Ch14 Flashcards
relationship in which both members benefit from their interaction
Mutualism
eg: termites and protozoa that break down the cellulose with the help of bacterial enzymes that live in protozoa
eg: bacteria in human colon
How many more bacterial cells are living on humans than human cells
10 times more
relationship in which one member of the relationship benefits without significantly affecting the other.
Commensalism
eg: Staphylococcus epidermis living on human skin
Relationship in which the host is harmed and the recipient (pathogen-cause diseas) benefits
Parasitism
eg: Tuberculosis bacteria in human lung
What are the three types of symbiotic relationships
1) Mutualism
2) Commensalism
3) Parasitism
Over time, what will parasitism eventually lead to
“Coevolution” towards commensalism or mutualism
sites that are free of any microbes
axenic
eg: mother’s uterus, alveoli of lungs
Microbes that colonize the surfaces of the body without normally causing disease
Normal microbiota or normal flora/indigenous microbiota
What are the two main types of normal microbiota
1) Resident microbiota
2) Transient microbiota
remain a part of the normal microbiota of a person throughout life, found on the skin, mucous membranses of digestive tract, upper respiratory tract, distal portion of the urethra, and vagina
Resident Microbiota
T of F , most of the resident microbiota are commensal
True
Remain in the body for only a few hours, days, or months before disappearing
Transient Microbiota
How does your normal microbiota begin to develop?
during the birthing process, microbes entered nose and mouth via the birth canal, first breath established microbiota in respiratory tract, first meal for your colon, staphylococcus on skin from hospital staff
Review resident microbiota
table 14.2
What are the 3 conditions in which normal microbiota become “opportunistic pathogens-opportunists”
1) Introduction of a memeber of the normal microbiota into an unusual site in the body
2) Immune suppression
3) Changes in the normal microbiota
Where is E coli’s normal microbiota, where does it become an opportunistic pathogen
normal microbiota is in the colon, it becomes opportunistic pathogen in the urethra
The term used to describe carriers of disease that are asymptomatic and infective for years.
“Carriers”- eg: Tuberculosis, syphilis, and AIDS
the term used to describe when a microbe overcomes body’s external defenses, multiplies, and becomes established in the body-successfully invades body
“infection”
refers to the mere presence of microbes in or on the body
contamination
The sites at which pathogens enter the body
“Portals of entry”
What are the three major Portals of entry
1) the skin
2) the mucous membranes
3) the placenta
4) parenteral route
Which portal of entry do pathogens find more hospitable and easier portals of entry
mucous membranes
eg: respiratory tract is the most frequently used portal of entry for pathogens (whooping cough, diphtheria, pneumonia, strep throat, meningitis
eg: prions enter via oral mucous membranes
How does skin become a portal of entry
1) hair follicles
2) sweat glands
3) cuts, abrasions (parenteral route)
4) parasitic worms that burrow thru skin
5) fungi that digest outer layer skin
What are forms of the parenteral route-
punctures by a nail, thorn, or hypodermic needle, cuts, bites, stab wounds, surgery
Chemicals that either harm tissues or trigger host immune responses that cause damage.
Toxins
two types of toxins
1) Exotoxins-secreted by microbes that are central to their pathogenicity in that they destroy host cells or interfere with metabolism (More lethal than Endotoxin)
2) Endotoxin-lipid A (portion of membrane’s lipopolysaccharide)…released when “Gram negative bacteria” divide, die naturally, or are digested by phagocytic cells such as macrophages.
