1. Body Defenses 2015- 2016

2. At the completion of this lecture the student will be able to identify the following: 1.Discuss types of infection. 2.Explain chain of infection. 3.Identify actions we take to break the chain of infection. 4.Identify micro – organisms relevant to health care.

3. 1.Local – Specific area of body is infected. 2.Systemic – Microorganisms spread & damage other body areas. Bacteremia: when microbes enter blood stream. Septicemia: when bacteremia spreads through all of the body systems. Acute vs. chronic infection

4. Acute infection means a short term illness or disease and does not refer to the severity of the disease. This phase of infection is often very mild, lasts less than 6 months. The term ‘chronic infection’ refers to an infection that has been ongoing for more than 6 months. The term refers specifically to the duration of infection, not to the severity of the disease. Example: Hepatitis C virus can exist in the body for years without causing symptoms. Chronic infection with hepatitis C virus may lead to liver damage.

5. A pathogen may be transmitted in several different ways, but there is usually one predominant mode of transmission.

6. Reservoir Portal of Exit Mode of Transmission Portal of Entry Susceptible Host Causative Agent Bacteria Viruses Fungi Protozoa Helminthes People Equipment Water Secretions Excretions Droplets Skin Direct-Indirect Contact/Fomite Injection/Ingestion Airborne/Aerosols Broken Skin/Mucous Membrane Gastrointestinal/Respiratory/ Urinary Tract Neonates Diabetics Immunosuppressed Cardiopulmonary Disease Chain of Infection

7. The spread of infection is best described as a chain with six links: 1.A pathogen or causative agent. 2.A reservoir (human, animal, or environmental source of the pathogen). 3.A portal of exit from the reservoir. 4.Mode of transmission. 5.A portal of entry into a susceptible host. 6.A susceptible host.

8. A key goal of infection control programs is to reduce the number of infectious microbes in the healthcare settings through hygienic practices such as hand washing and environmental cleaning.

9. 1. Bacteria Are single-celled organism Important bacteria causing human disease include:-  E. coli (urinary tract infection, diarrhea),  Streptococci (wound infection, sepsis, death),  Clostridium (severe diarrhea, colitis, death),  Mycobacterium (tuberculosis).  Staphylococcus (skin, sepsis, pneumonia, endocarditis, death). 2. Viruses Smallest known pathogens Disease:- – The common cold – Influenza, herpes, chicken pox, measles, HIV. – Hepatitis: three different types A (HAV) B (HBV) C (HCV)

10. Fungi – Plants that live on other plants or animals. – Include yeasts, molds, and mushrooms, Aspergillus. – Diseases: Vaginal yeast infections, athlete’s foot, ringworm Protozoa – One-celled animals that can infect the brain, blood, intestines – Diseases: malaria, dysentery Parasites: are multicellular organisms – grow and feed on a host – possibly kill the host – They infect humans principally through ingestion of eggs or when the larvae penetrate the skin or mucous membranes. – Example: Ascaris, amoebae.

11. We eliminate the causative organism by several methods, including: 1.Hand hygiene, which physically removes and/or kills germs on the hands. 2.Sterilizing surgical instruments and anything that touches the body. 3.Using good food safety methods. 4.Providing safe drinking water. 5.Vaccinating people so they do not become reservoirs for infectious agents. 6.Treating people who are ill. 7.Cleaning surfaces and objects.

12. The reservoir of an agent is the habitat in which an infectious agent normally lives, grows, and multiplies. Types of reservoirs: Humans, animals, and the environment. 1. Human reservoirs:- Two types of human reservoir exist: Cases: persons with symptomatic illness Carriers: A person or animal without apparent disease who a specific infectious agent and is capable of transmitting the agent to others.

13. 2. Animal reservoirs:- Zoo noses: Infectious diseases that are transmissible under normal conditions from vertebrate animals to humans. Zoonotic : diseases include: (cows and pigs), (sheep), (bats, dogs, and other animals ). 3. Environmental reservoirs: Soil, and water Soil: Agents live and multiply in the soil. Examples: Tetanus spores and, Fungal agents, Pools of water

14. 1.Treating people who are ill. 2.Vaccinating people. 3.Handling and disposing of body fluids responsibly. 4.Storing equipment dry. 5.Cleaning the healthcare environment using appropriate disinfectants. 6.Monitoring soil and contaminated water in sensitive areas of the hospital and washing hands carefully after contact with either.

15. The portal of exit is the route by which the causative agent gets out of the reservoir. Examples of portals of exit from the human body include: 1.Respiratory tract. 2.Gastrointestinal (or alimentary) tract. 3.Skin. 4.Genitourinary tract. 5.Circulatory system (e.g., blood).

16. 1.Covering: coughs and sneezes with a tissue. 2.Handling: bodily fluids with gloves, then practicing hand hygiene. 3.Keeping: draining wounds covered with a dressing. 4.Not working: when one has (wet) lesions.

17. 1.Direct transmission — Direct contact — Droplet spread 2. Indirect transmission — Vehicle borne — Vector borne: Mechanical Biologic — Airborne

18. 1. Direct contact: Is person-to-person transmission of pathogens through touching, biting, kissing, or skin, sexual contact.

19. 2. Droplet spread Transmission by direct spray of relatively large, short-range aerosols over a few feet, before the droplets fall to the ground. These aerosols may be produced by sneezing, coughing, or even talking.

