Chapter 17
Microorganisms
and Asepsis
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Review Tip
This chapter begins the review of clinical topics. Asepsis is a
cornerstone of safe, healthy practices in the medical office and in
personal life. To reinforce these principles, look for applications at
work and at home as each topic is addressed.
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Microorganisms
Microorganisms, or microbes or germs, are living organisms that are too
small to see with the naked eye. These organisms surround us and are
part of every living process. Some of these microbes cause disease,
and others cause disease only under certain circumstances; for
example, Escherichia coli (E. coli), which is found normally in the
intestinal tract, may cause sepsis if introduced into the bloodstream.
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Microorganisms, cont'd.
Common Pathogens
Common pathogens are prevalent microorganisms that cause disease.
■
Bloodborne pathogen—any type of pathogen that lives in and is
transmitted through blood
• Bacteria (singular bacterium)—one-celled microorganisms; may
be found singularly or in chains
- Types defined by principal shapes
- Spherical (cocci; singular coccus; Latin, meaning “berry”)—
examples are streptococci, staphylococci, pneumococci
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Microorganisms, cont'd.
- Rod (bacilli; singular bacillus; Latin, meaning “little staff ”)—
examples are Bacillus anthracis (cause of anthrax),
Mycobacterium tuberculosis (cause of tuberculosis),
Bacillus tetanus (cause of tetanus)
- Spiral (spirilla or spirochete; singular spirillum; Latin,
meaning “spiral”); corkscrew-shaped; an example is
Helicobacter pylori (one cause of chronic gastritis)
- Spores—encapsulated (shell or capsule) bacteria in an
inactive or resting state; in the medical office, spores are
killed only by autoclaving
• Types defined by air need
- Aerobic—bacteria that require oxygen for survival
- Anaerobic—bacteria that live without oxygen
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Microorganisms, cont'd.
• Virus—extremely small microbes that pass through most filters;
examples of viral diseases include measles, mumps, rubella,
herpes, hepatitis B, and influenza
• Fungus (plural fungi )—microbes that grow on other organisms,
causing diseases such as tinea (ringworm), candidiasis
(thrush), histoplasmosis, or coccidioidomycosis
• Protozoa—simplest form of animal pathogen; parasites;
examples of diseases caused by protozoa are malaria,
giardiasis, and trichomonas (one cause of vaginitis)
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Microorganisms, cont'd.
Portals of Entry
Portals of entry are the ways microorganisms enter the body.
Respiratory system—nose, mouth (air)
■ Gastrointestinal system—mouth, rectum (food and water)
■ Integumentary system—any break in the skin
■ Eyes and ears
■ Vascular system—through blood supply
■
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Microorganisms, cont'd.
Chain of Infection
The chain of infection illustrates the elements necessary for disease to
spread.
1. Reservoir host—initial carrier of the microbe; may be a person, an
animal, an insect
2. Means of exit—method of leaving the reservoir host (e.g.,
sneezing, coughing, feces, blood)
3. Means of transmission—method of moving from the exit of the
reservoir host to the entrance of the susceptible host, such as air,
contaminated materials called fomites (such as food or water), or
soiled hands
4. Means of entrance—see “Portals of Entry”
5. Susceptible host—person with no previous immunity or with
weakened immunity resulting from illness, injury, or poor nutrition,
or if the pathogen is too virulent
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Microorganisms, cont’d.
Figure 17-1. Chain of infection.
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Microorganisms, cont'd.
Localized versus Generalized Infections
Localized—infection confined to one area of the body (e.g., a pustule)
■ Generalized or systemic—infection spread throughout the body (e.g.,
septicemia)
■
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Microorganisms, cont'd.
Biochemical Agents to Combat Pathogens
■ Antibiotics—substances
ingested, injected, or applied to a living being
that have the power to inhibit the growth of or to destroy bacteria
■ Chemotherapy—ingestion, injection, or application of chemical agents in
treating disease
■ Immunizations—biological or chemical agents that create immunity to
specific diseases when ingested or injected
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Asepsis
Asepsis is the absence or the control of microorganisms. Many of the
U.S. Occupational Safety and Health Administration (OSHA)
guidelines and mandates address asepsis.