Virulence factors related to the evasion of phagocytosis
Antiphagocytic Factors
What are two antiphagocytic factors which bacteria use to evade phagocytosis
1) Capsules- composed of chemicals normally found in the body including polysaccharides-does not stimulate host’s immune response, they are slippery too
2) Antiphagocytic Chemicals-
Source of exotoxins
Gram-positive and gram-negative bacteria
What are types of Antiphagocytic chemicals
1) M protein- made by Streptococcus pyogenes , resists phagocytosis and thus increases virulence
2) leukocidins-chemicals capable of destroying phagocytic white blood cells outright
Chemical nature of exotoxins
It’s a protein or short peptide
Toxicity of exotoxins
High
Exotoxins affect on host
It is variable depending on source maybe cytotoxin neurotoxin enterotoxin
Are exotoxins fever producing
No
Anti-genicity of exotoxins
It is strong stimulates antitoxin (anti-body) production
Anti-genicity of endotoxins
note: anti genitcity mean ability of a chemical to trigger a specific immune response
Weak
Representative diseases for exotoxins
Botulism ,tetanus, gas gangrene, Diphtheria, cholera , plague staphylococcal food poisoning
What is the source of endotoxins
Gram-negative bacteria
What is the chemical nature of endotoxins
Lipid portion of Lipopolysaccharide(lipid A)of outer cell wall membrane
Toxicity of endotoxins
Low, but maybe fatal in high doses
Endotoxins affect on host
Fever, lithargy, malaise, shock ,blood Coagulation
Do endotoxins cause fever
Yes
Antigenicity of endotoxins
Weak
Toxoid formation for immunization of endotoxins
Not feasible because endotoxins are stable at 121°C
Representative diseases for endotoxins
Typhoid fever, tularemia , endotoxic shock , urinary tract infections , meningococcal meningitis
What makes up innate immunity?
The first and second lines of defense
What makes up the first line of defense
External physical barriers to pathogens especially the skin and mucous membranes and their secretions
eg: Tissues and Organs: Barriers, Lymph, Blood, normal microbiota (microbial antagonism)
What makes up the second line of defense
Is internal ,and is composed of protective cells , blood-borne chemicals, and processes that can inactivate or kill invaders
eg: Cells: Local cells, mast cells, macrophages, tissue, endothelial
Chemical: Activators, chemotaxis, growth factors, vasodilators
What makes up adaptive immunity
The third line of defense
Note: Respond against unique species or strains of pathogens and alters the body’s defenses such that they act more effectively upon subsequent infection with the specific strain
What is the role of Normal Microbiota in Innate Immunity (first line of defense)
- normal microbiota help protect the body by competing with potential pathogens
- activities of normal microbiota make it hard for pathogens to compete
a) consumption of nutrients unavail to pathogens
b) create env. unfavorable to other pathogens by changing pH
c) stimulate bodys second line of defense
d) promote overall health by providing vitamins
What is the role of Skin in Innate Immunity I (first line of defense)
a) Epidermis-tightly packed cells, few pathogens can penetrate these layers, shedding of dead skin cells remove attached pathogens, epidermal dendric cells phagocytize pathogens
b) Dermis-have collagen (protein)-give strength and pliability to resist abrasions that could introduce microbes
What is the role of skin in innate immunity II (first line of defense)
Skin has chemicals that defend against pathogens
eg: perspiration secreted by sweat glands:
a) salt-inhibit growth of by drawing water from pathogens cells
b) antimicrobial peptides-sweat glands secrete dermicidins
c) Lysozyme-destroys cell wall of bacteria
Sebum secreted by sebaceous glands(oil)
a) help keep skin pliable and less likely to break
b)lowers pH of skin to a level inhibitory to many bacteria
Number of cell layer in skin
many
Cells tightly packed in skin?
Yes
Cells dead or alive in skin
epidermis: dead
dermis: alive
Mucus present in skin
no
Relative water content in skin
dry
defensins present in skin?
yes
lysozyme present in skin
yes
Sebum present in skin
yes
Cilia present in skin
no
Constant shedding and replacement of cells in skin
yes
number of cells layers in mucous membrane
one to a few
cells tightly packed in mucous membrane?
yes
cells dead or alive in mucous membrane?
alive
Mucus present in mucous membrane?
yes
Relative content of water in mucous membrane
moist
Defensins present in mucous membrane
yes
Lysozyme present in mucous membrane
with some
Sebum present in mucous membrane
no
Cilia present in mucous membrane
not all, present in trachea and uterine tubes
Constant shedding and and replacement of cells
yes
what makes goblet cells and ciliated columnar cells
Stem cells
secrete an extremely sticky mucus that traps bacteria and other pathogens
goblet cells
has cilia that propel the mucus and its trapped particles and pathogens up from the lungs
ciliated columnar cells
Where do dendritic cells reside?
