Microbiology: Nosocomial Infections 2023 Practice
Questions and Answers with complete solution
What is the best method of decreasing the spread of nosocomial infection?
Hand washing between patients is main key to stopping the spread of infection.
What are the associated problems with nosocomial infections?
1. The risk of death approximately doubles in patients who acquire hospital infection.
2. Increased morbidity: Increase length of hospital stay, leads to more complications
and disability
3. Hospital-acquired infections are very expensive and
contribute significantly to escalating costs (for hospitals).
What is the definition of a nosocomial infection?
An infection NOT present when a patient entered the hospital, most nosocomial
bacterial infections become evident at after 72 hours (a typical incubation period) after
admission. Therefore infections appearing for the first time at 72+ hours are nosocomial
in nature unless proven otherwise. Exceptions include chronic conditions like TB, where
the lesions don't become evident until long after.
What is an endemic infection?
1. Those infections occurring as part of the normal background of infections in a
community.
2. The usual low sporadic rate of infection in a specified population.
What is an epidemic infection?
It's an "Outbreak" with a higher number of infections than the usual rate of infection in
the specified population.
What is the prevalence rate?
It is the total number of cases of infection in the defined population at risk during a
specific time period:
1. Point prevalence: Case count taken at one instant point in time (snapshot).
2. Period prevalence: Case count taken over a given time span such as a year or month
or season.
What is the attributable mortality rate?
It's the ratio of the number of patients who die as a direct result of the disease of interest
to the overall population with the disease. Example: 1 death due to influence / 100
cases of influenza = 1% mortality.
What is the device-associated incidence rate?
Ratio of the number of new cases of device-related infection to the number of days of
device utilization in the population at risk.
• ex. 0.6 infections / 100 device use days
What are two conditions that are NOT infections?
1. Colonization
2. Simple tissue inflammation
What is colonization?
Presence of superficial microbes on skin, mucous membranes, open wounds or
secretions that are not causing clinical symptoms.
What is simple tissue inflammation?
, Tissue response to injury or stimulation by noninfectious agents such as chemicals or
physical stress.
What aspects of the hospital should be targeted for surveillance?
1. Special patient populations: Surgical, pediatric, ICU
2. Medical procedures: Diagnostic and therapeutic
3. Specific pathogens: S. aureus, MRSA, C. difficile
4. Specific areas of the hospital: common air, water, etc.
What are the methods of spread of nosocomial infections?
- Direct contact
- Indirect contact
- Droplet contact
- Airborne contact
- Vector-borne contact
Give an example of direct nosocomial disease spread.
Examples include contaminated food or IV solutions.
Give an example of indirect nosocomial disease spread.
Disease can be transmitted from patient to patient on the hands of health care workers
(MRSA and rotavirus).
Give an example of droplet contact nosocomial disease spread.
It involves inhalation of larger droplets 5+ um in diameter, that cannot travel more than
three feet from person to person. (Pertussis)
Give an example of airborne nosocomial disease spread.
It involves inhalation of droplets less than 5 um in diameter that can travel large
distances on air currents (like tuberculosis).
Give an example of vector-borne nosocomial disease spread.
It includes disease spread by vectors such as mosquitoes (malaria), rats, fleas, body
lice, etc. This mode of transmission, while rare in hospitals in developed countries, may
be encountered in conditions of war, famine, and disaster.
When should standard precautions be taken for protection?
These precautions require that protective protocols be followed whenever contact is
made with blood or body secretions, excretions, body fluids (with the exception of
sweat), broken skin, and mucous membranes.
What are the guidelines for standard safety precautions?
1. Gloves when touching any body fluids, mucous membranes, and non-intact skin.
2. Gowns and face protection, such as masks and goggles, or face shields, should be
worn whenever there is a danger of splashing liquids or creating aerosols during a
specific procedure or process.
3. Hand washing!!
Describe contact precautions for safety.
• Wearing gloves when making contact with the patient's skin or with inanimate objects
that have been in direct contact with the patient.
• Use of gowns when there is a likelihood that the healthcare worker's clothing will come
in contact with the patient or items in the patient's room.
• Used for patients with highly antibiotic-resistant bacteria or organisms causing wound
infections.
