Microbiology Exam 4

type of vaccine: · *Vaccines made from pathogens that have been killed by heat or chemicals* · Can be produced faster and more easily, but they are less effective than live vaccines · Examples: Hepatitis A, influenza, anthrax, cholera, pertussis, typhoid fever

Inactivated Vaccines

colonization by a pathogen (when a pathogen lands on or enters a person's body and establishes residence there, then the person is infected with that pathogen)

Infection

disease that is caused by a microbe; the microbes that cause these diseases are referred to as pathogens - the pathogen may or may not go on to cause disease in the person; it is possible for a person to be infected with a certain pathogen, but not have the diseases caused by the pathogen

Infectious disease

*Three major events that occur* during this component of the second line of defense: 1. Increase in the diameter of capillaries (vasodilation), which then increases the blood flow to the site 2. Increased permeability of capillaries, allowing the escape of plasma and plasma proteins 3. Escape of leukocytes from the capillaries and their accumulation at the site of injury

Inflammation

Four main signs and symptoms of the physiologic reactions to this include: 1. Redness 2. Heat 3. Swelling or edema 4. pain Other symptoms: pus formation, loss of function at the damaged area

Inflammation

Steps that result in this component of the second line of defense include: · Events that occur immediately after the initial damage to the tissue - vasodilation at the site of injury will occur, mediated by vasoactive agents (histamine and prostaglandins) released from damaged cells. · Plasma then escapes from the capillaries into the surrounding area, which causes the site to become swollen (can be severe enough to interfere with the bending of a particular joint, ex. elbow, knuckle, knee) · When this process is over, phagocytes clean up the area and help to restore order. · The cells and tissues can then repair the damage and begin to function normally again

Inflammation

component of the second line of defense: They body's normal response to any local injury, irritation, microbial invasion, or bacterial toxin by this complex series of events

Inflammation

the *primary purposes* of this component of the second line of defense: · Localize an infection · Prevent the spread of microbial invaders · Neutralize any toxins being produced at the site · Aid in the repair of damaged tissue

Inflammation

the accumulation of fluid, cells, and cellular debris at the inflammation site · Ex. Infections that are caused by pseudomonas aeruginosa often have a blueish green exudate

Inflammatory exudate

step in phagocytosis in which: · The phagocyte will surround the object with its pseudopodia, which fuse together, and the object is ingested · During this phase, the particle will then become surrounded by a membrane bound vesicle called a *phagosome*

Ingestion

type of immunodeficiency: · Can be the result of deficiencies in antibody production, complement activity, phagocytic function, or NK cell function · Examples: · Chediak-Higashi syndrome · Agammaglobulinemia - when some people are born lacking the ability to produce antibodies because they have no gammaglobulins in their blood (bone marrow transplant can be an effective treatment option)

Inherited

resistance that is observed among species of animals and some persons who have a natural resistance to certain diseases. · Inherited characteristics make these people and animals more resistant to some diseases than to others · Some factors that may cause this may be related to chemical, physiologic, and temperature differences, as well as general state of physical and emotional health, and environmental factors that affect certain races, but not others

Innate (or inborn) resistance

Three known types of these components of the second line of defense include: · Alpha - produced by B-lymphocytes, monocytes, and macrophages. · Beta - produced by fibroblasts and other virus-infected cells · Gamma - activated by T lymphocytes and natural killer cells

Interferons

component of the second line of defense: · Small antiviral proteins that are produced by *virus-infected cells* · Interfere with *viral replication* · Induced by different stimuli including viruses, tumors, bacteria, and other foreign cells · when produced by a virus-infected cell, they are not able to save that cell from destruction, but once they are released from that cell, they then attach to the membranes of surrounding cells, and prevent viral replication from occurring in those cells; causes many viral diseases to be limited in duration · *Not virus specific* · They are *species specific *- infective only in the animal that produced them

Interferons

Steps in the pathogenesis of infectious diseases: (6) · not all infectious disease involve all of these steps (ex. some *intestinal pathogens* are capable of causing disease without adhering to the intestinal wall or invading tissue

1. *Entry* of the pathogen into the body 2. *Attachment* of the pathogen to some tissues within the body 3. *Multiplication* of the pathogen 4. *Invasion or spread* of the pathogen 5. *Evasion* of host defenses 6. *Damage* to host tissues

Reasons infection does not always occur following colonization of a pathogen: (7)

1. The microbe may land at an *anatomic site* where it is unable to multiply (ex. respiratory pathogen landing on the skin, which lacks proper environment for microbe) 2. Many pathogens must attach to *specific receptor sites* before they are able to multiply and cause damage. (if they land at a site where they receptors are absent, they can't cause disease) 3. *Antibacterial factors* may be present that destroy or inhibit the growth of bacteria (ex. lysosome present in tears, saliva, and perspiration) 4. *Indigenous microbiota* of the site may inhibit the growth of the foreign microbe by occupying space and using up available nutrients; type of *microbial antagonism* - in which one microbe or group of microbes wards of another 5. *Individual's nutritional and overall health status* 6. *Immunity* to that particular pathogen 7. *Phagocytic WBCS* may be present in the blood that can engulf and destroy the pathogen before it has an opportunity to multiply, invade, and cause disease

type of immunodeficiency: · May be caused by drugs, (ex. cancer chemotherapeutic agents and drugs given to transplant patients), irradiation, or certain infectious diseases (ex. HIV, which leads to a decrease in T helper cells)

Acquired

· Types of immunity that humans acquire as life progresses from conception onward · Often the result of the presence of protective antibodies that are directed against various pathogens · Results from active production or receipt of protective antibodies during one's lifetime.

