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167 Cards in this Set

  • Front
  • Back
Study of disease
Pathology
Study of cause of disease, not always known
Etiology
Manner in which disease develops
Pathogenesis
Disease causing, from the Greek word pathos meaning "suffering"
Pathogen
Invasion of colonization of the body by pathogenic microbes
Infection
When an infection results in any change from a state of health
Disease
The degree to which an organism can cause disease
Virulence
Microbes found on/in a healthy body
Normal flora
present for only a short period of time
Transient Flora
Living together
Symbiosis
From whence an infection originates, can be living or non-living
Reservoir
The individual or location from when the pathogen is acquired
Source
Normal microbial flora
Commensal flora
Source is commensal flora
Endogenous infection
Source is from elsewhere
Exogenous infection
A disease that has its natural reservoir in animals and is secondarily transmitted to humans.
Zoonosis

- Some zoonotic diseases, once aquired by humans, can be transmitted from human to human
an agent that transfers pathogens from one host to another
Vector

-insects (usually an arthropod from one host to another
-fomites (inanimate objects)
From person-to person by close association
Direct Contact
Handling or contaminated food/water
Indirect contact
Where/How a pathogen enters the body
Portals of Entry

-most pathogens must gain access to the inside of the body by crossing the epidermis-skin or mucous membranes.
- Dental cavities and acne are exceptions (stay on skin or close to surface)
Respiratory and gastrointestinal tracts
Mucous membranes

-respiratory tract is the easiest and most common
-gastrointestinal tract is the most infectious agents destroyed by digestive system
is the amount of pathogen (measured in number of microorganisms) required to cause an infection in the host. Varies according to the pathogen and an individual’s age and overall state of health.
Infectious dose (ID)
Amoutn of a pathogen to kill the host
Lethal Dose (LD)
Infectious Dose for Entamoeba Coli
-Extremely low
-From 1 Cyst
Impedes phagocytosis, may enhance adherence to tissues
Bacterial capsules
Prevents destruction via phagocytosis.
Cell wall components
Some pathogens produce more than one type
Enzymes:
leukocidin - kill WBC hemolysin - lysis of RBC
coagulase - wall off infections Ex. boil hyaluronidase - digests tissues, enhances invasion streptokinase – breaks down blood clots

-damage may occur in immediate vicinity of pathogen or toxins are carried elswhere
-poisonous substances produced by some pathogens
Toxins
Exotoxins
-proteins produced by the living bacteria
-Small Lethal Dose
-degraded quickly in the bloodstream
-body may produce antitoxins witch neutralize the toxins
-Either solely responsible for or make a major contribution to the disease.
-Ex. cytotoxins - kill host cells. neurotoxins - interfere with normal nerve functions. enterotoxins - affect the lining of the gastrointestinal tract. cardiotoxins – affect cardiac cells
Endotoxins
Lipopolysaccharides, a part of the outer portion of the cell wall, mostly GN
-released when cell lyses
-Large Lethal Dose
-not degraded as quickly in the bloodstream
-no antitoxins made
-All endotoxins produce same signs and symptoms: fever, weakness, aches, shock, heart disturbances
Factors that affect host resistance:
-injury
-age
-drugs - prescription, non-prescription, and recreational drugs all impact body defenses
-malnutrition
-pre-existing disease condition
-sex - males and females do respond differently to some diseases
-environment - residential, occupational, & natural
-dosage of disease agent -heredity
first line of defense against disease. Mechanical factors: continuous barrier, keratin, mucous, tears, urine flow. Chemical factors: sebum, salt, low pH, lysozyme, gastric juice, competition of normal flora.
Skin/mucous membrane
performed by a several types of white blood cells (leukocytes). Macrophages can leave the circulation and migrate throughout the tissues or remain in a tissue such as the spleen. Natural killer cells target infected cells.
Phagocytosis
a defensive response to many things not limited to pathogens. Characterized by redness, pain, heat, and swelling. Damaged cells release cytokines that encourage this action.
Inflammation
increase in body temperature, a systemic response to bacterial or viral infection. Also chemicals and tissue damage can induce a fever. Body temperature is controlled by the hypothalamus in the brain. Toxins may set body thermostat higher. As body temperature climbs, the skin remains cold, thus shivering occurs. When skin temperature increases, then shivering stops. When toxins are cleared and thermostat is reset to normal body temperature, then skin tries to cool down and sweating begins. Up to a certain point, fever is considered to be a defense. Extreme fevers may cause damage to brain cells.
Fever
a collection of ~20 plasma proteins that act together to produce a cascade response. Can work with antibodies to kill pathogens.
Complement
Specific resistance developed naturally during lifetime
-Naturally Acquired Immunity

