INTRODUCTION TO DIAGNOSTIC MICROBIOLOGY
FOR THE LABORATORY SCIENCE 2ND EDITION BY
MARIA DANNESSA DELOST QUESTIONS AND
ANSWERS (2024/2025)
The catalase test on the isolate shows no bubbles. Which of the following organisms
MIGHT be the organism in question?
✓ strep pyogenes
Which species of Staphylococcus is one of the most important human pathogens?
✓ s. aureus
Colony characteristics of Staphylococcus aureus on blood agar after 18 to 24 hours
incubation at 35 degrees C include all the following EXCEPT:
✓ swarming
A young girl goes to her doctor's office with a fever, headache, and a sore throat. The
mother states the girl has a fever of 38.8°C (102 degrees F). What test should the physician
perform?
✓ throat swab for a rapid strep test
The tube coagulase test:
✓ detects free coagulase (extracellular proteins)
If an organism is a gram positive cocci, non-hemolytic, catalase negative, bile esculin
positive and 6.5% NaCl positive, which is most likely the organism?
✓ enterococcus faecalis
Bacitracin, pyrrolidonyl arylamidase (PYR), CAMP factor, and hippurate are tests most
likely performed on a(n) __________ Streptococcus.
pg. 1
, ✓ beta hemolytic
An organism was isolated on a BAP that was alpha hemolytic. The gram stain showed
elongated GPC in pairs, and the catalase was negative. Which of the following should be
the next test for identification?
✓ bile solubility and optochin
Which group of bacteria is described as catalase positive gram-positive cocci that are
facultatively anaerobic and show grapelike clusters on a Gram stain?
✓ staphylococcus
What are the staphylococcal products that cause diarrhea and vomiting in humans?
✓ enterotoxins
What name is given to the type of hemolysis that produces complete hemolysis and a
clearing of the medium?
✓ beta hemolysis
The the colonies of this gpc resemble a donut as it ages, and it has a polysaccharide
capsule that is responsible for its virulence. What two characteristics describe this
organism?
✓ alpha hemolytic and bile solubility positive
If an organism is a gram positive cocci, alpha hemolytic, catalase negative, bile esculin
positive and 6.5% NaCl negative, what is the organism?
✓ Group D strep
This staphylococcal species is associated with urinary tract infections in young, sexually
active females.
✓ s. saprophyticus
The identification test performed on a clinical isolate of gram-positive, catalase-positive,
microdase negative cocci would likely be the:
✓ coagulase test
pg. 2
,How do you confirm that beta hemolytic colonies seen on a BAP are a beta strep species
and not Staph aureus?
✓ perform a catalase test
What is the identity of a gram positive organism in pairs and chains that is beta-hemolytic
on BAP, catalase negative, bacitracin sensitive, PYR positive and hippurate negative?
✓ streptococcus pyogenes
Enterococcus sp. and Group D Strep can be differentiated by which of the following?
✓ PYR
The major etiologic agent of bacterial endocarditis in the United States is:
✓ viridian's streptococci
The development of acute rheumatic fever and subsequent valvular heart disease are
problems that may be encountered by patients infected with:
✓ s. pyogenes
The two most common species of coagulase-negative staphylococci are:
✓ s. Epidermis
✓ s. saprophyticus
Which of the following is NOT true?
✓ micrococcus and staphylococcus are facultative anaerobes
This disease is an extensive exfoliative dermatitis caused by staphylococcal exfoliative
toxin.
✓ scalded skin syndrome or ritter's disease
The bacterial species that is a gpc and can be described as able to hydrolyze hippurate, is
beta-hemolytic, is a major cause of neonatal meningitis and sepsis, and is a producer of
the Christie, Atkins, Munch-Petersen (CAMP) factor is:
✓ s. agalactiae
pg. 3
, What are the effects of the alpha hemolysin produced by Staphylococcus aureus?
✓ it lyses red blood cells, damages platelets and macrophages, and can cause severe
tissue damage
Enterococci can be described as:
✓ able to hydrolyze bile esculin
What morphologic feature is a major consideration in determining an identification
scheme for streptococci?
✓ hemolytic pattern
Which of the following staphylococci are coagulase positive?
✓ staphylococcus aureus
What disease is produced by group A streptococci that is characterized by a rapidly
progressing inflammation and necrosis of the skin, subcutaneous fat, and fascia?
✓ necrotizing fasciitis
The development of glomerulonephritis is a problem that may be encountered by patients
infected with:
✓ s. pyogenes
Optochin, PYR, bile solubility, and bile esculin are tests most likely performed on a(n)
__________ Streptococcus.
✓ alpha hemolytic
The slide coagulase test is a rapid screening test for the production of:
✓ bound coagulase or clumping factor
Which of the following tests is used routinely to identify Staphylococcus aureus?
