Cycle of Infection

1. Cycle of Infection HST I

2. Objectives / Rationale • Infection Control is an increasingly important aspect of health care for the client and the health care professional.

3. Upon completion of this lesson, the student will be able to: • Identify the cycle of the infectious process; • Investigate ways to protect themselves and patients from infection; and • Research common human pathogens.

4. Infections and diseases are classified as: Endogenous – it originates within. Includes: metabolic disorders, congenital abnormalities, tumors, infections from microorganism within the body. Exogenous – originates outside the body; includes invading pathogens, radiation, chemical agents, trauma, electric shock, temperature extremes.

5. Nosocomial – is one that is acquired in a health care facility, which is transmitted by health care workers to the patient. • Opportunistic – those that occur when the body’s defenses are weak; i.e. weakened immune system.

6. Infections are also: • Aerobic – the organism requires oxygen to live. • Anaerobic – the organism lives and reproduces in the absences of oxygen.

7. Infection Cycle: • Infective Agent – pathogens include bacteria, viruses, funguses, rickettsiae, protozoa. • Reservoir – where causative agent can live. Includes the human body, animals, environment, and fomites or objects contaminated with infectious material that contains the pathogens.

8. Portal of exit – way for causative agent to escape from the reservoir. • Pathogens can leave the body through urine, feces, saliva, blood, tears, mucous discharge, sexual secretions, draining wounds.

9. Means of transmission – how it is transmitted to another host. • By: Direct Contact – person to person, physical contact, or contact with body secretions containing the pathogen. • Indirect Contact – from contaminated sources such as food, air, soil, equipment, etc.

10. Indirect contact can include touching contaminated equipment or surfaces, breathing in droplets carrying airborne pathogens, or receiving the bite of an insect carrying the pathogen.

11. Portal of entry – way to enter a new reservoir or host. • Breaks in the skin or mucous membrane; respiratory tract; digestive tract; genitourinary tract; circulatory system.

12. Susceptible host – individual who can contract the disease, unless: • Defense mechanisms are intact. • Immune system is functioning.

13. The cycle of infection can be broken: • The infectious agent can be neutralized or destroyed by treatment. • The reservoir host must maintain personal hygiene. • The portal of exit is closed by the use of proper attire (gowns, gloves, etc), control of body secretions, proper handwashing.

14. The route of transmission is minimized through proper handwashing, disinfection, sterilization, and proper disposal of contaminated materials. • The portal of entry is blocked by asepsis, disinfection, and sterilization procedures. • Health and wellness of the individual is maintained.

15. Microorganisms and Disease • Microorganism – an organism that is too small to be seen by the human eye. • Fungi – simple plants such as molds and yeasts • Protozoa – only group classified as an animal. • Virus – cannot be seen by ordinary microscope; not destroyed by antibiotics.

16. Bacteria – classification is determined by the shape of the bacteria and whether it grows with or without oxygen. Only a few, such as staphylococcus and streptococcus cause disease. • Cocci – round; includes staphylococci which is in clusters like grapes; causes boils, impetigo and osteomyelitis.

17. Cocci also includes streptococci, round bacteria arranged in chains; causes rheumatic fever, streptococcal pneumonia, and scarlet fever. • Cocci also includes diplococci, arranged in pairs – causes gonorrhea and meningitis.

18. Bacilla (i) – rod-shaped bacteria. • Spirilla – bacteria shaped like spirals. • Rickettsiae – smaller than bacteria; barely visible under microscope. Causes typhus, Rocky Mountain Spotted Fever. • Pathogen – the term for a disease-causing microorganism.

19. Vocabulary terms: • Sterile means “free from all organisms”, including spores and viruses. • Contaminated – organisms and pathogens are present.

20. Asepsis – the absence of infection • Medical Asepsis – practices and techniques designed to protect individuals from the spread of disease. • Antiseptic – substances that inhibit the growth of bacteria. Some can be used on the skin. • Disinfectant – cannot be used on skin; includes chemicals and boiling.

21. Sterile – absence of all microorganisms • Surgical asepsis – the use of sterile technique to handle equipment, maintain sterile fields, change dressings, and dispose of contaminated materials without introducing harmful microorganisms.

22. Sterilizing with an Autoclave • The autoclave is the safest, most efficient sterilization method. • An autoclave is a piece of equipment that uses steam under pressure or gas to sterilize equipment and supplies. • It will destroy ALL microorganisms, both pathogenic and non-pathogenic, including spores and viruses.

23. Using an autoclave - • Items that are to remain sterile must be wrapped before they are Items are cleaned and prepared before being put in autoclave. • autoclaved. • Autoclave indicators are used to insure sterility of the item.

24. Using chemicals for ‘disinfection’ - • Since many chemicals do not kill spores and viruses, chemicals are not a method of sterilization. • Chemicals are used to disinfect instruments that do not penetrate body tissue. • Examples: 90% isopropyl alcohol, formaldehyde-alcohol; 10% bleach; Lysol, Cidex.

25. Epidemiology • Tracing the occurrence of health related events in society. • Epidemiologist – a person who specializes in the study of outbreaks of diseases within a population group. • Endemic – the ongoing presence of a disease within a population, group or area. Example: the common cold.

26. Epidemic– a sudden and widespread outbreak of a disease within a population, group or area. Example: a widespread outbreak of measles or influenza. • Pandemic- an outbreak of a disease occurring over a large geographic area, possibly worldwide. Ex: AIDS, H1N1 flu.