1. Active: resulting from infection, long-lasting
2. Passive: from mother to infant, crossing the placenta or mother's milk, short lasting
Specific resistance acquired through artificial means
-Afrtificially Acquired Immunity

1. Active:resulting from vaccination, long-lasting
2. Passive: from receiving pre-formed antibodies, short lasting
fluid remaining after a clot has formed, clotting factors no longer available becasue they are now tied up in the clot. Clotting factors include calcium
Serum
Whole Blood
-fluid component: plasma
-cellular component: all originate in active bone marrow (RBCs, WBCs, Platelets)
Anything the body recognizes as foreign or non-self. Usually large stable molecules. May be inanimate. Usually only a portion of the molecule is recognized (antigenic determinant).
Antigen (Ag)
proteins produced by plasma cells (stimulated B cells) in response to an antigen.
Ag + B cell ----> plasma cell and antibody production, Ab bind to specific sites on Ag called epitopes.
Antibody (Ab)
Involves B cells and antibody production
Humoral Immune system
When B-cells encounter an antigen some are induced to form plasma cells and produce antibody against that antigen. Others become memory cells that "remember" the antigen in subsequent encounters
Active Immunity
~80%, can leave blood -> tissues, can cross the placenta, Second to appear in an immune response, but levels are higher and longer lasting. Subsequent responses result in high levels produced quickly.
IgG
~5-10%, largest Ab, does not enter tissues, first to appear in an immune response, levels rapidly decline.
IgM
~5%, associated with mucous membranes, present in colostrum, mucus and saliva.
IgA
~0.2%, found in blood and lymph, does not cross placenta, not much known.
IgD
~0.002%, involved in allergic reactions and parasitic infections
IgE
produced by hybridomas - the fusing of a tumor cell with an antibody producing plasma cell. All monoclonal antibodies arising from the same clone have the same antigen-binding site. Used as diagnostic and research tools. Ex. Blood typing anti-sera
Monoclonal antibodies
~65% of circulating T-cells, (CD4 cells) recognize antigens and “process and present” Ag information to B cells, also release lymphokines (chemical messages) that stimulate T and B-cells.
Helper T Cells
Inhibit development of B-cells to plasma cells. Modulate amplifier T-cells
Suppressor T-cells
Promote B-cells to turn into plasma cells. Modulate suppressor T-cells.
Amplifier
~35%, lyse target cells, mainly virus infected and tumor cells.
Killer T cells (Cytotoxic cells)
deactivate T-killer cells
Regulatory T cells
remember an AG. Also part of active immunity
Memory T-cells
When both T and B memory cells are produced
Complete immunity
When suppressor and amplifier T-cells are out of balance (antibodies attack own cells)
Autoimmune disease
cell markers (antigens) found on all body cells, genetically determined, compatibility concern in tissue transplants. Interesting note - may contribute to pheromones and mate attraction.
Major Histocompatibility Complex (MHC)
Inflammatory responses of immunological origin. Leads to tissue damage rather then immunity. Occurs only when a person has been sensitized to an allergen.
Hypersensitivity Reaction
Type I Immediate Hypersensitivity or Anaphylaxis
-signs and symptoms occure within seconds or minutes after exposure to an Ag.
-includes common allergies (asthma and anaphylaxis)
-reactions depend upon the nature of the antigen, the frequency and route of antigen contact, and the type of antibody reacting with the antigen
-mast cells
-first exposure to an allergen B-cells are stimulated to produce IgE. IgE binds to mast cells found among connective tissues throughout the body. No symptoms are apparent. Subsequent exposure to the same allergen results in the hypersensitivity reaction. The allergen binds with the IgE on the mast cell and triggers the release of the mast cell contents to the circulation.
-Symptoms include increased mucous production, leaky blood vessels, edema, smooth muscle contraction, itching, and skin rash.
contain histamine, herapin, and other substances capable of attracting phagocytes to the site of bacterial invasions
Mast Cells
Anaphylaxis or anaphylactic shock:
-usually occurs when allergen directly enters the body via insect sting or digestive absorption, the result is systemic.
-the release of mast cell products is greater than the bodys ability to respond to the rapid changes in the vascular system.
-systemic shock will develop and the patient will die.
-first signs are restlessness, tightening of the throat, gasping for air and coughing, shortness of air and increased heart rate due to bronchial constriction. Blood pools and death occurs.
-can be counteracted by early administration of epinephrine.
Common allergens include:
-pollen
-some helminths
-animal dander
-dust mites
-mold spores
-penicillin
-seafoods
-nuts
-strawberries
-eggs
-peanuts
-bee and wasp stings
-MORE COMMON IN MALES AND OFTEN HEREDITARY
Desensitization (allergy shots)
-attempt to stimulate IgG production to compete with the allergen binding to IgE on the mast cells.
-also stimulates suppressor cell action
