PRINCIPLES OF INFECTION CONTROL

MICROORGANISM OR MICROBE 1. Small living organism 2. Not visible to the naked eye 3. Must be viewed under a microscope 4. Found everywhere in the environment, including on and in the human body

Many microorganisms are part of normal flora of the body; flora is microbial organisms in environment such as the intestinal, vaginal, oral, or urinary systems a. Beneficial in maintaining certain body processes b. Called nonpathogens

Other microorganisms cause infection and disease a. these are called pathogens or germs At times, a microorganism that is beneficial in one body system can become pathogenic in another body system a. Bacteria called Escherichia coli (E. coil) is part of the natural flora of the large intestine b. If E. coli enters urinary system, it causes an infection

CLASSIFICATION OF MICROORGANISMS Bacteria a. Simple one-celled plants that multiply rapidly b. Classified by shape and arrangement c. Some diseases caused by bacteria: (1) meningitis (2) gonorrhea (3) boils (4) wound infections (5) typhoid (6) syphilis

Congenital Syphilis Primary Syphilis Secondary Syphilis

Boils

Antibiotics are used to kill bacteria Some strains of bacteria have be come antibiotic- resistant Means that the antibiotic is no longer effective against the bacteria MRSA

PROTOZOA a. One-celled animal-like organism b. Often found in decayed materials and contaminated water d. Some protozoa are pathogenic and cause diseases such as: (1) malaria (2) amebic dysentery trichomonas (3) African sleeping sickness

Malaria African Sleeping Sickness

FUNGI Simple plantlike organisms Live on dead organic matter Yeasts and molds are two common forms of fungi that can be pathogenic Cause diseases such as: (1) ringworm (2) athlete’s foot (3) histoplasmosis (4) yeast vaginitis (5) thrush

Athlete’s Foot Thrush Ringworm

Antibiotics do not kill fungi Antifungal medications are available for many of the pathogenic fungi These medications are expensive, must be taken internally for a long period of time, and may cause liver damage

RICKETTSIAE Parasitic microorganisms (1) Cannot live outside the cells of an other living organism (2) Commonly found on fleas, lice, ticks, and mites (3) Transmitted to humans by the bites of these insects Cause diseases such as: (1) typhus fever (2) Rocky Mountain spotted fever Antibiotics are effective against many different rickettsiae

Rocky Mountain spotted fever cycle Typhus lesion Fleas, Ticks, Lice

VIRUSES Smallest microorganisms, visible only in an electron microscope Cannot reproduce unless they are inside another living cell Spread from human to human by blood and body secretions

Very difficult to kill (1) Resistant to many disinfectants (2) Not affected by antibiotics Cause many diseases such as: (1) common cold (2) measles (3) mumps (4) chicken pox (5) herpes (6) influenza (7) polio

Chicken pox Measles Herpes Mumps

Three diseases of major concern to health care workers (1) Hepatitis B or serum hepatitis Caused by the HBV virus Transmitted by blood serum and body secretions Affects the liver and can lead to destruction and scarring of liver cells Vaccine has been developed to protect individuals from this disease Vaccine is expensive and involves a series of three injections Under federal law, employers must provide the vaccination at no cost to any health care worker with occupational exposure to blood or other body secretions Individual does have the right to refuse the vaccination, but a written record must be kept proving that the vaccine was offered

(2)Hepatitis C Caused by the hepatitis C virus, or HCV Transmitted by blood and blood containing body fluids Many individuals who contact the disease are asymptomatic (display no symptoms) Others have mild symptoms that are often diagnosed as influenza or flu HCV can cause serious liver damage At present there is no preventive immunization, but a vaccine is being developed Both HBV and HCV are extremely difficult to destroy Viruses can even remain active for several days in dried blood Health care workers must take every precaution to protect themselves from hepatitis viruses

(3)Acquired immune deficiency syndrome (AIDS) Caused by the HIV (Human Immunodeficient Virus) Suppresses the immune system Individual cannot fight off many cancers and infections that would not affect a healthy person No cure at present and no vaccine available

FACTORS REQUIRED FOR GROWTH: 1. Microorganisms need certain things to grow and reproduce 2. Most microorganisms prefer a warm environment, and body temperature is ideal 3. Darkness is also preferred by most microorganisms, and many are killed quickly by sunlight 4. Source of food and moisture is needed 5. Need for oxygen varies a. Aerobic organisms require oxygen to live b. Anaerobic organisms live and reproduce in absence of oxygen 6. Human body is ideal supplier of all of the requirements

HOW DO PATHOGENIC ORGANISMS CAUSE DISEASE? PATHOGENIC MICROORGANISMS CAUSE INFECTION AND DISEASE IN DIFFERENT WAYS: 1. Some pathogens produce poisons, called toxins, which harm body a. Example is bacillus tetanus b. Produces toxins that damage central nervous system

2. Some pathogens cause an allergic reaction resulting in a runny nose, watery eyes, and sneezing 3. Other pathogens attack and destroy the living cells they invade a. Example is the protozoan that causes malaria b. Invades red blood cells and causes them to rupture

CLASSIFICATIONS OF DISEASES AND INFECTIONS Classified as endogenous, exogenous, nosocomial, and opportunistic Endogenous 1) Means the infection or disease originates within the body 2). Includes metabolic disorders, congenital abnormalities, tumors, and infections caused by microorganisms within the body

Exogenous 1) Means that the infection or disease originates outside the body 2) Examples include pathogenic organisms that invade the body, radiation, chemical agents, trauma, electric shock, and temperature extremes

Nosocomial 1) Infections acquired by an individual in a health care facility, such as a hospital or long-term care facility 2) Usually present in facility and transmitted by health care workers to the patient 3) Many of the pathogens transmitted in this manner are antibiotic-resistant 4) Can cause a serious and even life-threatening infection 5) Common examples: (a) Staphylococcus (b) Pseudomonas (c) Enterococci 6) Infection control programs are used in health care facilities to prevent and deal with nosocomial infections

Opportunistic 1) Infections that occur when the body’s defenses are weak 2) Diseases do not usually occur in individuals with an intact immune system 3) Examples include the development of Kaposi’s sarcoma (a rare type of cancer) or Pneumocystis carinii pneumonia in individuals with AIDS

COMMON BODY DEFENSES 1. Mucous membrane that lines the respiratory, digestive, and reproductive tract and traps pathogens 2. Cilia (tiny, hairlike structures) lining the respiratory tract to propel pathogens out of the body 3. Coughing and sneezing 4. Hydrochloric acid in the stomach to destroy pathogens 5. Tears in the eye that contain bacteriocidal (killing bacteria) chemicals 6. Fever 7. Inflammation resulting in leukocytes or white blood cells destroying pathogens

8. Immune response a. Body produces antibodies, protective proteins that combat pathogens b. Cells secrete protective chemicals such as interferon

9. Human becomes susceptible host in some instances a. Large numbers of the pathogen invade the body b. Body defenses are weak 10. Ending the chain of infection a. If any part of the chain can be eliminated, the spread of disease or infection will be stopped b. Follow practices to interrupt or break this chain c. Prevent the transmission of disease d. Important to remember that pathogens are everywhere e. Preventing pathogen transmission is a continuous process