describes the relationship between microorganisms and their host
Mutualism, Commensalism, and Parasitism
What are the three types of symbiotic relationships?
type of symbiotic relationship in which both organisms benefit from the relationship
examples of mutualism
Trichonympha (protozoan) in Termite intestines; and Vitamin-synthesizing bacteria in the human colon
type of symbiotic relationship in which one organism benefits from the relationship and the other neither benefits nor is harmed
Staphylococcus sp. on the human skin
what is an example of a Commensalistic relationship?
type of symbiotic relationship in which one organism benefits from the relationship (parasite) and the other is harmed (host)
Pathogenic organisms in the body
What is an example of a Parasitic relationship?
the organisms that colonize the body's surfaces without normally causing disease (AKA Normal Flora or Indigenous Microbiota)
Resident Microbiota and Transient Microbiota
What are the two types of Normal Microbiota?
Which type of Normal Microbiota is part of the Normal Microbiota throughout life?
Normal Microbiota that are usually Commensal
Type of Normal Microbiota that feeds on excreted cellular wastes and dead cells
Resident Microbiota and Transient Microbiota
Found on the skin, and on Mucous Membranes of the Digestive tract, upper respiratory tract, and distal part of the urethra and vagina
Which type of Normal Microbiota remain in the body for only hours to months before disappearing?
Which type of Normal Microbiota cannot persist in the body due to competition from other microorganisms, elimination by the body's defense cells, and chemical or physical changes in the body that expel them?
Microbiota begins to develop during the _________ ________.
Much of one's _________ Microbiota is established during the first months of life.
normal microbiota or other normally harmless microbes that can cause disease under certain circumstances
Conditions that provide opportunities for Pathogens
Immune Suppression, Reduction in Microbial Antagonism, and introduction of Normal Microbiota into an unusual site in the body
Factors that can suppress the immune system
Disease, malnutrition, physical or emotional stress, extremes of age, radiation and chemotherapy (for cancer treatment), and Immunosuppressive Drugs (for organ transplants)
Candida albicans (yeast) may cause vaginal infections with long-term antibiotic therapy. This is an example of a reduction in what?
example of a normal microbiota being introduced into an abnormal part of the body
Escherichia coli is usually nonpathogenic in the colon, but can cause UTIs in the urethra
the mere presence of Microbes in or on the body
results when the organism has evaded the body's external defenses, multiplied, and become established in the body
skin, mucous membranes, placenta, and parenteral route
What are the four major types of portals of entry into the body?
portals of entry
sites through which pathogens enter the body
natural openings or cuts
Some Pathogens enter the skin through what?
by burrowing into or digesting the outer layers of skin
How do Hookworm Larvae (parasitic roundworms; adults of which live in intestines) and Blood Fluke Larvae (parasitic flatworms; adults of which live in blood vessels in the liver) enter the body?
parasitic roundworms; adults of which live in intestines
Blood Fluke Larvae
parasitic flatworms; adults of which live in blood vessels in the liver
type of portal of entry that lines the body cavities that are open (meaning it has a natural opening) to the environment
what is the most commonly used site of entry?
Cold and Influenza Viruses
What usually enter the body via contamination of Conjuctiva by fingers, and then are carried into the Nasal Cavity by tears?
Pathogens able to survive the acidic pH of the stomach may use the ______________ tract as a route of entry
deposition directly into tissues beneath the skin or mucous membranes; NOT A TRUE PORTAL OF ENTRY, but a means by which typical portals of entry can be circumvented
Punctures, cuts, deep abrasions, and surgery
Pathogens can enter the body through the parenteral route by __________, ____, ____ _________, and _________.
process by which microorganisms attach themselves to cells; it is required to successfully establish colonies within the host
Used in Adhesion and include Specialized structures such as Adhesion Discs in some protozoans, hooks and suckers in some helminthes, and Ligands (called Adhesins in bacteria and Attachment Proteins in viruses)
surface Lipoproteins and glycoproteins that enable bacteria and viruses to bind to complementary receptors on host cells
What are Ligands called in Bacteria?
