Chapter 1 - Principles of asepsis. Our bodies are amazing structures that defend us against infections under normal circumstances. As you read this chapter you will learn about disease-causing microorganisms, how the body defends itself against infections, and ways that infections might occur.
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Principles of
Asepsis
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infectious disease prevention.
1.2 Identify the types of microorganisms that
cause disease.
1.3 List some infectious diseases, and identify
their signs and symptoms.
1.4 Discuss the importance of preventing
antibiotic resistance in a health-care setting.
1.5 Describe ways you can help prevent
antibiotic resistance in health-care settings.
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1.7 Explain how the body’s defenses protect
against infection.
1.8 Describe the cycle of infection.
1.9 Identify and describe the various methods of
disease transmission.
1.10 Explain how you can help break the cycle of
infection.
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– Antibiotic-resistant organisms
– Importance of patient education on the proper use of antibiotics
You will learn about:
– Disease-causing
microorganisms – How the body fights
disease – Ways infections occur
structures that defend us
against infections under
normal circumstances
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Edward Jenner (1749–1823) • Developed first effective
of puerperal fever to women in childbirth
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Louis Pasteur (1822–1895) • Helped develop the germ
theory of infectious disease, stating that disease is
caused by microorganisms
Joseph Lister (1827–1912) • Helped develop germ theory
• Introduced aseptic techniques through the use of antiseptics
on wounds, surgical sites, and surgical instruments
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Robert Koch (1843–1910) • Developed a set of proofs,
known as Koch’s postulates, claiming that microbes cause disease
Sir Alexander Fleming
(1881–1955)
• Discovered penicillin
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• Threat of infection still present
– New infectious diseases
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though great advances have been made in
controlling infections over the past century?
ANSWER: The threat of infection is still present because
of new diseases and diseases that have become resistant
to treatments.
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• Pathogens
– Microorganisms capable of causing disease
– Evade host defenses
• People avoid infections most of the time
– Many microorganisms are beneficial or harmless
– Normal defenses resist infection
– Conditions are not favorable for pathogens to grow
and be transmitted
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Prions* • Infectious particle
made of protein
• No nucleic acid
• Reproduction unknown
Pr P
Creutzfeldt-Jakob disease Mad cow disease
* Experts disagree as to whether prions are directly responsible
for disease or merely aid an unknown agent in causing disease
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Viruses • DNA or RNA
surrounded by protein coat
• Reproduced in living cells
• Very small
zoster virus Chickenpox
Varicella-Bacteria • Single-celled
• Reproduce quickly
• Mostly asexual reproduction
Vibrio cholerae Cholera
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Protozoans • Single-celled
• Reproduction mostly asexual
Entamoeba histolytica Amebic dysentery
Fungi • Multicellular
• Reproduction is sexual and asexual
Candida albicans Candidiasis
Helminths • Multicellular
parasitic
• Contain specialized organs
• Sexual reproduction
Enterobius vermicularis Pinworms
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exposed to microorganisms What are the reasons for
this?
ANSWER: This is because:
many microorganisms are beneficial or harmless
we have normal defenses to resist infection
conditions are not favorable for the pathogen to grow
and be transmitted
Correct!
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symptoms of common
infectious diseases
can help protect
against exposure
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• Itchy rash fluid-filled blisters
• Slight fever, headache, general malaise
• Spread by direct, indirect, droplet, or airborne transmission
• Isolate until all blisters have scabbed over
• 1996 – live vaccine approved
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• Characterized by a harsh, barking cough, difficulty breathing, hoarseness, and low-grade fever
• Most common in infants and young children
• Symptoms lessened by humidification of air, rest, and clear fluids
• Commonsense precautions to prevent spread
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– 35 – 50% of teens develop mononucleosis
• Symptoms – fever, sore throat, swollen lymph nodes
• Virus remains dormant for life
• Occasionally reactivates as tumors
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• Monitor closely – bacterial meningitis
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• Spread through blood or fecal-oral route
• Acquired immune deficiency syndrome
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(Flu) body aches, upper respiratory congestion
• Isolation and commonsense precautions
• Vaccines
– Live, attenuated virus – nasal spray – Inactivated virus – IM injection
• Annual vaccination
– People at risk for complications
• People older than 50 years old
• People in close contact with persons at risk for complications
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(Rubeola) • Spread by droplets or direct transmission
• Initial symptom of fever develops 8 to 13 days after exposure, followed by a
characteristic itchy rash 14 days after exposure
• Isolation for 7 days after rash appears
• Keep children under 3 years old away from anyone with the disease
• Reportable to state or county health dept
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coverings of brain and spinal cord and the fluids around them
• Viral – milder form
– Clears in 1 to 2 weeks without treatment – Aseptic meningitis
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requiring immediate treatment
– Vaccination available for people in high-risk groups
– Symptoms – red, blotchy rash, confusion, delirium, light sensitivity, headache, fever and chills, nausea and vomiting, sleepiness, stiff neck – May spread through exchange of respiratory and throat secretions
– Reportable to state or county health dept.
