Controlling Controlling MicrobesMicrobes

Microbes and SocietyMicrobes and Society

Different Ways of Different Ways of Controlling MicrobesControlling Microbes

PhysicalPhysical ChemicalChemical AntibioticsAntibiotics ImmunologicalImmunological

Physical Control Physical Control MethodsMethods

Sterilization- destruction of all forms Sterilization- destruction of all forms of lifeof life Heat- causes denaturation (unfolding of Heat- causes denaturation (unfolding of

proteins)proteins) Moist heat- steam, boiling waterMoist heat- steam, boiling water Pressure heat- autoclave, as pressure Pressure heat- autoclave, as pressure

raises, temperature raises and sterilization raises, temperature raises and sterilization is better achievedis better achieved

Heat ContinuedHeat Continued

Pasteurization- a process of using Pasteurization- a process of using hot water to destroy most of the hot water to destroy most of the heat-resistant microbial pathogens. heat-resistant microbial pathogens. Not a sterlization technique as it Not a sterlization technique as it does not affect bacterial sporesdoes not affect bacterial spores

Dry heat- hot air ovens. Takes a Dry heat- hot air ovens. Takes a longer time but effective for longer time but effective for powders, oily materials and dry powders, oily materials and dry instruments.instruments.

RadiationRadiation

Radiation disrupts the nucleic acid Radiation disrupts the nucleic acid components of a microbecomponents of a microbe

Ultraviolet (UV)Ultraviolet (UV) X rayX ray Gamma rayGamma ray Electron beamsElectron beams

Other Physical MethodsOther Physical Methods

Drying (desiccation)Drying (desiccation) Disrupt osmotic balance (salting)Disrupt osmotic balance (salting) Filtration (remember Giardia!) Filtration (remember Giardia!) Refrigeration-slows enzymatic Refrigeration-slows enzymatic

activity, but doesn’t come near to activity, but doesn’t come near to sterilizationsterilization

ChemicalChemical

Disinfectants- chemicals used to Disinfectants- chemicals used to “sterilize” inanimate objects“sterilize” inanimate objects

Antiseptics- chemicals used to Antiseptics- chemicals used to “sterilize” surfaces of the body“sterilize” surfaces of the body

Alcohols and AldehydesAlcohols and Aldehydes

Ethyl and isopropyl alcohol are two Ethyl and isopropyl alcohol are two very important very important antiseptic/disinfectantsantiseptic/disinfectants

Aldehydes are effective but toxic. Aldehydes are effective but toxic. Need to be completely dried before Need to be completely dried before material can be used.material can be used.

Halogens and Heavy Halogens and Heavy MetalsMetals

Iodine and chlorine (halogens) are Iodine and chlorine (halogens) are very good disinfectants.very good disinfectants.

Silver, mercury, copper and others Silver, mercury, copper and others are heavy metals that are good are heavy metals that are good antiseptics/disinfectants. These are antiseptics/disinfectants. These are useful metals but are used with useful metals but are used with caution as they can be toxic.caution as they can be toxic.

Detergents and PhenolsDetergents and Phenols

Detergents- wetting agents can lift Detergents- wetting agents can lift microbes off of surfaces for better microbes off of surfaces for better removal. They can also cause cell removal. They can also cause cell membranes to leak and cause cell membranes to leak and cause cell death.death.

Phenols- good chemical disinfectants. Phenols- good chemical disinfectants. However, trichlosan (the antibacterial However, trichlosan (the antibacterial chemical in soaps) has been implicated chemical in soaps) has been implicated in resistance to such compounds due to in resistance to such compounds due to overuse.overuse.

AntibioticsAntibiotics Penicillins-group of drugs that act Penicillins-group of drugs that act

primarily against Gram-positive bacteria primarily against Gram-positive bacteria and function during the synthesis of the and function during the synthesis of the bacterial cell wall.bacterial cell wall.

Cephalosporins- a group of antibiotics Cephalosporins- a group of antibiotics also made from mold that also interfere also made from mold that also interfere with cell wall synthesis.with cell wall synthesis.

Aminoglycosides- (streptomycin is an Aminoglycosides- (streptomycin is an example)- produced by a soil bacteria example)- produced by a soil bacteria and function by inhibiting bacterial and function by inhibiting bacterial protein synthesis.protein synthesis.

Antibiotics ContinuedAntibiotics Continued

Broad Spectrum- kills numerous types Broad Spectrum- kills numerous types of microbes (gram Pos, gram neg, of microbes (gram Pos, gram neg, rickettsiae, chlamydiae, and fungi) rickettsiae, chlamydiae, and fungi) Tetracycline is the most prescribed but Tetracycline is the most prescribed but may be overused (resistance). Some may be overused (resistance). Some side effects may be yellowing of the side effects may be yellowing of the teeth and stunted bones in children.teeth and stunted bones in children.

