Infection control principles Practice Questions
20 free Infection control principles practice questions for the USMLE Step 1. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
A healthcare worker performs hand hygiene after removing gloves. Which statement best explains why this step is necessary?
- A Gloves are sterile and cannot transmit infection
- B Gloves may tear or become contaminated during removal
- C Hand hygiene is only required before patient contact
- D Alcohol-based sanitizer is unnecessary after glove removal
Correct answer: Gloves may tear or become contaminated during removal
Gloves may have small tears or contamination during removal. Hand hygiene after glove use ensures removal of any pathogens that may have contacted the skin.
Which method is most effective at inactivating bacterial spores on surgical instruments?
- A Alcohol-based surface disinfectant
- B Prolonged boiling in water
- C Autoclaving under pressure
- D Ultraviolet light exposure
Correct answer: Autoclaving under pressure
Autoclaving uses high pressure and temperature to reliably destroy all microorganisms, including resistant spores. Other methods are insufficient for sterilization.
A patient with Clostridioides difficile infection is placed on which type of precautions?
- A Airborne precautions
- B Contact precautions
- C Droplet precautions
- D Standard precautions only
Correct answer: Contact precautions
C. difficile forms spores that are resistant to alcohol-based sanitizers. Contact precautions and soap-and-water handwashing are required.
Which pathogen requires airborne precautions in a hospital setting?
- A Influenza virus
- B RSV
- C Mycobacterium tuberculosis
- D Staphylococcus aureus
Correct answer: Mycobacterium tuberculosis
Mycobacterium tuberculosis is transmitted via airborne particles. Airborne precautions use N95 respirators and negative-pressure rooms.
A patient with suspected meningococcal meningitis should be placed under which precautions?
- A Contact precautions
- B Airborne precautions
- C Droplet precautions
- D Enteric precautions
Correct answer: Droplet precautions
N. meningitidis is transmitted via large respiratory droplets. Droplet precautions help prevent spread during close contact.
A nurse touches a contaminated wound and then adjusts her face mask without performing hand hygiene. Which type of transmission is most likely?
- A Droplet respiratory transmission
- B Airborne particle transmission
- C Indirect contact transmission
- D Self-inoculation via hands
Correct answer: Self-inoculation via hands
Touching the face with contaminated hands can introduce pathogens to mucous membranes. This is a common mechanism of self-inoculation.
Which disinfectant is most effective against enveloped viruses such as influenza?
- A Alcohol-based agents
- B Soap and water only
- C Chlorinated water
- D Dry heat at low temperature
Correct answer: Alcohol-based agents
Alcohol disrupts lipid envelopes, making enveloped viruses highly susceptible. This is why alcohol-based sanitizers are effective against influenza.
Which scenario requires sterilization rather than disinfection?
- A Cleaning a reusable blood pressure cuff
- B Cleaning surgical instruments
- C Cleaning a hospital bed rail
- D Cleaning a shared stethoscope
Correct answer: Cleaning surgical instruments
Surgical instruments enter sterile body spaces and therefore require sterilization. Disinfection is insufficient for invasive devices.
A healthcare worker caring for a patient with MRSA should use which precautions?
- A Airborne precautions
- B Droplet precautions
- C Contact precautions
- D Enteric precautions
Correct answer: Contact precautions
MRSA is primarily spread via direct or indirect contact. Contact precautions prevent cross-contamination and spread.
A patient with varicella (chickenpox) is admitted. What combination of precautions is required?
- A Droplet and contact
- B Airborne and contact
- C Contact only
- D Standard precautions only
Correct answer: Airborne and contact
Varicella is highly contagious via airborne droplets and direct contact. Both airborne and contact precautions are necessary.
A nurse recaps a used needle and accidentally sustains a finger-stick injury. What is the most important immediate step?
- A Report the injury to the supervisor
- B Wash the wound with soap and water
- C Start prophylactic antibiotics
- D Apply a sterile bandage immediately
Correct answer: Wash the wound with soap and water
Immediate washing of the wound reduces pathogen load and infection risk. Reporting and follow-up testing occur after initial wound care.
Which type of hand hygiene is required after caring for a patient with norovirus?
- A Alcohol-based sanitizer
- B Soap and water
- C Waterless antiseptic gel
- D Glove use alone
Correct answer: Soap and water
Norovirus is resistant to alcohol-based sanitizers. Soap-and-water washing physically removes viral particles.
A hospital wants to reduce central line–associated bloodstream infections. Which intervention is most effective?
- A Routine saline line flushing
- B Maximal barrier precautions
- C Using shorter catheter lines
- D Routine daily line replacement
Correct answer: Maximal barrier precautions
Maximal barrier precautions significantly reduce central line infections. These include sterile gowns, gloves, drapes, and masks.
A patient with active measles is admitted. What preventive measure must all healthcare workers entering the room take?
- A Wear a surgical mask
- B Wear an N95 respirator
- C Wash hands before and after entry only
- D Use face shields
Correct answer: Wear an N95 respirator
Measles spreads via airborne particles. N95 respirators provide the required level of protection.
Which statement best describes standard precautions?
- A Used only for patients with confirmed infections
- B Used for all patients regardless of status
- C Applied only in intensive care units
- D Used only when transmission-based precautions fail
Correct answer: Used for all patients regardless of status
Standard precautions apply to every patient and include hand hygiene, PPE as needed, and safe injection practices. They are universal.
Which organisms are NOT reliably inactivated by alcohol-based hand sanitizers?
- A Enveloped viruses
- B Bacterial spores
- C Gram-negative bacteria
- D Gram-positive bacteria
Correct answer: Bacterial spores
Spores, such as those from C. difficile, resist alcohol-based agents. Soap-and-water handwashing is necessary to remove them.
A patient with suspected pertussis is admitted. Which precautions are needed?
- A Airborne
- B Droplet
- C Contact
- D Enteric
Correct answer: Droplet
Pertussis spreads through large respiratory droplets. Droplet precautions prevent transmission during close contact.
Which of the following items requires high-level disinfection rather than sterilization?
- A Surgical scalpel
- B Endoscope
- C Cardiac pacemaker
- D Implantable orthopedic screw
Correct answer: Endoscope
Endoscopes contact mucous membranes but do not enter sterile body cavities. High-level disinfection is recommended for such devices.
An outbreak of Pseudomonas in a burn unit is traced to contaminated sink drains. What infection control measure is most effective?
- A Increased hand hygiene compliance
- B Sink drain disinfection and redesign
- C Routine systemic antibiotic prophylaxis
- D Less frequent wound dressing changes
Correct answer: Sink drain disinfection and redesign
Moist environments like sinks can harbor Pseudomonas. Environmental controls and disinfection are critical for prevention.
A hospitalized patient with scabies requires what type of precautions?
- A Droplet precautions
- B Airborne precautions
- C Contact precautions
- D Standard precautions only
Correct answer: Contact precautions
Scabies spreads through direct skin contact. Contact precautions prevent transmission to staff and other patients.