, presenting approximately 2-3 weeks post-infection.
Streptococcus, E. coli, pseudomonas, and klebsiella are all capable of causing what disease? -
CORRECT ANSWER - All of the above foreign microbes are capable of causing
septicemia, also known as blood poisoning.
What is a facultative anaerobe? - CORRECT ANSWER - A facultative anaerobe is
capable of growth under both aerobic (with oxygen) and anaerobic (in the absence of oxygen)
condition.
,How can Staphylococcus be differentially tested? - CORRECT ANSWER -
Staphylococcus species are capable of growth in the presence of bile salts.
A bacterial swab is taken from a patient with impetigo and streaked across an MSA plate.
Following incubation at 37C, what will be the color of the agar? - CORRECT ANSWER -
The causative agent of impetigo is staph aureus, a Gram-positive bacterium capable of
fermenting mannitol. Fermentation will lower the pH of the agar and change the dye color from
red to yellow.
If a patient were suspected to have tuberculosis (TB), which differential stain would you select
and why? - CORRECT ANSWER - To stain for TB, one would utilize an acid-fast stain to
best visual the foreign microbe. As a mycobacterium tuberculosis would stain poorly
(indeterminate) using the Gram stain.
According to the module, which mycobacterium infection will be treated free of charge by the
World Health Organization (WHO)? - CORRECT ANSWER - Leprosy is completely
curable using a multiple-drug therapy regimen consisting of various combinations of the drugs
dapsone, rifampin and clofazimine—all of which is given free of charge.
What are the three main conditions caused by the botulism toxin? - CORRECT
ANSWER - Foodborne, infant and wound. Foodborne botulism is often the result of
improperly canned, contaminated, low-acidic foods such as green beans, corn and beats. Infant
botulism occurs when children, usually under the age of 6 months consume foods containing the
bacteria. A potential source of infant botulism is honey (which is why pediatricians recommend
avoiding feeding honey to infants) but can also be found in common places such as soil. Wound
botulism occurs when C. botulinum bacteria colonize a deep wound, often a puncture such as
those who inject street drugs such as heroine. As contaminated needles are injected through the
skin, spores enter the body and, in the absence of oxygen, release the toxin.
Why are infants (< 6 months) more susceptible to botulism? - CORRECT ANSWER - Due
to infants still maturing intestinal tract and lack of an adult microbiota, the bacteria are able to
colonize and produce the associated toxin. In adults, only the direct ingestion of the pre-formed
toxin causes disease—ingestion of C. botulinum or the associated spores do not cause illness as a
mature intestinal microbiota sufficiently prevents bacterial germination and growth.
, What is the mechanism of action of the toxin produced by clostridium tentani (tetanus)? -
CORRECT ANSWER - The toxin acts on inhibitory neurons causing systemic muscle
stiffness and spasms. Muscle stiffness can be observed in the jaw (lock-jaw) or spread
systemically (if left untreated) to muscles relating to respiratory function.
What Gram-negative bacterium might you come into contact with in a unsanitary hot tub? -
CORRECT ANSWER - Legionella is often associated with unclean water systems such as
hot tubs, hot water tanks and AC units. Notably, legionella can only be transmitted through water
droplets small enough to be inhaled.
What are the three forms of plague, and what regions do they affect? - CORRECT
ANSWER - Bubonic (lymph), pneumonic (lungs) and septicemic (blood). Bubonic plague
is best characterized by painfully swollen lymph nodes. Pneumonic plague affects the respiratory
system (lungs). The most rare of all three plagues, septicemic plague targets the blood system
and, if left untreated, will develop into a life-threatening illness as the blood-borne bacteria can
infect all major organs.
According to the module, which STD might be best identified via dark-field microscopy? -
CORRECT ANSWER - Syphilis. The causative agent, treponema pallidum, is a thin
spirochete, making Gram staining (and visualization) difficult. Treponema is therefore most
often best identified via dark-field microscopy.
Streptococcal Pharyngitis (Strep Throat) - CORRECT ANSWER - Streptococcus
Gram-positive, round bacterium that tends to link to other bacteria in chain-like structures
rheumatic fever - CORRECT ANSWER - When streptococcal pharyngitis is left untreated
(3% of cases). Gram-positive
Streptococcal septicemia (Blood poisoning) - CORRECT ANSWER - Group B
Streptococcus infection
Gram-positive
Folliculitis (Inflammation of the hair follicle) - CORRECT ANSWER - Staph aureus
UPDATED ACTUAL Exam Questions and
CORRECT Answers
Define the concept of universal precautions. - CORRECT ANSWER - Universal
precautions means any and all samples, whether known or unknown, are to be treated as
potentially hazardous (or pathogenic) materials.
