Lecture 10
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| Give an example of a genetic disease | hemophilia (a disease where blood does not clot properly), or sickle cell (where red blood cells to take on a sickle shape).
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| What is the cause of genetic diseases | Genetic diseases are caused by a difference in the DNA of a person or animal.
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| Give an example of a degenerative disease | Some diseases are degenerative, for example cirrhosis of the liver (when it is caused by alcohol consumption).
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| What causes infectious diseases? | infectious diseases are caused by microorganisms.
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| What is the function of the normal flora in the human body? | Normal flora may compete for nutrients, affect pH, affect available oxygen, or generate compounds which prevent the growth of other organisms
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| Give 2 examples of of flora which prevent the growth of other organisms. | Streptococci in mouth produce compounds that prevent the growth of gram + and gram - cocci. E. coli in large intestine produce bacteriocins which inhibit the growth of Salmonella and Shigella.
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| Define Noncommunicable disease | Noncommunicable diseases are not spread from one host to another
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| Whgat may cuase non-communicable disease? | Noncommunicable diseases may be caused by organisms that normally inhabit the body and only occasionally produce disease
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| Give examles of non-communicable diseases | a normal flora like Candida albicans causes vaginitis or thrush. Thrush is a yeast infection in the mouth.
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| A normal flora that causes disease such as Candida albicans which causes thrush are called.... | opportunistic pathogen
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| Non communicable diseases can exst outside the body. Give two examples and the disease they cause. | Clostridium botulinum causes food poisoning and Clostridium tetani is introduced into a wound and causes tetanus.
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| Whatis a communicable disease and give three examples.? | Communicable diseases are passed from one host to another: Examples include measles, herpes and tuberculosis
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| What is a contagious disease? | A disease which easily spread from person to person is a contagious disease
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| Whatis the 1st stage of a disease between initial infection and the first symptoms called? | The incubation period of a disease is the period between the initial infection and the frist appearance of any signs or symptoms
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| What is the differencetween a symptom and a sign? | Symptoms are subjective- such as aches or pains. They cannot be measured. Signs are measurable and can be observed by another person. E.g.: lesions, swelling, fever, paralysis.
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| What factors determine the length of the incubation period? | The length of the incubation depends on the kind of organism, the number of infecting organisms and the resistance of the host to the organism.
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| What is the prodromal period? | The prodromal period is a short period of relatively mild signs and symptoms.
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| What is the period of illness? | The period of illness is when the disease is most acute and signs and symptoms are clear
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| What is the outcome if the immune system or medical treatments fail? | If immune or medical treaments fail the person may die during this phase
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| What is the period of decline? | If a person recovers, the illness goes through a period of decline as symptoms become less severe.
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| What is the period of convalescence? | The time period following the period of decline
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| When can people spread infection? | During times of incubation, convalsence, and when they have the full blown disease.
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| What is a nosoicomal infection? | Hospital-acquired infections
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| What percentage of patients acquire ? | It is estimateed that 5 - 15% of all hospital patients acquire some type of noscocomial infection
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| How many people die in the US each year from nosoicomal disease? | About 20,000 people die of nosocomial infections each year.
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| What two facators contribute to the spread of noisocomal diseases in the hospital? | There are microorganisms in the hospital environment, it's unavoidable. Also, the hospitalized person is compromised and less able to fight off disease
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| Many procedures in the hospital break the skin. How are patients compromised while in the hospital? | Skin helps to keep microorganisms from entering the body. Surgery, burns or trauma, break down this barrier. So do injections, intravenous therapy, and catheters. Invasive procedures increase the susceptibility to disease.
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| Whatis the chain of transmission for disease in a hospital? | chain of transmission exists in the hosital which facilitates the spreading of disease. The chain of transmission involves staff contact, patient to patient contact, and indirect transmission via fomites (inanimate objects) and the ventilation system.
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| Opportunistic infections arise in compromised pats. Most nosocomial infects were caused by gram+ S. aureus. Staph, inc. S. aureus is norm. flora of the skin and is abundant in nasal passages.S. invades through skin breaks resists Penic. Use what instead? | methicillin or vancomycin
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| Name two opportunistic infections common in hospitals. | Pseudomonas aeruginosa, and E. coli
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| Are Pseudomonas aeruginosa, and E. coli inherently dangerous? | No. Pseudomonas aeruginosa, and E. coli. P. aeruginosa rarely makes healthy people sick, but in immunosuppressed people it can cause respiratory infections.
