Chapter 20 - Promoting Asepsis & Preventing Infection (2)

Fundamentals of Nursing

Infection

is the invasion of and multiplication in the body by a pathogen (a microorganism capable of causing disease)

healthcare-associated infections (HAIs)

refers to infections associated with healthcare given in any setting

nosocomial infection

refers more specifically to hospital-acquired infections

Clostridium difficile

is one of the most common and most serious infections

Patients who take antibiotics, especially older adults, are at greatest risk for acquiring 

C. difficile

Methicillin-resistant ? infecion (MRSA)

Staphylococcus aureus

? infection (CDI) and hospitalization

Clostridium difficile

Infections spread through a

chain of infection

Other microorganisms live on or in the human body without causing harm (e.g., the ? bacteria growing on human skin).

Staphylococcus

Other microorganisms are beneficial or even essential for human health and well-being, this is referred to as

normal flora

Transient flora

are normal microbes that you acquire by coming in contact with objects or another person (e.g., when you touch a soiled dressing)

Resident flora

are permanent inhabitants of the skin and cannot usually be removed with routine hand washing

The largest groups of pathogens

are bacteria, viruses, and fungi (which include yeasts and molds)

(1) are protozoa, helminths (commonly called worms), and (2), which are infectious protein particles that cause certain neurological diseases.

1. Less common pathogens

2. prions

(1) when a patient is especially vulnerable to disease or if they enter regions of the body they do not normally inhabit (2), harmless in the bowel, cause infection when they multiply in the urinary tract).

1. Normal flora may become pathogenic

2. Escherichia coli

Virulence of the organism

(its power to cuase disease)

Host environment

ability of the organism to thrive in it

Number of organisms

(the greater the number, the more likely they are to cause disease)

Host defenses

ability to prevent infection

A ? is a source of infection: a place where pathogens survive and multiply

reservoir

Some people, called ?, can defend themselves from active disease but harbor the pathogenic organisms within their bodies

carriers

The bacteria ?, which causes salmonellosis (“food poisoning”), can contaminate raw and undercooked meat and eggs.

Salmonella enteritidis

The spores formed by some bacteria allow them to live without water (e.g., the (1) and (2) species, both of which cause foodborne disease).

1. Bacillus

2. Clostridium

Many bacteria and most protozoa and fungi are

Example: Candida albicans

aerobic

Anaerobic organisms

do not require oxygen for growth and may even be killed in its presence

An example of anaerobic organism is ? which causes tetanus when a spore enters the body through an open wound.

Clostridium tetani

Ultraviolet light is sometimes used to remove pathogens such as (1), (2), and viruses from surgical instruments and other objects.

1. Staphylococcus

2. Salmonella

What is a pathogen?

A pathogen is any microorganism or agent that can cause disease in its host.

Normal flora protect the body by competing with pathogens, supporting the immune system, aiding in digestion, producing vitamins, and maintaining a healthy balance of microbes.

Identify at least five reservoirs of infection

Here are five reservoirs of infection:

1. Humans (sick individuals or asymptomatic carriers)

2. Animals (e.g., bats, dogs, birds, rodents)

3. Soil (e.g., Clostridium tetani, fungi)

4. Water (e.g., Vibrio cholerae)

5. Food (e.g., contaminated meat, dairy, or produce)

In the case of human or animal reservoirs, the most frequent ?is through body fluids.

portal of exit

Contact, either direct or indirect, is the most frequent ? of infection.

mode of transmission

Direct contact

usually involves physical contact, sexual intercourse, and contact with wound drainage, but it can involve scratching and biting

(1)  involves contact with a (2), a contaminated object that transfers a pathogen.