Purposes of Asepsis
Protect patient/public
■ Protect health care worker
■ Prevent infectious disease from starting
■ Stop infectious disease from spreading
■
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Asepsis, cont’d.
Types of Asepsis
Medical asepsis (clean technique)—techniques and procedures to
reduce number of microorganisms in an environment and
decrease opportunities for further spread
■ Surgical asepsis (sterile technique)—techniques and procedures to
eliminate all microorganisms in an environment
■
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Asepsis, cont’d.
Common Methods of Asepsis
■
Medical handwashing
1. Remove jewelry (wedding and engagement rings usually
remain)
2. Use hand- or foot-controlled faucet
3. Wash hands and wrists for 2 to 3 minutes
4. Use brush and cuticle stick on nails
5. Hold hands in downward position while rinsing
6. Dry hands with paper or clean cloth towel
7. Turn off hand faucets with paper or clean cloth towel
8. Lotion may be applied
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Asepsis, cont’d.
■
Surgical handwashing
1. Remove all jewelry
2. Use foot- or knee-controlled faucet
3. Wash hands, wrists, and forearms for 10 minutes with brush
(first surgical scrub of day)
4. Use cuticle stick on nails
5. Hold hands in upward position while rinsing
6. Dry with sterile towel
7. Do not apply lotion
8. Keep hands upright and do not touch anything until sterile
gloves are applied
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Asepsis, cont’d.
■ Antiseptics—bacteriostatic
chemical cleaning agents used on skin
to remove and to inhibit the growth of bacteria; these agents do
not destroy all pathogens
■ Disinfectants—bacteriostatic chemical agents used to clean and to
decrease the pathogens on inanimate objects (e.g., surgical
instruments, countertops); these agents do not destroy all
pathogens
■ Sterilization—process of destroying all living organisms
• Gas—used for wheelchairs, beds, and other large equipment;
very toxic
• Dry heat—used for instruments that corrode easily; requires at
least 1 hour at 320ºF
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Asepsis, cont’d.
• Chemical (cold sterilization)—used for heat-sensitive
equipment such as fiberoptic endoscopes; equipment is
soaked in closed containers with strong agents (e.g.,
glutaraldehyde); specific time recommendations are
determined by the manufacturer of the chemical agent
• Steam heat (autoclave)—the most common method of
sterilization used in the medical office; the steam is under
pressure to achieve higher temperatures
- Water temperature must be 212ºF
- Steam temperature must be 250ºF to 254ºF
- Time required is between 20 and 40 minutes, depending on
how tightly items are wrapped (the looser the wrap, the
shorter the time required)
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Asepsis, cont’d.
- Sterilization bags or pouches, disposable paper wraps, or
surgical towels are used for autoclaving surgical instruments,
including those that will be placed on sterile fields; usually,
double wrapping is required when using disposable paper
wraps or surgical towels
- Packages must be dry before removing them from the
autoclave
- Procedure:
1. Place cleaned and dried instruments in center of wrap
(hinged instruments in open position) with sterilization
indicator tape
2. Position opened wrap on a flat surface in a diamond
shape with a point toward you
3. Fold the corner closest to you over the instrument
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Asepsis, cont’d.
4. Fold the first side corner toward the center, completely
covering the instrument; fold extra material
back to form a tab; repeat with the second side corner
5. Fold the last corner toward the center and around
the packet, ensuring the instrument is completely
covered
6. Fasten the packet with sterilization-sensitive tape
■ Standard or universal precautions
• Treat all blood and bodily fluids as contaminated
• Protect the patient from you (especially when patient’s immune
system is compromised)
• Protect yourself from the patient
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Asepsis, cont’d.
Personal protective equipment (PPE)
• Gloves (nonsterile used for majority of patient procedures;
sterile used only for procedures requiring
sterile aseptic technique, e.g., surgery)
• Goggles or eye shields
• Masks
• Gowns
• Aprons
■ Other safety materials and actions
• Safety plan and policies and procedures
• Material Safety Data Sheets (MSDS) and labels for all
hazardous agents
• Employee training
■
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Asepsis, cont’d.
• Sharps (needles, scalpels, glass vials, etc.) containers
• Other biohazard receptacles for non-sharp material
contaminated with body fluids
• Eyewash stations
• Showers
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