Chapter 25: Diagnostic Clinical Microbiology
MULTIPLE CHOICE
1. Identifying infectious agents is important because
a. it costs less money to run numerous tests than to treat with antibiotics empirically.
b. antibiotic-resistant bacteria are becoming a major global threat.
c. pathogens must be identified before antibiotics are effective.
d. antibiotics are only effective against viruses.
ANS: B DIF: Easy REF: 25.1
OBJ: 25.1a List the reasons for identifying the cause of an infectious disease.
MSC: Understanding
2. How does identifying the cause of an infectious disease help prevent the development of antibiotic-
resistant bacteria?
a. Knowing the identity and properties of the causative agent allows targeting with an
appropriate drug.
b. Treating bacterial infections with multiple antibiotics helps prevent the development of
antibiotic-resistant bacteria.
c. Knowing the identity and properties of the causative agent allows a physician to
empirically treat an infection.
d. Treating viral infections with multiple antibiotics helps prevent secondary infections
caused by antibiotic-resistant bacteria.
ANS: A DIF: Difficult REF: 25.1
OBJ: 25.1a List the reasons for identifying the cause of an infectious disease.
MSC: Analyzing
3. Twenty-five individuals with shigellosis are reported within a community. Which of the following
pieces of information would be most useful to public health officials who are trying to stop the spread
of this infection?
a. whether all individuals are infected with the same strain of bacteria
b. the antibiotic sensitivity of the causative agents
c. the complete health history of infected individuals
d. the day care centers attended by any children of infected individuals
ANS: A DIF: Moderate REF: 25.1
OBJ: 25.1b Explain the basic epidemiologic purpose of identifying the cause of an infectious disease.
MSC: Applying
4. Which of the following is considered to be a sterile body site?
a. cerebrospinal fluid c. urethra
b. nasopharynx d. large intestine
ANS: A DIF: Easy REF: 25.2
OBJ: 25.2a Identify sterile and nonsterile body sites. MSC: Remembering
, 5. Which of the following samples would be expected to be free of microorganisms unless an infection is
present?
a. blood c. nasopharyngeal swab
b. fecal stool sample d. urethral swab
ANS: A DIF: Easy REF: 25.2
OBJ: 25.2a Identify sterile and nonsterile body sites. MSC: Understanding
6. Which of the following samples would be expected to contain normal microbiota?
a. peritoneal fluid c. blood
b. cerebrospinal fluid d. fecal stool sample
ANS: D DIF: Easy REF: 25.2
OBJ: 25.2a Identify sterile and nonsterile body sites. MSC: Remembering
7. Which of the following samples would be LEAST likely to require anaerobic incubation?
a. nasopharyngeal swab c. blood
b. cerebrospinal fluid d. synovial fluid
ANS: D DIF: Easy REF: 25.2
OBJ: 25.2b List procedures and precautions used to collect specimens from sterile body sites.
MSC: Applying
8. Which of the following would typically be the initial indicator of bacteria growing within a blood
culture tube?
a. An automated incubator will detect fluorescence.
b. Bacterial colonies will appear on blood agar.
c. Bacterial colonies will appear on MacConkey agar.
d. Centrifugation will cause sediment to appear at the end of the tube.
ANS: A DIF: Moderate REF: 25.2
OBJ: 25.2b List procedures and precautions used to collect specimens from sterile body sites.
MSC: Understanding
9. Lumbar puncture is the most common method for obtaining a sample of
a. blood. c. synovial fluid.
b. cerebrospinal fluid. d. peritoneal fluid.
ANS: B DIF: Easy REF: 25.2
OBJ: 25.2b List procedures and precautions used to collect specimens from sterile body sites.
MSC: Understanding
10. Jose is seen for a draining abscess on his left forearm. Which of the following would most likely be
used to collect a sample from this site?
a. needle aspiration c. sputum sample
b. skin scraping d. swab
ANS: D DIF: Easy REF: 25.2
OBJ: 25.2c List procedures used to collect specimens from body sites containing normal microbiota.
MSC: Understanding
, 11. A lab technician intern is asked to apply a 10% KOH (potassium hydroxide) solution on a sample.