Acquired Immunity

Type of acquired immunity: · Immunity that occurs when * antibodies are produced within the person's body* · Such protection is long-lasting · Immunity may result from either a natural or artificial event

Active Acquired immunity

diseases that have a rapid onset, usually followed by a rapid recovery (ex. measles, mumps, influenza)

Acute

component of the second line of defense: · Increase rapidly in response to infection, inflammation, and tissue injury. · Enhance resistance to infection and promote the repair of damaged tissue. · These include C-reactive protein, serum amyloid A protein, protease inhibitors, and coagulation proteins

Acute Phase Proteins

component of the virulence factor attachment: · the molecule *on the surface of a pathogen* that is able to recognize and bind to a particular receptor · Considered virulence factors because they enable pathogens to attach to host cells

Adhesion

response that occurs when the IgE molecules bind to the surface of basophils and mast cells by their Fc region in a type I hypersensitivity reaction

Allergic Response

type of hemolysis: · partial lysis of the RBCs causing the blood agar to turn green

Alpha

Species of bacteria that are closely related to Rickettsias; obligate intracellular, gram neg bacteria that live within leukocytes (Intraleukocytic pathogens) that *causes human anaplasmosis, a condition in which the bacteria infect granulocytes; these bacteria are able to prevent the fusion of lysosomes with phagosomes*

Anaplasma

An obligate intracellular pathogen: · *Intraleukocytic bacteria* - live within WBCs (specifically the *granulocytes* - the neutrophils, basophils, eosinophils)

Anaplasma spp

· when an antibody combines with an antigen · A complex is formed - an immune complex; these complexes are capable of activating the complement cascade, resulting in the activation of leukocytes, lysis of bacterial cells, and increased phagocytosis as a result of opsonization

Antigen-antibody Complex

Mechanism by which Pathogens Escape Immune Responses: · pathogens are able to change their surface antigens · Examples of pathogenic pathogens capable of this are: Influenza viruses, HIV, and N. gonorrhoeae

Antigenic Variation

*Immunity that is required in response to vaccines* · Vaccine stimulate a person's immune system to produce specific protective antibodies

Artificial Active Acquired immunity

*immunity accomplished by transferring antibodies from an immune person to a susceptible person* · Examples: Can be acquired when a person receives antibodies contained in *antisera or gamma globulin* · After a person has been exposed to a disease, the length of incubation period usually does not allow time for post exposure vaccination; to provide temporary protection, the person is given *human gamma globulin, or pooled immune serum globulin* - antibodies taken from the blood of many people and given to provide temporary protection, especially against measles, mumps, polio, Diptheria, and hepatitis in people, especially infants, who are not immune and have not been exposed to these diseases

Artificial Passive Acquired Immunity

a virulence factor that includes *receptors, adhesins, and bacterial Fimbriae (attachment pili)*

Attachment

step in phagocytosis in which: · Attachment of the phagocyte to the object to be ingested; ex. yeast or bacterial cell · Phagocytes can only ingest objects to which they can attach; sometimes opsonization is needed to enable phagocytes to attach to certain particles, such as encapsulated bacteria

Attachment

type of vaccine: · *Prepared from weakened pathogens that have been genetically changed so that they are no longer pathogenic* · Should not be administered to immunosuppressed individuals - the weakened pathogens could cause disease in these persons · Examples: Adenovirus, Chicken Pox, Measles, Mumps, Polio, Rotavirus, small pox, yellow fever

Attenuated Vaccines

type of vaccine: · *Vaccine that has been prepared from bacteria isolated from a localized infection* · The pathogens are killed and then infected into the same person to induce production of more antibodies

Autogenous vaccines

major cell type that is the source of antibodies within the body · derived from lymphoid stem cells of bone marrow

B lymphocytes (B cells)

component of the virulence factor attachment: · Thin, hair-like projections composed of an array of proteins called pilin · Considered to be virulence factors because they allow bacteria to attach to surfaces, including various tissues within the human body · Ex. the Fimbriated strains of N. gonorrhoeae are able to anchor themselves to the inner walls of the urethra and cause urethritis; nonfimbriated strains are flushed out by urination and are unable to cause urethritis · Ex. Fimbriated strains of E. coli that gain access to the urinary bladder are able to anchor themselves to the inner walls of the bladder and cause cystitis; nonfimbriated are flushed out by urination

Bacterial Fimbriae (Attachment pili)

*bacteria that produce proteins that kill other bacteria*; ex. certain strains of E. coli produce colicin; Pseudomonas and Bacillus species also produce similar substances · Have a narrow range of activity than antibiotics, but they are more potent than antibiotics

Bacteriocins

type of hemolysis: · complete lysis of the RBCs causing the blood agar to be clear

Beta

Mechanism by Which Pathogens Escape Destruction by Phagocytes: component that serves as antiphagocytic function, protecting the encapsulated bacteria from being phagocytized

Capsules

Virulence factor: · Function: considered to be virulence factors because they serve an *antiphagocytic function* - they protect the encapsulated bacteria from being phagocytized by phagocytic WBCs) · Phagocytes are unable to attach to encapsulated bacteria because they do not have the surface receptors for the polysaccharide material of which the capsule is made of · If the phagocytes cannot adhere to the bacteria, they cannot digest them, which means that the bacteria are then able to multiply, invade, and cause disease · Examples of encapsulated bacteria and yeast: Streptococcus pneumoniae, Klebsiella pneumoniae, Haemophilus influenzae, and Neisseria meningitis, and the capsule of the yeast, Cryptococcus neoformans

Capsules

Major component of the immune system: · Immunity that *does not involved the production of antibodies*, however antibodies produced during humoral immunity play a minor role in some of these responses · *Complex system of interactions among many types of cells and cellular secretions.* · Included among the various cells that participate in this immunity are macrophages, DCs, Th cells, Tc cells, NK cells, and granulocytes

Cell-mediated immunity

step in phagocytosis in which: phagocytes move to the site where they are needed · The result of chemical attractants referred to as *chemotactic agents,* which are: · Produced by various cells of the human body and are chemokines · Produced during the complement cascade and inflammation. · The phagocytes move along a concentration gradient, moving from areas of low concentration of these agents to areas of high concentration; areas of highest concentration is at the site where the chemotactic agents are being produced or released - often at the site of inflammation

Chemotaxis

An obligate intracellular pathogen: · Gram-negative bacteria · Invade a variety of cells, including conjunctival epithelial cells and cells of the respiratory and genital tracts · They produce their own ATP, but they use the ATP produced by the host cells

Chlamydias

diseases that have a slow onset and last a very long time (ex. TB, leprosy, syphilis)

Chronic

an often fatal genetic disorder that is characterized by repeated bacterial infections because the phagocytes can ingest the bacteria, but they cannot kill certain species

Chronic granulomatous disease

bacterium that causes botulism, producing the botulinum toxin, a neurotoxin, which blocks nerve impulses and leads to a generalized, flaccid type of paralysis in which the patient's *muscles are relaxed*

Clostridium botulinum

A *superinfection of _____________ ____________* bacteria in the colon may lead to C. difficile-associated diseases, such as antibiotic-associated diarrhea and pseudomembranous colitis

