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84 terms

Microbiology- Exam #3

May 16, 2012
STUDY
PLAY
Antifungals
-Nystatin
-Griseofulvin
-Amphotericin B
-Miconazole (very common- used in Micatin & Monistat)
Antivirals
-Attack replication cycle
-Acyclovir
-Azidothymidine (AZT)
Infection
Relationship between host & parsite, and the ensuing struggle for supremacy
-If host loses = disease
Normal Flora
Infection that does NOT cause disease
-It is a symbiotic association (Mutualism, Commensalism; Thus, no harm to the host)
Pathogenicity
Ability of a parasite to enter host tissue and/or cells --> physiological change --> disease
Opportunist
Organism that is normally a commesal
-Due to circumstances that debilitate host defenses, organism invades & causes disease
Virulence
Degree of pathogenicity
Stages of Disease
1.) Incubation Period
2.) Prodromal Period
3.) Period of Acme
4.) Period of Decline
5.) Period of Convalescence
Organism Establishes Infection:
1.) Travel to an area where it can divide
2.) Has to find a way around the immune response
Period of Incubation
-No signs or symptoms
-Amount of time that elapses between entry of organism & appearance of symptoms
Period of Prodomal Symptoms
-Mild signs or symptoms
-Period characterized by general symptoms, i.e. nausea, fever, etc.
Period of Acme
-Most severe signs of symptoms
-Acute stage of disease, characterized by specific symptoms, i.e. skin rash, jaundice, etc.
Period of Decline
-Signs & symptoms
-Symptoms begin to subside
-May be preceded by "crisis" period, then rapid recovery
Period of Convalescence
Important due to carrier status
Modes of Transmission
1.) Direct contact
2.) Indirect contact
Direct Contact
Close or personal contact with individual who has disease, shaking hands, kissing, etc.
Indirect Contact
By consumption of contaminated food or water, contact with fomites (contaminated inanimate objects, i.e. towels)
Vectors
Organisms carry pass disease agents from one host to another, i.e. arthropods
Communicable
Diseases that can be passed from host to host
Contagious
Passed easily
Non-Communicable
Singular events whereby agent is acquired directly from environment, and NOT transmitted to a new host
Outbreak of Disease
1.) Endemic
2.) Epidemic
3.) Pandemic
Endemic
Disease occurs at a low level in a certain geographic area
Epidemic
Outbreak of disease in great numbers within a population
Pandemic
Worldwide outbreak of disease
Acute Disease
Disease develops rapidly with severe symptoms, then fades quickly
Chronic Disease
-Disease develops slowly
-No real crisis is reached
-Convalescence may last for months
Bacteremia
Presence of bacteria in bloodstream
Septicemia
Bacterium in bloodstream is the cause of the disease
Portal of Entry
Site at which pathogenic organism enters host
Infectious Dose
Number of pathogens that must enter host to establish disease
Invasiveness
Ability of a pathogen to penetrate tissues of the host
Virulence Factors
-Substances or structures that allow a pathogen to generate disease in the host
1.) Enzymes
2.) Toxins
3.) Capsules
Enzymes
-Coagulase
-Streptokinase
-Hyaluronidase
- Leukocidins & Hemolysins
Coagulase
Clot fibrinogen proteins around organism
Streptokinase
Dissolves clots
Hyaluronidase
Digest hyaluronic acid (ground substance of tissue)
Leukocidins & Hemolysins
-Destroy blood cells
-Hemolysin
-Hemolysis
Hemolysin
Enzyme that produces lysis
Hemolysis
Actual rupture of red blood cells
Toxins
-Exotoxin
-Endotoxin
Exotoxins
-Produced by Gram +'s
-Released from cell
-Very specific effects
Endotoxins
-Part of Gram - cell wall
-Released only when cell disintegrates
Natural Defense Mechanisms
1.) Skin
2.) Mucous membranes
3.) Ciliated epithelium
4.) Various enzymes
5.) Other proteins
6.) pH
7.) Inflammatory response
8.) Phagocytosis
Skin
-Desquamation
-Sweat, sebaceous secretions
Mucous Membranes
Mucus
Various Enzymes
-Proteolytic enzymes
-Lysozyme
Other Proteins
-Complement system
-Interferon
pH
-Fatty acids
-Stomach
Inflammatory Response
1.) Capillary Dilation
2.) Cells escape capillary bed
-Edema (Fluid escape= swelling)
-Redness (RBC's escaping)
1.) Neutrophil
2.) Macrophage
3.) Lymphocytes
Chemotaxis
Movement along a chemical gradient
Phagocytosis
-Neutrophil- blood
-Macrophage- tissues
Defenses
1.) Non-specific
2.) Specific
Non-Specific
Innate
Specific
-Generated to respond to a particular parasite
-Directed solely at that parasite
-Expandable
-"Memory"
Antigen (Aspect of Specific Responses)
Foreign substance that stimulates the generation of an immune response, "Non-Self vs. Self"
Lymphatic System
Second circulatory system
Circulatory & Lymphatic Meet At:
Thoracic duct & right lymphatic duct (Dumps back into blood)
Cells of Immunity
1.) Lymphocytes
2.) Macrophages
Lymphocytes
-Have very specific surface receptors for antigen
-All look alike, but actually 2 major types
T-lymphocytes (T-cells)
Develop in thymus
B-lymphocyte (B-cells)
Develop in Bone Marrow compartment
Macrophages
-Found in tissues & organs
-Plays major role in immunity
-Phagocytose antigen
-Degrade it ("processed antigen")
-Redisplay processed antigen on surface
-Transport processed antigen to lymphoid tissue where T- and B-cells are waiting
Endocytosis
Taking things in
Exocytosis
Releasing material to the outside
Phagosome & Lysosome
Phagolysosome (Phagocytosis)
Two Divisions of Immune Response:
1.) Antibody-Mediated Immunity (Humoral)
2.) Cell-Mediated Immunity
Antibody-Mediated Immunity (Humoral)
Defense processes that are mediated by antibodies
Cell-Mediated Immunity
Defense mechanisms that are mediated by T-cells and:
-Eukaryotic Pathogen
-"Antigen-marked" cell i.e. cell modified by viral infection, cancer or mutation
-Foreign transplants
-Delayed-type hypersensitivity
TH Cell
T helper cell (CD4+ cell)
-Chief regulatory cell of immune response
TC Cell
T cytotoxic cell (CD8+ cell)
-Precursor to the CTL "killer" cell
CTL- Cytotoxic T Lymphocyte
The end-stage cell that has the ability to actively destory non-self cells
B Cell
Line of lymphocytes that produce antibodies
-End-stage cell= plasma cell
Apoptosis
Programmed cell death
MHC - Major Histocompatibility Complex
A cassette of genes that controls all of adaptive immunity
MHC I
Genes that control ability to generate cell-mediated functions
MHC II
Genes that control the activation of TH cells
MHC III
Genes that are involved in the production of components of the complement system
Interleukins
Small peptides that allow immune cells to communicate with each other
Five Classes of Antibodies
1.) IgM
2.) IgG
3.) IgA
4.) IgE
5.) IgD
IgM
-First to appear following stimulation
-Very large pentameter
IgG
-Longest lasting
-Most abundant
-Principle antibody in "memory" response
-Only class to cross placenta = passive immunity
IgA
-Serum IgA - monomer in blood
-Secretory IgA- polymer in secretions
-GI tract
-Respiratory tree
-Passive transfer in mother's milk
-Colostrum
IgE
Major role in dangerous allergic reactions