There are four patient samples sitting on the lab bench and he is trying to remember which sample
should be treated. Which of the following four samples would require treatment with KOH?
a. a skin scraping from a site suspected to be a fungal infection
b. a nasopharyngeal swab suspected of containing Bordetella pertussis
c. a sputum sample from a patient with tuberculosis
d. a fecal sample from an individual with bloody diarrhea
ANS: A DIF: Difficult REF: 25.2
OBJ: 25.2c List procedures used to collect specimens from body sites containing normal microbiota.
MSC: Analyzing
12. In which of the following scenarios would selective media most likely be used to DECREASE the
number of normal microbiota?
a. A nasopharyngeal swab is used to collect a sample from a young woman with inflamed
tonsils.
b. A midstream clean catch is used to collect urine in a young woman with a suspected
urinary tract infection.
c. Venipuncture is used to collect blood from an elderly man with a possible blood infection.
d. A lumbar puncture is used to collect cerebrospinal fluid from a toddler exhibiting signs of
meningitis.
ANS: A DIF: Moderate REF: 25.2
OBJ: 25.2c List procedures used to collect specimens from body sites containing normal microbiota.
MSC: Evaluating
13. A young child arrives at a local hospital with neck stiffness, nausea, and vomiting. The attending
physician suspects bacterial meningitis and sends a sample of cerebrospinal fluid to the hospital
laboratory. Which of the following actions would most quickly identify the bacterial species?
a. using sequential biochemical tests in which each test dictates the next test
b. carrying out a series of tests simultaneously and then interpreting the tests sequentially
c. plating the species first on selective media to eliminate the number of normal microbiota
d. obtaining a sequence of the patient’s genome to determine his or her susceptibility to
specific microbes
ANS: B DIF: Difficult REF: 25.3
OBJ: 25.3a Explain how biochemical profiles can be used to identify microbial pathogens.
MSC: Analyzing
14. The figure shown illustrates a small portion of an algorithm used to identify Gram-negative rods. This
diagram is referred to as a(n)
MULTIPLE CHOICE
1. Identifying infectious agents is important because
a. it costs less money to run numerous tests than to treat with antibiotics empirically.
b. antibiotic-resistant bacteria are becoming a major global threat.
c. pathogens must be identified before antibiotics are effective.
d. antibiotics are only effective against viruses.
ANS: B DIF: Easy REF: 25.1
OBJ: 25.1a List the reasons for identifying the cause of an infectious disease.
MSC: Understanding
2. How does identifying the cause of an infectious disease help prevent the development of antibiotic-
resistant bacteria?
a. Knowing the identity and properties of the causative agent allows targeting with an
appropriate drug.
b. Treating bacterial infections with multiple antibiotics helps prevent the development of
antibiotic-resistant bacteria.
c. Knowing the identity and properties of the causative agent allows a physician to
empirically treat an infection.
d. Treating viral infections with multiple antibiotics helps prevent secondary infections
caused by antibiotic-resistant bacteria.
ANS: A DIF: Difficult REF: 25.1
OBJ: 25.1a List the reasons for identifying the cause of an infectious disease.
MSC: Analyzing
3. Twenty-five individuals with shigellosis are reported within a community. Which of the following
pieces of information would be most useful to public health officials who are trying to stop the spread
of this infection?
a. whether all individuals are infected with the same strain of bacteria
b. the antibiotic sensitivity of the causative agents
c. the complete health history of infected individuals
d. the day care centers attended by any children of infected individuals
ANS: A DIF: Moderate REF: 25.1
OBJ: 25.1b Explain the basic epidemiologic purpose of identifying the cause of an infectious disease.
