The Chain of Infection How does Infection Occur?

Microorganisms Small, living organism not visible to the naked eye

Pathogens Microorganism that cause disease

Susceptible Host An organism capable of contracting a specific disease

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

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

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

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

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

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  

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

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.

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

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

There are six links in the chain of infection :

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

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

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

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.

-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

Sneezing

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

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

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

-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

Respiratory System inhalation

Gastrointestinal System ingestion

Urinary & Reproductive Tracts Sexual contact

Breaks in Protective Skin Barrier

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

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

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

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

The infectious agent can be neutralized or destroyed by treatment

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

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

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

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

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 -

AIDS Transplant Patients Infant & Elderly Patients Cancer patients

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