What are Ligands called in viruses?
Interaction of a Ligand with a host receptor
What can determine specificity of microorganisms for host cells?
bacteria that has Adhesins on its Fimbriae that stick to cells lining the human Urethra and Vagina
The ability to change or block the Ligand or its Receptor
What can prevent infection (in regards to Adhesion Factors)?
The inability to make Adhesins or Attachment Proteins renders the microorganism ________.
Infection is the invasion of the host by a pathogen, whereas _________ occurs if the invading pathogen alters the normal functions of the body
Another term for disease; any change from a state of good health
subjective characteristics of disease felt only by the patient
objective manifestations of disease that can be observed or measured by others
group of symptoms and signs that characterize a disease or abnormal condition
Asymptomatic (or Subclinical) Infections
Infections that lack symptoms, but may still have signs of infection
study of the cause of disease
Germ Theory of Disease
the theory that disease is caused by infections of Pathogenic Microorganisms
Who developed a set of postulates one must satisfy to prove a particular pathogen causes a particular disease?
Is using Koch's postulates feasible in all cases?
Why using Koch's Postulates is not feasible in all cases
Some Pathogens cannot be cultured in the laboratory, some diseases are caused by a combination of Pathogens and other Cofactors, and the fact that ethical considerations prevent applying Koch's postulates to Pathogens that require a human host
Pathogenic bacteria that has never been grown on lab media
Hepatitis B and Hepatitis D
Liver cancer can occur when liver cells are infected with both _________ and __________ viruses, but usually not when infected by only one of them. (example of a disease caused by a combination of Pathogens and other Cofactors)
Example of a Pathogen that requires a human host, and therefore should not be used in Koch's Postulates for ethical reasons.
Pneumonia, Meningitis, and Hepatitis
What are 3 diseases that can be caused by more than one pathogen?
the ability of a microorganism to cause disease
the degree of pathogenicity
_________ _______ contribute to an organism's virulence
Types of Virulence Factors
Adhesion Factors, Biofilms, Extracellular Enzymes, Toxins, and Antiphagocytic Factors
Enzymes secreted by the Pathogen that act as Virulence Factors and dissolve structural chemicals in the body
maintain infection, invade further, and avoid body defenses
What do Extracellular Enzymes help the Pathogen do?
Hyaluronidase, Collagenase, Coagulase, Staphylokinase, and Streptokinase
What are the 5 Extracellular Enzymes?
Extracellular enzyme that breaks down Hyaluronic Acid, which holds animal cells together.
Extracellular Enzyme that digests Collagen, which is the main structural protein in the body.
Extracellular enzyme that causes Coagulation (blood clotting) to surround bacteria and protect them from host defenses
Extracellular enzymes that break up blood clots, enabling the bacteria to spread (includes Staphylokinase and Streptokinase)
Chemicals that harm tissues or trigger host immune responses that cause damage
the presence of Toxins in the bloodstream that are carried beyond the site of infection
Exotoxins and Endotoxins
What are the two types of Toxins?
Proteins or Peptides secreted by microorganisms that destroy host cells or interfere with their metabolism
Cytotoxins, Neurotoxins, and Enterotoxins
What are the main types of Exotoxins?
toxins that kill host cells or impair their function
toxins that adversely affect nerve cell function
Clostridium tetani and Clostridium botulinum
what are 2 examples of bacteria that secrete neurotoxins?
toxins that adversely affect cells lining the G.I. tract
Staphylococcus aureus and Escherichia coli
What are 2 pathogenic bacteria that secrete enterotoxins?
Lipid portion of the Lipopolysaccharide of the Outer Membrane of Gram (-) Bacteria released when cells die
What kind of toxins stimulate the body to release chemicals that cause fever, inflammation, bleeding, diarrhea, shock, and blood clotting?
