principles of asepsis

CHAPTER

32Principles of

Asepsis

Learning Outcomes

32.1 Explain the historical background of infectious disease prevention.

32.2 Identify the types of microorganisms that cause disease.

32.3 List some infectious diseases, and identify their signs and symptoms.

32.4 Discuss the importance of preventing antibiotic resistance in a health-care setting.

32.5 Describe ways you can help prevent antibiotic resistance in health-care settings.

Learning Outcomes (cont.)

32.6 Explain the disease process.

32.7 Explain how the body’s defenses protect against infection.

32.8 Describe the cycle of infection.

32.9 Identify and describe the various methods of disease transmission.

32.10Explain how you can help break the cycle of infection.

Introduction

– 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

Our bodies are amazing structures that defend us against infections undernormal circumstances

History of Infectious Disease Prevention

• Throughout history people have attempted to discover

– Causes of infection

– How to prevent infections

– How to treat infections

History of Infectious Disease Prevention (cont.)

Scientist ContributionEdward Jenner (1749–1823) • Developed first effective

vaccine• Used cowpox to vaccinate against smallpox

Ignaz Semmelweis (1818–1865) and Oliver Wendell Holmes (1809–1894)

• Promoted handwashing as a means of reducing the spread of puerperal fever to women in childbirth

Scientist Contribution

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

Scientist Contribution

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

• Remarkable advances in the past century

• Threat of infection still present– New infectious diseases

• AIDS• Ebola

– Resistant diseases• MRSA• VRSA• Multidrug-resistant TB

Apply Your Knowledge

Why is the threat of infection still present even 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.

Microorganisms and Disease

• Microorganisms live all around us

• 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

Microorganisms and Disease (cont.)

Classification Characteristics Example DiseasePrions* • Infectious particle

made of protein

• No nucleic acid

• Reproduction unknown

Pr P Creutzfeldt-Jakob diseaseMad cow disease

* Experts disagree as to whether prions are directly responsible for disease or merely aid an unknown agent in causing disease.

Classification Characteristics Example DiseaseViruses • DNA or RNA

surrounded by protein coat

• Reproduced in living cells

• Very small

Varicella-zoster virus

Chickenpox

Bacteria • Single-celled • Reproduce quickly• Mostly asexual reproduction

Vibrio cholerae

Cholera

Classification Characteristics Example Disease

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

In many cases, we avoid contracting infections when 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!

Infectious Diseases • Knowing signs and

symptoms of common infectious diseases can help protect against exposure

Infectious Diseases (cont.)

Chickenpox (Varicella)

• Contagious viral infection

• Incubation period of 7 to 21 days

• 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

Common cold

• Viral infections of upper respiratory tract• No isolation needed• Commonsense precautions to prevent

spread– Use tissues when coughing or sneezing– Wash hands frequently– Use disposable dishware, if possible

• Incubation – 2 to 3 days

Croup • Most often caused by a virus

• 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

Diphtheria • Bacterial infection of nose, throat, and larynx

• Symptoms: pain, fever, respiratory obstruction

• Incubation – 2 to 5 days

• Isolation required

• Antibiotic therapy (fatal if untreated)

• Immunization available

Epstein-Barr Virus

• Common human virus

• 95% of adults have had virus– 35 – 50% of teens develop mononucleosis

• Symptoms – fever, sore throat, swollen lymph nodes

• Virus remains dormant for life

• Occasionally reactivates as tumors

Haemophilus Influenzae Type B

• Bacterial infections in infants and young children

• Spread – direct, indirect, and droplet transmission

• Incubation – 3 days

• Upper respiratory symptoms, fever, drowsiness, body aches, diminished appetite

• Monitor closely – bacterial meningitis

Hepatitis • Viral infection of liver

• Spread through blood or fecal-oral route

HIV/AIDS • Human immunodeficiency virus

• Acquired immune deficiency syndrome

Influenza (Flu)

• Symptoms – fever, chills, headaches, 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

Measles (Rubeola)

• Infectious viral disease

• 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.

