CIC Practice Questions: Identification of Infectious
Disease Processes & Answers | Comprehensive
Certification Review With Detailed Rationales,
Infection Prevention & Control Principles,
Epidemiology, Transmission-Based Precautions, Signs
& Symptoms, Diagnostic Testing, Outbreak
Investigation, Surveillance, Isolation Practices &
Scenario-Based Questions
Question 1
A patient was hospitalized for 2 days and calls 3 days after discharge, complaining
that he has developed healthcare-associated scabies due to his recent inpatient
stay. The Infection Preventionist (IP) knows that his scabies infestation is NOT
healthcare-associated because:
A. Scabies is only transmitted through contaminated linens, and the IP confirmed that all
linens the patient came into contact with had been properly laundered
B. the incubation period for scabies is longer than 5 days
C. the incubation period for scabies is shorter than 3 days
D. Scabies is only transmitted through direct contact and none of the healthcare
personnel who cared for the patient are infested
Answer: B. the incubation period for scabies is longer than 5 days
Rationale: The incubation period for a first-time scabies infestation is typically 2-6
weeks (14-42 days) before symptoms appear. In a previously infested person, symptoms
can appear in 1-4 days due to hypersensitivity. A 3-day post-discharge presentation (5
days total from admission) is too soon for a primary infestation to be attributed to the
healthcare stay. Scabies is primarily transmitted through prolonged direct skin-to-skin
contact, not through linens, making options A and D incorrect as stated.
,Question 2
The causative organism of Creutzfeldt-Jakob disease (CJD) is a:
A. helminth
B. diphtheroid
C. spirochete
D. prion
Answer: D. prion
Rationale: Creutzfeldt-Jakob disease is caused by a prion—an abnormally folded
protein that induces other proteins to misfold. Prions are unique infectious agents that
contain no nucleic acid (DNA or RNA). They are highly resistant to standard sterilization
methods (autoclaving at 121°C is insufficient; 134°C for 18 minutes or 132°C for 1 hour
is recommended). CJD is not caused by a bacterium, virus, helminth, or spirochete. Prion
diseases are transmissible spongiform encephalopathies (TSEs).
Question 3
Which of the following is TRUE about a tuberculin skin test (TST):
A. Positive TST indicates active tuberculosis (TB) infection
B. Negative TST rules out active TB infection
C. Positive TST indicates past exposure to TB
D. Negative TST indicates past exposure to TB
Answer: C. Positive TST indicates past exposure to TB
Rationale: A positive TST indicates that a person has been infected with Mycobacterium
tuberculosis at some point (latent TB infection or LTBI) but does not distinguish between
latent infection and active disease. To determine active TB disease, chest X-ray,
symptom assessment, and sputum culture are required. A negative TST does NOT rule
out active TB, especially in immunosuppressed individuals (false negatives are common
in HIV/AIDS or severe TB). This is a critical concept for infection preventionists to
understand when screening healthcare workers and patients.
,Question 4
The optimal time to collect a sputum specimen for acid-fast bacilli (AFB) testing to
rule out TB would be:
A. First thing in the morning
B. After a respiratory treatment
C. Prior to the patient going to bed
D. Prior to a respiratory treatment
Answer: A. First thing in the morning
Rationale: Morning specimens are preferred for AFB culture because mycobacteria are
concentrated overnight in the lower respiratory tract. The specimen should be collected
before the patient eats, drinks, or brushes their teeth to minimize contamination. Three
consecutive morning sputum specimens are typically collected on different days for
optimal sensitivity.
Question 5
A 14-year-old boy from rural Maryland was seen in the emergency department
with fever, fatigue, chills, headache, and a large annular lesion on his left thigh.
What is the most probable vector of this child's illness?
A. tick
B. mosquito
C. flea
D. louse
Answer: A. tick
Rationale: The presentation is classic for Lyme disease caused by Borrelia burgdorferi.
The large annular lesion is erythema migrans (the classic "bull's-eye" rash). The tick
vector is Ixodes scapularis (deer tick or black-legged tick), which is endemic in the
northeastern United States, including Maryland. Early localized Lyme disease presents
with fever, fatigue, headache, and erythema migrans at the site of the tick bite.
, Question 6
A patient is newly diagnosed with secondary syphilis and has no known drug
allergies. Which of the following is the preferred treatment for treating patients in
all stages of syphilis?
A. Azithromycin
B. Penicillin G
C. Rifampin
D. Clindamycin
Answer: B. Penicillin G
Rationale: Penicillin G is the treatment of choice for all stages of syphilis. For primary,
secondary, and early latent syphilis, the regimen is Benzathine penicillin G 2.4 million
units IM as a single dose. For late latent or tertiary syphilis, 3 doses at weekly intervals
are recommended. Azithromycin is not recommended due to resistance. Patients with
penicillin allergy require desensitization, as there is no equally effective alternative for
treating syphilis during pregnancy (to prevent congenital syphilis).
Question 7
What is the causative agent of syphilis?
A. Human Papilloma Virus
B. Chlamydia trachomatis
C. Treponema pallidum
D. Neisseria gonorrhoeae
Answer: C. Treponema pallidum
Rationale: Syphilis is caused by the spirochete bacterium Treponema pallidum. It is a
highly motile, spiral-shaped bacterium that cannot be cultured on artificial media.
Darkfield microscopy is used for direct visualization from primary or secondary lesions.
This distinguishes it from viral causes (HPV), chlamydia, or gonorrhea.
