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Microbiology Ch 8-13
From 'Chain of Infection' (Chapter 8) to 'Emerging Diseases' (Chapter 13).
Question | Answer |
---|---|
Name the links (in order) in the 'chains of infection'? | Infectious Agent; Reservoir; Portal of Exit; Mode of Transmission; Portal of Entry; Susceptible Host |
Describe 'Infectious Agent'? | A microbial organism with the ability to cause disease. |
Describe 'Reservoir'? | A place where micro-organisms can thrive and reproduce. |
Describe 'Portal of Exit'? | A place of exit providing a way for a micro-organism to leave the reservoir. |
Describe 'Mode of Transmission'? | Method of transfer by which the organism moves or is carried from one place to another. |
Describe 'Portal of Entry'? | An opening allowing the micro-organism to enter the host. |
Describe 'Susceptible Host'? | A person who cannot resist a micro-organism invading the body, multiplying and resulting in infection. |
What is the weakest link in the chain of infection? | Mode of transmission. |
What is direct contact? | Person to person transmission of pathogens through touching, biting, kissing or sexual intercourse. |
What is indirect contact? | Spread of pathogens by inanimate objects such as equipment, utensils, soiled laundry, door knobs and tissues. |
What is droplet transmission? | Produced when an infected person coughs, sneezes or speaks. They travel approximately 3 feet before drying out or falling to the ground. |
What is airborne transmission? | Occurs when respiratory droplets evaporate, leaving behind droplet nuclei that are so small they remain suspended in the air. Very few diseases are transmitted by this route. |
What are common modes of transmission? | Blood, serum, plasma, water, food and milk. |
What does it mean by 'Vector-borne'? | A transmission by an animate intermediary such as an animal, insect or parasite that transports a pathogen from reservoir to host. |
What is resistance? | The ability of a host to ward off diseases through non-specific and specific defences. |
What is susceptibility? | The lack of resistance to a disease. |
Name the two categories to the human defence mechanisms? | Specific Resistance and Non Specific Resistance. |
What is non specific resistance also known as? | 1st and 2nd line of defence. |
What is specific resistance also known as? | 3rd line of defence. |
Name 1st line defences? | Skin, mucous membranes, and body secretions. |
What are the benefits of normal flora? | Suppress growth of pathogenic bacteria by 1/ competing for essential nutrients; 2/ changing environmental conditions to be unfavourable to other micro-organisms eg low ph; 3/ secreting toxic substances; 4/ forming bacterial layers over tissue surfaces. |
Name 2nd line defences? | Inflammation, fever, phagocytosis and natural killer cells (NK), protective proteins and cytokines. |
What are cytokines? | Molecules which produce inflammatory response. |
Name 3 types of cytokines? | Chemokines, Interleukins and Interferons. |
What is the function of Chemokines? | Drive cell chemotaxis. |
What is the function of Interleukins? | Act as messengers between Leucocytes. |
What is the function of Interferons? | Make cells non permissable to viral replication. |
What are the characteristics of inflammation? | Redness, heat, pain and swelling. |
What is a fever? | An abnormally high body temperature produced in response to a bacterial or viral infection. |
What is phagocytosis? | The ingestion of a micro-organism by cells known as Phagocytes. |
What is a Phagocyte? | A type of white blood cell. |
What are the 4 phases of phagocytosis? | Chemotaxis. adherence, ingestion and digestion. |
What are natural killer cells? | Lymphocytes capable of destroying tumour cells and virus infected cells. |
What are the 2 categories of antimicrobial substances? | The complement system (protective proteins) and cytokines. |
What is the function of the complement system? | 1/ Flow freely in blood to quickly reach site of invasion where they react with antigens to trigger inflammation; 2/ attract eater cells (macrophages) to the area; 3/ coat intruders so that eater cells more likely to devour them; 4/ kill intruders. |
Explain the importance of skin in the 1st line of defence? | A barrier against pathogens, low ph inhibit microbial growth and keratin is a protective protein. |
Explain the role of mucous membranes in 1st line of defence? | Trap microbes, acts as a barrier. |
What is a pyrogen? | Chemicals that produce fever. |
Other names for the immune system? | Acquired immunity, specific immunity, 3rd line of defence and antibody-mediated immunity. |
What is meant by antibody-mediated immunity? | Controlled by antibodies. |
Where does specific immunity begin? | In the blood. |
What is immunology? | The study of specific defences against pathogens. |
What are the components of human blood? | Plasma, red blood cells (erythrocytes), white blood cells (leukocytes), platelets (thrombocytes), fat globules, chemical substances (carbohydrates, proteins and hormones) and gases (Oxygen, Carbon dioxide and Nitrogen). |
Name 5 types of white blood cells? | Lymphocytes, Monocytes, Eosinophils, Basophils and Neutrophils (granulocytes). |
What is an antigen? | Something that provokes a highly specific immune response in an organism. They are usually proteins or large polysaccharides that make up part of an invading microbe. |
What are antibodies? | Are members of a group of soluble proteins known as immunoglobulins which are produced by B cells in response to the presence of an antigen, which it combines specifically with. |
What are the 5 classes of antibodies? | IgG, IgD, IgE, IgA and IgM. |
What are the characteristics of acquired immunity? | Able to distinguish between self and non self; It is foreign body specific; It has a memory. |
What are the 2 main divisions of specific immunity? | Humoral immunity and cell mediated immunity. |
What is humoral immunity? | Involves antibodies produced by B cells in response to a specific antigen. The antibody locks onto the antigen. |
What is cell mediated immunity? | Depends on T cells, does not involve antibody production, responds to intracellular (within the cell) bacteria and viruses, multicellular parasites, transplanted tissue and cancer cells. T cells detect infected cells and kill them. |
What are the 4 types of acquired immunity? | Naturally active, artificially active, naturally passive and artificially passive. |
Explain naturally active immunity? | A person develops antibodies through naturally being exposed to antigens. These immunities can last a lifetime. |
