Microbiology- Exam #3

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May 16, 2012

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

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