Disease Processes & Answers | Comprehensive
Certification Review With Detailed Rationales,
Infection Prevention & Control Principles,
Epidemiology, Transmission-Based Precautions, Signs
& Symptoms, Diagnostic Testing, Outbreak
Investigation, Surveillance, Isolation Practices &
Scenario-Based Questions
Question 1
A patient was hospitalized for 2 days and calls 3 days after discharge, complaining
that he has developed healthcare-associated scabies due to his recent inpatient
stay. The Infection Preventionist (IP) knows that his scabies infestation is NOT
healthcare-associated because:
A. Scabies is only transmitted through contaminated linens, and the IP confirmed that all
linens the patient came into contact with had been properly laundered
B. the incubation period for scabies is longer than 5 days
C. the incubation period for scabies is shorter than 3 days
D. Scabies is only transmitted through direct contact and none of the healthcare
personnel who cared for the patient are infested
Answer: B. the incubation period for scabies is longer than 5 days
Rationale: The incubation period for a first-time scabies infestation is typically 2-6
weeks (14-42 days) before symptoms appear. In a previously infested person, symptoms
can appear in 1-4 days due to hypersensitivity. A 3-day post-discharge presentation (5
days total from admission) is too soon for a primary infestation to be attributed to the
healthcare stay. Scabies is primarily transmitted through prolonged direct skin-to-skin
contact, not through linens, making options A and D incorrect as stated.
,Question 2
The causative organism of Creutzfeldt-Jakob disease (CJD) is a:
A. helminth
B. diphtheroid
C. spirochete
D. prion
Answer: D. prion
Rationale: Creutzfeldt-Jakob disease is caused by a prion—an abnormally folded
protein that induces other proteins to misfold. Prions are unique infectious agents that
contain no nucleic acid (DNA or RNA). They are highly resistant to standard sterilization
methods (autoclaving at 121°C is insufficient; 134°C for 18 minutes or 132°C for 1 hour
is recommended). CJD is not caused by a bacterium, virus, helminth, or spirochete. Prion
diseases are transmissible spongiform encephalopathies (TSEs).
Question 3
Which of the following is TRUE about a tuberculin skin test (TST):
A. Positive TST indicates active tuberculosis (TB) infection
B. Negative TST rules out active TB infection
C. Positive TST indicates past exposure to TB
D. Negative TST indicates past exposure to TB
Answer: C. Positive TST indicates past exposure to TB
Rationale: A positive TST indicates that a person has been infected with Mycobacterium
tuberculosis at some point (latent TB infection or LTBI) but does not distinguish between
latent infection and active disease. To determine active TB disease, chest X-ray,
symptom assessment, and sputum culture are required. A negative TST does NOT rule
out active TB, especially in immunosuppressed individuals (false negatives are common
in HIV/AIDS or severe TB). This is a critical concept for infection preventionists to
understand when screening healthcare workers and patients.
,Question 4
The optimal time to collect a sputum specimen for acid-fast bacilli (AFB) testing to
rule out TB would be:
A. First thing in the morning
B. After a respiratory treatment
C. Prior to the patient going to bed
D. Prior to a respiratory treatment
Answer: A. First thing in the morning
Rationale: Morning specimens are preferred for AFB culture because mycobacteria are
concentrated overnight in the lower respiratory tract. The specimen should be collected
before the patient eats, drinks, or brushes their teeth to minimize contamination. Three
consecutive morning sputum specimens are typically collected on different days for
optimal sensitivity.
Question 5
A 14-year-old boy from rural Maryland was seen in the emergency department
with fever, fatigue, chills, headache, and a large annular lesion on his left thigh.
What is the most probable vector of this child's illness?
A. tick
B. mosquito
C. flea
D. louse
Answer: A. tick
Rationale: The presentation is classic for Lyme disease caused by Borrelia burgdorferi.
The large annular lesion is erythema migrans (the classic "bull's-eye" rash). The tick
vector is Ixodes scapularis (deer tick or black-legged tick), which is endemic in the
northeastern United States, including Maryland. Early localized Lyme disease presents
with fever, fatigue, headache, and erythema migrans at the site of the tick bite.
, Question 6
A patient is newly diagnosed with secondary syphilis and has no known drug
allergies. Which of the following is the preferred treatment for treating patients in
all stages of syphilis?
A. Azithromycin
B. Penicillin G
C. Rifampin
D. Clindamycin
Answer: B. Penicillin G
Rationale: Penicillin G is the treatment of choice for all stages of syphilis. For primary,
secondary, and early latent syphilis, the regimen is Benzathine penicillin G 2.4 million
units IM as a single dose. For late latent or tertiary syphilis, 3 doses at weekly intervals
are recommended. Azithromycin is not recommended due to resistance. Patients with
penicillin allergy require desensitization, as there is no equally effective alternative for
treating syphilis during pregnancy (to prevent congenital syphilis).
Question 7
What is the causative agent of syphilis?
A. Human Papilloma Virus
B. Chlamydia trachomatis
C. Treponema pallidum
D. Neisseria gonorrhoeae
Answer: C. Treponema pallidum
Rationale: Syphilis is caused by the spirochete bacterium Treponema pallidum. It is a
highly motile, spiral-shaped bacterium that cannot be cultured on artificial media.
Darkfield microscopy is used for direct visualization from primary or secondary lesions.
This distinguishes it from viral causes (HPV), chlamydia, or gonorrhea.