-treatment with drugs that block the receptor sites on mast cells (antihistamine) however the best effect is seen when administered prior to allergen exposure.
-Corticosteroids used for contact dermatitis.
-cant be done for food and skin allergies
-avoidance of the allergens is the best prevention
Type IV Delayed Hypersensitivity
-symptoms occure greater then 12 hours after exposure to the allergen.
-reaction results from a cell-mediated response to an antigen/
-Mechanisms involve T-cells, macrophages and mast cells
-T-cells produce lymphokines which stimulate an influx of machrophages to perform phagocytosis. The result is an exaggeration of the immune response and the phagocytes bring about the destruction of the local tissue.
-EX. allergic contact dermatitis (mild redness to severe inflammation and blister formation) from aniline dyes (dyed leather), metals such as nickel and mercury.
Autoimmune disease
when the body develops an immune response against its own tissues.
-tends to run in families
-possible viral involvement
-Ex. Junvenile diabetes, multiple sclerosis, rhumatoid arthritis
A material administered to a subject to produce artificially acquired active immunity. Vaccines are designed to create the benefits of a rapid antibody response without undergoing an actual infection.
Vaccines
To develop a vaccine
MUST KNOW PORTAL OF ENTRY
1. mucosal surface fo respiratory tract
2. mucosal surfaces spread systemically to the blood
3. needles or insect bites
Properties of a good vaccine:
1. ability to stimulate a robust immune response. Not all types of molecules are equally effective in doing this and the age of the individual play a part in the response.
2. Obtaining the right kind of immune response. Bloodstream antibodies will be of little use unless the organism invades the body.
3. 3. Vaccines make a substantial contribution to public health only if they can be administered cheaply and easily to millions of people
4. Vaccine safety
Attenuated Vaccine
-"live vaccine"
-consits of live microorganisms that have been rendered avirulent or with reduced virulence.
-Avirulent strains are obtained by mutation or due to repeated replication under laboratory conditions (tend to cause disease like symptoms)
-Since the injected microbe is still alive, it multiplies in the host and provides a source of antigen stimulation of protective antibody production, and a source of memory cells for subsequent infection by the virulent strain.
-Live vaccines are extremely effective in preventing disease, but concern always exists that back mutation to a virulent form may occur or that some host may be unable to cope with even an attenuated organism. Ex. MMR (mumps, measles, rubella), oral Sabin polio vaccine
Killed Vaccine
-contains the virulent infectious agent killed by chemicals or radiation
-Killed vaccines are safer to administer than live vaccines, but do not normally provide long-term immunity. Repeated immunization by booster doses is often required to maintain immunity.
-Ex. HAV vaccine. injected Salk polio vaccine (primary polio vaccine used in the U.S.)
Toxoids and/or cellular components
-toxoids are toxins that have been chemically modified to nontoxic forms, (usually by treatment with formalin) but still retain their immunologic characteristics.
-Cellular components, such as pieces of capsule material, are sometimes used to illicit antibody responses
-Ex. Tetanus, Meningitis
DNA Vaccines
-still experimental but trials very promising
-injections of naked DNA, host cells will decode DNA and make small quantities of the microbial antigen, thus stimulating an immune response.
-seem to stimulate T and B cell responses, thus a more complete immunity.
Herd Immunity
-the goal of the public health immunization programs is to immunize a large enough population (80%) of the susceptible population that the spread of the infectious agent is greatly reduced or eliminated,
-. If the number of individuals susceptible to a disease is decreased through immunization, the chances of contact between infected and susceptible persons are also reduced.
Vaccine Successes
Worldwide eradication of smallpox:
-no animal reservoir for smallpox
-lifelong immunity
-asymptomatic cases are rare and so an infected person can be identified and isolated
-one smallpox serotype and so the vaccine is effective against all virus strains
-very effective
-major comittment by government
Destruction of all life forms, including bacterial spores
sterilization
used on inanimate objects, not living tissues, to destroy harmful pathogens in their vegetative state. Disinfection can be achieved by physical and chemical antimicrobial procedures. Most are not sporicidal.
Disinfectant
kills both vegetative and spore forms of microbes.
Complete disinfectant
kill vegetative forms of microbes only.
Incomplete disinfectant
an agent applied externally on living tissues to kill or inhibit the growth of organisms. Milder than disinfectants.
Antiseptic
reduction in the numbers of pathogens to a level deemed safe by public health guidelines. Not sterilization.
Sanitization
reduction in the numbers of pathogens to a level deemed safe by public health guidelines. Not sterilization.
Degerming
any chemical agent that kills microbes.
Germicidal

