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Chapter 19
Infection Control
2
Learning Objectives
 Define and spell key terms
 Identify the role of the medical
assistant in infection control
 Identify disease-producing
microorganisms
 List common infectious diseases
 Identify the links in the chain of
infection
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Learning Objectives
 Differentiate between the stages of
disease
 Describe the body’s defense
mechanisms
 Demonstrate the performance of
handwashing with soap and water
 Demonstrate the performance of hand
sanitization with an alcohol-based hand
rub
 Explain standard precautions
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Learning Objectives
 List common types of personal
protective equipment
 Describe strategies to increase health
and safety in the workplace
 Differentiate medical asepsis and
surgical asepsis
 Differentiate sanitization, disinfection,
and sterilization
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Learning Objectives
 Demonstrate equipment and instrument
sanitization
 Demonstrate equipment and instrument
disinfection
 Demonstrate wrapping a pack for
sterilization
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Learning Objectives
 Demonstrate the performance of
sterilization using an autoclave
 Educate patients regarding methods to
reduce disease transmission
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Microorganisms and
Pathogens
 A microorganism is a microscopic
organism seen only by using a
microscope
 Not all microorganisms cause disease
 Harmless microorganisms on our body
are called “normal flora”
 Microorganisms that cause disease are
called “pathogens”
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Pathogens
 Require nutrients, moisture, warmth,
and neutral pH to grow and thrive
 Aerobic pathogens require oxygen to
survive
 Anaerobic pathogens require oxygenfree environment to survive
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Types of Pathogens
 Five main types of pathogens:
 Bacteria
 Rickettsia
 Virus
 Fungus
 Protozoa
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Bacteria
 One-celled organisms
 Three types: cocci—round shape,
bacilli— rod shape, spirilla—spiral shape
 Bacterial infections include staph
infections, strep throat, Lyme disease,
and gonorrhea
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Rickettsia (parasite)
 Parasitic nature—organism depends on
host to survive
 Spread to humans via vectors: lice,
ticks, fleas
 Infections include Rocky Mountain
spotted fever, and typhus
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Virus
 Pathogen that grows and reproduces
after infecting a host cell
 More than 400 types
 Smallest of all pathogens
 Viral infections include common cold,
hepatitis, chicken pox, and HIV
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Fungus
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Yeast, mold, and mushroom
Many present in body’s normal flora
Many do not cause disease
Fungal infections include athlete’s foot,
ringworm, and yeast infections
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Protozoa
 Live mainly in soil
 Spread through fecal–oral route by
ingested contaminated food or water
 Some spread by mosquitoes or other
insects
 Protozoan infections include malaria,
Giardia, and trichomoniasis
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Chain of Infection
Pathogen
Reservoir host
Means of exit
Method of
transmission
 Means of entry
 Susceptible host

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

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Pathogen
 Disease-producing
 Pathogens need an
microorganism;
environment that
bacteria, virus, fungus,
enables them to
protozoa, and
survive, grow, and
rickettsia
multiply
 Present in blood or
 The human body is a
body fluids, called
perfect environment
“bloodborne
pathogens”
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Reservoir Host
 Human, animal, or
insect that is
infected with disease
 Other reservoirs may
be water, food, and
contaminated
objects
 Host may be
symptomatic or
asymptomatic
 Reservoir host is
contagious even
though he or she
may not appear ill
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Means of Exit
 Pathogen must be
able to exit reservoir
host
 Any body opening
lined with mucous
membranes: eyes,
nose, throat, vagina,
rectum, penis
 Injury or surgery
 Blood, body fluids:
vaginal secretions,
semen, urine, feces
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Mode of Transmission
 Direct contact—
person-to-person
contact or skin-toskin contact
 Handshaking,
kissing, and sexual
contact
 Indirect contact—
fomites; ticks, fleas,
lice, and countertops
 Indirect contact
includes airborne
and droplet
infection—sneezing,
coughing, and
talking
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Means of Entry
 Pathogen must find
entry into new host
 Any opening in the
body lined with
mucous membranes:
nose, mouth, throat,
vagina, penis,
rectum
 Wounds to the skin
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Susceptible Host
 Weakened immune
system
 Poor hygiene
 Inadequate nutrition
 Stress
 Chronic disease
 Poor environmental
conditions
 Elderly
 Very young
 Certain medications
 Smoking
 Alcohol abuse
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Stages of Disease
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Incubation stage
Prodromal stage
Acute stage
Declining stage
Convalescent stage
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Incubation Stage
 Beginning stage of infection (latent)
 Starts when person first contacts
pathogen
 Person may be asymptomatic
 Person is contagious
 First appearance of symptoms
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Prodromal Stage
 Earliest symptoms
 Fever (febrile) or rash
 Person may state “I just don’t feel
right”
 Person is contagious
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Acute Stage

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Symptoms are at their worst
Person is obviously ill
Person is contagious
During this time the patient should take
medications, rest, and avoid contact
with others
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Declining Stage
 Acute stage ends
 Symptoms begin to decrease
 Patient starts to feel better
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Convalescent Stage
 Symptoms are gone
 Recovery time
 Continues until patient regains
homeostasis
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Defense Mechanisms
 The body has natural defense
mechanisms to protect itself against
disease:
 Mechanical
 Chemical
 Cellular
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Mechanical Defenses
 First line of defense against pathogens
is “intact” skin
 Serves as barrier to environment
 Cilia movement in lower airways
 Coughing and sneezing
 Eyelashes and eyebrows
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Chemical Defenses