Clostridium difficile

bacterium that produces neurotoxins, causing tetanus; it produces a tetanospasm toxin which effects nerve transmission which leads to a spastic, rigid type of paralysis in which the patient's *muscles are contracted*

Clostridium tetani

An exoenzyme: · Identifying feature of *Staphylococcus aureus* ·Binds to prothrombin, forming a complex called staphylothrombin · The protease activity of thrombin is activated in this complex, causing the conversion of fibrinogen to fibrin · In the body, this exoenzyme can allow staphylococcus aureus to clot plasma and thereby form a sticky coat of fibrin around themselves for protection from phagocytes, antibodies, and other defense mechanisms

Coagulase

An exoenzyme: · Breaks down collagen which is the supportive protein found in tendons, cartilage, and bones; this allows the pathogens to invade tissue · Example: *Clostridium perfringens*, which is the major cause of gas gangrene, and is able to spread deeply into the body by secreting both collagenase and hyaluronidase

Collagenase

type of vaccine: · Made by conjugating bacterial capsular antigens to molecules that stimulate the immune system to produce antibodies against the less antigenic capsular antigens · Examples: Hib (protection against H. influenzae type b), meningococcal meningitis, pneumococcal pneumonia

Conjugate Vaccines

component of the second line of defense: · Chemical mediators that are released from different types of cells in the human body which *allow cells to communicate* with each other and act as chemical messengers (both within the immune system and other systems of the body) · A cell is able to sense the presence of these if it possesses appropriate surface receptors that can recognize these · Some are *chemoattractant* - recruit phagocytes to locations where they are needed · Others are like *interferons* - direct role in the host defense

Cytokines

Category of T lymphocytes ( T cells) that *destroy virally infected host cells, foreign cells, and tumor cells*

Cytotoxic T cells

toxins that damage the lining of the colon; can lead to *pseudomembranous colitis*, which sloughs the lining of the colon, leading to bloody, mucousy stools

Cytotoxin

type of vaccine: · Vaccines that are currently are only experimental in humans · A particular gene from a pathogen is inserted into plasmids and the plasmids are then infected into skin or muscle tissue · inside the host cell, the genes will direct the synthesis of a particular microbial protein or antigen, once the cells start making copies of that antigen, the body then produces antibodies directed against the antigen · Examples: West Nile virus vaccine for horses · Clinical Trials in progress for mycobacterium TB, malaria, and Zika virus

DNA Vaccines

Vaccinate against several disease by combining specific vaccines into a single injection: · Vaccine for Diptheria, tetanus and pertussis - it contains toxoids to prevent Diptheria and tetanus, and then antigenic portions of killed bacteria to prevent whooping cough · Vaccine for measles, mumps, and rubella

DTaP, MMR

type of hypersensitivity reaction: · reaction usually takes more than 24 hrs to manifest itself · Also known as type IV hypersensitivity reactions and cell-mediated reactions

Delayed-type hypersensitivity (DTH)

Mechanism by which Pathogens Escape Immune Responses: · Several bacterial pathogens (including H. influenzae, N. gonorrhoeae, and streptococci) produce an enzyme called *immunoglobulin A protease* that destroys IgA antibodies · Therefore these pathogens are capable of destroying some of the antibodies that the host's immune system produced in an attempt to destroy them

Destruction of Antibodies

step in phagocytosis in which: the phagosome fuses with a nearby lysosome to form a digest vacuole called a *phagolysosome*, which is where the killing and digestion occurs

Digestion

toxin produced by the toxigenic strains of *C. diphtheriae*, which inhibits protein synthesis; it kills the mucosal epithelial cells and phagocytes and adversely affects the heart and nervous system

Diphtheria toxin

Species of bacteria that are closely related to Rickettsias; obligate intracellular, gram neg bacteria that live within leukocytes (Intraleukocytic pathogens) that *cause human monocytic ehrlichiosis, a condition in which the bacteria infect monocytic phagocytes*

Ehrlichia

An obligate intracellular pathogen: · Gram-negative bacteria · *Intraleukocytic pathogens - live within WBCs* (this group specifically lives within *monocytes*) · Cause human monocytic ehrlichiosis

Ehrlichia spp

*toxins that affect the gastrointestinal tract*, often causing diarrhea and sometimes vomiting. · Examples of bacterial pathogens that produce these toxins: Bacillus cereus, certain serotypes of E. coli, C. diff, C. perfringens, Salmonella spp, Shigella spp, V cholerae, and some strains of S. aureus

Enterotoxins

Virulence factor: · The major mechanisms by which pathogens cause disease are by these or toxins that they produce (some pathogens can produce both these and toxins) · Some pathogens release these - *allow them to evade host defense mechanisms, invade, or cause damage to body tissues* · They include: Necrotizing enzymes, Coagulase, Kinases, Hyaluronidase, Collagenase, Hemolysins, and Lecithinase

Exoenzymes

type of toxin: · Produced within cells and then released from the cells · Poisonous proteins that are secreted by a variety of pathogens · Often named for the *target organ that they affect* · Examples: neurotoxins, enterotoxins, cytotoxins, erythrogenic toxins, and Diptheria toxins

Exotoxin

Virulence factor: · Pathogens capable of both intracellular and extracellular existence (able to live inside or outside of a cell) · Ex. M. tuberculosis - have a cell wall composition that resists digestion, which means when WBCs engulf them, they are able to survive within it; their cell walls contain waxes, and these waxes are what protect them from digestion

Facultative Intracellular Pathogens

This component of the second line of defense amplifies the host's defenses in the following ways: · Stimulates *WBCs* to deploy and destroy invaders · Reducing available free plasma iron, which then limits the growth of pathogens that require iron for replication and synthesis of toxins · Introduces the producing of *interleukin-1*, which causes the proliferation, maturation, and activation of lymphocytes in the immunologic response. may slow down the growth rate of certain pathogens and can even kill some especially fastidious pathogens

Fever

component of the second line of defense: stimulated by *pyrogens, or pyrogenic substances* - · May originate either outside or inside the body: · Those that outside include pathogens and various pyrogenic substances that they produce and release (ex. endotoxin) · Interleukin-1, a cytokine that is produced by certain WBCs, is an example of an endogenous pyrogen (originates within the body)

Fever

type of macrophages that remain within the tissues and organs and serve to trap foreign debris