1. Indirect contact

2. fomite

Droplet transmission

occurs when the pathogen travels in water droplets expelled as an infected person exhales, coughs, sneezes, or talks, in addition to during suctioning and oral care

Airborne transmission

occurs when microorganisms float considerable distances on air currents to infect large numbers of people

A ? is an organism that carries a pathogen to a susceptible host.

vector

Pathogens can enter the body through various

portals of entry

A (or compromised) ? is a person who is at risk for infection because of inadequate defenses against the invading pathogen

susceptible host

Age 

(very young, very old)

Compromised immune system

(immune suppression for organ transplantation or treatment of cancer)

Immune deficiency conditions

(e.g., HIV, leukemia, malnutrition, lupus)

Identify the six links in the chain of infection.

• Infectious Agent

• Reservoir

• Portal of Exit

• Mode of Transmission

• Portal of Entry

• Susceptible Host

What kinds of microbes favor the human body as a reservoir of infection?

Microbes that favor the human body as a reservoir of infection include bacteria, viruses, fungi, and parasites that thrive in warm, moist, nutrient-rich environments, such as:

• Bacteria – e.g., Staphylococcus aureus, Mycobacterium tuberculosis

• Viruses – e.g., influenza virus, HIV, hepatitis viruses

• Fungi – e.g., Candida albicans

• Parasites – e.g., Giardia lamblia, Plasmodium species

You are working as a nurse on a medical-surgical unit. What roles might you play in the chain of infection?

As a nurse on a medical-surgical unit, you may play roles in the chain of infection by:

1. Reservoir – potentially carrying pathogens if proper hygiene isn’t followed.

2. Portal of Exit – spreading microbes through coughing, sneezing, or contact with body fluids if not protected.

3. Mode of Transmission – transferring pathogens between patients or surfaces if hand hygiene, PPE, or aseptic technique are not maintained.

4. Portal of Entry – introducing pathogens into patients through invasive procedures, wounds, or improper device care.

5. Susceptible Host – being at risk yourself if your immunity is low or you experience occupational exposure.

Local infections

are those that cause harm in a limited region of the body, such as the upper respiratory tract, skin, urethra, or a single bone or joint

Systemic infections

occur when pathogens invade the blood or lymph and spread throughout the body

Bacteremia

is the clinical presence of bacteria in the blood

Septicemia

is a symptomatic systemic infection spread via the blood

A primary infection

is the first infection that occurs in a patient

A secondary infection

is one that follows a primary infection, especially in immunocompromised patients

In ?, the pathogen is acquired from the healthcare environment.

exogenous healthcare-related infections

In ?, the pathogen arises from the patient’s normal flora when some form of treatment (e.g., chemotherapy or antibiotics) causes the normally harmless microbe to multiply and cause infection.

endogenous healthcare-related infections

Acute infections

have a rapid onset but last only a short time (e.g., the common cold, urinary tract infection)

Chronic infections

(e.g., a wound abscess, hepatitis) develop slowly and last for weeks, months, or even years

Latent infections

cause no symptoms for long periods of time, even decades

An ? condition occurs at a stable, predictable rate within a particular environment, region, or population.

endemic

An ? is when there is a sudden increase in the number of people with a condition that is greater than expected.

outbreak

An ? is an outbreak of a disease that spreads over a large geographic region or in a defined population group (e.g., elderly, healthcare workers)

epidemic

A ? is an exceptionally widespread epidemic—that is, one that affects a large number of people in an entire country or worldwide.

pandemic

Newly identified diseases

caused either by an unrecognized microorganism (e.g., the virus causing AIDS, unknown before 1980; SARS-CoV-2, not previously identified before 2019]) or by a known organism causing a new response (e.g., enterovirus D68, Streptococcus infection triggering toxic shock syndrome)

Diseases occurring in new geographic areas

(e.g., Ebola virus originating in western Africa; SARS-CoV-2, first identified in Wuhan, China) or settings (e.g., C. difficile was primarily an HAI and now occurs in the community).

Microorganisms in animals or insects that extend their host range to begin infecting humans

e.g., avian influenza, or “bird flu”; H1N1 virus from swine; or Zika virus, which is carried by mosquitos and can cause birth defects when acquired during pregnancy)

Microbes that evolve to become more virulent

(e.g., a strain of E. coli, which now causes severe illness)

Organisms that are deliberately altered for bioterrorism

(e.g., the contamination of mail with Bacillus anthracis [anthrax])

Why are emerging infections of special concern in healthcare?

