1. Copyright © 2008 Delmar Learning. All rights reserved. Unit 12 Infection

2. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. Objectives List natural body defenses against infections. Explain why patients are at risk for infections.

5. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. Microbes There are many different types of microbes –Many of which are pathogenic to humans

7. Copyright © 2008 Delmar Learning. All rights reserved. Bacteria Simple one-celled microbes Named according to their shapes and arrangement Cause infections in the skin, respiratory tract, urinary tract, and bloodstream

8. Copyright © 2008 Delmar Learning. All rights reserved. Fungi Two groups of fungi are most commonly associated with infection in humans –Yeasts –Molds

9. Copyright © 2008 Delmar Learning. All rights reserved. Viruses Smallest microbe Has a variety of shapes

10. Copyright © 2008 Delmar Learning. All rights reserved. Protozoa Simple one-celled organisms Live on living matter

11. Copyright © 2008 Delmar Learning. All rights reserved. The Chain of Infection Infections occur when certain conditions exist Conditions are called the chain of infection Refer to Figure 12-3A

12. Copyright © 2008 Delmar Learning. All rights reserved. The Chain of Infection

13. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. Chain of Infection

15. Copyright © 2008 Delmar Learning. All rights reserved. Causative Agent Microorganism that can produce the disease process in humans

16. Copyright © 2008 Delmar Learning. All rights reserved. Susceptible Host Person who can become infected with a pathogen Unable to resist a microorganism invading the body, multiplying, and causing infection

17. Copyright © 2008 Delmar Learning. All rights reserved. Susceptible Host Host is susceptible to the disease –Lacks immunity or physical resistance to overcome the invasion of pathogens

18. Copyright © 2008 Delmar Learning. All rights reserved. Reservoir Where pathogens live, multiply, and survive May or may not multiply in the reservoir

19. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. Source This distinction is important when deciding the types of precautions and control measures to use to prevent further spread

22. Copyright © 2008 Delmar Learning. All rights reserved. Portals of Entry Where organisms enter the body are called portals of entry

23. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. Types of Infections Infections can be: –Local –Generalized –Systemic

28. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. How Pathogens Affect 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. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. Immunity Immunity is the ability to fight off disease caused by microbes

33. Copyright © 2008 Delmar Learning. All rights reserved. Immunizations Artificial defenses called immunizations protect against specific pathogens Immunization is provided by vaccines

34. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. 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 sensitivity test may be ordered

37. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. Escherichia Coli 0157:H7 You have learned that Escherichia coli can cause serious problems outside the intestinal tract. E. coli 0157:H7 –Caused outbreaks resulting in serious illness and death

40. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. Viral Infections Viral infections include: –Shingles –Influenza –Hepatitis –Acquired immune deficiency syndrome (AIDS)

42. Copyright © 2008 Delmar Learning. All rights reserved. Other Important Infections Infection caused by fungi: –Coccidioidomycosis Infection caused by protozoa: –Giardiasis –Cryptosporidiosis

43. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. Parasites Both head lice and scabies are known for spreading rapidly through health care facilities

48. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. 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. Copyright © 2008 Delmar Learning. All rights reserved. Bedbugs Bedbugs hide in or around the bed, including: –In the mattress –Behind the headboard –Behind the baseboard on the wall

51. Copyright © 2008 Delmar Learning. All rights reserved. Bioterrorism Use of biological agents –Pathogenic organisms or agricultural pests, for terrorist purposes

52. Copyright © 2008 Delmar Learning. All rights reserved. Smallpox Smallpox is a serious viral infection that is sometimes fatal Disease emerged thousands of years ago but was eliminated during the twentieth century

53. Copyright © 2008 Delmar Learning. All rights reserved. Outbreak of Infectious Disease in a Health Care Facility An outbreak of an infection in a health care facility can be serious for all patients Unless steps are taken immediately –Infection can spread rapidly