Others- erythromycin, vancomycin, Others- erythromycin, vancomycin, rifampin and more.rifampin and more.

Control and SocietyControl and Society

We have learned from history that We have learned from history that science is not capable of eradicating science is not capable of eradicating infectious disease. Humans will always infectious disease. Humans will always fight infections, and they can use all fight infections, and they can use all the weapons at hand to help control the weapons at hand to help control (physical, chemical and antibiotic).(physical, chemical and antibiotic).

However, the ultimate control relies in However, the ultimate control relies in the immune system’s ability to the immune system’s ability to overcome pathogenic microbes.overcome pathogenic microbes.

ImmunologicalImmunological

The defense of pathogens using the The defense of pathogens using the immune system (natural defenses).immune system (natural defenses).

The Establishment of The Establishment of DiseaseDisease

Respiratory DropletsRespiratory Droplets Dust (aerosols)Dust (aerosols) Contaminated food or waterContaminated food or water Direct contact with contaminated Direct contact with contaminated

objectobject Arthropod bitesArthropod bites Contact with animalsContact with animals Injection with contaminated soil/objectInjection with contaminated soil/object

Types of PathogensTypes of Pathogens

BacterialBacterial ViralViral ParasitesParasites FungiFungi PrionsPrions

What is Immunity?What is Immunity?

A complicated web of cells and A complicated web of cells and chemical signals that work in chemical signals that work in concert to protect the body from concert to protect the body from pathogens and injurypathogens and injury

Cells are educated to distinguish Cells are educated to distinguish between “self” and “non-self”between “self” and “non-self”

Two Branches of Two Branches of ImmunityImmunity

Innate (Non-specific)Innate (Non-specific) AdaptiveAdaptive

Innate ResponsesInnate Responses

Physical/Chemical Barriers- skin, Physical/Chemical Barriers- skin, pH, mucous membranes, cilia, sweat pH, mucous membranes, cilia, sweat glands, othersglands, others

Microbiogical- Direct competition of Microbiogical- Direct competition of good microbes over bad microbesgood microbes over bad microbes

Cellular- Phagocytosis, Granulocytes Cellular- Phagocytosis, Granulocytes and Inflammationand Inflammation

Cells without Memory Cells without Memory (innate)(innate)

Macrophages-very important cell of the immune Macrophages-very important cell of the immune system. An antigen presenting cell (APC), phagocytic system. An antigen presenting cell (APC), phagocytic cell, and recruiting cell in the inflammatory responsecell, and recruiting cell in the inflammatory response

Neutrophils- phagocytic cell that is often the first line Neutrophils- phagocytic cell that is often the first line of defense. Short lived but effective.of defense. Short lived but effective.

Dendritic Cells- Professional APCDendritic Cells- Professional APC Mast Cells- tissue dwelling cell, often involved with Mast Cells- tissue dwelling cell, often involved with

allergiesallergies Eosinophils- responsible for killing parasites, often Eosinophils- responsible for killing parasites, often

involved with allergies/asthmainvolved with allergies/asthma Basophils- similar to eosinophilsBasophils- similar to eosinophils Natural Killer Cell (NK)- direct cell killing and/or Natural Killer Cell (NK)- direct cell killing and/or

recruiting cellrecruiting cell

Inflammation (Innate Inflammation (Innate Response)Response)

Signs of InflammationSigns of Inflammation

Heat, Pain, Redness, Swelling (calor, Heat, Pain, Redness, Swelling (calor, dolor, rubor, tumor).dolor, rubor, tumor).

Cells involved- Macrophages, Cells involved- Macrophages, NeutrophilsNeutrophils

Other substances involved- Other substances involved- cytokines, complementcytokines, complement

Specific Resistance Specific Resistance (Cells with Memory)(Cells with Memory)

Terminology: Terminology: Antigens- chemical substances capable Antigens- chemical substances capable

of stimulating the immune response of stimulating the immune response (mostly proteins)(mostly proteins)

Antigenic determinant (epitope)- the Antigenic determinant (epitope)- the small part of an antigen that the small part of an antigen that the lymphocytes recognize in order to lymphocytes recognize in order to stimulate the specific responsestimulate the specific response

Cells with MemoryCells with Memory

B lymphocytes (B Cells)- B lymphocytes (B Cells)- differentiate into antibody secreting differentiate into antibody secreting plasma cellsplasma cells

T lymphocytes (T Cells)- T lymphocytes (T Cells)- CD4 (T Helper Cells)- help with the CD4 (T Helper Cells)- help with the

inflammatory response and/or help B inflammatory response and/or help B Cells make antibodiesCells make antibodies

CD8 (Cytotoxic T Cells)- directly kill CD8 (Cytotoxic T Cells)- directly kill virally infected cellsvirally infected cells

Adaptive ResponseAdaptive ResponseClonal Selection TheoryClonal Selection Theory

Random unique receptors confer Random unique receptors confer specificityspecificity

ClonesClones Some clones become memory cellsSome clones become memory cells Response gets better over time (more Response gets better over time (more

cells, faster response, better cells, faster response, better specificity)specificity)

Cells capable of recognizing “self” Cells capable of recognizing “self” molecules are destroyed.molecules are destroyed.