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| Where is P. aeruginosa found in the patient population? | It is unfortunately common in burn patients where a skin infection may produce a blue-green pus. P. aeruginosa is not a fussy organism. It can grow in almost any moist environment, including in flower vases, mop water and even dilute disinfectants
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| What principles apply to the control of nosoicomal infections. | use aseptic technique, handle contaminated materials carefully, wash hands frequently, work closely with the infection control committee of your institution
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| What is the most common point of entry for pathogens? | The most common portals of entry are the mucous membranes These include the respriratory tract, the gastrointestinal tract, the genitourinary tract, and the conjuntiva of the eye
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| T/F STD's must have broken skin in order to enter the body. | F. Some do and some don't
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| What is the most important line of defense against microorganisms? | Unbroken skin is an important defense and is almost impentetrable by most microorganisms.
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| Whatis the name of the parasite that can bore through unbroken skin? | The parasite Necator americaus can bore through intact skin.
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| What is the method called that allows some microorganisms to cause disease when skin or mucous membranes are injured, for example by puncture wounds, injections, bites, or surgery? | The parenteral route is when organisms are deposited into the tissues beneath the skin or into mucous membranes.
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| What is the preferred route of entry for Streptococci? What disease can it cause? | It's worth knowing that organisms have a preferred portal of entry. For example, the preferred route of entry for Streptococci is inhalation.When inhaled, Strep can cause pneumonia
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| If Strep is swallowed is it pathogenic? | If Strep is swallowed, howed it does not usually produce symptoms. Some organisms have more than one portal of entry
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| Almost all microorganisms have a means of attaching themselves to their host. What method do bacteria use? What are they mnade of? How do they attach? | Adhesins on bacteria are generally glycoproteins or lipoproteins. They bind specifically to receptors on host cells. The host cell receptors are typically sugars, such as mannose.
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| T/F Bacteria have a phospholipid plasma membrane and a peptidoglycan cell wall | T Remember that bacteria have a plasma membrane (made of phospholipids), and a cell wall (peptidoglycan).
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| Some bacteria have a capsule around the cell wall. | T Around the cell wall many bacteria also have a capsule.
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| A capsule will not prevent a bacteria from being phagocytized? | F Around the cell wall many bacteria also have a capsule.
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| If a bacteria had a capsule, what would the purpose of the capsule be? | A capsule may determine whether a strain of bacteria is virulent or not (whether it will cause disease). A capsule may prevent a bacteria from being phagocytized. Bacteria which produce capsules related to virulence are:
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| List two bacteria which produce capsules related to virulence. | Klebsiella pneumoniae, Streptococcus pneumoniae
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| What illness does the bacteria Hemophilus influenza | Hemophilus influenza (causes pneumonia and meningitis)
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| What illness does the bacteria Bacillus anthraciss cause? | Bacillus anthraciss (causes anthrax)
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| What illness does the bacteria Yersinia pestis cause? | Yersinia pestis (causes plague
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| What bacteria causes tooth decay? | Streptococcus mutans
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| What is the action of plaque creation and buildup?? | S. mutans can convert glucose into a sticky polysaccharide called dextran, which forms its glycoclayx (a loose capsule). Additional bacteria, such as Actinomyces, will bind to the glycocalyx of S. mutans and further contribute to plaque
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| What is dental plaque? | plaque is a build up of bacteria, dextran and debris which occurs on teeth
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| Can cell wall components contribute to virulence? If yes, How? | Yes.For example the waxy cell wall of Mycobacterium turberculosis helps the organism resist digestion by phagocytes. The tuberculosis bacteria can even multiply inside phagocytes.
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| What are leukcidins? | Strep and staph produce leukocidins. These are enzymes which destroy white blood cells.
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| What is the function of hemolysins? | On blood agar some strains of streptococci produce these enzymes -- which lyse red blood cells. They will also lyse white blood cells. Strains which produce beta hemolysin are more pathogenic--they evade host defenses better.
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| What are coagulases? Give an example. | Coagulases are enzymes which coagulate blood (the fibrinogen in blood). When coagulase enzymes are produced by an organism they help to wall the organism off from host defenses. An example of this is the Staphylocci which cause boils
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| What are kinases? Give an example of a bacteria that usesKinases. | Kinases are bacterial enzymes which dissolve clots. Clots help the body isolate infections. Streptococcus pyogenese produces a clot dissolving enzyme which helps the organism to spread.
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| What is the effect of the Clostridium species? | Clostridium species which cause gas gangrene produce enzymes which dissolve a polysaccharide (hyaluronic acid) and a protein (collagen) which are important to tissue structure
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| What are the two enzymes associated with Clostridium called? | These enzymes are called hyaluronidase and collagenase, respectively.
