BIOL 251 Microbiology Week 13 & 14 Lecture Notes

Microbiology: An Introduction 13th Edition - Ch. 13 & Ch. 18-19

Pathogens

Disease-causing microorganisms

Pathogenicity

Ability to cause dieases

Virulence

Degree of pathogenicity

Infection

When the body is invaded by a harmful microorganism

Disease

When the body’s health is affected by infection

Mucous membranes

Skin

Parenteral route

What are some portals of entry for pathogens?

Parenteral

_____ Route: Direct deposition beneath the skin or membranes

ID

LD

____₅₀: Infectious does for 50% of a sample population

• Skin, inhalation, ingestion

• measures microbe virulence

____₅₀: Lethal does for 50% of a sample population

• measures potentcy of toxin

ligands

glycocalyx

Mannose

Adherence of Microorganisms to Host Cells

• Surface molecules on pathogens

  • Adhesions or _____

  • Located on - _____ or fimbriae or pili

  • Glyco- or lipoproteins

• Bind to complementary surface receptors of host cell

  • _____ - sugar

Capsule

Cell wall components

Enzymes

Antigenic variation

Invasins

What are some ways microbes penetrate host defenses?

phagocytosis

Capsule;

Glycocalyx around cell wall

Impairs _____

M

Opa

Waxy

Cell Wall Components

• __ protein resists phagocytosis

• __ protein allows attachment to host cells

• ____ lipid resists digestion

Coagulase

Kinases

Hyaluronidase

Collagenase

IgA

Enzymes

_____: Coagulate fibrinogen

_____: Digest fibrin clots

_____: Digests polysaccharides that holds cells together

_____: Breaks down collagen

_____ Proteases: Destroy IgA antibodies

antigens

antibodies

Antigenic Variation:

Pathogens alter surface _____

Evade destruction by host _____

Invasins

Actin

_____: Surface proteins produced by bacteria

• Rearrange _____ filaments in cytoskeleton

• Cause membrane ruffling

• Use actin to move from one membrane to the next

Use host’s nutrients

Direct damage

Toxin production

What are some ways microbes damage host cells?

Siderophores

Using Host’s Nutrients;

• _____: Proteins secreted by pathogens

  • Binds ions more tightly than host cells

Function

waste

ruptures

Direct Damage;

• Disrupts host cell _____

• Uses host cell nutrients

• Produces _____ products

• Multiples in host cell and causes _____

Toxins

Toxigenicity

Toxemia

Toxin Production;

_____: Poisonous substances produced by microorganisms

• Fever, cardiovascular problems, diarrhea, shock

_____: Ability of a microorganism to produce a toxin

_____: Presence of toxin in hosts’ blood

Exotoxins

_____: Proteins secreted and produced by bacteria

• Soluble in body fluids; destroys host cells and inhibit metabolic functions

Enterotoxins

_____: Exotoxins whose activity affects the small intestine

• Causes; massive fluid secretion into intestinal lumen, vomiting & diarrhea

Endotoxins

_____: Present inside a bacterial cell and is released when the cell disintegrates.

• Lipid A component of Gram-negative bacteria

Respiratory tract

GI tract

Genitourinary tract

Skin

Blood

What are some portals of exit?

Variolation

Obsolete medical procedure that involved intentionally infecting a healthy person with a mild form of smallpox virus to induce immunity against the disease

Vaccine

Term from Edward Jenner

Suspension of organisms or fractions of organisms that induce immunity

primary

secondary

Principles and Effects of Vaccination;

1. Provokes a _____ immune response

2. Produces a rapid, intense _____ response

Herd

_____ Immunity: Refers to immunity among most of the population

Attenuated

Live _____ Vaccines: Weakened pathogen to mimic actual infection.

Ex. MMR

Inactivated

_____ Killed Vaccines: Require repeated booster doses

Ex. rabies, influenza

Subunit

_____ Vaccines: Use antigenic fragments to stimulate an immune response

• Recombinant vaccines

• VLP Vaccines

• Toxoids

Conjugated

_____ Vaccines: Contain bacterial capsule polysaccharides combined with proteins

Ex. H. influenzae

Nucleic

_____ Acid Vaccines: Injected naked DNA produces protein antigen encoded in the DNA

Ex. West Nile for horses

Hypersensitivity

_____ Reactions: An altered, enhanced immune reaction leading to pathological changes

• Responses to antigens (allergens)

Anaphylactic

basophils

degranulation

Type 1 (_____) Reactions:

• IgE attached to mast cells and _____

• Antigen binds to two adjacent IgE

• Mast cells and basophils undergo _____, which releases mediators;

  • Histamine

  • Leukotrienes

  • Prostaglandin
    

Systemic

Localized

Anaphylactic Reactions

_____ Anaphylaxis: May result in circulatory collapse and death

• Epinephrine treatment

_____ Anaphylaxis: Hives, hay fever, asthma

Cytotoxin

Type 2 (_____) Reactions:

• Involve IgG or IgM antibodies and complement

• Complement activation causes cell lysis

• ABO Blood system group

  • Antibodies form against certain carbohydrate antigens on RBC’s

Cytotoxic Reactions

• Rh blood group system: Rh+ given to Rh- recepient - stimulates anti-Rh antibodies

Immune Complex

complexes

Type 3 (_____ _____) Reactions:

• IgG antibodies and antigens form immune _____ that lodge in basement membranes

• Involves soluble antigens in serum

Cell Mediated

T

Type 4 (_____ _____) Reactions:

• Delayed type sensitivities due to ___ cells

• Cytokines attract macrophages and T cells

  • Initiate tissue damage

Autoimmunity

_____ is a loss of self-tolerance

• leads to production of antibodies or a response by sensitized T cells against a person’s own tissues

Cytotoxic

Immune

Cell

Autoimmune Diseases

• _____: Antibodies react with cell-surface antigens

  • Grave’s disease

• _____ Complex: IgM, IgG, complement immune complexes deposit in tissues

  • Systemic lupus

• _____-mediated: Mediated by T cells

  • Psoriasis, multiple sclerosis

Congenital

Acquired

Autoimmundeficiencies

• _____: Due to missing or defective genes

• _____: Develop during one’s life

  • Drugs, cancer, infections

  • HIV, AIDS