What would a researcher be certain to note while analyzing a microbial sample? - CORRECT
ANSWER - 1. Size and shape
2. Any observable motility
3. Gram status (positive or negative)
4. The presence of any chemical reactions
5. Changes in color localized to the organism or the surrounding media
6. Capture (or draw) images of any of the characteristics described above
Which non-selective yet differential agar plate should be used if a Streptococcus sample is
suspected? - CORRECT ANSWER - A BAP (blood agar plate) would be the quickest way
to identify and classify a potential streptococcus microbe based on its hemolytic properties.
What disease can result if a patient with streptococcal pharyngitis goes untreated? - CORRECT
ANSWER - Rheumatic fever occurs in approximately 3% of untreated cases of
streptococcal pharyngitis, presenting approximately 2-3 weeks post-infection.
Streptococcus, E. coli, pseudomonas, and klebsiella are all capable of causing what disease? -
CORRECT ANSWER - All of the above foreign microbes are capable of causing
septicemia, also known as blood poisoning.
What is a facultative anaerobe? - CORRECT ANSWER - A facultative anaerobe is
capable of growth under both aerobic (with oxygen) and anaerobic (in the absence of oxygen)
condition.
,How can Staphylococcus be differentially tested? - CORRECT ANSWER -
Staphylococcus species are capable of growth in the presence of bile salts.
A bacterial swab is taken from a patient with impetigo and streaked across an MSA plate.
Following incubation at 37C, what will be the color of the agar? - CORRECT ANSWER -
The causative agent of impetigo is staph aureus, a Gram-positive bacterium capable of
fermenting mannitol. Fermentation will lower the pH of the agar and change the dye color from
red to yellow.
If a patient were suspected to have tuberculosis (TB), which differential stain would you select
and why? - CORRECT ANSWER - To stain for TB, one would utilize an acid-fast stain to
best visual the foreign microbe. As a mycobacterium tuberculosis would stain poorly
(indeterminate) using the Gram stain.
According to the module, which mycobacterium infection will be treated free of charge by the
World Health Organization (WHO)? - CORRECT ANSWER - Leprosy is completely
curable using a multiple-drug therapy regimen consisting of various combinations of the drugs
dapsone, rifampin and clofazimine—all of which is given free of charge.
What are the three main conditions caused by the botulism toxin? - CORRECT
ANSWER - Foodborne, infant and wound. Foodborne botulism is often the result of
improperly canned, contaminated, low-acidic foods such as green beans, corn and beats. Infant
botulism occurs when children, usually under the age of 6 months consume foods containing the
bacteria. A potential source of infant botulism is honey (which is why pediatricians recommend
avoiding feeding honey to infants) but can also be found in common places such as soil. Wound
botulism occurs when C. botulinum bacteria colonize a deep wound, often a puncture such as
those who inject street drugs such as heroine. As contaminated needles are injected through the
skin, spores enter the body and, in the absence of oxygen, release the toxin.
Why are infants (< 6 months) more susceptible to botulism? - CORRECT ANSWER - Due
to infants still maturing intestinal tract and lack of an adult microbiota, the bacteria are able to
colonize and produce the associated toxin. In adults, only the direct ingestion of the pre-formed
toxin causes disease—ingestion of C. botulinum or the associated spores do not cause illness as a
mature intestinal microbiota sufficiently prevents bacterial germination and growth.
, What is the mechanism of action of the toxin produced by clostridium tentani (tetanus)? -
CORRECT ANSWER - The toxin acts on inhibitory neurons causing systemic muscle
stiffness and spasms. Muscle stiffness can be observed in the jaw (lock-jaw) or spread
systemically (if left untreated) to muscles relating to respiratory function.
What Gram-negative bacterium might you come into contact with in a unsanitary hot tub? -
CORRECT ANSWER - Legionella is often associated with unclean water systems such as
hot tubs, hot water tanks and AC units. Notably, legionella can only be transmitted through water
droplets small enough to be inhaled.
What are the three forms of plague, and what regions do they affect? - CORRECT
ANSWER - Bubonic (lymph), pneumonic (lungs) and septicemic (blood). Bubonic plague
is best characterized by painfully swollen lymph nodes. Pneumonic plague affects the respiratory
system (lungs). The most rare of all three plagues, septicemic plague targets the blood system
and, if left untreated, will develop into a life-threatening illness as the blood-borne bacteria can
infect all major organs.
According to the module, which STD might be best identified via dark-field microscopy? -
CORRECT ANSWER - Syphilis. The causative agent, treponema pallidum, is a thin
spirochete, making Gram staining (and visualization) difficult. Treponema is therefore most
often best identified via dark-field microscopy.
Streptococcal Pharyngitis (Strep Throat) - CORRECT ANSWER - Streptococcus
Gram-positive, round bacterium that tends to link to other bacteria in chain-like structures
rheumatic fever - CORRECT ANSWER - When streptococcal pharyngitis is left untreated
(3% of cases). Gram-positive
Streptococcal septicemia (Blood poisoning) - CORRECT ANSWER - Group B
Streptococcus infection
Gram-positive
Folliculitis (Inflammation of the hair follicle) - CORRECT ANSWER - Staph aureus