Meningitis • Inflammation and infection of protective coverings of brain and spinal cord and the fluids around them

• Viral – milder form – Clears in 1 to 2 weeks without treatment

– Aseptic meningitis

Meningitis • Bacterial – serious, life-threatening, 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.

Mumps • Viral infection – Primarily affects salivary glands

• Incubation – 2 to 3 weeks

• Pain related to inflammation of parotid gland and fever

• Isolate until glandular swelling stops

Pertussis (Whooping Cough)

• Highly contagious bacterial infection of respiratory tract

• Symptoms – fever, sneezing, runny nose, quick short coughs, characteristic “whoop” during inhaled breath following coughing fit

• Isolate for 3 weeks following onset of spasmodic coughs

Roseola • Rose-colored rash possibly caused by human 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

Streptococcal pharyngitis (strep throat)

• Bacterial infection of 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

Streptococcal pharyngitis(cont.)

• Rheumatic fever

– 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

Tetanus • Acute infectious bacterial disease following a contaminated puncture wound

• Incubation – 3 to 21 days• Late symptoms – lockjaw, paralysis• No isolation needed, but reportable

Tuberculosis • Infectious bacterial disease affecting mainly 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

Tuberculosis (cont.)

• Increasing resistance to TB– 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

Tuberculosis (cont.)

• Treating TB– Mantoux TB test

• Positive test = Induration – skin turns red and becomes raised and hard

• Positive result from immunization or exposure to TB bacteria

– Treatment based on area affected and type of TB involved– Patients must complete entire course of treatment – 12 to 18 months on medication– Isolation

Preventing the Spread of TB

• Containment of the tuberculosis bacteria

• Patient measures– Covering mouth– Proper disposal of

tissues– Take medication as

directed– Avoid close contact

with others– Air out their room

• Office measures– Use negative pressure

area– Use personal respirator– Apply standard

sanitization, disinfection, and sterilization techniques

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

How can the spread of many infectious diseases can be limited or prevented?

Excellent!

Drug-Resistant Microorganisms• MRSA – methicillin/oxacillin-resistant S. aureus

• VRE – vancomycin-resistant enterococci

• VISA – vancomycin-intermediate S. aureus

• VRSA – vancomycin-resistant S. aureus

• ESBLS – extended-spectrum beta-lactamases

• PRSP – penicillin-resistant Streptococcus pneumoniae

Drug-Resistant Microorganisms (cont.)

• MRSA and VRE– 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)

Drug-Resistant Microorganisms (cont.)

• Risk factors for development of infections 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

Preventing Antibiotic Resistance

• Four strategies to reduce incidence of antibiotic-resistant microorganisms– Prevent infection– Diagnose and treat infection

appropriately– Use antibiotics carefully– Prevent transmission of

infections

What strategies reduce the incidence of antibiotic-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!

Disease Process• Begins with

microorganisms finding host

• Grows with specific requirements

– Proper temperature

– pH

– Moisture level

• Virulence – microorganism’s disease-producing power

• Damage is caused by:

– Depleting nutrients

– Reproducing themselves

– Making body cells the target of body’s own defenses

– Producing toxins

Disease Process (cont.)

• Once exposed to a pathogen, the body goes 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

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

What are the four stages of illness?

The Body’s Defenses• Immunity – condition

of being resistant to pathogens and the disease they cause

• First lines of defense Skin Sweat glands Mucous membranes Cilia Lacrimal glands Saliva Hydrochloric acid Lysozyme

The Body’s Defenses (cont.)

• Resident normal flora – microorganisms found 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

Nonspecific Defenses• Inflammation

– Signs• Redness• Localized heat• Swelling• Pain

– Purpose• Summon immunologic

agents to site• Begin tissue repair• Destroy invading

microorganisms

Nonspecific Defenses (cont.)

– Steps of inflammation1.Initial constriction, then dilation of blood vessels,

causing redness and heat

2.Fluid leakage from local vessels swelling

3.Scar tissue formation

– Chronic inflammation • Damage to tissues

• Loss of function

Nonspecific Defenses (cont.)

