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Chapter 27
Asepsis and Infection Control
Copyright © 2008 Wolters Kluwer Health | Lippincott Williams & Wilkins
Components of the Infection Cycle
• Infectious agent—bacteria, viruses, fungi
• Reservoir—natural habitat of the organism
• Portal of exit—point of escape for the organism
• Means of transmission—direct contact, indirect contact,
airborne route
• Portal of entry—point at which organisms enter a new
host
• Susceptible host—must overcome resistance mounted by
host’s defenses
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The Infection Cycle
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Infectious Agents
• Bacteria—most significant and most prevalent in hospital
settings
• Virus—smallest of all microorganisms
• Fungi—plantlike organisms present in air, soil, and water
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Classification of Bacteria
• Spherical (cocci), rod shaped (bacilli), corkscrew shaped
(spirochetes)
• Gram positive or gram negative—based on reaction to
Gram stain
• Aerobic or anaerobic—based on need for oxygen
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Factors Affecting an Organism’s
Potential to Produce Disease
• Number of organisms
• Virulence
• Competence of person’s immune system
• Length and intimacy of contact between person and
microorganism
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Possible Reservoirs for Microorganisms
• Other humans
• Animals
• Soil
• Food, water, milk
• Inanimate objects
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Common Portals of Exit
• Respiratory
• Gastrointestinal
• Genitourinary tracts
• Breaks in skin
• Blood and tissue
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Laboratory Data Indicating Infection
• Elevated white blood cell count—normal is 5000 to
10,000/mm3
• Increase in specific types of white blood cells
• Elevated erythrocyte sedimentation rate
• Presence of pathogen in urine, blood, sputum, or
draining cultures
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Aseptic Technique
• Includes all activities to prevent or break the chain of
infection
• Two categories
– Medial asepsis—clean technique
– Surgical asepsis—sterile technique
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Factors Predisposing Patients
to Nosocomial Infections
• Use of invasive medical devices
• Antibiotic-resistant organisms developed in hospitals
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Measures to Reduce Incidence
of Nosocomial Infections
• Constant surveillance by infection-control committees
and nurse epidemiologists
• Written infection-prevention practices for all agency
personnel
• Hand hygiene recommendations
• Infection control precaution techniques
• Keeping patient in best possible physical condition
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Bacterial Flora
• Transient—attached loosely on skin, removed with
relative ease
• Resident—found in creases in skin, requires friction with
brush to remove
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Stages of Infection
• Incubation period—organisms growing and multiplying
• Prodromal stage—person is most infectious, vague and
nonspecific signs of disease
• Full stage of illness—presence of specific signs and
symptoms of disease
• Convalescent period—recovery from the infection
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Factors Affecting Host Susceptibility
• Intact skin and mucous membranes
• Normal pH levels
• Body’s white blood cells
• Age, sex, race, hereditary factors
• Immunization, natural or acquired
• Fatigue, climate, nutritional and general health status
• Stress
• Use of invasive or indwelling medical devises
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Body’s Defense Against Infection
• Body’s normal flora
• Inflammatory response
• Immune response
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Factors Determining Use of Sterilization
and Disinfection Methods
• Nature of organisms present
• Number of organisms present
• Type of equipment
• Intended use of equipment
• Available means for sterilization and disinfection
• Time
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Personal Protective Equipment
and Supplies
• Gloves
• Gowns
• Masks
• Protective eye gear
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Evolution of Specialized Infection
Control Precautions
• Early CDC guidelines
• Specific isolation techniques
• Disease-specific isolation
• Universal precautions
• OSHA regulations for universal precautions
• Body substance precautions
• Current CDC guidelines
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Current CDC Guidelines
• Standard precautions—used in care of all hospitalized
patients
– Apply to blood, body fluids, secretions, excretions,
non-intact skin, mucous membranes
• Transmission-based precautions—used in addition to
standard precautions for patients with suspected
infection
– Include airborne, droplet, or contact precautions
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Type N95 Particulate Respirator
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Use of Surgical Asepsis
• Operating room, labor and delivery areas
• Certain diagnostic testing areas
• Patient bedside
– e.g., for procedures that involve insertion of urinary
catheter, sterile dressing changes, or preparing and
injecting medicine
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Patient Teaching for Medical
Asepsis at Home
• Wash hands before preparing or eating food
• Prepare foods at high enough temperatures
• Use care with cutting boards and utensils
• Keep food refrigerated
• Wash raw fruits and vegetables
• Use pasteurized milk and fruit juices
• Wash hands after using bathroom
• Use individual care items
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Evaluating Patient Goals
• Use techniques of medical asepsis
• Identify health habits and lifestyle patterns promoting
health
• State signs and symptoms of an infection
• Identify unsafe situations in the home environment
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Question
Which of the following is the most significant and
commonly found infection-causing agent in healthcare
institutions?
A. Bacteria
B. Fungi
C. Viruses
D. Mold
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Answer
Answer: A. Bacteria
Rationale:
Bacteria are the most significant infection-causing agents
in the healthcare system. Bacteria can be categorized by
shape, by their reaction to the Gram stain, or according
to their need for oxygen.
Fungi (molds and yeasts) can cause infection and are
present in the air, soil, and water.
Viruses cause infections including the common cold, and
do not respond to antibiotics.
Copyright © 2008 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
Which one of the following infections or diseases may be
spread by touching a contaminated inanimate article?
A. Rabies
B. Giardia
C. E. coli
D. Influenza
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Answer
Answer: D. Influenza
Rationale:
Influenza may be spread if a person touches a
contaminated article and then touches his eyes or nose.
The reservoir for rabies is animals; for Giardia, water;
and for E. coli, water or food.
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Question
In which of the following stages of infection is the patient
most contagious?
A. Incubation period
B. Prodromal stage
C. Full stage of illness
D. Convalescent period
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Answer
Answer: B. Prodromal stage
Rationale:
The patient is most infectious during the prodromal stage
when early signs and symptoms of the disease are
present but are often vague and nonspecific. During this
stage, the patient often does not realize he or she is
contagious and spreads the infection.
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Question
Tell whether the following statement is true or false.
Soaps and detergents (nonantimicrobial agents) are
considered adequate for routine mechanical cleansing of
the hands and removal of most transient
microorganisms.
A. True
B. False
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Answer
Answer: A. True
Soaps and detergents (nonantimicrobial agents) are
considered adequate for routine mechanical cleansing of
the hands and removal of most transient
microorganisms.
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Question
Tell whether the following statement is true or false.
Standard precautions should be used when caring for a
noninfectious, post-operative patient who is vomiting
blood.
A. True
B. False
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Answer
Answer: A. True
Standard precautions should be used when caring for a
noninfectious, post-operative patient who is vomiting
blood.
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