Fixed macrophages

Virulence factor: · Function: enable flagellated (motile) bacteria to invade aqueous areas of the body that nonflagellated bacteria are unable to reach · It is more difficult for phagocytes to catch a moving target

Flagella

Cellular and Chemical factors of the first line of defense: · Factors that protect this system from bacterial colonization: - Digestive enzymes - Acidity of the stomach (pH of 1.5) - Alkalinity of the intestines · *Bile* - secreted from the liver into the small intestine, which lowers the surface tension and causes chemical changes in bacterial cell walls and membranes; this makes the bacteria easier to digest · As a result of the combination of stomach acid, bile salts, and rapid flow of its contents, the small intestine is relatively free of bacteria · *Mucous lining of the digestive tract* - many invading microbes are trapped here, where they may be destroyed by bactericidal enzymes and phagocytes The expulsion of *feces* serve to remove bacteria from the intestine

GI tract

type of hemolysis: · no change in the blood agar; bacteria does not produce hemolysin

Gamma

small molecules that may act as antigens only if they are coupled with a large carrier molecule such as a protein · Once they are coupled with the protein, the antibodies are formed against the antigenic determinants of this, and they may combine with the these molecules · Ex. penicillin and other low-molecular-weight chemical molecules, which cause some people to become allergic to them

Haptens

Category of T lymphocytes ( T cells) that *secrete cytokines*

Helper T cells

An exoenzyme: · Enzymes that cause damage to the host's *RBCs* - this will cause harm to the host and will also provide the pathogen with a source of iron · In the lab, the effect an organism has on the RBCs in the sheep blood agar enables differentiation between alpha and beta hemolytic bacteria · They are produced by many pathogenic bacteria, but the type of hemolysis produced by an organism is of the most importance when attempting to speciate a Streptococcus in the lab (some are beta, alpha, and gamma)

Hemolysins

ways in which the body protects itself from pathogens - can be thought of as an army of 3 lines of defense

Host defense mechanisms

Major component of the immune system: · Immunity that always *involves the production of antibodies* in response to antigens; after their production, these humoral (circulating) antibodies remain in blood plasma, lymph, and other body secretions where they protect against the specific pathogens that stimulated their production · a person is immune to a particular pathogen because of the presence of specific protective antibodies that are effective against that pathogen · Because it is mediated by antibodies, it is also known as *anti-mediated immunity*

Humoral immunity

An exoenzyme: · Function: allows pathogens to spread through connective tissue by breaking down hyaluronic acid, which is the polysaccharide that holds tissue cells together · Examples: secreted by several pathogenic species of Streptococcus, Staphylococcus, and Clostridium

Hyaluronidase

refers to an overly sensitive or overly reactive immune system · The immune system in an attempt to protect the person, caused irritation or damage to certain cells and tissues in the body · Some types involve antibodies, whereas others do not · All types depend on the presence of an antigen and T cells that are sensitized to that antigen · Reactions are divided into two general categories: immediate type and delay-type hypersensitivity (DTH)

Hypersensitivity

class of immunoglobulins: · Can exist as a monomer or as a dimer · Predominant in saliva, tears, seminal fluid, colostrum, breast milk, and mucous secretions of the nose, lungs, and GI tract

IgA

class of immunoglobulins: · Monomer · Found in large quantities on the surface of B cells · Function is unknown

IgD

class of immunoglobulins: · Monomer · Produced in response to *allergens* · Found on the surface of basophiles and mast cells · Plays a major role in *allergic responses*

IgE

class of immunoglobulins: · Monomer; the lightest of the immunoglobulins · Only class that can cross the *placenta* · Help to protect newborn during its first few months of life · High levels are produced rapidly during the secondary response to antigens · Long-lived, sometimes persisting for a lifetime

IgG

class of immunoglobulins: · Pentamer, held together by a J-chain; *largest immunoglobulins* · Have 10 antigen bonding sites (can potentially bind to 10 antigenic determinants) · First antibodies formed in to primary response to antigens · Short-lived, do not cross placenta, and provide protection in the earliest stages of infection

IgM

type of hypersensitivity reaction: · when reactions occur within a few minutes to 24 hrs after contact with a particular antigen · Three categories: type I, type II, and type III

Immediate type

laboratory procedures that help to diagnose infectious diseases by either antigens or antibodies in clinical specimens; some are designed to detect antigens, whereas others are designed to detect antibodies

Immunodiagnostic procedures

the study of the immune system and responses

Immunology

An exoenzyme: · AKA fibrinolysins · Function: opposite effect of coagulase; *they lyse, or dissolve clots* · Two types - Streptokinase and Staphylokinase

Kinases

a substance found in mucous that serves as a first line of defense: · *a protein that binds to iron*, a mineral that is required by all pathogens. · Because the pathogens are unable to compete with this from free iron, the pathogens are deprived of this essential nutrient

Lactoferrin

a substance found in mucous that serves as a first line of defense: · an enzyme that produces superoxide radicals, which is highly reactive forms of oxygen, which are toxic to bacteria

Lactoperoxidase

· When an infectious disease goes from being symptomatic, to asymptomatic, to symptomatic again · Examples: herpes virus infections (cold sores, genital herpes infection, shingles) · Cold sores - virus remains dormant in the cells of the nervous system, until some type of stress acts as a trigger

Latent infection

An exoenzyme: · Breaks down phospholipids that are referred to as lecithin · This enzyme is destructive to cell membranes of red blood cells and other tissues

Lecithinase

Mechanism by Which Pathogens Escape Destruction by Phagocytes: an exoenzyme, which is a toxin produced by some bacteria, which kills phagocytes

Leukocidin

a type of cytotoxin produced by some strains of staph, strep, and clostridium, which causes the *destruction of WBCs*

Leukocidins

a disorder that adversely affects phagocytic and inflammatory processes characterized by: · an abnormally low number of circulating leukocytes · May result from bone marrow injury as a result of ionizing radiation or drugs, nutritional deficiencies, or congenital stem cell defects

Leukopenia

pathogens are contained at the site of infection

Localized infection

type of phagocytes that develop from monocytes during the inflammatory response to infections

Macrophages

major cell type that are present in tissues that are in contact with the external environment, such as skin and the linings of the nose, lungs, stomach, and intestines: · these process ingested antigens and they display antigenic determinants on their surface · Once activated, they migrate to lymph nodes where they interact with T cells · originate in the bone marrow

Macrophages and dendritic cells (DCs)