on the epidermis and below the mucous epithelium to phagocytize invaders
Locations of where you can find lysozyme
nasal mucous, tears made by the lacrimal apparatus, skin
how does the lacrimal apparatus rid itself of irritants
it floods the eyes with tears
how is the second line of defense different from the first line of defense
has no barriers associated with it
What line of defense is contained in or originate in the blood
Second line of defense
What is the second line of defense composed of
phagocytes (cells), antimicrobial chemicals(peptides, complement, interferons), processes (inflammation, fever)
What are the plasma proteins of the second line of defense
Complement proteins (serum)
a process where blood stem cells located in the bone marrow of large bones produce three types of formed elements
hematopoesis
what are the three main types of formed elements
1) Erythrocytes
2) Platelets
3) Leukocytes
what is the most numerous among the formed elements
erythrocytes
a formed element Involved in the clotting of blood
Platelets
What are the two groups leukocytes are divided into
1) granulocytes
2) agranulocytes
Have large granules in their cytoplasm that stain different colors
Granulocytes
it’s cytoplasm appear uniform when viewed under a light microscope, named for not having granules but in actuality, they have them
Agranulocytes
a process of escaping the blood via squeezing between the cells lining capillaries
diapedesis
are not phagocytic, instead release inflammatory chemicals, an aspect of the second line of defense
Basophils
The only lymphocyte that is considered a part of innate immunity (second line of defense)
NK (natural killer) lymphocyte
What cells are considered Agranulocytes?
Lymphocytes and Monocytes
mature into macrophages when they leave the blood via diapedises
Monocytes
The two cells that phagocytize pathogens and inform cells of the adaptive immunity that there is a microbial invasions
Dendritic cells and Macrophages
increase percentage of neutrophils and number of leukocytes are indicative of what type of disease?
Bacterial
An increase in the number of lymphocytes are indicative of what type of infection?
viral infection
What are the six steps of phagocytosis
1) chemotaxis
2) adherance
3) ingestion
4) maturation
5) killing
6) elimination
What attract phagocytic leukocytes
1) microbial components and secretions
2) components of damaged tissues and white blood cells
3) Chemotactic factors
4) chemokines
What are chemotactic factors
defensins, peptides derived from complement, and chemokines
What are chemokines
chemicals released by leukocytes already at the site of infection
what is defensins
They are, and function as, host defense peptides. They are active against bacteria, fungi and many enveloped and nonenveloped viruses
The process of covering pathogens with antimicrobial proteins (complement) or specific antimicrobial proteins called antibodies
opsonization
What are the proteins used to cover pathogens during opsonization called?
note: these types of proteins also increase the number and kinds of binding sites on a microbes surface
opsonins
phagosome
vessicle used by phagocytes to contain microbe during phagocytosis
contain anttimicrobial substances such as highly reactive toxic forms of oxygen, lipases, proteases, nucleases
phagolysosome (lysosome)
the elimination of remnants of microbes during the end of phagocytosis
exocytosis
How do phagocytes destroy only invading pathogens and not self cells
1) phagocytes have toll like receptors for various microbial surface components lacking on body’s cells
2) Opsonins such as complement and antibody provide a signal to the phagocyte
What cells are responsible for Nonphagocytic Killing
1) Eosinophils
2) NK lymphocytes (perforin and granzyme)
3) Neutrophils
although it is capable of phagocytosis this cell’s mode of attack is secreting antimicrobial chemicals (extracellular protein toxins onto the surface of the parasite (worms) or the ejecting of mitochondrial DNA is used to kill Gram negative bacteria
Eosinophils
secretes toxins onto the surfaces of “virally” infected cells and neoplasms (tumors)
NK natural killer cells (lymphoctyes) second line of defense “innate immunity”
What are the chemical defenses that augment phagocytosis in the second line of defense
Lysozyme, defensins, toll like receptors, NOD proteins, interferons, and complement
receptors found on phagocytic cells (macrophages, dendritic cells, epithelial cells) to detect molecules shared by bacteria and viral pathogens
Toll like receptors (receptors for pathogen associated molecular patterns)
Term used to describe pathogenic microbial molecules such as: flagellin, unmethylated pairs of cytosine and guanine nucleotides from bacteria and viruses, double stranded RNA, single stranded viral RNA
Pathogen associated molecular patterns (PAMPS)
Which TLRs are found in cytoplasmic membrane
TLR 1, 2, 4, 5, 6
Which TLRs are found in phagosome membrane
TLR 3, 7, 8, 9
another set of receptors for pathogen associated molecular patterns , but these are found inside of cell instead of the membrane
NOD proteins
What are the four attributes of adaptive immunity?