-effected by temperature, type of microbe, and environment.
means to inactivate or inhibit, but not killing
Germistatic
prevents the further multiplication of bacteria without necessarily killing all that are present.
Bacteriostatic
Heat Methods
-need to know the heat susceptibility of an organism to know what heat treatment to apply
-need to know thermal death time, thermal death point, and decimal reduction time
Dry heat
-kills by oxidizing proteins
-slower and requires a higher temperature than moist heat
-170 C for 2 hours for sterilization
Moist Heat
-denatures and coagulates proteins
-To kill vegetative bacteria, yeast and mold: 80 C for 5-10 minutes;
-To kill mold spores: 80 C for 30 minutes;
-To kill bacterial spores: autoclaving = 121 C, 15 lbs/psi (need pressure), for at least 15 minutes.
kills vegetative forms, unreliable for spores.
Boiling
lowers bacterial counts, hopefully removes pathogens. Does not sterilize.
Pasteurization

-Vat Pasteurization - 63°C (145°F) 30 minutes

-High Temperature Short Time Pasteurization (HTST) - 72°C (161°F) 15 seconds

-Ultra Pasteurization (UP) - 89°C (191°F) 1.0 second
used when heat-sensitive materials are to be sterilized.
Filtration
removal of water, can be done by salts or sugars.
Drying
refrigeration or freezing.
Cold Temperatures
using x-ray or gamma radiation. Highly reactive toxic radicals are formed.
Radiation
affects nucleic acids and death soon results.
UV Light
direct effect is minimal. The length of heat exposure is too short to be effective.
Microwaving
Chemical Methods
-generally not intended to achieve sterilization
first chemical used. Used by Lister. Damages cell membranes and inactivates enzymes while denaturing their proteins. Ex. Used to be basis for Lysol products, hexachlorophene.
Phenol
chlorine and iodine. Both inactivate proteins.
Halogens
no effect against spores.
Alcohols
silver, copper, zinc. Believed to act by combining with cellular proteins.
Heavy Metals
soaps emulsify the microbes thus aiding in physical removal. Detergents solubilize the cell membranes resulting in cell death.
Soaps and detergents
formaldehyde and glutaraldehyde. Exposure of several hours is required to destroy spores.
Aldehydes
denatures proteins. Need exposure for several hours. Good for plastics.
Ethylene oxide (ETO)
hydrogen peroxide, benzoyl peroxide, and ozone. Release large amounts of oxygen to the area thus killing anaerobes
Oxidizing agents
organic acids help maintain a low microbial population. Sorbic acid - cheeses, benzoic acid in soft drinks, calcium propionic acid - bakery goods.
Food preservatives
How to make a disinfectant from cholrine
A simple formula to prepare an effective antimicrobial dilution of bleach is to add 2.0 oz of concentrated bleach to one gallon of tap water, and then add 2.0 oz of 5% distilled white cooking vinegar. Adding the vinegar is optional but will make the bleach solution 80-200 times more antimicrobial than its original solution. Use in a well-ventilated area as there will be the odor of chlorine. Can be stored in a tightly closed container for a few days. Most effective if prepared fresh daily. Protect eyes and mucus membranes.