Emerging infections are of special concern in healthcare because they are often new, rapidly spreading, resistant to existing treatments, and can easily overwhelm healthcare systems, putting both patients and providers at higher risk.

Why are MDROs of special concern in healthcare?

Multidrug-resistant organisms (MDROs) are of special concern in healthcare because they limit treatment options, spread easily in healthcare settings, cause longer hospital stays and higher costs, and increase the risk of severe illness or death.

Primary defense

prevents organisms from entering the body

The normal flora of the body allows other kinds of pathogens to multiply, producing a ? or another opportunistic infection.

superinfection

Many pathogens that reach the stomach are destroyed in its ?environment.

acidic

The presence of such chemicals activates a set of

secondary defenses

Phagocytosis

is the process by which phagocytes (specialized white blood cells [WBCs]) engulf and destroy pathogens directly

(1) is a process by which a set of blood proteins, called (2), triggers the release of chemicals that attack the cell membranes of pathogens, causing them to rupture.

1. Complement cascade

2. complement

Inflammation

is a process that begins when histamine and other chemicals are released, either from damaged cells or from basophils being activated by complement

Fever

is a rise in core body temperature that increases metabolism, inhibits the multiplication of pathogens, and triggers specific immune responses

Active immunity

occurs when the body makes its own antibodies or T lymphocytes (also called T cells) to protect the body against a pathogen

Passive immunity

can also be achieved when an individual receives antibodies that come from someone else rather than producing them through their own immune system, such as through immunizations or breastfeeding

Specific immunity

is the process through which the immune cells “learn” to recognize and destroy pathogens they have encountered before

The cells involved in specific immunity are the ?, WBCs produced from stem cells in the red bone marrow

lymphocytes

The collection of dead neutrophils is called

pus

The ? acts directly to destroy infection-causing pathogens (i.e., viruses, fungi, protozoans, cancers) without using antibodies but rather by activating phagocytes and T cells

cellular (cell-mediated) immune response

The immune process starts when the body is exposed to a particular

pathogen

Antigens

are proteins on the outer surface of pathogens that evoke an immune response

Along come WBC ? that engulf and swallow the pathogen.

phagocytes

After the pathogen is destroyed, the phagocyte now displays pieces of itself on the antigens of the destroyed pathogen, known as an ? (APC).

antigen-presenting cell

Now ? bind to the APC to fight similar pathogens in the future.

memory T cells

Nearby ? come in and fight against the infecting agent by activating T cells and alerting B cells to get involved

helper T cells

(1) multiply to fight the infection by releasing proteins and enzymes to destroy the pathogen, known as (2).

1. Active T cells

2. cytotoxic (killer) T cells

Suppressor T cells

stop the immune response when the infection has been contained

A person is exposed to a

pathogen

(1) in the bone marrow activate proteins, called (2), that cause B cells to divide into (3) and (4).

1. Helper cells

2. interleukins

3. memory cells

4. active B cells

(1) produce Y-shaped (2) that bind to the pathogen’s attachment site (3) and interfere with its ability to infect other cells, a process called (4).

1. Active B cells

2. antibodies

3. antigen

4. neutralization

Antibodies also cause pathogens to clump together (?), reducing their activity and increasing the likelihood that the clump will be detected and phagocytized by leukocytes.

agglutination

? signal leukocytes (macrophages and neutrophils) to come in and engulf the pathogen and break it down.

Antibodies

Antibodies also fight infection by triggering (1) to destroy the pathogen, called the (2).

1. inflammatory chemicals

2. complement cascade

Suppressor cells

stop the immune response when the infection is contained

IgM

is the first antibody to appear when an antigen (e.g., pathogen) is encountered

IgG

is the most common immunoglobulin in the body

IgE

is the immunoglobulin primarily responsible for the allergic response

IgA

is found in mucous membranes in the intestines, respiratory and urinary tracts, saliva, tears, and breast milk