Question 1

Which of the following figure represents a spirochete?

Accepted Answer

Bacteria that are spiral are called spirochetes.The others are designated as follows: (A)streptococci,(B)diplococci,and (D)vibrio.

Question 2

Commercial-grade hydrogen peroxide is an effective disinfectant at room temperature after how many minutes?

Accepted Answer

Commercially available 3% solutions of hydrogen peroxide are effective disinfectants of bacteria (including Mycobacteria sp.),fungi,and viruses and are active within 10 minutes at room temperature.

Question 3

Which of the following should routinely be used to ensure proper function and quality control of an autoclave?
1)Pressure-sensitive tape
2)Biologic indicators
3)Chemical indicators
4)Heat-sensitive tape

Accepted Answer

Because the process of autoclaving depends on several factors,heat-sensitive tape and biologic indicators are routinely used to ensure quality control during the process.Heat-sensitive tape that is used for packaging materials for autoclaving changes color when it is exposed to a given temperature for a prescribed amount of time.The most common biologic indicators for autoclaving are strips of paper that are impregnated with Bacillus stearothermophilus spores.These strips should be used weekly (at a minimum)to ensure that the autoclave is working properly.Biologic indicators are also used for ethylene oxide sterilization.

Question 4

Which of the following illnesses requires airborne precautions?

Accepted Answer

Airborne precautions should be used for patients who are known to have or who are suspected of having illnesses transmitted by airborne droplet nuclei,such as measles,varicella,or tuberculosis.Clostridium difficile and the herpes simplex virus require contact isolation,because they are transmitted by direct patient contact or by contact with items in the patient's environment.Mycoplasma pneumoniae requires droplet precautions because it is spread by droplet transmission.

Question 5

Dry-heat sterilization involves a 1-hour to 2-hour exposure at approximately:

Accepted Answer

Dry heat is another effective method of heat sterilization.Its use is limited to items that are not heat-sensitive.Temperatures must be maintained between 160° C and 180° C for 1 to 2 hours for sterilization.

Question 6

Which of the following indicates the minimum time a tracheostomy inner cannula should be soaked in 3% hydrogen peroxide to be an effective disinfectant during a patient's tracheostomy care?

Accepted Answer

Commercially available 3% solutions of hydrogen peroxide are effective disinfectants of bacteria (including Mycobacteria sp.),fungi,and viruses and are active within 10 minutes at room temperature.To be effective against spores,the solution would need to be at 50° C and the equipment would need to be soaked for at least 20 minutes.

Question 7

A Gram stain leaves the following organism violet.Which pathogen could this be?

Accepted Answer

Streptococcus pneumoniae are gram-negative spheres that occur in chains. Escherichia coli are gram-negative and rod-shaped.Bacillus anthracis are gram-positive and rod-shaped.Staphylococus aureus are gram-positive spheres that occur in irregular clusters.

Question 8

Which of the following physical properties are required for an autoclave to sterilize biohazardous material?
1)Dry heat
2)A vacuum
3)100% humidity
4)Increased air pressure

Accepted Answer

Air is evacuated,moisture is added (100% humidity),and the pressure inside the autoclave is raised to 15 to 20 lb-force per square inch gauge (psig).Air is evacuated from the chamber because residual air prolongs the penetration time of steam,thus increasing the total autoclave cycle time.Pressure is used to raise the temperature of the steam,which is critical because the amount of time required to achieve sterilization depends on the temperature inside of the autoclave.Dry heat is not used during autoclaving.

Question 9

Which isolation precaution requires the patient to be placed in a private isolation room?

Accepted Answer

Airborne precautions have two major components: (1)placement of the infected patient in an area with appropriate air-handling and ventilation and (2)use of respiratory protective equipment by health care workers and visitors entering the patient's room.In cases in which an infected patient must be transported,the patient should wear a surgical mask to minimize dispersal of droplet nuclei.Current standards require that infected patients be placed in a private,negative-pressure isolation room.Negative air pressure within the room should be monitored relative to other areas of the hospital.Severe acute respiratory syndrome,measles,chicken pox (primary varicella zoster virus),and tuberculosis are illnesses that require airborne precautions.