Cellular and Chemical factors of the first line of defense: *when resident microbes of the indigenous microbiota prevent colonization by new arrivals to a particular anatomic site* · How indigenous microbiota inhibit pathogens: - competing for colonization sites - competing for nutrients - producing substances that kill other bacteria · The effectiveness of this process is decreased after *prolonged administration of broad-spectrum antibiotics* - which reduce and eliminate certain members of the indigenous microbiota, which leads to the overgrowth by bacteria or fungi that are resistant to the antibiotic being administered: referred to as a *superinfection*

Microbial Antagonism

Also serve as a physical or mechanical barrier in the first line of defense: · Composed of only a single layer of cells · Most pathogens can only pass through when these membranes are cut or scratched · The sticky mucous that is produced by goblet cells within these serves to entrap invaders

Mucous membranes

Cellular and Chemical factors of the first line of defense: · Mucus produced here contains a variety of substances that can kill bacteria or inhibit their growth - · *Substances found in mucus - lysozyme, lactoferrin, and lactoperoxidase* · Mucosal cells rapidly divide in the body and are constantly being produced and released from mucous membranes · Bacteria that adhere to the cells are often expelled along with the cells to which they are attached

Mucous membranes

Bacteria that is not destroyed within phagolysosomes after being engulfed: the waxes in the cell walls protect the organism from digestion; these bacteria are even able to multiply within the phagocytes and are transported within them to other parts of the body · Other pathogens that are able to survive the phagocytes include - *Rickettsia rickettsia, Legionella pneumophilia, Listeria monocytogenes, and Salmonella spp.*

Mycobacterium tuberculosis

*Immunity that is acquired in response to the entry of a live pathogen into the body* · *Response to an actual infection* · People who have had a specific infection usually have developed some resistance to reinfection by the causative pathogen because of the presence of antibodies and stimulated lymphocytes; such resistance may be permanent or temporary · Sometimes, there is no immunity to reinfection after recovery even though antibodies are produced against the pathogens - this is because the antibodies that were produced are not protective antibodies

Natural Active Acquired immunity

Major cell type that is a category of lymphocytes: · Target cells, including foreign cells, host cells infected with viruses or bacteria, and tumor cells · Their activity is not dependent on antibodies · They have receptors on their surface for the Fc region of IgG antibodies, which allows the cells to attach to and kill and body coated target cells · derived from lymphoid stem cells of bone marrow

Natural Killer Cells (NK)

*Immunity that is acquired by a fetus when it receives maternal antibodies* · Examples: colostrum - milky fluid secreted by mammary glands a few days before and after delivery, which contains maternal antibodies to protect the infant during the first months of life · IgG that are present in the mothers blood can cross the placenta to reach the fetus while it is in uterus

Natural Passive Acquired Immunity

An exoenzyme: · Function: exoenzymes that *destroy tissues* · Examples: flesh-eating strains of *Streptococcus pyogenes*, which produce proteases and other enzymes that cause very rapid destruction of soft tissue, leading to a disease called *necrotizing fasciitis* · Another example is various Clostridium species, specifically those species that cause gas gangrene, which is a myonecrosis necrotic damage specific to muscle tissue; they produce a variety of necrotizing enzymes including proteases and lipases

Necrotizing enzymes

Phagocytic granulocytes include neutrophils and eosinophils; these granulocytes are much more efficient at phagocytosis:

Neutrophils

category of autoimmune diseases that include: · Myasthenia gravis (result of type II hypersensitivity) · Scleroderma · Rheumatoid arthritis (result of type III hypersensitivity) · SLE (lupus) · *Involve the skin, kidneys, joints, and muscles*

Non-Organ Specific

They are general and serve to protect the body against harmful substances

Nonspecific host defense mechanisms

Virulence factor: Pathogens that must live within host cells to survive and multiply · includes Rickettsias, Chlamydias, Ehrlichia spp, Anaplasma spp, and Plasmodium spp

Obligate intracellular pathogens

component of The Complement System in the second line of defense: the process by which phagocytosis is facilitated by the deposition of *opsonins*, such as antibiotics or certain complement fragments onto the surface of particles or cells · In some cases, phagocytes are unable to ingest certain particles or cells, such as encapsulated bacteria until this process occurs

Opsonization

category of autoimmune diseases that include: · Hashimoto thyroiditis · Graves disease · Pernicious anemia · Addison Disease · Insulin-dependent diabetes mellitus

Organ specific

Type of acquired immunity: · *when the person receives antibodies that were produced by another person or more than one person, or in some cases by an animal* · Protection is usually temporary (lasting about 3-6 weeks) · Immunity may result from either a natural or artificial event

Passive Acquired Immunity

component of the second line of defense: · Process by which phagocytes surround and engulf foreign material · Two most important groups of phagocytes in the human body are *macrophages and neutrophils*

Phagocytosis

the 4 steps in this component of the second line of defense include: chemotaxis, attachment, ingestion, and digestion

Phagocytosis

An obligate intracellular pathogen: · Sporozoan protozoa · Cause malaria · *Intraerythrocytic pathogens - live within RBCs*

Plasmodium spp

the initial response to a particular antigen · it takes about 10-14 days for antibodies to be produced; when the antigen is used up, the number of antibodies in the blood declines as the plasma cells die

Primary Response

thick and greenish red and contains many live and dead leukocytes

Purulent exudate

microbes that produce pus, such as staph and strep; when they are present, additional pus is produced as a result of the killing effect of bacterial toxins on phagocytes and tissue cells

Pyogenic microbes

Substances that stimulate the production of a fever

Pyrogens

substances that cause fever

Pyrogens

component of the virulence factor attachment: the molecule *on the surface of a host cell* that a particular pathogen is able to recognize and attach to; these are often glycoprotein molecules · ex. certain viruses cause respiratory infections because they are able to recognize and attach to certain receptors that are present on cells that line the respiratory tract · similarly, certain viruses cause infection in dogs, but not in humans, because dog cells possess a receptor that human cells lack

Receptor

Category of T lymphocytes ( T cells) that *serve as a brake on the immune response to infection* · derived from lymphoid stem cells of bone marrow