What, generally, are airborne precautions?
Questions and Answers with complete solution
What is the best method of decreasing the spread of nosocomial infection?
Hand washing between patients is main key to stopping the spread of infection.
What are the associated problems with nosocomial infections?
1. The risk of death approximately doubles in patients who acquire hospital infection.
2. Increased morbidity: Increase length of hospital stay, leads to more complications
and disability
3. Hospital-acquired infections are very expensive and
contribute significantly to escalating costs (for hospitals).
What is the definition of a nosocomial infection?
An infection NOT present when a patient entered the hospital, most nosocomial
bacterial infections become evident at after 72 hours (a typical incubation period) after
admission. Therefore infections appearing for the first time at 72+ hours are nosocomial
in nature unless proven otherwise. Exceptions include chronic conditions like TB, where
the lesions don't become evident until long after.
What is an endemic infection?
1. Those infections occurring as part of the normal background of infections in a
community.
2. The usual low sporadic rate of infection in a specified population.
What is an epidemic infection?
It's an "Outbreak" with a higher number of infections than the usual rate of infection in
the specified population.
What is the prevalence rate?
It is the total number of cases of infection in the defined population at risk during a
specific time period:
1. Point prevalence: Case count taken at one instant point in time (snapshot).
2. Period prevalence: Case count taken over a given time span such as a year or month
or season.
What is the attributable mortality rate?
It's the ratio of the number of patients who die as a direct result of the disease of interest
to the overall population with the disease. Example: 1 death due to influence / 100
cases of influenza = 1% mortality.
What is the device-associated incidence rate?
Ratio of the number of new cases of device-related infection to the number of days of
device utilization in the population at risk.
• ex. 0.6 infections / 100 device use days
What are two conditions that are NOT infections?
1. Colonization
2. Simple tissue inflammation
What is colonization?
Presence of superficial microbes on skin, mucous membranes, open wounds or
secretions that are not causing clinical symptoms.
What is simple tissue inflammation?
, Tissue response to injury or stimulation by noninfectious agents such as chemicals or
physical stress.
What aspects of the hospital should be targeted for surveillance?
1. Special patient populations: Surgical, pediatric, ICU
2. Medical procedures: Diagnostic and therapeutic
3. Specific pathogens: S. aureus, MRSA, C. difficile
4. Specific areas of the hospital: common air, water, etc.
What are the methods of spread of nosocomial infections?
- Direct contact
- Indirect contact
- Droplet contact
- Airborne contact
- Vector-borne contact
Give an example of direct nosocomial disease spread.
Examples include contaminated food or IV solutions.
Give an example of indirect nosocomial disease spread.
Disease can be transmitted from patient to patient on the hands of health care workers
(MRSA and rotavirus).
Give an example of droplet contact nosocomial disease spread.
It involves inhalation of larger droplets 5+ um in diameter, that cannot travel more than
three feet from person to person. (Pertussis)
Give an example of airborne nosocomial disease spread.
It involves inhalation of droplets less than 5 um in diameter that can travel large
distances on air currents (like tuberculosis).
Give an example of vector-borne nosocomial disease spread.
It includes disease spread by vectors such as mosquitoes (malaria), rats, fleas, body
lice, etc. This mode of transmission, while rare in hospitals in developed countries, may
be encountered in conditions of war, famine, and disaster.
When should standard precautions be taken for protection?
These precautions require that protective protocols be followed whenever contact is
made with blood or body secretions, excretions, body fluids (with the exception of
sweat), broken skin, and mucous membranes.
What are the guidelines for standard safety precautions?
1. Gloves when touching any body fluids, mucous membranes, and non-intact skin.
2. Gowns and face protection, such as masks and goggles, or face shields, should be
worn whenever there is a danger of splashing liquids or creating aerosols during a
specific procedure or process.
3. Hand washing!!
Describe contact precautions for safety.
• Wearing gloves when making contact with the patient's skin or with inanimate objects
that have been in direct contact with the patient.
• Use of gowns when there is a likelihood that the healthcare worker's clothing will come
in contact with the patient or items in the patient's room.
• Used for patients with highly antibiotic-resistant bacteria or organisms causing wound
infections.
What, generally, are airborne precautions?