Cell-Mediated ImmunityCell-Mediated Immunity

Macrophage (or other APC) processes Macrophage (or other APC) processes and presents antigen on MHC class Iand presents antigen on MHC class I

CD8 (or Cytotoxic T Cell) recognizes CD8 (or Cytotoxic T Cell) recognizes antigen being displayed on MHCantigen being displayed on MHC

ClonesClones Some become effector cells (kills virally Some become effector cells (kills virally

infected cells)infected cells) Some become memory cells for the next Some become memory cells for the next

timetime

Cell-Mediated ImmunityCell-Mediated ImmunityEffector CellsEffector Cells

Antibody-Mediated Antibody-Mediated ImmunityImmunity

(Humoral Immunity)(Humoral Immunity) B Cell recognizes (binds to) antigen.B Cell recognizes (binds to) antigen. B Cell processes antigen and displays it on B Cell processes antigen and displays it on

MHC class IIMHC class II Meanwhile, a macrophage activates a T Meanwhile, a macrophage activates a T

Cell which clones itselfCell which clones itself T Cell activates B Cell by binding with the T Cell activates B Cell by binding with the

MHC displayed on B Cell surfaceMHC displayed on B Cell surface T Cell activates B CellT Cell activates B Cell Some B Cells become plasma cells and Some B Cells become plasma cells and

secrete antibodies while others become secrete antibodies while others become memory B Cellsmemory B Cells

Humoral ImmunityHumoral Immunity

Structure of an AntibodyStructure of an Antibody

Types of AntibodiesTypes of Antibodies

Antibody Isotype Antibody Isotype FunctionsFunctions

IgG- most abundant in blood/serum. Crosses IgG- most abundant in blood/serum. Crosses the placenta. Found in extracellular fluids.the placenta. Found in extracellular fluids.

IgM-first antibody produced, excellent at IgM-first antibody produced, excellent at activating complement (proteins used in activating complement (proteins used in immune reactions)immune reactions)

IgA-protects the mucosal surfaces, passed in IgA-protects the mucosal surfaces, passed in breast milkbreast milk

IgE-specific for parasitic infections, often IgE-specific for parasitic infections, often seen in allergic reactionsseen in allergic reactions

IgD- receptor on B Cell surfacesIgD- receptor on B Cell surfaces

Antibody FunctionsAntibody Functions

Neutralization- neutralizes toxins so Neutralization- neutralizes toxins so they can’t hurt cellsthey can’t hurt cells

Opsonization- allows for more efficient Opsonization- allows for more efficient phagocytosis of organismsphagocytosis of organisms

Agglutination- clumps non-soluble Agglutination- clumps non-soluble antigens antigens

Precipitation-forms lattices of antibody Precipitation-forms lattices of antibody and soluble antigensand soluble antigens

Inhibition- keeps pathogens from Inhibition- keeps pathogens from binding to receptors and gaining accessbinding to receptors and gaining access

OpsonizationOpsonization

NeutralizationNeutralization

InhibitionInhibition

Immunity Gone WrongImmunity Gone WrongHypersensitivity ReactionsHypersensitivity Reactions

4 Types of Hypersensitivity Reactions4 Types of Hypersensitivity Reactions Type I- allergiesType I- allergies Type II- Cytotoxic- antibodies to cell surface Type II- Cytotoxic- antibodies to cell surface

antigens (incompatible blood types or hemolytic antigens (incompatible blood types or hemolytic disease of the newborn)disease of the newborn)

Type III- Immune complex hypersensitivity- Type III- Immune complex hypersensitivity- accumulation of immune complexes in blood accumulation of immune complexes in blood tissues (Systemic lupus erythematosus-SLE) or tissues (Systemic lupus erythematosus-SLE) or Rheumatoid arthritisRheumatoid arthritis

Type IV- Delayed or cellular hypersensitivity- T Type IV- Delayed or cellular hypersensitivity- T Cell mediated, takes 24-72 hours for effects. Cell mediated, takes 24-72 hours for effects. Poison ivy and other chemical/skin reactionsPoison ivy and other chemical/skin reactions

Allergy SensitizationAllergy Sensitization

Allergy ElicitationAllergy Elicitation