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Sebaceous glands
Stomach fluids
Tears and saliva contain lyzozyme
Interferons have antiviral activity
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Cellular Defenses
 Various cells also act to protect the
body from pathogens
 Inflammatory response
 Cell-mediated immunity
 Antibody-mediated immunity
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Inflammatory Response
 Inflammation occurs when damage or
trauma is done to tissues
 Body responds by releasing chemical
substances such as histamine,
prostaglandins, and kinins
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Inflammatory Response
 Chemical substances
initiate changes:
dilation of blood
vessels, increased
permeability of blood
vessels, attraction of
white blood cells
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Phagocytosis
 Phagocytosis—the
ability of white blood
cells to engulf
pathogens and
cellular debris and
then destroy that
matter
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Immunity
 Protection from infectious disease
 Active or passive
 Further categorized as acquired
naturally or passively
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Active Natural Immunity
 Develops when body is exposed to
pathogenic microorganisms
 Microorganisms contain antigens (cell
markers)
 White blood cells develop antibodies
 Antibodies protect during second
exposure
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Active Artificial Immunity
 Develops when antigen is purposely
introduced into body
 Vaccine
 Live, weakened, dead microorganism
 Stimulates antibody formation without
causing disease
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Passive Natural Immunity
 Develops when antibodies from mother
cross placenta to fetus
 Provide protection to fetus for several
months
 Additional antibodies are found in
breastmilk
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Passive Artificial Immunity
 Develops when preformed antibodies
from animal or human are then injected
into an individual with known exposure
 Antiserum provides temporary passive
immunity
 Helps in cases of exposure to rabies,
botulism, venomous snake or spider
bites, hepatitis, and diptheria
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Standard Precautions
 Centers for Disease Control and
Prevention (CDC)
 Occupational Safety and Health
Administration (OSHA)
 Workplace guidelines to promote safety
 Bloodborne pathogens
 Personal protective equipment
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Personal Protective Equipment
 Degree of risk to
exposure
 Gloves, masks, eye
protection, shoe
covers, and gowns
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Disposal of Biohazardous
Waste
 Containers that hold
blood or body fluids
 Containers are
required to have
biohazardous labels
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Sharps and Needlestick Safety
 “Sharps”—needles, scalpel blades,
capillary tubes, and broken glass or
slides
 Dispose of in puncture-resistant
containers
 Never recap an uncapped needle
 Replace biohazard containers when full
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Vaccinations
 If no Hepatitis B vaccination prior to
employment, the employer must
provide it for the employee within 10
days of employment at no cost to
employee
 Series of three injections
 Documentation
 Test for TB exposure
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Exposure Control
 All employers must have exposure
control plan and review with employees
 Exposure incident is any contact with
blood or body fluid, and any accidental
injury
 Report exposure to employer
immediately
 Follow policy and procedure for your
facility
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Biohazard Spill
 Protect yourself with PPE, control spill
with paper towels
 Cover entire spill with 10% bleach
solution and let stand for 20 minutes
 Clean up spill with mechanical device,
do not use hands
 Repeat bleach application, wait another
20 minutes
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Asepsis
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Condition free from pathogens
Handwashing
Sanitization
Disinfection
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Hand Sanitization
 Single most effective way to prevent
the spread of disease
 Soap and warm water, rub vigorously
15 seconds
 Antiseptic hand wash, cover all surfaces
of hands, and air dry
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Typical Times to Wash Hands
 Beginning work
 Before and after
rooming patients
 Before and after
cleaning exam rooms
 Before and after
assisting the
physician with
procedures
 Before and after
cleaning equipment
 Before and after
using the restroom
 Before and after
taking a break or
eating lunch
 At the end of the day
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Sanitization of Equipment
 Inactivating or removing
microorganisms on reusable equipment
and surfaces to a safe level
 Chemicals, heat, and gas are used
 Low-suds detergents are commonly
used
 Read labels, follow manufacturer’s
directions, rinse all instruments, and
protect yourself
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Disinfection
 More thorough than sanitization
 Kills bacteria and most microorganisms
but not spores
 Use different disinfectants for surfaces
and equipment vs. skin surfaces
 Read labels and follow manufacturer’s
directions
 Iodine, household bleach, and 70%
alcohol
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Sterilization
 Complete destruction of all
microorganisms including spores
 Autoclave sterilization involves heat,
pressure, steam, and time
 Sanitize and disinfect instruments and
equipment before sterilizing
 All surfaces of instruments must be
exposed
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Sterile Packs
 Sanitize and disinfect
instruments prior to
wrapping
 Hinged instruments
should be left open,
surfaces of instruments
should not be touching
 Use indicator tape and
label
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Chemical Sterilization
 Certain instruments should not be
autoclaved; for example, fiberoptic
endoscopes
 Sterilize using chemicals
 Solution is caustic; wear PPE
 Immerse for a specified time
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Medical Asepsis
 Destruction of pathogenic organisms
after they leave the body
 Follow standard precautions
 Consider specimens to be contaminated
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Surgical Asepsis
 Destroying all pathogenic organisms
before they enter the body
 Use surgical aseptic technique
 Normal protective barriers are
punctured or disrupted
 Injections, urinary catheterization,
wound care, and surgical procedures
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Discussion
 List five types of pathogens
 Discuss difference between aerobes and
anaerobes
 Discuss differences in handwashing with
soap and handwashing with alcoholbased hand sanitizer
 Identify procedures that require medical
asepsis vs. surgical asepsis
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Credits
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