*CAN NOT BE SCENTED BLEACH
are used in disinfectants and antiseptics to kill microbes (additive)
-most common is Triclosan
Biocides
Emergency Water Supply
• Store at least 1 gallon of water per day for each person and each pet. You should consider storing more water than this for hot climates, for pregnant women, and for persons who are sick.
• Store at least a 3-day supply of water for each person and each pet (try to store a 2-week supply if possible).
• Observe the expiration date for store-bought water; replace other stored water every six months.
• Store a bottle of unscented liquid household chlorine bleach to disinfect your water and to use for general cleaning and sanitizing.
Proper Water storage
• Label container as "drinking water" and include storage date.
• Replace stored water that is not commercially bottled every six months. Look at expiration dates on bottled water!
• Keep stored water in a place with a fairly constant cool temperature.
• Do not store water containers in direct sunlight.
• Do not store water containers in areas where toxic substances such as gasoline or pesticides are present.
Make safe water
Water often can be made safe to drink by boiling, adding disinfectants, or filtering.
IMPORTANT: Water contaminated with fuel or toxic chemicals will not be made safe by boiling or disinfection. Use a different source of water if you know or suspect that water might be contaminated with fuel or toxic chemicals.
Filters
-use activated carbon
-to deactivate viruses must use water purification (with iodine) not just filtering
-water filters get rid of the big debris
Chemical substances produced by various microorganisms to supress the growth of other microorganisms
Antibiotics

-act on structures found in bacteria but not in the host
-work best in conjunction with an active immune system
bacteriocidal
kills bacteria
bacteriostatic
suppress bacteria and allow the immune system to catch up

-When a bacteriostatic antibiotic is used the duration of therapy must be sufficient to allow cellular and humoral defense mechanisms to eradicate the bacteria.
should kill or inhibit the growth of many different types of bacteria.
broad spectrum

-useful because the same symptoms can be caused by different bacterial species and it is not always possible to wait for isolation and identification of the causative organism before therapy is begun. However, they not only attack pathogens, but also reduce the numbers of resident microflora.
only kills or inhibits the growth of a select group of microorganisms.
selective activity

-more ideal
Evaluating Antimicrobial Drugs
-isolate pure colony
-form a lawn of the bacteria
-place small sections of filter paper impregnated with different concentrations of the antibiotic and see where bacterial growth stops due to the antibiotic
the lowest concentration of an antibiotic that stops visible growth (the zone of inhibition around a disk impregnated with antibiotic)
Minimal inhibitory concentration
to determine antibiotic sensitivity
What affects the antibiotics effectiveness
-location of the infection
-pharmacolgocial absorption and distribution
-route
-frequency of administration
inhibits the synthesis of peptidoglycan. Once cell wall synthesis is inhibited, autolysis of the cell wall can occur. These antibiotics are generally bactericidal.
Inhibitors of cell wall synthesis
Polymyxin B disrupts the outer membrane of Gram negative bacteria. Since the cell membrane is not exposed in Gram positive bacteria polymyxin has little activity against them. This drug is toxic to human cells, since it can also lyse eukaryotic membranes.
Act directly on cell membrane leading to cell leakage.
Tetracyclines are broad spectrum antibiotics and are useful against intracellular bacteria. Resistance to these antibiotics is common. Adverse effects: Destruction of normal intestinal flora often occurs, resulting in increased secondary infections. There can also be staining and impairment of the structure of bone and teeth

The selectivity of these agents is a result of differences in the prokaryotic 70S ribosome and the 80S eukaryotic ribosome. Since mitochondrial ribosomes are similar to Affect function of prokaryote ribosome therefore halting or interfering with protein synthesis. prokaryotic ribosomes, there can be some host toxicity. They are mostly bacteriostatic
Affect function of prokaryote ribosome therefore halting or interfering with protein synthesis.
All bacteriocidal
Inhibitors of nucleic acid synthesis and function
Used to treat tuberculosis.
Affects mycolic acid synthesis.
block specific steps in prokaryote metabolism.