✓ mannitol salt agar
What organism is a GPC in pairs and chains, catalase negative, optochin (P) disk sensitive,
alpha hemolytic on BAP and PYR negative?
pg. 4
FOR THE LABORATORY SCIENCE 2ND EDITION BY
MARIA DANNESSA DELOST QUESTIONS AND
ANSWERS (2024/2025)
The catalase test on the isolate shows no bubbles. Which of the following organisms
MIGHT be the organism in question?
✓ strep pyogenes
Which species of Staphylococcus is one of the most important human pathogens?
✓ s. aureus
Colony characteristics of Staphylococcus aureus on blood agar after 18 to 24 hours
incubation at 35 degrees C include all the following EXCEPT:
✓ swarming
A young girl goes to her doctor's office with a fever, headache, and a sore throat. The
mother states the girl has a fever of 38.8°C (102 degrees F). What test should the physician
perform?
✓ throat swab for a rapid strep test
The tube coagulase test:
✓ detects free coagulase (extracellular proteins)
If an organism is a gram positive cocci, non-hemolytic, catalase negative, bile esculin
positive and 6.5% NaCl positive, which is most likely the organism?
✓ enterococcus faecalis
Bacitracin, pyrrolidonyl arylamidase (PYR), CAMP factor, and hippurate are tests most
likely performed on a(n) __________ Streptococcus.
pg. 1
, ✓ beta hemolytic
An organism was isolated on a BAP that was alpha hemolytic. The gram stain showed
elongated GPC in pairs, and the catalase was negative. Which of the following should be
the next test for identification?
✓ bile solubility and optochin
Which group of bacteria is described as catalase positive gram-positive cocci that are
facultatively anaerobic and show grapelike clusters on a Gram stain?
✓ staphylococcus
What are the staphylococcal products that cause diarrhea and vomiting in humans?
✓ enterotoxins
What name is given to the type of hemolysis that produces complete hemolysis and a
clearing of the medium?
✓ beta hemolysis
The the colonies of this gpc resemble a donut as it ages, and it has a polysaccharide
capsule that is responsible for its virulence. What two characteristics describe this
organism?
✓ alpha hemolytic and bile solubility positive
If an organism is a gram positive cocci, alpha hemolytic, catalase negative, bile esculin
positive and 6.5% NaCl negative, what is the organism?
✓ Group D strep
This staphylococcal species is associated with urinary tract infections in young, sexually
active females.
✓ s. saprophyticus
The identification test performed on a clinical isolate of gram-positive, catalase-positive,
microdase negative cocci would likely be the:
✓ coagulase test
pg. 2
,How do you confirm that beta hemolytic colonies seen on a BAP are a beta strep species
and not Staph aureus?
✓ perform a catalase test
What is the identity of a gram positive organism in pairs and chains that is beta-hemolytic
on BAP, catalase negative, bacitracin sensitive, PYR positive and hippurate negative?
✓ streptococcus pyogenes
Enterococcus sp. and Group D Strep can be differentiated by which of the following?
✓ PYR
The major etiologic agent of bacterial endocarditis in the United States is:
✓ viridian's streptococci
The development of acute rheumatic fever and subsequent valvular heart disease are
problems that may be encountered by patients infected with:
✓ s. pyogenes
The two most common species of coagulase-negative staphylococci are:
✓ s. Epidermis
✓ s. saprophyticus
Which of the following is NOT true?
✓ micrococcus and staphylococcus are facultative anaerobes
This disease is an extensive exfoliative dermatitis caused by staphylococcal exfoliative
toxin.
✓ scalded skin syndrome or ritter's disease
The bacterial species that is a gpc and can be described as able to hydrolyze hippurate, is
beta-hemolytic, is a major cause of neonatal meningitis and sepsis, and is a producer of
the Christie, Atkins, Munch-Petersen (CAMP) factor is:
✓ s. agalactiae
pg. 3
, What are the effects of the alpha hemolysin produced by Staphylococcus aureus?
✓ it lyses red blood cells, damages platelets and macrophages, and can cause severe
tissue damage
Enterococci can be described as:
✓ able to hydrolyze bile esculin
What morphologic feature is a major consideration in determining an identification
scheme for streptococci?
✓ hemolytic pattern
Which of the following staphylococci are coagulase positive?
✓ staphylococcus aureus
What disease is produced by group A streptococci that is characterized by a rapidly
progressing inflammation and necrosis of the skin, subcutaneous fat, and fascia?
✓ necrotizing fasciitis
The development of glomerulonephritis is a problem that may be encountered by patients
infected with:
✓ s. pyogenes
Optochin, PYR, bile solubility, and bile esculin are tests most likely performed on a(n)
__________ Streptococcus.
✓ alpha hemolytic
The slide coagulase test is a rapid screening test for the production of:
✓ bound coagulase or clumping factor
Which of the following tests is used routinely to identify Staphylococcus aureus?
✓ mannitol salt agar
What organism is a GPC in pairs and chains, catalase negative, optochin (P) disk sensitive,
alpha hemolytic on BAP and PYR negative?
pg. 4