• Phagocytosis– 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

Humoral Immunity

• Lymphocytes – B cells and T cells– 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

Humoral Immunity (cont.)

• Types of immunity– 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

Cell-Mediated Immunity

• T cells attack invading pathogen directly – Helper T cells

• Activate

– Killer T cells • Bind with antigen and kill it

– Suppressor T cells • Slow down or stop attack after antigen is destroyed

– Memory T cells• Respond quickly to another attack by same

antigen

What is the difference between active and passive 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!

Cycle of Infection

• A reservoir host – animal, insect, or human body capable of sustaining pathogen growth– Carrier – unaware of presence of pathogen– Subclinical case – unnoticeable infection– Endogenous infection – normally harmless

microorganisms become pathogenic– Exogenous infection – pathogen introduced

into the body

Click for Cycle of Infection

Cycle of Infection (cont.)

• Means of exit – how the pathogen leaves the host–Nose, mouth, eyes, or ears–Feces or urine–Semen, vaginal fluid, or other

reproductive discharge–Blood or blood products

• Means of transmission – how a pathogen spreads to a host– Airborne

– Blood-borne

– During pregnancy or birth

– Foodborne

– Vector-borne• Living organism that

carries microorganisms to another person

– Touching• Direct

• Indirect through fomites

– Inanimate reservoir of pathogens

– Drinking glass, door knob, etc.

• Means of entrance– 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

– Pathogen factors

• Number and concentration

• Virulence

• Point of entry

Susceptible host Individual with little or no

immunity to infection by a pathogen

Host factors influencing susceptibility Age Genetic predisposition Nutritional status Other disease processes Stress levels Hygiene habits General health

• Environmental factors– Dense populations– Animals – unpasteurized

milk– Insects– Economic and political

factors– Availability of

transportation– Population growth rates– Sexual behavior

Breaking the Cycle• Asepsis – condition in

which pathogens are absent or controlled Maintain strict

housekeeping standards

Adhere to government guidelines to protect against disease

Educate patients in hygiene, health promotion, and disease prevention

ANSWER: Fomites are inanimate objects such as clothing, water, and food that serve as a means of transportation for microorganisms.

What are fomites?

Nice Job!

In Summary

32.1 Infection control has been a problem throughout history. Though there have been many advances, controlling infection continues to be a challenge for doctors.

32.2 There is great variety in the types of pathogenic organisms. Types of potentially infectious microorganisms include prions, viruses, bacteria, protozoans, fungi, and helminths.

In Summary (cont.)

32.3 It is important to be familiar with the diseases that infect people so that you can protect your patients, coworkers, and yourself. These diseases include but are not limited to chickenpox, croup, diphtheria, hepatitis, influenza, measles, mumps, and polio.

32.4 Antibiotic resistance of microbial pathogens is a growing problem. The number of infections for which there is little or no treatment is increasing. It is the responsibility of health-care workers to use antibiotics wisely.

In Summary (cont.)

32.5 The CDC began a campaign to prevent antimicrobial resistance. There are four strategies outlined in the campaign: 1) prevent infection; 2) diagnose and treat infection appropriately; 3) use antibiotics carefully; and 4) prevent transmission of infections.

32.6 There are numerous human pathogens. These pathogens cause disease by damaging the body in a number of ways including depleting nutrients needed by cells, reproducing themselves within body cells, making body cells the targets of the body’s own defenses, and producing toxins that damage cells and tissues.

In Summary (cont.)

32.7 The body is able to protect itself from disease through the use of several lines of defense. These lines of defense may be nonspecific or specific.

32.8 In order for an infection to occur, five elements must be in place. There must be a reservoir host, a means of exit, a means of transmission, a means of entrance, and a susceptible host.

32.9 Direct disease transmission occurs when the pathogen moves immediately from one host to another. Indirect transmission is possible only if the pathogen is able to survive outside the host for some period of time.

In today's world, new infections and

diseases can spread across the country

and even across the world in a matter of

days, or even hours, making early

detection critical.

~ John Linder

Member of the U.S. House of Representatives,

Georgia

End of Chapter 32

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