1) Memory-
2) Diversity
3) Tolerance- tolerating our own antigens our own body, ability to distinguish ourselves from foreign material (express proteins that don’t belong to body)
4) Specificity
What cells do adaptive immunity involve?
1) B lymphocytes (B cells) -Humoral immune response
2) T lymphocytes (T cells)-cell mediated immune responses
The maturation process of our immune system in which deletion of lymphocytes that respond to self are deleted until those lymphocytes that don’t respond to self and respond to only foreign antigens are left
Clonal Deletion
note: this is a Tolerance attribute of “adaptive immunity”
Cells that are specific to an antigen are?
The T lymphocytes and the B lymphocytes
The cell that responds to a certain antigen undergoes? hint: considered a specific attribute of adaptive immunity
Clonal selection
note: selected cell proliferates and produces antibodies against a certain antigen
The ability of our aquired immune system to make antibodies against a wide variation of antigens shows what specific attribute
Diversity
The cells undergoing cloning selection will eventually become ?
memory cells and will make more antibodies with subsequent exposure to the antigen in the future
Responded to very specifically by a lymphocyte
Viral Epitope
a “B” cell receptor or “T” cell receptor will respond to only a specific?
epitope found on an antigen
Where does the epitope and receptor make contact?
At the antigen binding sites of the “variable region” of the lymphoctye (B or T)
if you build up a response to a vaccination injection it is considered ? What adaptive immunity attribute does this reflect?
Active immunity (creating antibodies in response to the vaccination)
note: just because you got a vaccination shot does not mean you immediately have active immunization….your body must produce the antibodies to a level considered an active response
note: this demonstrates memory
Any immune response against a foreign antigen that is exagerated beyond the norm
Hypersensitivities
What are the two types of hypersensitivities focused in lecture?
1) Type 1 (immediate)
2) Type 4 (delayed or cell mediated)
What is Type 1 (immediate) hypersensitivity also known as?
Allergy
How do allergy responses take place
an antigen activates a B cell response (in the mucous membrane) that make IgE and attach to mast cells, when the mast cells is exposed to subsequent antigen, the mast cell will release alergic mediators (histamines, serotonin so forth) which lead to allergies (hay fever and asthma)
note: this is an immediate type I hypersensitivity
eg: pollen could be considered the allergen
Characteristics of Type I Immediate hypersensitivity
- *Localized or systemic in response to antigen
- *Develops within seconds or minutes
- *commonly called allergy, and antigens that stimulate it are called allergens
Systemic response to a food alergy
anaphylactic response
Treatments for hypersensitivity Type 1 (immediate) for pollen, asthma, anaphylaxis
1) anti-histamines
2) corticosteroid and a bronchodilator
3) epinephrine for anaphylaxis
Type IV (Delayed or cell mediated) hypersensitivity symptoms
1) inflammation 12 to 24 hours after contact with certain antigens
2) results from interactions betweenantigen, antigen presenting cells, T cells,
3) the delayed response is attributed to the time it takes for macrophages and T cells to proliferate at original site of antigen
Examples of Type IV hypersensitivity conditions
1) poison ivy
2) poison oak
subsequent antibody response by B cells is called what type of respones
Humoral response
What does diversity in B cells allow us to do?
Allows us to clone selection and to develop a specific response to a particular antigen and then remember exposure to that specific antigen
what is something that can happen during antigen and antibody interaction
agglutination
What is the advantage of the antibody receptor being a “Y” shape
it can bind to more than one antigen
how can you tell if a soluble antigen interacts with its corresponding antibody?
The soluble antigen will precipitate out of the solution forming a white line (line of precipitation)
a person that is type B blood will form agglutination of blood when exposed to
anti-B antibody
note:
What does ELISA stand for?
enzyme linked immunosorbent assay
What is ELISA ?
1) antigen attached to bottom of well
2) gelatin added to block uncoated surface of well
3) patient serum is added to antigen: complimentary antibody binds to antigen
4) Enzyme linked antibody is added and binds to already bound antibody
5) Enzyme substrate is added and there is a color change if there is an complimentary antibody within the initial blood serum.
note: the ELISA test is so specific, we can use it to quantify the amount of antibody present in blood serum
Sandwich Elisa
the opposite of Elisa, well is lined with the antibody, and put blood serum on to see if blood serum has complimentary antigen to antibody in the well
What can the ELISA test do?
