An agent that causes infection or disease, especially a microorganism, such as a bacterium or protozoan, or a virus

*causing damage to cells tissues

Criteria for pathogen to be causing an infectious disease:

1) organism must get into biological space

2) as it lives, grows, & reproduces, it MUST do damage

3) mustbe able to avoid the removal of bacteria by your normal immune system.

virulence

&

characteristics determining virulence

Extremely infectious, malignant, or poisonous. Used of a disease or toxin.

* degree of pathogenicity/ability and likelihood to cause damage/disease

characteristics determining virulence:

1) protection against nonspecific destruction in the body (nonrecognition & resistance to killing).

2) invasiveness & tissue destruction

***production of exotoxins:

***production of bacterial endotoxins

1) toxic proteins from living cell or when it undergoes lysis

2) all exotoxins are PROTEINS

3) often encoded on plasmid DNA

4) proteins can be used to form anti-toxins

1)Lipopolysaccharides from gram - cell walls

2) produce effects when large #s of bacterial cells grow in the body (*especially when they are in the blood stream)

3) cause release of endogenous pyrogens from WBCs, causing fever, activates complement system, macrophages, and the Hageman factor

antibodies that can detoxify toxins

immunoglobulins

1. The presence of pathogenic organisms or their toxins in the blood or tissues.

profuction of exotoxin causing toxic shock syndrome

it is related to a super antigen and release another series of cytokines into the bloodstream.

dosage of pathogen

sheeding organism during the symptomatic phase of disease

(we know one has the disease and we can identify they are sick)

incubatory carrier

sheeding organisms prior to onset of symptoms

examples:

1) chicken pox (most contagious 3-4 days before "pox" arise and spread via respiratory tract)

2)HIV

shedding organisms after disappearance of primary/acute symptoms

examples: typoid fever (typhoid mary) & syphilis

shedding organisms without overt symptoms in carrier, thus not being diagnosed

example: Mumps

immunoglobulins--antibodies

T cell lymphocytes recognize and attack infected cells

phase of getting rid of all the bacteria

(pts may see symptoms are gone when bacteria #s get under the clinical horizon, but there is still bacteria present, so must continue taking antibiotics to fully eradicate pathogens)

virus completely disappears from the body at resolution

Example: Hepatitis A

disease is present after an amoutn of time and it never drops back down below the clincal horizon.

there is always symptoms and ongoing damage from it

example: Hepatitis B/C

disease resolves, but virus goes into hiding and survives in neural tissue w/o symptoms. it re-emerges when immune system is vulnerable. after it resolves again, it still does not disappear.

example: chicken pox/shingles 

never rises above the clinical horizon. the immune system responds before symptoms arise.

basis of vaccines ("attenuated/weakened viruses")

disease is not lethal; people always recover

example: common cold

only infects one location in the body.

organism causes damage where it reproduces

Illness caused by new bacteria, viruses, or fungi becoming established in the wake of an initial infection

example: get chicken pox from being infected with varicella/zoster pathogen, but if one scratches the "pox," then could be secondarily infected by Staph. aureus.

--Material, such as fluid, cells, or cellular debris, which has escaped from blood vessels and has been deposited in tissues or on tissue surfaces, usually as a result of inflammation.

--An exudate, in contrast to a transudate, is characterized by a high content of protein, cells, or solid materials derived from cells.

phagocytic attachment

--Chemoattractants draw phagocytes to an area &/or recognize molecules that enhance the binding of phagocytes to their targets

--this enhanceent of binding is opsonization & micromolecules that bind to an antigen and increase the efficiency of phagocytosis are opsonins

--opsonins provide molecular handles for the phagocyte to grab onto

the digestive vacuole formed when the membranes of pre-existent lysosomes within the cytoplasm merge with the phagosome; the lysosomes then discharge their hydrolytic enzymes, resulting in digestion of the phagocytized material.

any of a group of small antimicrobial cationic peptides occurring in neutrophils and macrophages; they act by binding fungal and bacterial membranes and increasing membrane permeability.