Ex. sulfonamides - block folic acid synthesis. Mammals don’t have this pathway. They acquire folic acid through their diet. Therefore, they are not affected by this antibiotic.
Antimetabolites
Since viruses use the host metabolic machinery during replication, treatment of viral diseases is difficult without affecting the host cell. Most antiviral agents block viral DNA or RNA synthesis by inhibiting the viral polymerase or becoming incorporated in the growing viral DNA or RNA molecule, resulting in a nonfunctional viral nucleic acid.
Antiviral Agents
Resistance
-First recognized in 1944 due to production of penicillinase by Staph. aureus.
-May be acquired by mutation, transduction, transformation, or conjugation:
-1. Organism may lack the structure the antibiotic inhibits. Ex. Mycoplasma lack cell walls.
-2. Cell wall may be impermeable, the antibiotic can't enter cell. Ex. Many GN contain lipids in the cell wall that prevent antibiotics from entering.
-3. May be able to change antibiotic to an inactive form. Ex. penicillinase produced by some bacteria destroy the penicillin in the environment before it can attack the cell.
-4. May be able to modify the target structure so the antibiotic is no longer effective.
-5. A mutation in metabolic pathway may not be affected by an antibiotic.
Downsides of Antibiotics!
They are the most misused drugs!

Overprescribed by physicians. >60% of people with common colds receive an antibiotic!

Patients do not use the complete prescription.

Patients give to others or use others prescribed antibiotics.

Additives in livestock feed to promote growth, particularly tetracyclines.

Continued exposure to antibiotics increases the chances of bacteria developing resistance.
One is benefits, other is unaffected
Commensalism
both benefit
mutualism
one benefits at the expense of the other
parasitism
usually normal body flora, under certain circumstances will become pathogenic
Opportunists
a change in body function Ex. headache, muscle pain
symptoms
measurable changes in body function Ex. body temp, blood pressure
Sign
specific symptoms and signs that always accompany a particular disease
syndrome
spreads from one host to another
Communicable disease
easily spread
contagious
not easily spread
non communicable disease
occurs only occasionally
sporadic disease
constantly present in population
endemic disease
when many people in a given area acquire a certain disease in a relatively short period of time
Epidemic disease
occurs worldwide
pandemic
the science the studies when and where diseases occur and how they are transmitted in populations
Epidemiology
entails a collecting of all data that describes the occurrence of the disease under study
descriptive epidemiology
analyzes a particular disease to determine its probable cause
Analytical epidemiology
begins with a hypothesis about a particular disease; experiments to test the hypothesis are then conducted with a group of people
Experimental epidemiology
a branch of the U.S. Public Health Service, a central source of epidemiological information in the U.S. Publishes the MMWR. Located in Atlanta, Georgia
Center for disease control and prevention (CDC)
incidence of specific notifiable diseases
morbidity
the number of deaths resulting from a disease in a population in a given period of time in relation to the total population
morbidity rate
the ratio of deaths to population, death rate
mortality
contains data on morbidity and mortality in all the states
Morbidity and Mortality Weekly Report
are those diseases which physicians are required by law to report to the U.S. Public Health Service
Notifiable Disease
develops rapidly, last only a short time
acute disease
develops more slowly longer lasting
chronic disease
inactive fro a long time
latent disease
invovles a relativly small area of the body
local infection
found throughout the body
systemic infection
bacteria actually multiply in the blood
septicemia
ability of a bacterium to remain at a particular site and multiply there.
colonization
clumping of cells by specific antibody
agglutination
systemic reaction caused when a releases of cytokines have a variety of effects on body temperature control and blood pressure, symptoms include fever, acute respiratory distress, and multiple organ system failure
septic shock
tissues cells with granules that contain histamine, heparin, and other substances capable of attracting phagocytes to the site of bacterial invasions; also produce cytokines
mast cells
signaling proteins produces by some mammalian cells in response to stimuli; mediators of inflammation, septic shock
cytokines
the number of bacteria or the amount of toxin required to kill 50% of the animals experimentally inoculated
Lethal Dose (LD50)
the number of bacteria or the amount of toxin required to cause infection in 50% of experimentally infected animals, a measure of infectivity
Infectious Dose (ID50)