Regulatory T cells

Cellular and Chemical factors of the first line of defense: · The hair, mucous membranes, and irregular chambers of the nose serve to trap as much of the inhaled debris as possible. · The *cilia* present on epithelial cells of the posterior nasal membranes, nasal sinuses, bronchi, and trachea sweep the trapped dust and microbes upward toward the throat, where they are swallowed or expelled by sneezing and coughing · Lysozyme and other enzymes that lyse or destroy bacteria are present in nasal secretions, saliva, and tears · The swallowing of saliva can be thought of a nonspecific host defense mechanism because thousands of bacteria are removed from the oral cavity every time we swallow (swallow 1 L of saliva / day)

Respiratory system

An obligate intracellular pathogen: · Gram-negative bacteria · They invade and live within endothelial cells and vascular smooth muscle cells · They are capable of synthesizing proteins, nucleic acids, and ATP · Thought to require an intracellular environment because they possess an unusual membrane transport system; they are said to have leaky membranes

Rickettsias

· the flesh eating strains of this bacterium are more virulent than the other strains because they produce certain necrotizing enzymes that are not produced by the other strains · Certain strains of this bacterium produce erythrogenic toxin (the cause of scarlet fever), these strains are considered more virulent that the strains that do not produce erythrogenic toxin

S. pyogenes

type of response: other antigen-stimulated B cells will become *memory cells*, which are small lymphocytes that can be stimulated to rapidly produce large quantities of antibodies when later exposed to the same antigens

Secondary Response

Example: serious cases of bacterial pneumonia frequently follow relatively mild viral respiratory infections · the virus causes damage to the ciliated epithelial cells that line the respiratory tract: · Ciliated epithelial cells - function of these cells is to move foreign materials up and out of the respiratory tract and into the throat where than can get swallowed · While coughing, the patient may inhale some saliva, containing an opportunistic bacterial pathogen, such as Streptococcus pneumoniae or Haemophilus influenzae · The ciliated epithelial cells are damaged from this virus, so they are unable to clear the bacteria from the lungs; the bacteria then multiply and cause pneumonia

Secondary infection

some type of *objective* evidence of a disease; something that can be measured · Ex. when a physician discovers a lump, enlarged liver or spleen, abnormal heart or breath sounds, abnormal VS, abnormal lab results, abnormalities on radiographs, ultrasound studies, or computed scans

Sign

· Type of immunodiagnostic procedure · Performed in vivo rather than in vitro (in the patient rather than in the lab) · Antigens are injected within or beneath the skin · An example would be the TB skin test · Can also be used to determine the allergens to which an atopic individual is allergic

Skin Testing

certain strains of this bacterium produce an exotoxin called the Staphylococcal TSST-1 and an exfoliative toxin: · *Staphylococcal TSST-1* - causes *toxic shock syndrome*(which can also be caused by S. pyogenes) · An *exfoliative toxin* - which causes the epidermal layers of the skin to slough away, leading to *scalded skin syndrome*

Staphylococcus aureus

· Strains of the bacterium that produce toxic shock syndrome are considered more virulent than those that do not produce this toxin

Staphylococcus aureus

type of Kinase: · (the name of a kinase produced by staphylococci) · Because *Staphylococcus aureus* produces both coagulase and this, it can not only cause the formation of clots but can also dissolve them

Staphylokinase

Some strains of this bacterium produce an *erythrogenic toxin* which causes *Scarlet fever*

Streptococcus pyogenes

type of Kinase: the name of a kinase produced by streptococci - used to treat patients with coronary thrombosis (blockage of blood to heart caused by blood clot in coronary artery)

Streptokinase

diseases that come on more suddenly than chronic disease, less suddenly than acute (ex. bacterial endocarditis)

Subacute

type of vaccine: · *One that uses antigenic portions of a pathogen, rather than using the whole pathogen.* · Examples: Anthrax, Hepatitis B, whooping cough

Subunit Vaccines

some evidence of a disease that is experienced or perceived by the patient *(subjective)* · any type of pain or ache, ringing of the ears, blurred vision, nausea, dizziness, itching, and chills · Diseases can be either asymptomatic or symptomatic

Symptom

AKA generalized infection; when the infection has spread throughout the body (ex. when TB starts in the lungs, it may spread to may internal organs, resulting in a condition known as military TB) - pathogens may have been carried to other parts of the body by way of lymph, blood, or in some cases phagocytes

Systemic infection

The major cell types that participate in the immune response are:

T cells: Helper T cells, Cytotoxic T cells Regulatory T cells B cells NK cells Macrophages and dendritic cells

component of the second line of defense: · A group of about 30 different proteins that are found in normal blood plasma make up this system, which is complimentary to the action of the immune system · The major consequences of the activation of this system are: - Initiation and amplification of inflammation - Attraction of phagocytes to sites where they are needed - Activation of leukocytes - Lysis of bacteria and other foreign cells - Increased phagocytosis by phagocytic cells

The Complement System

Primary functions of this system: 1. Differentiate between "self" and "nonself" 2. Destroy that which is nonself

The immune system

system that is is considered to be the third line of defense · Considered a specific host defense mechanism because it springs into action to defend against a specific pathogen that has gained entrance to the body · The two major components of it are *humoral immunity* and *cell-mediated immunity*

The immune system

system that plays an important role in defending the body against invaders · Primary functions: draining and circulating intercellular fluids from the tissues and transporting digested fats from the digestive system to the blood · Macrophages, B cells, and T cells in the lymph nodes filter the lymph by removing foreign matter and microbes, by producing antibodies and to aid in the destruction and detoxification of any invading microbes.

The lymphatic System

Virulence factor: · The ability of pathogens to damage host tissues and cause disease, may depend on the production and release of various types of poisonous substances, referred to as these · Two major categories: endotoxins and exotoxins

Toxins

type of vaccine: · Vaccine in which *an exotoxin that has been inactivated by heat or chemicals* · Can be injected safely to stimulate the production of antibodies that capable of neutralizing the exotoxins of pathogens · Examples: Diphtheria and tetanus

Toxoid Vaccines

component of the second line of defense: · A glycoprotein, synthesized in the liver, has a high affinity for iron · Normal function is to store and deliver iron to host cells. · Serves as a nonspecific host defense mechanism by sequestering iron and depriving pathogens of this essential nutrient · Levels of this in the blood increase dramatically in response to systemic bacterial infections

Transferrin

Cellular and Chemical factors of the first line of defense: · Usually sterile in healthy persons (with the exception of the indigenous microbiota that colonize the distal urethra) · Frequent urination and expulsion of mucus secretions flushes microbes out of the body · The *low PH* of the vaginal fluid usually inhibits the colonization of the vagina by pathogens.

