Chapter 14 and 15: Infection Control and Promotion of Safety

Infectious dsease

A clinically evident illness resulting from the presence of infectious agents

• Microbes, viruses, bacteria, protozoa, parasites

Microorganisms (microbe)

Microscopic organism found everywhere in the environment including on and in the human body

• Many are part of normal flora of body

  • Ex: skin, nose, throat, mouth, gut

• Many are beneficial - help maintain certain body processes

  • Ex: aid in digestion, help fight against other bacteria

Pathogens

Microorganisms that cause infection and disease

• Require dark environment, food source, appropriate temperature, and moisture to survive and reproduce

• Aerobic organisms: organisms that require oxygen to live

• Anaerobic organisms: organisms that live and reproduce in the absence of oxygen

• 6 main classes of pathogens

  • Bacteria

  • Protozoa

  • Fungi

  • Rickettsia

  • Helminths

  • Viruses

Bacteria

Simple, single-celled organisms that multiply rapidly

• Classified by shape and arrangement

  • Cocci: spherical, occur in pairs

    • Ex: streptococcus, staph

  • Bacilli: rod shaped, occur singularly, in pairs, or in groups

    • Ex: tetanus, pertussis, tuberculosis

  • Spirilla: spiral shaped

    • Ex: cholera, leptospirosis

• Antibiotics used to treat bacterial infections

  • Overuse and misuse cause resistance

  • “Superbugs”

Protozoa

One-celled animal-like organism often found in decaying materials, feces, insect bites, and contaminated water

• Can be free-living (live in outside environment) or parasitic

• Ex: African sleeping sickness, malaria, dysentery

Fungi

Organisms that feed off of decaying organic matter, can be single-celled or multi-cellular

• Not all are pathogenic, usually single-celled (yeasts, molds)

• Only killed by antifungal medications

  • Must be taken long term

  • Expensive

  • Can cause liver damage

• Ex: ringworm, athlete’s foot, thrush

Rickettsia

Group of related bacteria that are parasitic organisms (cannot live outside host)

• Commonly found in fleas, ticks, lice, and mites

• Most are zoonotic (animal to human transmission)

  • No human to human transmission

• Transmitted by bites from other organisms

• Antibiotics used to cure disease

• Ex: Rocky Mountain spotty fever, typhus

Helminths

Multicellular parasitic worms

• Live in and feed on hosts

• Life cycle includes in host (living) and cut of host (egg/larval) stage

• Transmitted by investing eggs or larvae through contaminated food, or water, or entering the skin

• Ex: hookworms, roundworms, flatworms, tapeworms

Viruses

Microscopic, non-living, unable to reproduce unless in another living cell

• Spread by blood and other bodily fluids and direct contact

• Unaffected by antibiotic

• Prone to mutation and changing genetic information

• 2 types of viral replication:

  • Lytic cycle

  • Lysogenic cycle

Lytic cycle

Virus uses host cell to manufacture more viruses

• Viral genes are transcribed and translated by host cell

• New viruses assemble

• Host cell breaks open and releases new viruses

• Viruses free to infect other cells

• Ex: common cold, flu

Lysogenic cycle

Incorporation of vital genome into host cell genome (stay with you forever)

• Virulent genetic information copied when host cell replicates

• Little or no reproduction of new viruses

• Genetic information passed to new cells

• Can transform to lytic cycle and become active

• Stress, pre-existing conditions, other diseases

• Ex: chicken pox (varicella), HIV

Hepatitis B

HBV virus transmitted by blood, serum, and other body fluids, causes destruction of liver cells, manageable but no cure, vaccine available

• Federal law requires free vaccine for health care workers

Hepatitis C

Virus, transmitted by blood and blood-containing fluids, causes serious liver damage, treatable, no vaccine

Acquired immune deficiency syndrome (AIDS)

HIV virus, suppresses the immune system, no cure, no vaccine

Our body’s physical defenses

• Skin - several cell layers thick to keep pathogens out

• Hair - catches bacteria and foreign materials

• Mucus - viscous fluid, catches and traps pathogens (gut, nose, respiratory tract)