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| What are the 3 ways bacteria can gain access to the host? | Penetration or evasion of host defenses can be facilitated by bacterial capsules, cell wall componenets and enzymes.
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| There are 3 types of damage to host cells. What are they? | A disease progresses when damge is done to host cells. Some of this damage is direct. Most is caused by toxin produced by bacteria. Other damage is done by hypersensitivity, the immune response of the host.
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| T/F Some pathogens entice phagocytes to engulf them. | E. coli, and Salmonella are among the organisms which can induce host cells to phagocytize them. The organisms can be extruded from the host cell to enter other cells. The extrusion is a sort of reverse phagocytosis and damages cells.
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| T/F Some bacteria invade host cells by excreting enzymes to penetrate the cell. | Some bacteria damage host cells by excreting enzymes to penetrate the cell.
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| T/F Most cell damage is cause by toxins. | T 40% of bacterial toxins cause disease by damaging host cell membranes
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| What are the two types of bacterial toxins? | There are two types of toxins: exotoxins and endotoxins.
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| What are exotoxins? | Exotoxins are produced inside bacteria while they are growing. These toxins are released into the medium surrounding the organism. They are mostly made by gram positive bacteria.
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| What are endotoxins? | produced by growing gram positives. Inhibit certain metabolic functions.
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| What are cytotoxins? | cytotoxins (kill host cells)
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| List 1 cytotoxin and explain how it works | Corynebacteria diptheriae produces this toxin only when infected by a lysogenic phage carrying the proper gene. The toxin inhibits protein synth. in the host. The exotoxin has two components, the A active and B binding polypeptides
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| What is the function of the A component of a cytotoxin? | The A component of the toxin then alters cell function by inhibiting protein synthesis.
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| How do neurotoxins perform their work? | Neurotoxins interfere with normal nerve impulse transmission
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| Give an example of a neurotoxin and how it works. | Botulinum. Botulinum toxin binds to nerve cells and prevents the release of acetylcholine, a neurotransmitter.
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| What type of toxin is tetanus and how does it work? | Clostridiium tetani. A neurotoxin. Binds to nerve cells that control the contract. of skele. muscles. Muscle contracts when nerve impulse fires. Opposing muscle receives signal to relax. Tetanospasmin, the exotoxin blocks relaxastion. Death by suffocation
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| Where would one find enterotoxins? Give one example | enterotoxins (affect the lining the the gastrointestinal tract) E. Coli certain strains produce enterotoxins
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| What are endotoxins? | Endotoxins, again, are part of the outer portion of the cell wall of gram-negatives.
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| Remember that gram negative cells have an outer membrane external to the peptidoglycan layer. Imbedded in that membrane are lipopolysaccharides. Each lipopolysaccharide has an O polysaccharide tail and a Lipid A portion. | The lipid A is the endotoxin. (So, extoxins are proteins, and endotoxins are lipopolysaccharides)
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| Endotoxins produce the same signs and symptoms no matter what the species of microorganism. What are the symptoms? | Chills, fever, weakness, aches, and shock (shock is a life-threatening loss of blood pressure). Endotoxins can also cause bood clots which will obstruct capiillaries. Endotoxins can cause death
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| Endotoxin fever is mediated by macrophages. When a mphage ingests a gram- bact, the it is degraded and endotoxins are rel. inside the mphage. Endotoxins induce mphage to produce interleukin-1. I-1 is rel. by the mphage and travels through the bloodstream | In the hypothalamus, I-1 induces the hypothalamus to produce prostaglandins. These protaglandins reset the body's thermostat to a higher temperature, fever.
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| Remember that we have talked about how information determining a bacteria's pathogenicity can be carried on plasmids. What are the 4 substances are carried by plasmid genes? | tetanospasmin (the exotoxin of tetanus), Staphylococcal enterotoxin, Staphylococcus aureus adhesins, Staphylococcus aureus coagulase
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| Phage genes that contribute to pathogenicity include: | diptheria toxin, Staphylococcal enterotoxin and pyrogenic toxin, botulinum neurotoxin, capsule produce by Streptococcus pneumoniae.
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| Define epidemiology | The science that studies when and where disease occur and how they are tranmitted.
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| What agency of the government is responsible for monitoring epidemiological information? | The Center for Disease Control is the federal agency involved in monitoring epidemiological information. By evaluating case reports, an understanding of the chain of transmission of diseases can be established.
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| What is the MMWR? | The MMWR (Morbidity and Mortality Weekly Report ) is available online at http://www.cdc.gov
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| What does the MMWR provide? | It provides statistics regarding both the morbidity (number of people affected in a certain time) and mortality (number of deaths) for notifiable diseases
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