Urinary tract

Defined as material that can artificially induce immunity to an infectious disease, usually after injection or in some cases, ingestion of the material (ex. oral polio vaccine) · Part of artificially active acquired immunity · Most are made from living, dead, or inactivated pathogens, or from certain toxins that they produce · A person is deliberately exposed to a harmless version of a pathogen (or toxin), which will stimulate his or her immune system to produce protective antibodies and memory cells, but will not cause disease in the person

Vaccines

· This material is known as ideal in that it: · Contains enough antigenic determinants to stimulate the immune system to produce protective antibodies · Contains enough antigenic determinants from all the strains of the pathogen that cause the disease - referred to as *multivalent or polyvalent vaccines* · Has few or no side effects · Does not cause disease in the vaccinated person

Vaccines

process that occurs after injury and allows more blood flow to the site, brining redness and heat; also causes the endothelial cells that line the capillaries to stretch and separate, resulting in increased permeability

Vasodilation

*the measure of pathogenicity* · ex. in bacterial diarrhea, it only takes about 10 Shigella cells to cause shigellosis; but it takes between 10,000 and 100,000 salmonella cells to cause salmonellosis · Therefore Shigella is considered to be more virulent that salmonella · In some cases, certain strains of a particular species are more virulent than others · Sometimes it is used in reference to the severity of the infectious disease that are caused by the pathogens (one pathogen is more severe than another if it causes a more serious disease)

Virulence

Examples of these include: · Attachment · Obligate Intracellular Pathogens · Facultative Intracellular Pathogens · Capsules · Flagella · Exoenzymes · Toxins · Mechanisms by which Pathogens Escape Immune Responses

Virulence factors

the physical attributes or properties that enable microbes to escape various host defense mechanisms and cause disease · The phenotypic characteristics that allow microbes to be virulent or cause disease, which are dictated by the organisms genotype

Virulence factors

type of macrophages that leave the bloodstream and migrate to infected areas

Wandering macrophages

Disorders and Conditions Affecting Leukocyte Motility and Chemotaxis: · The inability of leukocytes to migrate in response to chemotactic agents may be related to defect in the production of this *protein associated with motility* in addition: · *Certain drugs* - may inhibit the chemotactic activity of leukocytes · *Chediak-Higashi Syndrome* - decreased neutrophil chemotaxis occurs

actin

The detection of _____________ directed against a particular pathogen is an *indirect evidence of infection* with that pathogen

antibodies

an example of how these protect us from pathogens and infectious diseases: · A pathogen has entered a person's body and has started producing a toxin. That person's immune system responds by producing antibodies against the toxin - these antibodies are called *antitoxins* · Once they are produced, they will then recognize, bind to and neutralize the toxin molecules

antibodies

an example of how these protect us from pathogens and infectious diseases: · A person has received a vaccine containing an attenuated virus. · The vaccine will stimulate the persons immune system to produce antibodies against the adhesin molecules on the virus · If they enter the person's body, those antibodies will adhere to the adhesin molecules, making it impossible for the virus to bind to the hose cells and enter

antibodies

an example of how these protect us from pathogens and infectious diseases: · A person is infected with a fimbriated bacterium; the person's immune system response by producing antibodies against the fimbriae · The antibodies will bind to the fimbriae, making it impossible for the bacterial cells to bind to tissue, making them unable to cause disease

antibodies

an example of how these protect us from pathogens and infectious diseases: · A person is infected with an encapsulated bacterium; that person's immune system responds by producing antibodies against the capsular polysaccharide molecules · The antibodies then attach to the capsule, and now the phagocytes can bind to the encapsulated bacteria, because they have receptors on their surface that can recognize and bind to antibody molecules

antibodies

protein molecules that a person's immune system (lymphocytes) produces in response to antigens

antibodies

· 4 explanations for the presence of these to a particular pathogen in the body: · Present infection · Past infection · Vaccination · Cross-reactivity or cross-reaction - when the antibodies react with epitopes that are molecularly similar to, but not identical to the epitope that stimulated production of the antibodies

antibodies

Example of this type of detection procedure: · a drop of serum from a patient suspected of having Lyme disease is mixed with a suspension of Borrelia burgdorferi · Visible reaction is evidence that the patient's serum contained antibodies against B. burgdorferi, and the patient has Lyme disease

antibody

type of detection procedure: · Clinical specimen is mixed with the suspension of a particular *antigen* · Visible reaction - indicates that the antibodies against that pathogen are present in the clinical specimen, and the test result is positive · No visible reaction observed indicates the antibodies against that pathogen are not present in the specimen

antibody

Example of this type of detection procedure: · a drop of CSF from a patient with meningitis is mixed with a drip of reagent that consists of latex particles coupled to antibodies against Cryptococcus neoformans · A visible antigen-antibody reaction, which leads to clumping of the latex particles, is evidence that the patient's CSF contained C. neoformans antigens

antigen

type of detection procedure: · The clinical specimen is mixed with a particular *antiserum* · *Visible reaction* - the result of the formation of antigen-antibody complexes and indicates that the antigen is present in the clinical specimen; the test result is considered positive · The antiserum has antibodies and the clinical specimen is mixed with it; if there is a visible reaction, the antigen is present

antigen

Mechanism by which Pathogens Escape Immune Responses: · the foreign molecules that evoke an immune response; they often stimulate the immune system to produce antibodies

antigens

The detection of _____________ in a clinical specimen is *an indication that a particular pathogen is present* in the patient, thus providing direct evidence that the patient is infected with that pathogen

antigens

The presence of ____________ provides the best prove of current infection

antigens

molecules, usually proteins, that stimulate a person's immune system to produce antibodies; *antibody-generating* · foreign organic substances that are large enough to stimulate the production antibodies; generates antibody production

antigens

diseases that result when a person's immune system no longer recognizes certain body tissues as self and attempts to destroy those tissues as if they were nonself or foreign · Either the result of type II, III, or IV hypersensitivity reactions · 2 categories: Organ specific, non-organ specific

autoimmune diseases

4th Period in the course of an Infectious Disease: · *the time during which the patient recovers* · For viral respiratory diseases, this period can be quite long · Although the patient may recover from the illness, permanent damage may be caused by the destruction of tissues in the affected area (ex. brain damage can follow encephalitis or meningitis)

