Unit 12

1. Unit 12 Infection

2. Objectives • Spell and define terms. • Identify the most common microbes and describe some of their characteristics. • List the links in the chain of infection. • List the ways that infectious diseases are spread.

3. Objectives • Define spores and explain how spores differ from other pathogens. • Name five serious infectious diseases. • Identify the causes of several important infectious diseases. • Describe common treatments for infectious disease.

4. Objectives • List natural body defenses against infections. • Explain why patients are at risk for infections.

5. Introduction • Humans are surrounded by a world of tiny organisms • These beings cannot be seen with the naked eye • They make their presence known only by their effects • Same way we become aware of the wind

6. Microbes • There are many different types of microbes • Many of which are pathogenic to humans

7. Bacteria • Simple one-celled microbes • Named according to their shapes and arrangement • Cause infections in the skin, respiratory tract, urinary tract, and bloodstream

8. Fungi • Two groups of fungiare most commonly associated with infection in humans • Yeasts • Molds

9. Viruses • Smallest microbe • Has a variety of shapes

10. Protozoa • Simple one-celled organisms • Live on living matter

11. The Chain of Infection • Infections occur when certain conditions exist • Conditions are called the chain of infection • Refer to Figure 12-3A

12. The Chain of Infection

13. Chain of Infection • Breaking one link in the chain of infection is all that is needed to prevent the spread of disease • Refer to Figure 12-3B

14. Chain of Infection

15. Causative Agent • Microorganism that can produce the disease process in humans

16. Susceptible Host • Person who can become infected with a pathogen • Unable to resist a microorganism invading the body, multiplying, and causing infection

17. Susceptible Host • Host is susceptible to the disease • Lacks immunity or physical resistance to overcome the invasion of pathogens

18. Reservoir • Where pathogens live, multiply, and survive • May or may not multiply in the reservoir

19. Reservoir • Source • Person, animal, or substance from which the infectious agent passes to the host • May also be an inanimate object, such as water, a sink or counter top, or doorknob

20. Source • Reservoir may be the same as the source or different from the source • Reservoir is where the pathogen lives or resides • Source is the site from which the pathogen is transmitted to a susceptible host • Directly or indirectly through an object or in the environment

21. Source • This distinction is important when deciding the types of precautions and control measures to use to prevent further spread

22. Portals of Entry • Where organisms enter the body are called portals of entry

23. Portals of Entry • Portals • Body openings, mucous membranes, and breaks in the skin • Portals also result from tubes placed in body • Urinary catheters, or from punctures produced by invasive procedures such as intravenous fluids

24. Portals of Exit • Infectious organisms leave the reservoir of the human host through body secretions or portals of exit • Portal provides a way for a pathogen to leave the reservoir • Leaving nose or mouth on a sneeze or cough

25. Mode of Transmission • Mode or method of transmission: • Method by which the infectious agent passes from a source to the host • May be transmitted by more than one route

26. Mode of Transmission • Methods of transmission are: • Direct contact • Indirect contact • Airborne and droplet spread • Fomites (a method of indirect contact) • Vectors • Common vehicles

27. Types of Infections • Infections can be: • Local • Generalized • Systemic

28. Body Flora • Different microbes live on our body surfaces • Microbes are called the normal body flora • Flora are not the same in all body areas

29. Body Flora • They are not harmful in the area in which they normally reside • But may cause infection if they are moved to another area of the body

30. How PathogensAffect the Body • Potential for infection depends on the risk factors listed previously • Two major factors are: • Susceptibility of the host • Amount of infectious agent that finds a portal of entry into the host

31. Body Defenses • The body has some natural defenses to protect itself from infections • There are several natural external defenses • The most important of these is the skin

32. Immunity • Immunityis the ability to fight off disease caused by microbes

33. Immunizations • Artificial defenses called immunizationsprotect against specific pathogens • Immunization is provided by vaccines

34. Immunosuppression • Occurs when the body’s immune system is inadequate • Fails to respond to the challenge of infectious disease organisms that it normally would fight successfully

35. Serious Infections in Health Care Facilities • Serious bacterial and viral infections are increasing in health care facilities as well as in the general public

36. Bacterial Infections • Bacteria are often the cause of serious skin, respiratory, urinary, and gastrointestinal infections in patients • If a physician suspects that a patient has a bacterial infection: • Culture and sensitivitytest may be ordered

37. MRSA and VRE • Two groups of organisms have become resistant to two powerful antibiotics • Methicillin and vancomycin • These organisms are: • Methicillin-resistant Staphylococcus aureus(MRSA) • Vancomycin-resistant enterococci (VRE)

38. Tuberculosis • Before the development of antibiotics: • Tuberculosis was a widespread disease with a high fatality rate • In the 1950s: • Use of antibiotics effective against tuberculosis caused deaths to drop sharply

39. Escherichia Coli 0157:H7 • You have learned that Escherichia colican cause serious problems outside the intestinal tract. • E. coli 0157:H7 • Caused outbreaks resulting in serious illness and death

40. Pseudomembranous Colitis • Many bacteria live in the bowel of a healthy person • Most of them are harmless • Some friendly bacteria help with digestion • A few of these have the potential to be troublemakers if they get out of control

41. Viral Infections • Viral infections include: • Shingles • Influenza • Hepatitis • Acquired immune deficiency syndrome (AIDS)

42. Other Important Infections • Infection caused by fungi: • Coccidioidomycosis • Infection caused by protozoa: • Giardiasis • Cryptosporidiosis

43. Spores • Microscopic reproductive bodies are responsible for the spread of some diseases • They can survive in a dormant form until conditions are ideal for reproduction • Spores will multiply and continue to spread infection • They are very difficult to eliminate

44. Spores • Avoid alcohol products for cleansing hands if a patient has a disease spread by spores: • Alcohol will not kill spores • Mechanical action of washing with soap and water loosens spores and washes them down the drain

45. Severe Acute Respiratory Syndrome • SARS is a highly contagious viral respiratory illness caused by a coronavirus • Special isolation precautions are required • Much remains to be learned about SARS

46. Parasites • Survive by feeding off another human or animal • Head lice are parasites that spread by direct and indirect contact • Scabies is a skin disease caused by a parasite called a mite • Mites are microscopic organisms that cannot be seen with the eye

47. Parasites • Both head lice and scabies are known for spreading rapidly through health care facilities

48. Bedbugs • Are real parasites • Most people believe they are imaginary • Survive in hot and cold environments and live up to a year without eating

49. Bedbugs • There is no recorded incidence of disease as a result of bedbugs, although it is suspected • Bites cause a painful rash on the skin • Bedbugs feed at night

50. Bedbugs • Bedbugs hide in or around the bed, including: • In the mattress • Behind the headboard • Behind the baseboard on the wall