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– Primarily affects salivary glands
• Incubation – 2 to 3 weeks
• Pain related to inflammation of parotid gland and fever
• Isolate until glandular swelling stops
• Reportable to state or county health dept
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(Whooping
quick short coughs, characteristic “whoop”
during inhaled breath following coughing fit
• Isolate for 3 weeks following onset of spasmodic coughs
• Reportable to state or county health dept
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herpes virus
• Infants and young children
• Incubation 5 to 15 days
• Symptoms – sudden, high fever; sore throat;
swollen lymph nodes; rash
Rubella (German
Measles) • Highly contagious viral disease
• Direct or droplet transmission
• Incubation 16 to 18 days
• Symptoms – fever and itchy rash
• Vaccination available
• Reportable
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pharyngitis
(strep throat) – Sore throat, swelling of pharyngeal mucosa, fever, headache, nausea,
abdominal pain – Treat with antibiotics
• Scarlet fever
– Bacteria becomes systemic – Characteristic “strawberry rash”
– Incubation 7 to 10 days – Isolate 7 days
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pharyngitis
(cont.) – Occurs after apparent recovery from strep throat– Autoimmune disorder – antibodies to
streptococci cross-react with heart tissues – Symptoms – carditis, ECG changes, joint pain and inflammation, fever
• Acute post-streptococcal glomerulonephritis
– Inflammation of glomerulus of the kidney resulting
in inadequate filtering of the blood – Symptoms – swelling of hands and feet, decreased urine output, hypertension, protein in urine
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following a contaminated puncture wound
• Incubation – 3 to 21 days
• Late symptoms – lockjaw, paralysis
• No isolation needed, but reportable
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lungs
• Symptoms – night sweats, productive cough, fever, chills, fatigue, unexplained weight loss, diminished appetite, bloody sputum
• Incidence – higher in urban centers
• Transmission
– Mycobacterium tuberculosis
– Droplet
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(cont.)
– Early diagnosis, prompt treatment
– Compliance with treatment regimen
• Preventing TB
– Vaccination – BCG (not used in the U.S.)
– Causes false-positive with TB skin test
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• Patient measures
– Covering mouth
– Proper disposal of
tissues– Take medication as
directed– Avoid close contact
with others– Air out their room
techniques
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ANSWER: The spread of many infectious diseases can be
limited or prevented by using commonsense precautions:
Using tissues when coughing or sneezing
Washing hands frequently
Using disposable dishware
can be limited or prevented?
Excellent!
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• VRE – vancomycin-resistant enterococci
• VISA – vancomycin-intermediate S aureus
• VRSA – vancomycin-resistant S aureus
• ESBLS – extended-spectrum beta-lactamases
• PRSP – penicillin-resistant Streptococcus
pneumoniae
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– Most common in non-hospital health-care facilities
• Community-associated MRSA
– Increasing in incidence
• PRSP
– Common in patients seeking care in physicians’
offices and clinics (pediatrics)
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by drug-resistant organisms
– Advanced age
– Invasive procedures
– Prior use of antibiotics
– Repeated contact with health-care system
– Severity of illness
– Underlying diseases or conditions
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antibiotic-resistant microorganisms
– Prevent infection
– Diagnose and treat infection
appropriately – Use antibiotics carefully
– Prevent transmission of
infections
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resistant microorganisms?
ANSWER: Strategies to reduce the incidence of
antibiotic-resistant microorganisms include:
Prevent infections
Diagnose and treat infections appropriately
Use antibiotics carefully
Prevent transmission
Good Job!
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disease-• Damage is caused by:
– Depleting nutrients – Reproducing themselves – Making body cells the target of body’s own defenses
– Producing toxins
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through 4 stages of illness:
– Incubation – begins at first exposure; ends when first
symptom appears
– Prodromal – begins at first onset of symptoms;
generally short
– Invasion – numbers of organisms are greatest;
symptoms are most pronounced– Convalescent – patient regains normal health status
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ANSWER: The four stages of illness are:
Incubation – begins at first exposure; ends when first
symptom appears
Prodromal – begins at first onset of symptoms; generally
short
Invasion – numbers of organisms are greatest;
symptoms are most pronounced
Convalescent – patient regains normal health status
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of being resistant to
pathogens and the
disease they cause
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in the body
– Provide a barrier against pathogens
– Normally live in balance
– Become pathogenic when host’s defenses are
compromised
• Opportunistic infections
– Infections occurring when a host’s resistance is low
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• Begin tissue repair
• Destroy invading microorganisms
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1.Initial constriction, then dilation of blood vessels, causing redness and heat
2.Fluid leakage from local vessels swelling3.Scar tissue formation
– Chronic inflammation
• Damage to tissues
• Loss of function
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– White blood cells ( phagocytes )
engulf and digest pathogens – Three types
• Neutrophils – found in pus
• Monocytes – formed in bone marrow and become
• Macrophages when they migrate to specific tissues
– Found in lymph nodes, liver, spleen, lungs, bone marrow, and connective tissue
– Deliver antigens (foreign substances) to lymphocytes
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– T cells activate B cells to produce antibodies
to neutralize an antigen – Memory B cells respond quickly to produce
antibodies in later invasions – Specific antibodies are produced in response
to specific antigens – Antibodies attract phagocytes, which destroy
antigens
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– Active – body produces own antibodies
• Natural active
• Artificial active
– Passive – antibodies that are produced
outside body enter the body
• Natural passive
• Artificial passive
• Complement
– Proteins activated by antibodies
– Helps white blood cells destroy pathogens
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immunity?
ANSWER: Active immunity is long-term immunity in which
the body produces its own antibodies.
Passive immunity results when antibodies produced
outside the body enter the body.
Both can be natural or artificial.
Impressive!
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human body capable of sustaining
pathogen growth
– Subclinical case – unnoticeable infection
microorganisms become pathogenic
into the body
Click for Cycle
of Infection
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leaves the host
–Nose, mouth, eyes, or ears
–Feces or urine
–Semen, vaginal fluid, or other
reproductive discharge –Blood or blood products
Click for Cycle
of Infection
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Click for Cycle
of Infection
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– Enter through any
cavity lined with mucous membrane
• Mouth, nose, vagina, rectum
• Ears, eyes, intestinal tract, urinary tract, reproductive tract, breaks in the skin
Click for Cycle
of Infection