convalescent period

when an antibody binds to an antigenic determinant that is similar, but not identical in structure to the antigenic determinant that stimulated its production

cross-reacting antigen

type of toxin: · Found in the cell walls of *Gram-negative bacteria* · The cell walls of gram negative bacteria contain lipopolysaccharide, the lipid portion is called lipid-A or endotoxin · It can cause serious adverse, physiologic effects such as fever (pyrogens) and shock

endotoxin

individual molecules or antigenic sites that are present on a bacterial cell wall's surface capable of stimulating the production of antibodies; AKA antigenic determinants

epitopes

line of defense: · *Skin and Mucous Membranes as Physical barriers* · *Intact, unbroken skin* is this type of defense in that it - · serves as a physical or mechanical barrier to pathogens · Very few pathogens are able to penetrate intact skin · *Certain helminth infections (hookworm infections)* are acquired by penetration of the skin by parasites; other bacteria unlikely capable of penetrating intact skin

first

when a person is resistant to a certain disease, they are said to be immune, and the condition of being immune is referred to as ______________

immunity

Substances that are capable of stimulating the production of antibodies are said to be antigenic or ________________

immunogenic

globular glycoproteins in the blood that participate in the immune reactions · Found in the lymph, tears, saliva, and colostrum, along with the blood · All antibodies are in this category · Antibodies that are found in the blood are called humoral or circulating antibodies

immunoglobulins

1st Period in the course of an Infectious Disease: · *the time that elapses between arrival of the pathogen and the onset of symptoms* · the length of this period is influenced by many factors including the overall health and nutritional status of the host, the immune status of the host, the virulence of the pathogen, and the number of pathogens that enter the body

incubation period

the site and source of most immune activity

lymphatic system

the most common cause of immunosuppression

malnutrition

· The most potent exotoxins (which effect the CNS) · Example: Clostridium tetani which tetanus and Clostridium botulinum which causes botulism

neurotoxins

Examples of this type of defense mechanism include: · mechanical and physical barriers to invasion · chemical factors · microbial antagonism by our indigenous microbiota · fever · the inflammatory response · phagocytic white blood cells

nonspecific

First 2 lines of defense are ______________ - ways in which the body attempts to destroy all types of substances that are foreign to, including pathogens

nonspecific

capable of causing disease

pathogenic

3rd Period in the course of an Infectious Disease: · *the time during which the patient experiences the typical symptoms associated with that particular disease* (ex. sore throat, headache, sinus congestion) · When communicable diseases are most easily transmitted

period of illness

a membrane bound vesicle in the ingestion phase of phagocytosis that contains digestive enzymes, such as lysozyme, lipases, proteases, and peptidases, which will degrade carbohydrates, lipids, proteins, and nucleic acids

phagosome

2nd Period in the course of an Infectious Disease: · *the time during which the patient feels out of sorts but does not yet experience actual symptoms of the disease*; may feel as if they are coming down with something

prodromal period

Components of this line of defense include: transferrin, fever, interferons, the complement system, acute-phase proteins, cytokines, inflammation, and phagocytosis

second

· The type of shock that results from gram negative sepsis (presence of the bacteria or their toxins in the bloodstream) · Symptoms include: · Reduced mental alertness · Confusion · Rapid breathing · Chills · Fever · As shock worsens, several organs fail including the kidneys, lungs, and heart

septic shock

a complication that can occur due to endotoxins, a life-threatening condition resulting from very low blood pressure and an inadequate blood supply to body tissues and organs, especially the kidneys and brain

shock

Cellular and Chemical factors of the first line of defense: · Features of the this that inhibit pathogens - *dryness, acidity* (pH of 5.0), *temperature* (<37 degrees Celsius), *oily sebum* that is produced by sebaceous glands contain fatty acids (which are toxic to some pathogens), *perspiration* by flushing organism from pores and the surface of this (contains lysozyme, which degrades peptidoglycan in bacterial cell walls, especially gram positive), and the *sloughing off of dead cells*

skin

· Pathogens can gain access into this barrier of the first line of defense: · When it is cut, scratched, or burned · or when pathogens are injected by arthropods or the sharing of contaminated needles

skin

Third line of defense is the *immune response*, which is very _____________ - antibodies are produced in response to the presence of foreign substances called antigens

specific

Immune responses to antigens in the blood are usually initiated in the ___________

spleen

type of hypersensitivity reaction: · Also known as *anaphylactic reactions* · These include the classic allergic responses, such as hay fever, asthma, hives, and GI symptoms · Result from food allergies, allergic responses to insect stings and drugs, and anaphylactic shock · These reactions all *involve IgE antibodies*, and the release of chemical mediators (especially histamine) from mast cells and basophils · involve the /-*allergic response*: · Result from the presence of IgE antibodies bond to basophils in the blood or mast cells

type I

a typical reaction of this type might follow this sequence: · A particular drug binds to the surface of a body cell · Antidrug antibodies then bind to the drug · This initiates complement activation on the cell surface · The complement cascade leads to lysis of the body cell

type II

type of hypersensitivity reaction: · Known as *cytotoxic reactions* · Body cells are destroyed during these reactions · Include reactions that occur during incompatible blood transfusions, Rh incompatibility reactions, and myasthenia gravis; all of these reactions involve *IgG or IgM antibodies and complement*

type II

type of hypersensitivity reaction: · Also known as* immune complex reactions* · Examples: · Serum sickness and certain autoimmune diseases - such as systemic lupus and rheumatoid arthritis · These reactions *involve IgG and IgM antibodies, complement, and neutrophils.* · Certain *complications of untreated strep throat* and other Streptococcus pyogenes infections are the result of these reactions

type III

type of hypersensitivity reaction: · Referred to as *DTH or cell-mediated immune reactions* · Part of cell-mediated immunity · Usually observed 24-48 hrs or longer after exposure or contact · Occur in tuberculin and fungal skin tests, contact dermatitis, and transplant rejection · *Antibodies do not play a major role in this type of reaction* · DTH is the prime mode of defense against intracellular bacteria and fungi · Involves various cell types including: Macrophages, DCs, Cytotoxic T cells, NK cells

type IV

Strains of bacteria that are *pathogenic*

virulent

A *superinfection of Candida albicans* yeasts in the vagina may lead to the condition known as _________ ___________

yeast vaginitis

The detrimental aspects of a prolonged fever include:

· Increased heart rate · Increased metabolic rate · Increased caloric demand · Mild to severe dehydration