,ATI Microorganism & Infection Assessment Exam Questions And
Answers 2026/2027
1.** A nurse is teaching a client about infection prevention. Which statement
accurately describes the difference between a bacterium and a virus?
A) Bacteria are always harmful, while viruses are beneficial
B) Bacteria are living organisms that can replicate independently, while
viruses require a host cell to replicate
C) Viruses are larger than bacteria and can be seen with a light microscope
D) Bacteria are not affected by antibiotics, while viruses are
**Correct Answer:** B) Bacteria are living organisms that can replicate
independently, while viruses require a host cell to replicate
**Rationale:** Bacteria are prokaryotic, single-celled organisms that can
replicate independently through binary fission. Viruses are acellular particles
that require a living host cell's machinery to replicate. Antibiotics are
effective against bacteria (not viruses), and many bacteria are beneficial or
harmless.
**2.** A nurse is caring for a client with a wound infection. The wound culture
grows *Staphylococcus aureus*. Which of the following best describes this
microorganism?
A) A gram-negative rod
B) A gram-positive coccus
C) A gram-negative coccus
D) A gram-positive rod
**Correct Answer:** B) A gram-positive coccus
,**Rationale:** *Staphylococcus aureus* is a gram-positive, spherical (coccus)
bacterium that grows in clusters. It is a common cause of skin and soft tissue
infections, pneumonia, and bloodstream infections. Gram-negative rods (A)
include *E. coli*; gram-positive rods (D) include *Clostridium* species.
**3.** A nurse is reviewing the chain of infection. Which of the following is an
example of a **reservoir** for infection?
A) A contaminated needle
B) A client with an active tuberculosis infection
C) Droplets from a cough
D) A break in the skin
**Correct Answer:** B) A client with an active tuberculosis infection
**Rationale:** A reservoir is the environment or site where a pathogen lives
and multiplies, such as a human host, animal, or environmental surface. A
client with an active infection serves as a reservoir. A contaminated needle
(A) is a vehicle of transmission, droplets (C) are a mode of transmission, and
a break in the skin (D) is a portal of entry.
**4.** A nurse is teaching a group of nursing students about virulence
factors. Which of the following statements about virulence is correct?
A) Virulence is the ability of a microorganism to cause disease
B) Virulence is the same for all microorganisms
C) Virulence refers to the size of the microorganism
D) Virulence is only relevant for viral infections
, **Correct Answer:** A) Virulence is the ability of a microorganism to cause
disease
**Rationale:** Virulence is the degree of pathogenicity—the ability of a
microorganism to invade a host and cause disease. It varies among different
pathogens and is influenced by factors such as toxins, enzymes, and
adhesion mechanisms.
**5.** A nurse is reviewing the classification of microorganisms. Which of the
following is a **prion**?
A) A type of bacteria that causes tuberculosis
B) An infectious protein particle that causes transmissible spongiform
encephalopathies
C) A single-celled fungus that causes yeast infections
D) A parasitic worm that causes intestinal infections
**Correct Answer:** B) An infectious protein particle that causes
transmissible spongiform encephalopathies
**Rationale:** Prions are infectious protein particles that lack nucleic acids.
They cause neurodegenerative diseases such as Creutzfeldt-Jakob disease
and variant CJD. They are not bacteria (A), fungi (C), or parasites (D).
**6.** A nurse is assessing a client with a suspected fungal infection. Which
of the following is an example of a fungal infection?
A) Tuberculosis
B) Candidiasis
C) Malaria
Answers 2026/2027
1.** A nurse is teaching a client about infection prevention. Which statement
accurately describes the difference between a bacterium and a virus?
A) Bacteria are always harmful, while viruses are beneficial
B) Bacteria are living organisms that can replicate independently, while
viruses require a host cell to replicate
C) Viruses are larger than bacteria and can be seen with a light microscope
D) Bacteria are not affected by antibiotics, while viruses are
**Correct Answer:** B) Bacteria are living organisms that can replicate
independently, while viruses require a host cell to replicate
**Rationale:** Bacteria are prokaryotic, single-celled organisms that can
replicate independently through binary fission. Viruses are acellular particles
that require a living host cell's machinery to replicate. Antibiotics are
effective against bacteria (not viruses), and many bacteria are beneficial or
harmless.
**2.** A nurse is caring for a client with a wound infection. The wound culture
grows *Staphylococcus aureus*. Which of the following best describes this
microorganism?
A) A gram-negative rod
B) A gram-positive coccus
C) A gram-negative coccus
D) A gram-positive rod
**Correct Answer:** B) A gram-positive coccus
,**Rationale:** *Staphylococcus aureus* is a gram-positive, spherical (coccus)
bacterium that grows in clusters. It is a common cause of skin and soft tissue
infections, pneumonia, and bloodstream infections. Gram-negative rods (A)
include *E. coli*; gram-positive rods (D) include *Clostridium* species.
**3.** A nurse is reviewing the chain of infection. Which of the following is an
example of a **reservoir** for infection?
A) A contaminated needle
B) A client with an active tuberculosis infection
C) Droplets from a cough
D) A break in the skin
**Correct Answer:** B) A client with an active tuberculosis infection
**Rationale:** A reservoir is the environment or site where a pathogen lives
and multiplies, such as a human host, animal, or environmental surface. A
client with an active infection serves as a reservoir. A contaminated needle
(A) is a vehicle of transmission, droplets (C) are a mode of transmission, and
a break in the skin (D) is a portal of entry.
**4.** A nurse is teaching a group of nursing students about virulence
factors. Which of the following statements about virulence is correct?
A) Virulence is the ability of a microorganism to cause disease
B) Virulence is the same for all microorganisms
C) Virulence refers to the size of the microorganism
D) Virulence is only relevant for viral infections
, **Correct Answer:** A) Virulence is the ability of a microorganism to cause
disease
**Rationale:** Virulence is the degree of pathogenicity—the ability of a
microorganism to invade a host and cause disease. It varies among different
pathogens and is influenced by factors such as toxins, enzymes, and
adhesion mechanisms.
**5.** A nurse is reviewing the classification of microorganisms. Which of the
following is a **prion**?
A) A type of bacteria that causes tuberculosis
B) An infectious protein particle that causes transmissible spongiform
encephalopathies
C) A single-celled fungus that causes yeast infections
D) A parasitic worm that causes intestinal infections
**Correct Answer:** B) An infectious protein particle that causes
transmissible spongiform encephalopathies
**Rationale:** Prions are infectious protein particles that lack nucleic acids.
They cause neurodegenerative diseases such as Creutzfeldt-Jakob disease
and variant CJD. They are not bacteria (A), fungi (C), or parasites (D).
**6.** A nurse is assessing a client with a suspected fungal infection. Which
of the following is an example of a fungal infection?
A) Tuberculosis
B) Candidiasis
C) Malaria
