Principles of Infection Control

1. Principles of Infection Control 14.1

2. Microorganisms or Microbes Small living organisms Not visible to the naked eye Microscope must be used to see them Found everywhere in the environment Found on and in the human body Many are part of normal flora of body May be beneficial

3. Microorganisms or Microbes • Called nonpathogens when not harmful to the body • Called pathogens (germs) when able to harm the body; cause infection and disease • A microorganism can be beneficial in one body system and harmful in another system • Example: E. coli

4. Microorganisms or Microbes • Most prefer warm environments (body temp.) • Most prefer darkness • Many are killed quickly by sunlight • Need source of food and moisture • Need for oxygen varies • Aerobic- require O2 to live • Anaerobic- do not require O2 • Human body is ideal supplier of all the requirements

5. Microbe Classifications

6. Bacteria Simple, one-celled organisms Multiply rapidly Classified by shape and arrangement

7. Cocci Bacteria • Cocci are round or spherical in shape • Diplococci—in pairs • Examples: gonorrhea, meningitis, pneumonia • Streptococci—in chains • Examples: strep throat, rheumatic fever • Staphylococci—clusters or groups • Most common pyogenic microorganisms • Examples: boils, UTIs, wound infections, toxic shock

8. Bacilli Bacteria • Bacilli are rod shaped • Occur singly, in pairs, or in chains • May have flagella • Ability to form spores (thick-walled capsules) when conditions are poor; extremely difficult to kill • Examples of diseases: • TB, tetanus, pertussis, botulism, diphtheria, typhoid

9. Spirilla Bacteria • Spirilla are spiral or corkscrew shaped • Includes comma-shaped vibrio and corkscrew spirochete • Diseases include syphilis and cholera

10. Antibiotics Antibiotics are used to kill bacteria Some strains of bacteria have become antibiotic-resistant Example: Methicillin-resistant staphylococcus (MRSA)

11. Protozoa • One-celled, animal-like organism • Found in decayed materials and contaminated water • May have flagella for movement • Some are pathogenic • Examples of diseases: • Malaria, amebic dysentery, trichomonas, African sleeping sickness

12. Fungi • Simple, plant-like organisms • Live on dead organic matter • Yeast and molds are 2 common forms • Can be pathogenic • Antibiotics do not kill • Antifungal medications-expensive, may cause liver damage • Examples of diseases: • Ringworm, athlete’s foot, histoplasmosis, yeast vaginitis, thrush

13. Rickettsiae • Parasitic microorganisms • Cannot live outside the cells of another living organism • Transmitted to humans by the bites of insects (e.g., fleas, lice, ticks, mites) • Examples of diseases: • Typhus and Rocky Mountain spotted fever • Antibiotics are effective against many of them

14. Viruses Smallest microorganisms Must use electron microscope to see Must be inside another living cell to reproduce Spread by blood and body secretions Very difficult to kill Cause many diseases: common cold, measles, mumps, chicken pox, herpes, influenza, and polio Prone to mutating

15. Severe Acute Respiratory Syndrome (SARS) Caused by a variant of coronavirus family Flu-like symptoms Can lead to respiratory failure and death

16. West Nile Virus (WNV) Mosquito-borne First infected birds but now humans Some individuals only have mild febrile illness Older or have poor immune systems it can cause severe neurologic illnesses such as encephalitis or meningitis

17. Monkeypox Hantavirus Affects monkeys, other primates, and rodents Mutated and spread to humans Infection occurs after contacting body secretions or excretions of infected animals Can also occur by ingesting food that has been contaminated from infected animals Causes severe flu-like symptoms, lympadenopathy, and pustules; can cause blindness Treated/prevented by smallpox vaccine

18. Ebola and Marburg • Filovirus • First affected primates and then spread to humans • Causes hemorrhagic fever • Begins with fever, chills, headache, myalgia, and a skin rash; Progresses to jaundice, pancreatitis, liver failure, massive hemorrhaging throughout body, delirium, shock and death

19. H5N1 • Causes avian or bird flu • Has appeared in humans • From contact w/ infected poultry or contaminated surfaces • Concern that virus will mutate and spread more readily in humans

20. Hepatitis B Serum hepatitis Caused by HBV Transmitted by blood serum and body secretions Affects the liver Vaccine available for protection Vaccine is expensive (3 injections) Employers must provide vaccine to health care workers

21. STOP Hepatitis C Caused by HVC Transmitted by blood and blood-containing body fluids Many infected individuals are asymptomatic Others have mild symptoms Can cause severe liver damage Can remain active for several days in dried blood

22. Acquired Immune Deficiency Syndrome (AIDS) Caused by the Human Immunodeficiency Virus (HIV) Suppresses the immune system Individual becomes susceptible to cancers and infections that would not affect a healthy person No cure presently and no vaccine

23. Helminths • Multicellular parasites otherwise known as worms or flukes • Are transmitted: • By eating contaminated food • Being bitten by infected insects • When worms enter the skin

24. How Pathogens Cause Infection and Disease Some produce poisons called toxins Some cause an allergic reaction Others attach and destroy the living cells they invade

25. Classifications of Diseases and Infections

26. Endogenous Infection or disease originates within the body Metabolic disorders, congenital abnormalities, tumors, and infections caused by microorganisms within the body

27. Exogenous Infections or disease originates outside the body Pathogenic organisms that invade the body, radiation, chemical agents, trauma, electric shock, and temperature extremes

28. Nosocomial Acquired by an individual in a health care facility Usually present in facility and transmitted by health care workers to patient Many are antibiotic resistant Can cause serious, life-threatening infections Examples: staphylococcus, psudomonas

29. Opportunistic infections Occur when body’s defenses are weak Examples: Kaposi’s sarcoma, Pneumocystis carinii in patients with AIDS

30. Chain of Infection • Present for disease to occur and spread from one individual to another • Causative agent- pathogen that can cause a disease • Reservoir- area where the causative agent can live • Fomites- objects contaminated with infectious material that contains the pathogen • Portal of exit- a way for the causative agent to escape from the reservoir

31. Chain of Infection • Mode of transmission- way that the causative agent can be transmitted to another reservoir • Direct contact- person-to-person or contact with a body secretion; contaminated hands • Indirect contact- pathogen is transmitted from contaminated substances

32. Chain of Infection • Portal of entry: a way for the causative agent to enter a new reservoir/host • Breaks in skin, mucous membrane, respiratory tract, digestive tract, genitourinary tract, circulatory system • Body’s defenses: mucous membrane, cilia, coughing and sneezing, hydrochloric acid, tears in the eye, fever, inflammation, and immune response • Susceptible host: person likely to get an infection or disease

34. Aseptic Techniques Asepsis: absence of disease-producing microorganisms Sterile: free from all organism both pathogenic and nonpathogenic Contaminated: any object or area that may contain pathogens Major aim: maintaining cleanliness and eliminating or preventing every aspect of contamination

35. Common Aseptic Techniques Thorough handwashing Good personal hygiene Disposable gloves Cleaning instruments and equipment Proper cleaning of environment

36. Levels of Aseptic Control Antisepsis—prevents or inhibits growth of pathogenic organisms (not spores or viruses);used on the skin Disinfection—destroys pathogenic organisms (not always spores and viruses)used mainly on objects; uses chemicals Sterilization—destroys all microorganisms;use of steam under pressure, gas, radiation, and chemicals on objects