1) can detect antibody or antigen
2) can quantify antibody or antigen
3) easy, cheap, and can test many samples quickly
4) plates coated with antigen and gelatin can be stored and used later
How can you use an antigen or antibody for diagnosis purposes
you can line the bottom of titter well in ELISA test with either antigen or antibody and test to see if person has been infected with a disease.
has to do with disease in populations
Epidemiology
When do people go to the doctor
When the symptoms and signs are most severe (number of pathogenic microorganisms are at there highest
How did Etiology come about?
It came about from the Germ theory (Pasteur and Koch), and Koch’s postulates
if everyone has a respiratory disease, how can you suspect the pathogen was contracted
via droplet (contact transmission), or airborne (vehicle transmission)
If everyone has a gastrointestinal infection such as diarrhea, how do you suspect the pathogen was contracted
waterborne or foodborne (vehicle transmission)
If everyone is getting a systemic disease such as malaria
It is most likely transmitted via vector
number of diseased cases goes much more above the expected number of cases
Epidemic (outbreak)
what are the two ways (measures) in which epidemiologist track occurrences of disease
1) incidence- number of new cases of a disease in a given area during a given time period
2) Prevalence-number of total cases of a disease in a given area during a given period of time
disease is always present in some number in the population
Endemic
Occurs in higer rates in seeming unrelated circumstances in different areas
Sporadic
eg: Eboli virus
An outbreak in a geographic area at a rate higher than normally expected
Epidemic
Pandemic
a worldwide epidemic
Diseases (eg: Salmonella) that are required by law for physicians to notify the health department (who reports it to the Center of Diseas and Control (CDC)) with each case that is diagnosed by physician
Nationally notifiable infectious diseases
The diseases that are reported to the CDC are published in what is known as the
MMWR (Morbidity/Mortality Weekly Report)
Consist of careful tabulation of data concerning a disease
-Record information about the location and time of the cases of disease
-Collect patient information
Try to identify the index case (first case) of the disease
Epidemiological Studies
eg: studies conducted by Robert Snow with the outbreak of Cholera
Seeks to find the probable cause, mode of transmission, and methods of prevention
- useful in situations where Koch’s postulates can’t be applied
- often retrospective-investigation occurs after outbreak has occured
Analytical Epidemiological study
Involves testing a hypothesis concerning the cause of a disease
Experimental Epidemiological study
eg: application of Koch’s postulates
Types of Nosocomial Infections
1) exogenous-pathogen acquired from health care environment
2) Endogenous-pathogen arises from normal microbiota due to factors within health care settings
3) Iatrogenic-results from modern medical procedures (surgery or catheter)
how do nosocomial infections take place
1) presence of microorganisms in hospital environment
2) immunocompromised patients
3) transmission of pathogens between staff and patients and among patients
What is the most effective way to reduce nosocomial infections
hand washing
What is the function of the complement
1) Opsonization
2) Chemotaxis
3) Cell lysis
4) Clumping of antigen bearing agents
t or f, there are more gram positive bacteria than gram negative bacteria on the normal microbial flora of skin
true
What is the environment of oral cavity
moist, nutrients, antibacterial compounds, anaerobic
what is related to dental plaque on teeth
high sugar, organic acids, attachment, caries, and gingivitis
normal microbial flora of Gastrointestinal tract
pH variations, anoxic, vit B12 and K, specific species selected for with different diet
what is the pH in the stomach, S. intestine, and L. intestine
1) Stomach (2)
2) S. Intestine (4-5)
3) L. Intestine (7)
Role of adhesion in infection
required to successfully establish colonies within the host
Virulence factors of infectious agents
1) extracellular enzymes-dissolve structural chemicals in body, help pathogen maintain infection
2) Toxins-
a) chemicals that harm tissues or trigger host immune
b) toxemia-toxins in bloodstream carried beyond site of infection
* **these are exotoxins and endotoxins
3) Antiphagocytic factors
a) bacterial capsule
b) antiphagocytic chemicals (leukocidins-destroy phagocytes and
4) Attachment factors
Stages of infectious disease
1) Incubation period
2) Prodromal period
3) Illness
4) Decline
5) Convalescence
Stage of infectious disease with highest number of microorganisms or intensity of signs or symptoms
Illness
Which cells has to do with Humoral immunity
B cells
Which cells has to do with Cellular Immunity
T cells