• Tears - bacteria fighting enzymes, flush out pathogens

Our body’s chemical defenses

• Skin - defensins (chemicals) that keep pathogens out, in sweat and oil

• Liver - protein produced by liver to kill bacteria by breaking cell membranes

• Stomach - acid produced kills bacteria and protects intestines

Our body’s cellular defenses

• Immune cells: body cells that fight infections

  • Neutrophils - first responders, phagocytes (‘eat” infections), bacteria and fungal infections

  • Eosinophils - parasitic infections, allergies

  • Basophils - rare allergies and inflammatory responses

  • Monocytes - chronic infections (long-term)

  • Lymphocytes - T-cells (attack invaded body cells) and B-cells (produce antibodies)

Types of Infections

Pathogens cause infections and disease in different ways

• Allergic reactions, production of toxins, attack and destroy living cells, etc.

Classified according to mode of transmission and orientations

• Endogenous

• Exogenous

  • Hospital acquired infections (HAIs)

• Opportunistic

Endogenous

infection/disease originated within the body

• Ex: microorganisms within the body, congenital abnormalities, tumors

Exogenous

Infection or disease originated outside the body

• Ex: chemical agents, invading microorganisms, trauma

• Hospital acquired infections (HAIs) - infection acquired in a health care facility

  • Transmitted by health care worker to patient

  • Often antibiotic resistant

  • Cause serious and life-threatening infection

Opportunistic

Occur when the body’s defenses are weak

Chain of infection

For a disease to occur and spread from one individual to another, certain conditions must be met

• Infectious agent - pathogen

• Reservoir - area where infectious agent can live

  • In/on animals/humans

  • Fomites: objects contaminated with infectious material (doorknobs, instruments, bed linens, etc.)

• Portal of exit - a way for infectious agent to escape from reservoir in which is has been growing

  • Pathogens leave humans through urine, feces, blood, saliva, tears, mucous discharge, and draining wounds, etc.

• Mode of transmission - the way a pathogen can be transmitted to another reservoir or host where it can live

  • Direct contact - person to person or contact with pathogen

  • Indirect contact - food, air, instruments, vectors, etc.

• Portal of entry - a way for the infectious agent to enter a new reservoir

  • Breaks in the skin, respiratory tract, digestive tract, circulatory system

  • Can be stopped by body’s defense mechanisms to fight off infections

• Susceptible host - person likely to get an infection or disease

  • Exposure time, compromised systems (patients with cancer, AIDS, or other infections, children, the elderly, other conditions)

Asepsis

Absence of disease-producing microorganisms or pathogens

• Aseptic techniques direct toward cleanliness and eliminating or preventing disease

• Simple techniques: hand washing, wearing gloves, cleaning instruments, and cleaning environment

• Various levels of aseptic control

Contaminated

Organisms and pathogens are present

Antiseptic

Prevent or inhibit growth of pathogenic organisms but are not effective against viruses or fungal spores

• Usually used on the skin

• Ex: alcohol, betadine, chlorhexidine

Disinfection

Process that uses chemical disinfectants to destroy or kill pathogenic organisms, not always effective against viruses and fungal spores

• Used mainly on objects

• Many can irritate skin and eyes

• Ex: bleach solutions, zephiran

Sterilization

Process that destroys all microorganisms (both pathogenic and nonpathogenic)

• Used to clean objects

• Objects that are sterillized are considered sterile

• Can be done by gas, radiation, chemicals, steam

• Instruments sterillized in autoclave

Washing hands

• Hand washing is the most important aseptic technique

• The most effective way to stop the spread of infection

• Waterless hand cleaning with alcohol-based gel, lotion, or foam has been approved for routine patient care

• Not recommended for contact with blood, other bodily fluids, or when dirt is visibly present

• Many health care facilities conduct hand washing audits

14 essential times to wash your hands

1. Before and after touching a patient

2. Before a clean or aseptic procedure

3. After bodily fluid exposure

4. After touching a patient’s surroundings

5. Immediately upon arrival and before leaving a facility

6. After touching a patient’s skin

7. Any time hands become contaminated during a procedure

8. Before applying and immediately after removing gloves

9. Any time gloves are torn or punctured

10. After contact with a soiled u=item

11. After picking up an item off the floor

12. Personal use of the bathroom

13. After you cough, sneeze, or use a tissue

14. Before and after contact with your mouth or mucous membranes