Question 10

The Centers for Disease Control and Prevention recommends a _____ dilution of bleach to water to clean up blood spills.

Accepted Answer

The Centers for Disease Control and Prevention recommends that a 1:10 dilution of sodium hypochlorite be used to clean up blood spills.

Question 11

Which type of germicide requires activation with bicarbonate?

Accepted Answer

Only alkaline glutaraldehyde requires activation with a bicarbonate solution.This yields a solution with a pH of 7.5 to 8.5.

Question 12

According to the classification of infection-risk devices described by Spaulding,ventilator tubing is considered:

Accepted Answer

Ventilator tubing comes in contact with intact mucous membranes and is considered semicritical.Critical items are those that are introduced into sterile tissue or the vascular system.Noncritical items come in contact with intact skin.Noncritical items include face masks,ventilators,stethoscopes,and blood pressure cuffs.Highly critical is not a descriptor that Spaulding used.

Question 13

Which of these precautions must be followed in the treatment of a patient with an influenza infection?
1)Contact
2)Droplet
3)Airborne
4)Standard

Accepted Answer

Standard precautions need to be used for all patients.Droplet precautions are used for patients known or suspected to have serious illnesses transmitted by large-particle droplets.Influenza is a serious viral infection spread by droplet transmission.Contact isolation is used for patients known or suspected to have serious illnesses easily transmitted by direct patient contact or by contact with items in the patient's environment.Airborne precautions should be used for patients who are known or suspected to have illnesses transmitted by airborne droplet nuclei,such as measles,varicella,or tuberculosis.

Question 14

The below figure represents which of the following bacteria?

Accepted Answer

Cocci that occur in irregular clusters are called staphylococci.A bacillus is rod-shaped; a diplococcus is paired,sphere-shaped bacteria; and a streptococcus is a chain of cocci.

Question 15

At high altitudes,sterilization by boiling must be prolonged primarily because of which of the following?

Accepted Answer

Because water boils at a lower temperature at high altitudes,exposure time must be prolonged during this form of sterilization at high elevations.

Question 16

According to the classification described by Spaulding,which of the following items of medical equipment fall into the category of noncritical infection risk?

Accepted Answer

Noncritical items come in contact with intact skin.These items include face masks,ventilators,stethoscopes,and blood pressure cuffs.Scalpels are introduced into sterile tissue and are considered critical items.Ventilator tubing and manual resuscitators come in contact with intact mucous membranes and are considered semicritical.

Question 17

In preparation for an arterial blood gas puncture on a noninfectious patient in the pulmonary laboratory,which of the following items of protective apparel should be used?
1)Gown
2)Gloves
3)Shoe covers
4)Eye protection

Accepted Answer

The least amount of protective apparel that should be worn when drawing an arterial blood gas includes gloves and eye protection.In the case of a patient in isolation,a gown should be worn if there is a chance of splashing blood.Shoe covers are not necessary in areas outside of the operating rooms.

Question 18

Which of the following is the most important infection control procedure for anyone who has direct patient contact?

Accepted Answer

Hand-washing is the most important prevention strategy to protect health care workers from being infected through contact with infected patients.It also reduces the risk of health care workers transmitting infectious microorganisms from one patient to another or from a contaminated site to a clean site on the same patient.Sterile gloves are worn during invasive procedures.Disposal of sharps is important when any sharps (e.g.,needles)are used.Face masks need to be worn when there is a possibility of blood or body fluid being splashed or sprayed,such as during an arterial blood gas stick.

Question 19

Droplet isolation precautions call for all of the following,except:

Accepted Answer

Droplet precautions include masks,gloves,and protective eyewear but not special air-handling.

Question 20

A 1.25% solution of acetic acid has been shown to be an effective bactericidal agent against:

Accepted Answer

Pseudomonas aeruginosa is killed by 1.25% acetic acid or one part 5% white household vinegar and three parts water.Pseudomonas aeruginosa transmission is through indirect contact via fomites,such as those on clothing,surgical bandages,and especially equipment.It is the most common respiratory pathogen in patients with cystic fibrosis and is encountered in patients with chronic obstructive pulmonary disease.

Quiz 2: Principles of Infection Control