2026 Nursing Microbiology Practice Questions
Answer Rationales Bacteria Viruses Fungi
Parasites Pathogens Infection Transmission
Clinical Application Exam Prep
SECTION 1: BACTERIA (Questions 1–30)
1. A nurse is reviewing the characteristics of bacteria. Which statement
accurately describes bacteria?
A. Bacteria are eukaryotic organisms.
B. Bacteria contain a true nucleus.
C. Bacteria are prokaryotic organisms.
D. Bacteria are obligate intracellular parasites.
Rationale: Bacteria are prokaryotic organisms, meaning they lack a true nucleus
and membrane-bound organelles. Their genetic material is contained in a single
circular chromosome. Eukaryotic organisms (fungi, parasites) have a true nucleus.
Viruses are obligate intracellular parasites.
2. A nurse is caring for a client with a wound infection. Which bacterium is
most commonly associated with wound infections?
A. Mycobacterium tuberculosis
B. Staphylococcus aureus
C. Treponema pallidum
D. Bordetella pertussis
Rationale: Staphylococcus aureus is the most common cause of wound infections.
It is a gram-positive cocci that commonly colonizes the skin and can cause
infection when the skin barrier is broken.
,3. A nurse is reviewing the mechanism of action of antibiotics. Which
antibiotic class inhibits bacterial cell wall synthesis?
A. Aminoglycosides
B. Macrolides
C. Penicillins
D. Fluoroquinolones
Rationale: Penicillins inhibit bacterial cell wall synthesis by interfering with
peptidoglycan cross-linking. Aminoglycosides inhibit protein synthesis, macrolides
inhibit protein synthesis, and fluoroquinolones inhibit DNA gyrase.
4. A nurse is caring for a client with a suspected urinary tract infection.
Which bacterium is the most common cause?
A. Staphylococcus aureus
B. Streptococcus pneumoniae
C. Escherichia coli
D. Pseudomonas aeruginosa
Rationale: Escherichia coli (E. coli) is the most common cause of urinary tract
infections, accounting for approximately 80% of cases. It is a gram-negative rod
that normally resides in the gastrointestinal tract.
5. A nurse is teaching a client about antibiotic resistance. Which statement
indicates understanding?
A. "Antibiotics work against viruses."
B. "Taking antibiotics incorrectly can lead to resistance."
C. "Antibiotic resistance is not a concern."
D. "I should stop antibiotics when I feel better."
Rationale: Taking antibiotics incorrectly, such as skipping doses or stopping early,
can lead to antibiotic resistance. Antibiotics do not work against viruses. Clients
should complete the full course as prescribed.
,6. A nurse is reviewing the gram stain results of a bacterial culture. Which
color indicates gram-positive bacteria?
A. Pink
B. Red
C. Purple
D. Green
Rationale: Gram-positive bacteria retain the crystal violet stain and appear purple
under the microscope. Gram-negative bacteria do not retain the crystal violet stain
and appear pink or red after counterstaining with safranin.
7. A nurse is caring for a client with tuberculosis. Which type of bacterium
causes tuberculosis?
A. Gram-positive cocci
B. Gram-negative rod
C. Acid-fast bacillus
D. Spirochete
Rationale: Mycobacterium tuberculosis is an acid-fast bacillus. It has a waxy cell
wall containing mycolic acid, which makes it resistant to Gram staining and
requires acid-fast staining for identification.
8. A nurse is reviewing the mode of action of antibiotics. Which antibiotic
class inhibits protein synthesis?
A. Penicillins
B. Cephalosporins
C. Aminoglycosides
D. Vancomycin
, Rationale: Aminoglycosides inhibit protein synthesis by binding to the 30S
ribosomal subunit. Penicillins, cephalosporins, and vancomycin inhibit cell wall
synthesis.
9. A nurse is caring for a client with a Clostridioides difficile infection. Which
finding is most characteristic?
A. Bloody diarrhea
B. Watery diarrhea with a foul odor
C. Constipation
D. Bloody emesis
Rationale: Clostridioides difficile infection typically presents with watery
diarrhea, often with a characteristic foul odor. It is associated with recent antibiotic
use and can cause pseudomembranous colitis.
10. A nurse is teaching a client about preventing foodborne illness. Which
bacterium is commonly associated with undercooked poultry?
A. Staphylococcus aureus
B. Escherichia coli
C. Salmonella
D. Clostridium botulinum
Rationale: Salmonella is commonly associated with undercooked poultry, eggs,
and meat. It causes gastroenteritis with diarrhea, fever, and abdominal cramps.
11. A nurse is reviewing the characteristics of bacterial spores. Which
statement is accurate?