TNF

(Tumor Necrosis Factor)

--produced by activated macrophages and T cells in response to gr- LPS

--most important mediator of acute inflammation

--mediate recruitment of neutrophils and microphages to site of inflammation by stimulating cells to secrete adhesion factor and chemokines

--potent PYROGEN.

secreted by macrophages

responsible for inflammation and hematopoesis

--produced by T-helper2 cells, macrophages, and B cells

--suppresses inflammatory responses

--stimulates B cells and mast cells

--limits Th-1 response, promotes Th2 cell development, 

--inhibits expression of MHCII

--produced by macrophages, dendritic cells, Tc cells, NK cells

--promotes Th1 cells, stimulates production of INF-gamma

--enhances immunity

IFN-alpha and beta

(I)

--inhibits viral replication

--increase expression of MHC I and Tc mobilization

--stimulates IFN--gamma by activated T cells

--activates NK cells

IFN-gamma

(II)

--produced by Th1 cells

--activates NK cells

--increase MHCI and MHCII expression to help Th cells and APC

--promotes B cell differentiation to plasma cell

--promotes Tc cell differentiation

a transient increase in the number of leukocytes in the blood; seen normally with strenuous exercise and pathologically accompanying hemorrhage, fever, infection, or inflammation. 

reduction in the number of leukocytes in the blood below about 5000 per mm3. Types are named for the type of cell,

--increase in the number of neutrophils in the blood;

--it is the most common form of leukocytosis

-- causes: acute infections, intoxications, hemorrhage, and rapidly growing malignant neoplasms. 

excess of normal lymphocytes in the blood or in any effusion

--a mature granular leukocyte that is polymorphonuclear

-- neutrophils have the properties of chemotaxis, adherence to immune complexes, and phagocytosis

--increase neutrophils tend to indicate increased bacterial infection

--a granular leukocyte with an irregularly shaped, pale-staining nucleus that is partially constricted into two lobes, and with cytoplasm that contains coarse, bluish-black granules of variable size.

--Basophils contain vasoactive amines such as histamine and serotonin, which are released on appropriate stimulation. 

--responsible for allergic rxns

--a granular leukocyte with a nucleus that usually has two lobes connected by a slender thread of chromatin, and cytoplasm containing coarse, round granules that are uniform in size.

--increased #s tend to indicate parasitic infection

--a mononuclear phagocytic leukocyte, 13 to 25 μm in diameter, with an ovoid or kidney-shaped nucleus, 

--Formed in the bone marrow from promonocytes

--monocytes are transported to tissues such as the lung and liver, where they develop into macrophages. 

--hematopoietic stem cells in the bone marrow, which develop according to the stages of the monocytic series until they are monocytes;

--these then enter the blood, circulate for about 40 hours, and subsequently enter tissues, where they increase in size, phagocytic activity, and lysosomal enzyme content to become macrophages.

--Two types, fixed macrophages and free macrophages 

--functions include nonspecific phagocytosis & pinocytosis, specific phagocytosis of opsonized microorganisms; killing of ingested microorganisms; digestion & presentation of antigens to T & B lymphocytes; & secretion of many different products, including enzymes

White Blood Cell Count

White blood cells protect the body against infection. If an infection develops, white blood cells attack and destroy the bacteria, virus, or other organism causing it. White blood cells are bigger than red blood cells but fewer in number. When a person has a bacterial infection, the number of white cells rises very quickly.

a leukocyte count that calculates the percentages of different types of cells

(Dorland, Newman W.. Dorland's Illustrated Medical Dictionary, 31st Edition. Saunders Book Company, 052007.). 

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• When we look at doing a blood count, used to count starting with most immature going to immature (left to right) thus "shift to the left"
• chronic inflammation is indicated by releasing more and more neutrophils, and body resorts to releasing the neutrophils when they are less and less mature

--elevation of body temperature above the normal;

--it may be due to physiological stresses such as ovulation, excess thyroid hormone secretions, or vigorous exercise; to central nervous system lesions or infection by microorganisms; or to any of a host of noninfectious processes, such as inflammation or the release of certain materials, as in leukemia.

• Malignant hyperthermia: life threatening high temp (not based on endog pyro.) usually occurs from gasseous anesthetics get into brain during a surgery...)(if you can remove the gasseous anesthetics, then the temp will go back down)

signals released in the body that reset the thermal set point

• Drug fevers: (sometimes binds to same receptors as the endogenous pyrogens should)

Self-limiting tonic/c/one seizure-20-60 seconds. 2-5% of young children exhibit brain stem synaptic immaturity usually disappears with childhood maturity cannot predict susceptibility. The actual damage done to the infant/toddler isn't very severe.

Self-limiting tonic/c/one seizure-20-60 seconds. 2-5% of young children exhibit brain stem synaptic immaturity usually disappears with childhood maturity cannot predict susceptibility. The actual damage done to the infant/toddler isn't very severe.

erythrocyte sedimentation rate

--the rate at which red blood cells precipitate in a period of 1 hour.

disseminated intravascular coagulation

--Bleeding disorder associated with meningococcal infections occuring when bacteria secrete large amounts of LPS molecules into the bloodstream.

--Symptoms: fever and shock accompany a reduction of clotting elements in the blood. Profuse hemorrahaing occurs in the late stages