1. The Chain of Infection
How does Infection Occur?

2. Microorganisms
Small, living organism not visible to the naked eye

3. Pathogens
Microorganism that cause disease

4. Susceptible Host
An organism capable of contracting a specific disease

5. Disease results if the invading pathogen causes
Impairment in the host.

6. Types of Pathogens There are different types of pathogens, including:
i. Fungi
ii. Bacteria
iii. Viruses
iv. Protozoa
v. Rickettsiae

7. b. Bacteria
i. Single celled organism
ii. Live in a variety of environments
iii. Only 1% cause disease
iv. Usually killed by antibiotics
v. examples of diseases caused by bacteria:
1. Pneumonias
2. Strep Throat
3. Tuberculosis

8. c. Viruses
i. Smallest of pathogens
ii. Viruses can reproduce only by invading a host cell
iii. NOT cured by antibiotics
iv. Examples of diseases caused by viruses
1. chicken pox
2. colds
3. flu
4. small pox
5. HIV

9. Types of Infections
Endogenous- means it originates within the body Examples
1. Metabolic Disorders
2. Birth defects/congenital abnormalities
3. Tumors
Exogenous- means it originates outside the body
Examples
1. Pathogenic organisms
2. Radiation
3. Chemicals
4. Trauma
5. Electric Shock
6. Temperature extremes

10. Types of Infections Nosocomial- infection is one that is acquired
by an individual in a health care facility
which are transmitted by health care workers
to the patient
Opportunistic- infections that occur when the body defense’s
are weak

11. Common body Defenses Mucous membrane: lines the respiratory, digestive
and reproductive tracts
b. Cilia: tiny hair like structures that line the respiratory
tract to propel pathogens out of the body
c. Coughing and Sneezing
d. Hydrochloric acid: destroys pathogens in
the stomach
e. Tears in eye: contain chemicals that kill bacteria
f. Fever: kills pathogens via heat
g. Immune response: body produces white blood
cells and antibodies to fight pathogens

12. Infections are also classified as Aerobic or Anaerobic:
Aerobic- means the organism requires oxygen to live
Anaerobic- means it lives and reproduces in the absences of oxygen.

13. As healthcare professionals, it is important to understand two things about infection:

14. The various ways infection can be transmitted
2. The ways the infection chain can be broken

15. There are six links in the chain of infection :

16. 1st - The Pathogen
- a pathogen such as bacterium or virus that can cause disease

17. -the place where pathogen can live
2nd - The Reservoir
-the place where pathogen can live

18. Common Reservoirs Human Body Animals Environment
Fomites- nonliving objects such as doorknobs,
cups, utensils, needles

19. What are “Carrier Hosts”
Hosts that do not show any outward signs or symptoms of a disease but are still capable of transmitting the disease are known as carriers.

20. -way for pathogen to escape from the reservoir
3rd - The Portal of Exit
-way for pathogen to escape from the reservoir
Pathogens can leave the body through urine, feces, saliva, blood, tears, mucous discharge, sexual secretions, and draining wounds

21. Sneezing

22. 4th – The Mode of Transmission
-the way that pathogen can be transmitted to a host

23. Direct contact = person to person
Transmission may occur through:
Direct contact = person to person
Examples: sex, saliva/kissing, handshake/touching

24. Indirect Contact =Contaminated substances
Examples: food, air, soil, insects, animals, feces, equipment

25. -way to enter a new reservoir or host
5th - The Portal of Entry
-way to enter a new reservoir or host
Different portals of entry include: Breaks in the skin or mucous membrane, Respiratory tract, Digestive tract, Genitourinary tract, Circulatory system

26. Respiratory System
inhalation

27. Gastrointestinal System
ingestion

28. Urinary & Reproductive Tracts
Sexual contact

29. Breaks in Protective Skin Barrier

30. 6th - The Susceptible Host
-individual who can contract or accept the disease
Humans become susceptible if…..
a. Large numbers of pathogens invade the body
b. Body defenses are weak

31. Organisms with strong immune systems are better able to fend off pathogens.
Humans may fight off pathogens and do not contract disease if
a. Defense mechanisms of body are intact
b. Immune system functioning

32. Organisms with weakened immune systems are more vulnerable to the support & reproduction of pathogens.
Human becomes susceptible host in some instances
a. Large numbers of the pathogen invade the body
b. Body defenses are weak

33. The cycle of infection can be broken at any link of the chain
-The essential part of patient care & self-protection.

34. The infectious agent can be neutralized or destroyed by treatment

35. The reservoir host must maintain personal hygiene
-potential hosts & carriers must practice asepsis & maintain proper personal hygiene

36. Control Portals of Exit
The portal of exit is closed by the use of proper attire (gowns, gloves, other clothing), control of body secretions, and proper hand washing

37. The route of transmission is minimized through proper hand washing, disinfection and sterilization and proper disposal of contaminated materials.

38. Prevent a Route of Transmission
The portal of entry is blocked by asepsis, disinfection, and sterilization procedures
Proper hand washing
Disinfection & sterilization techniques
Isolation of infected patients
Not working when contagious

39. Protect Portal of Entry
Host susceptibility is broken when the health and wellness of an individual is maintained.
Recognition of Susceptible Host
-health professionals must recognize & protect high-risk patients -

40. AIDS
Transplant Patients
Infant & Elderly Patients
Cancer patients

41. Remember--breaking the chain of infection is the responsibility
of each health professional.