20. 2. Indirect transmission: An agent is carried from a reservoir to a susceptible host by: A.Vehicle borne: inanimate vehicle 1.Contaminated food and water, typhoid, paratyphoid, food poisoning, dysentery and cholera. 2.Biologic products (blood), viral hepatitis, AIDS, syphilis and malaria. 3.Fomites (inanimate objects such as toys, handkerchiefs, bedding, or surgical instruments).

21. B. Vectors borne 1. Mechanical transmission: the agent does not multiply or undergo physiologic changes in the vector. For example, flies carry Shigella on appendages. 2. Biologic transmission: When the agent undergoes changes and/or multiplication within the vector before it is transmitted. (Extrinsic incubation period). Example: Malaria

22. C. Airborne transmission: occurs by particles that are suspended in air. There are two types of these particles: - Dust. - Droplet nuclei. 1.Dust particles: Result from re-suspension of particles that have settled on floor or bedding, Infectious particles blown from the soil by the wind. Example: Fungal spores.

23. 2.Droplet nuclei They represent the dried residue of droplets that have been coughed or sneezed into the air. They are very tiny particles less than 5 µ (microns) in size and may remain suspended in the air for long periods. Examples: Tuberculosis is transmitted more often indirectly, through droplet nuclei, than directly, through direct droplet spread.

24. 1.Hand hygiene. 2.Wearing gloves to minimize contamination of hands and discarding them after each patient. 3.Maintaining Contact, Droplet and Airborne Precautions as indicated. 4.Cleaning, disinfection, or sterilization of equipment used by more than one patient. 5.Cleaning of the environment, especially high-touch surfaces.

25. Infectious AgentBody Sources Modes of Transmission Disease Produced Staphylococcus (S. aureus, MRSA) Normal skin, nasal passages; exudates (pus) from boils, drainage from wounds, surgical incisions Direct skin-to-skin contact; Indirect contact via contaminated surfaces, hands and medical devices Skin infection, surgical wound infection, sepsis, death Clostridium difficile GI tract, feces; colonized skin Orally via ingestion of bacterium or spores from contaminated hands or environmental fomites; direct contact with skin Severe diarrhea, colitis, death

26. Infectious AgentBody SourcesModes of TransmissionDisease Produced E. coli and Enterococci GI tract, feces Orally via ingestion of bacteria in fecally contaminated food or water; endogenous spread from one body area to another (via catheters or poor hygiene) Urinary tract infection, gastrointestinal illness, bloodstream infection, sepsis, death HIV Blood, semen, vaginal secretions, breast milk, and other body fluids and tissue Direct contact with body fluids during sex, breastfeeding; blood splashes to eyes or other mucous membranes; indirect contact thru percutaneous exposure (e.g., needlestick injury, shared needles or equipment) AIDS-related illnesses, death Influenza Respiratory tract secretions, droplets from sneeze and cough Indirect contact via contaminated fomites, direct contact with nose Respiratory illness, pneumonia, death (especially in elderly)

27. An agent enters a susceptible host through a portal of entry. -The portal of entry must provide access to tissues in which the agent can multiply or a toxin can act. - Often, organisms use the same portal to enter a new host that they use to exit the source host. Inhalation

28. Examples of portals of entry include: 1.Mouth, nose, and eyes. 2.Skin “breaks” (cuts, rashes). 3.Surgical wounds. 4.Intravenous sites. 5.Anatomical openings with tubes in place (more susceptible than those without) 6. Needle puncture injuries. Ingestion

29. 1.Dressings on surgical wounds. 2.IV site dressings and care. 3.Elimination of tubes as soon as possible. 4.Masks, goggles, and face shields. 5.Keeping unwashed hands and objects away from the mouth. 6.Actions and devices to prevent needle sticks. 7.Food and water safety.

30. A susceptible host: is the final link in the chain of infection.The host is a person or other living organism that can be infected by an infectious agent under normal conditions. Susceptibility of a host depends on: 1. Genetic factors. 2. General factors. 3. Specific acquired immunity.

31. General factors which defend against infection: the skin, mucous membranes, gastric acidity, cilia in the respiratory tract, the cough reflex, and nonspecific immune response. malnutrition, alcoholism, and disease or therapy which impairs the immune response (Cortisone, cytotoxic drugs,...)

32. 2. 2. Specific acquired immunity: It refers to protective antibodies that are directed against a specific agent. Two types: 1.Active immunity: Resistance developed in response to stimulus by an antigen either; Naturally by infecting agent. Artificially by vaccine and usually characterized by the presence of antibody produced by the host.

33. 2. Passive immunity: Immunity conferred by an antibody produced in another host and may be acquired; Naturally by an infant from its mother. Artificially by administration of an antibody containing preparation (antiserum or immune globulin).

34. Natural Barriers Natural barriers to infection include: Intact : skin and mucous membranes Cilia: (small, hair like projections that line the respiratory system, filtering inhaled air and trapping microorganisms) Lung: macrophages (large white blood cells that ingest microorganisms, other cells, and foreign particles in a process called phagocytosis)

35. Antibodies (humoral immunity) resulting from immunization or previous disease Acidic environment in the stomach, urine, and vaginal secretions. Normal flora that provide competition to pathogens; an upset to the balance of normal flora can allow pathogens to cause infection.

36. 1.Vaccinating people against infections before they are exposed. 2.Preventing new exposure to infection in people who are already ill, are receiving immunocompromising treatment, or are infected with HIV. 3.Maintaining good nutrition. 4.Maintaining good skin condition. 5.Covering skin breaks. 6.Encouraging rest and balance in our lives.

37. If you can break any link of the chain of infection, you can prevent the occurrence of new infection. Infection control measures are designed to break the links and thereby, prevent new infections. The chain of infection is the foundation of infection prevention.