A. Spores are easily killed by antibiotics.
B. Spores are highly resistant to heat and disinfectants.
Answer Rationales Bacteria Viruses Fungi
Parasites Pathogens Infection Transmission
Clinical Application Exam Prep
SECTION 1: BACTERIA (Questions 1–30)
1. A nurse is reviewing the characteristics of bacteria. Which statement
accurately describes bacteria?
A. Bacteria are eukaryotic organisms.
B. Bacteria contain a true nucleus.
C. Bacteria are prokaryotic organisms.
D. Bacteria are obligate intracellular parasites.
Rationale: Bacteria are prokaryotic organisms, meaning they lack a true nucleus
and membrane-bound organelles. Their genetic material is contained in a single
circular chromosome. Eukaryotic organisms (fungi, parasites) have a true nucleus.
Viruses are obligate intracellular parasites.
2. A nurse is caring for a client with a wound infection. Which bacterium is
most commonly associated with wound infections?
A. Mycobacterium tuberculosis
B. Staphylococcus aureus
C. Treponema pallidum
D. Bordetella pertussis
Rationale: Staphylococcus aureus is the most common cause of wound infections.
It is a gram-positive cocci that commonly colonizes the skin and can cause
infection when the skin barrier is broken.
,3. A nurse is reviewing the mechanism of action of antibiotics. Which
antibiotic class inhibits bacterial cell wall synthesis?
A. Aminoglycosides
B. Macrolides
C. Penicillins
D. Fluoroquinolones
Rationale: Penicillins inhibit bacterial cell wall synthesis by interfering with
peptidoglycan cross-linking. Aminoglycosides inhibit protein synthesis, macrolides
inhibit protein synthesis, and fluoroquinolones inhibit DNA gyrase.
4. A nurse is caring for a client with a suspected urinary tract infection.
Which bacterium is the most common cause?
A. Staphylococcus aureus
B. Streptococcus pneumoniae
C. Escherichia coli
D. Pseudomonas aeruginosa
Rationale: Escherichia coli (E. coli) is the most common cause of urinary tract
infections, accounting for approximately 80% of cases. It is a gram-negative rod
that normally resides in the gastrointestinal tract.
5. A nurse is teaching a client about antibiotic resistance. Which statement
indicates understanding?
A. "Antibiotics work against viruses."
B. "Taking antibiotics incorrectly can lead to resistance."
C. "Antibiotic resistance is not a concern."
D. "I should stop antibiotics when I feel better."
Rationale: Taking antibiotics incorrectly, such as skipping doses or stopping early,
can lead to antibiotic resistance. Antibiotics do not work against viruses. Clients
should complete the full course as prescribed.
,6. A nurse is reviewing the gram stain results of a bacterial culture. Which
color indicates gram-positive bacteria?
A. Pink
B. Red
C. Purple
D. Green
Rationale: Gram-positive bacteria retain the crystal violet stain and appear purple
under the microscope. Gram-negative bacteria do not retain the crystal violet stain
and appear pink or red after counterstaining with safranin.
7. A nurse is caring for a client with tuberculosis. Which type of bacterium
causes tuberculosis?
A. Gram-positive cocci
B. Gram-negative rod
C. Acid-fast bacillus
D. Spirochete
Rationale: Mycobacterium tuberculosis is an acid-fast bacillus. It has a waxy cell
wall containing mycolic acid, which makes it resistant to Gram staining and
requires acid-fast staining for identification.
8. A nurse is reviewing the mode of action of antibiotics. Which antibiotic
class inhibits protein synthesis?
A. Penicillins
B. Cephalosporins
C. Aminoglycosides
D. Vancomycin
, Rationale: Aminoglycosides inhibit protein synthesis by binding to the 30S
ribosomal subunit. Penicillins, cephalosporins, and vancomycin inhibit cell wall
synthesis.
9. A nurse is caring for a client with a Clostridioides difficile infection. Which
finding is most characteristic?
A. Bloody diarrhea
B. Watery diarrhea with a foul odor
C. Constipation
D. Bloody emesis
Rationale: Clostridioides difficile infection typically presents with watery
diarrhea, often with a characteristic foul odor. It is associated with recent antibiotic
use and can cause pseudomembranous colitis.
10. A nurse is teaching a client about preventing foodborne illness. Which
bacterium is commonly associated with undercooked poultry?
A. Staphylococcus aureus
B. Escherichia coli
C. Salmonella
D. Clostridium botulinum
Rationale: Salmonella is commonly associated with undercooked poultry, eggs,
and meat. It causes gastroenteritis with diarrhea, fever, and abdominal cramps.
11. A nurse is reviewing the characteristics of bacterial spores. Which
statement is accurate?
A. Spores are easily killed by antibiotics.
B. Spores are highly resistant to heat and disinfectants.