MSC: Applying
4. Which of the following is considered to be a sterile body site?
a. cerebrospinal fluid c. urethra
b. nasopharynx d. large intestine
ANS: A DIF: Easy REF: 25.2
OBJ: 25.2a Identify sterile and nonsterile body sites. MSC: Remembering
, 5. Which of the following samples would be expected to be free of microorganisms unless an infection is
present?
a. blood c. nasopharyngeal swab
b. fecal stool sample d. urethral swab
ANS: A DIF: Easy REF: 25.2
OBJ: 25.2a Identify sterile and nonsterile body sites. MSC: Understanding
6. Which of the following samples would be expected to contain normal microbiota?
a. peritoneal fluid c. blood
b. cerebrospinal fluid d. fecal stool sample
ANS: D DIF: Easy REF: 25.2
OBJ: 25.2a Identify sterile and nonsterile body sites. MSC: Remembering
7. Which of the following samples would be LEAST likely to require anaerobic incubation?
a. nasopharyngeal swab c. blood
b. cerebrospinal fluid d. synovial fluid
ANS: D DIF: Easy REF: 25.2
OBJ: 25.2b List procedures and precautions used to collect specimens from sterile body sites.
MSC: Applying
8. Which of the following would typically be the initial indicator of bacteria growing within a blood
culture tube?
a. An automated incubator will detect fluorescence.
b. Bacterial colonies will appear on blood agar.
c. Bacterial colonies will appear on MacConkey agar.
d. Centrifugation will cause sediment to appear at the end of the tube.
ANS: A DIF: Moderate REF: 25.2
OBJ: 25.2b List procedures and precautions used to collect specimens from sterile body sites.
MSC: Understanding
9. Lumbar puncture is the most common method for obtaining a sample of
a. blood. c. synovial fluid.
b. cerebrospinal fluid. d. peritoneal fluid.
ANS: B DIF: Easy REF: 25.2
OBJ: 25.2b List procedures and precautions used to collect specimens from sterile body sites.
MSC: Understanding
10. Jose is seen for a draining abscess on his left forearm. Which of the following would most likely be
used to collect a sample from this site?
a. needle aspiration c. sputum sample
b. skin scraping d. swab
ANS: D DIF: Easy REF: 25.2
OBJ: 25.2c List procedures used to collect specimens from body sites containing normal microbiota.
MSC: Understanding
, 11. A lab technician intern is asked to apply a 10% KOH (potassium hydroxide) solution on a sample.
There are four patient samples sitting on the lab bench and he is trying to remember which sample
should be treated. Which of the following four samples would require treatment with KOH?
a. a skin scraping from a site suspected to be a fungal infection
b. a nasopharyngeal swab suspected of containing Bordetella pertussis
c. a sputum sample from a patient with tuberculosis
d. a fecal sample from an individual with bloody diarrhea
ANS: A DIF: Difficult REF: 25.2
OBJ: 25.2c List procedures used to collect specimens from body sites containing normal microbiota.
MSC: Analyzing
12. In which of the following scenarios would selective media most likely be used to DECREASE the
number of normal microbiota?
a. A nasopharyngeal swab is used to collect a sample from a young woman with inflamed
tonsils.
b. A midstream clean catch is used to collect urine in a young woman with a suspected
urinary tract infection.
c. Venipuncture is used to collect blood from an elderly man with a possible blood infection.
d. A lumbar puncture is used to collect cerebrospinal fluid from a toddler exhibiting signs of
meningitis.
ANS: A DIF: Moderate REF: 25.2
OBJ: 25.2c List procedures used to collect specimens from body sites containing normal microbiota.
MSC: Evaluating
13. A young child arrives at a local hospital with neck stiffness, nausea, and vomiting. The attending
physician suspects bacterial meningitis and sends a sample of cerebrospinal fluid to the hospital
laboratory. Which of the following actions would most quickly identify the bacterial species?
a. using sequential biochemical tests in which each test dictates the next test
b. carrying out a series of tests simultaneously and then interpreting the tests sequentially
c. plating the species first on selective media to eliminate the number of normal microbiota
d. obtaining a sequence of the patient’s genome to determine his or her susceptibility to
specific microbes
ANS: B DIF: Difficult REF: 25.3
OBJ: 25.3a Explain how biochemical profiles can be used to identify microbial pathogens.
MSC: Analyzing
14. The figure shown illustrates a small portion of an algorithm used to identify Gram-negative rods. This
diagram is referred to as a(n)