Explain naturally active immunity? | A natural transfer of antibodies from a mother to her infant either by transplacental or from breast milk. These antibodies only last a few weeks to a few months. |
Explain artificially active immunity? | Specially prepared antigens called vaccines are deliberately introduced into the body. Long term immunity. |
Explain artificially passive immunity? | Antibodies are introduced into the body that have been extracted from an immune animal or person, usually in an emergency situation eg snake bite. Short term immunity only. |
What are the different types of vaccines (what parts of an organism are used)? | Inactivated bacterial toxins; killed micro-organisms; living but attenuated (weakened) micro-organisms or parts of micro-organisms such as capsules. |
What are the 5 main categories of vaccines? | Live-attenuated vaccines; Inactivated vaccines; subunit vaccines; toxoids; DNA vaccines. |
Name the vaccines usually given in the first 6 months of life? | Diptheria, tetanus, hepatitis B, whooping cough, influenza type B, polio, rotavirus. |
What is infection control? | Doing everything possible to prevent the spread of infection. |
Why is infection control important? | To stop the spread of disease in health care facilities. Prevention of infections to help clients recover quickly and stay healthy. |
What kinds of infections occur in hospitals? | Urinary tract infections, wound infections after surgery, blood infections, respiratory infections. |
Who is at higher risk for infection? | Newborn babies; the elderly; people with diabetes; people who have had surgery or with large, broken skin areas; transplant patients taking immunosuppresive drugs; patients with decreased immune systems. |
What is Healthcare Associated Infection (HAI)? | An infection that was not apparent or incubating at the time of admission but appears at least 48 hours after admission or within a specified time (depending on causative bug) after discharge. |
What are the disadvantages of HAI's? | Increased morbidity and mortality; cost to health care systems; extended hospital stays; cost of antimicrobial therapy; cost to community and replacing workers; reduced productivity and medical insurance claims; loss of personal income for patients. |
What are standard precautions? | Hand hygiene; use of PPE; safe use and disposal of sharps; environmental cleaning; reprocessing of reusable medical equipment and instruments; respiratory and cough hygiene; aseptic non-touch technique; waste management and appropriate linen handling. |
What are additional precautions? | Required for patients with suspected or confirmed infection which is carried by airborne, droplet or contact route and cannot be contained by using standard precautions alone. |
What activities may put health care workers at risk? | Wound dressing; starting an IV line; giving injections; collecting blood/pathology specimens; anything that cuts through the skin; suturing; suctioning of patients airways; cleaning body fluids (faeces and urine). |
What other activities could cause a risk to health care workers? | Handling dirty linen; emptying sharps containers; handling biohazardous waste; processing/handling laboratory specimens; environmental cleaning; repairing client care equipment. |
What are risks in a health care organisation that should be reported? | Seeing a co-worker not wearing appropriate PPE or using hand hygiene; not disposing of waste appropriately; ignoring or not cleaning up spills. |
Name the document that help health care organisations to handle infection control? | Policies and procedures manual. |
What are the 3 different types of hand washes available in a health care setting? | Routine, aseptic, surgical. |
Name some personal protective equipment (PPE)? | Gloves, protective gowns, masks, protective eye wear, foot wear. |
Describe the term contaminated? | Infected by a pathogen. |
Describe the term virulence? | The severity of a disease caused by a micro-organism. |
Describe the term fomite? | An inanimate object or substance. |
Describe the term pathogenicity? | Describes micro-organisms that can cause disease. |
Describe the term pyrexia? | A fever when the human body temperature rises above the normal range. |
Describe the term inflammatory response? | A fundamental response by the body to disease and injury. |
Describe the term toxins? | A biologically produced poison. |
Describe the term transmission? | Passing of a pathogen causing communicable disease from an infected host (individual or group) to other individuals or groups. |
Describe the term sterile? | Totally clean and free from bacteria. |
Describe the term infectious? | A disease caused by pathogens that have entered into the body. |
Describe the term quarantine? | A period of isolation to control the spread of infectious disease. |
Describe the term isolate? | The voluntary or compulsory separation and confinement of those known or suspected to be infected with a contagious disease. |
Why would hospitals keep statistics of hospital acquired infections? | To track, alert healthcare staff to see if procedures are done properly. Feedback on quality of care given. To be accountable to keep standards high. |
What are antibiotic resistant micro-organisms or superbugs? | They are strains of bacteria that have changed (or mutated) after coming in contact with an antibiotic. these bacteria then become 'resistant' to that antibiotic. This prevents the antibiotic from killing the bacteria or stop them from multiplying. |
What are possible causes of drug resistance? | Overuse, unnecessary and inappropriate use of antibiotics; 3rd world purchase without prescriptions or outdated; people fail to finish courses. |
How can drug resistance be prevented? | careful antimicrobial use; timely hand washing; aseptic techniques; short hospital stays; minimal use and early removal of invasive procedures; adequate staffing; active infection control. |
What are emerging infectious diseases? | Infectious diseases whose incidence in humans has increased in the past 2 decades or threatens to increase in the near future. |
What are the possible causes of emerging infectious diseases? | 1/ Climate and changing ecosystems; 2/ Human demographic change (inhabiting new areas); 3/ Human behaviour (sexual and drug use); 4/ Human susceptibility to infection (immunosuppressant); 5/ Poverty and social inequality; 6/ 2/3rds from animals. |
Which disease in East Africa caused thousands of deaths in 2014? | Ebola. |