Antibodies that bind to Toxins and neutralize them
heat or chemically-treated Toxins that are inactive, but stimulate production of Antitoxins by the host
Certain factors which prevent Phagocytosis by the host's phagocytic cells
Bacterial Capsules and Antiphagocytic chemicals
What are 2 antiphagocytic factors?
What is the antiphagocytic factor that is often composed of chemicals found in the body and not recognized as foreign?
Bacterial Capsules can be _________, making it difficult for Phagocytes to engulf the bacteria
Antiphagocytic factors, some of which prevent fusion of Lysosomes and Phagocytic Vesicles to block digestion of microbes.
Antiphagocytic Chemical that resists phagocytosis and is on cell walls and fimbriae of Streptococcus pyogenes
Antiphagocytic chemicals that directly destroy phagocytic white blood cells
Many infectious diseases have __ _____ following infection
time between infection and appearance of first symptoms or signs of disease
The length of the _________ ______ of a disease depends on the Virulence of the pathogen, size of the inoculum, the pathogen's generation time, site of infection, and state of the host's immune system.
Incubation Period, Prodromal Period, Illness, Decline, and Convalescence
Name the stages of infectious disease in order
second stage of infection; short time with only mild symptoms (Malaise, muscle aches) before illness
third stage of infection; time of most severe symptoms and signs, since the host's immune response is not at its maximum
fourth stage of infection; time when the immune response peaks and/or medical treatment overcomes the Pathogen, so the body begins to return to normal
fifth stage of infection; time when host recovers, tissues are repaired, and the body returns to normal
during all stages
During which stages is the host usually infectious?
virus that can be spread even when there are no obvious lesions
Portals of Exit
Through what do pathogens leave their host?
Portals of Entry
Many Portals of Exit are the same as their _______ __ _____.
body secretions or body wastes
With what do pathogens usually exit the body?
Can most pathogens survive long outside of their host?
Reservoirs of Infection
sites where Pathogens are maintained as a source of infection
Animal, Human, and Nonliving
What are the three types of Reservoirs?
diseases that are naturally spread from their usual animal host to humans (over 150 known, including Yellow Fever, Bubonic plague, and rabies)
ways to acquire Zoonoses
through direct contact with an infected animal or its waste, by eating animals, or from bloodsucking Arthropods
dead end hosts
Humans are usually ____ ___ ____ to Zoonotic Pathogens
Human carriers are infected individuals who are ____________, but infective to others (as with AIDS and Syphilis)
Soil, Water, and Food
What are some examples of nonliving reservoirs?
Contact, Vehicle, and Vector Transmission
What are the 3 groups of infectious disease transmission?
Direct Contact Transmission
person-to-person spread by body contact between hosts (touching, kissing, and sexual intercourse)
Indirect Contact Transmission
Pathogens spread from host to host by Fomites -- contaminated inanimate objects (dishes, eating utensils, toys, toothbrushes, bedding, needles, medical equipment, etc.)
Pathogens carried within Respiratory Droplets that exit the body with coughing, sneezing, and exhaling - but traveling less than 1 meter
spread of Pathogens to respiratory mucous membranes via Aerosols (cloud of small droplets or solid particles suspended in the air) that travel more than 1 meter
a disease that occurs continually at a relatively stable incidence within a population or geographical area
a disease with only a few scattered cases in a population or area
when a disease occurs at a greater frequency than usual in a population or area
Epidemic occurring simultaneously on more than one continent
a disease that develops rapidly and lasts only a short time
example of an acute disease
a disease that develops slowly (usually with milder symptoms), but lasts a long time
Tuberculosis, Leprosy, Hepatitis C, and Infectious Mononucleosis
Give 4 examples (provided in the notes) of Chronic diseases
a disease with a duration and severity between that of Acute and Chronic diseases
Subacute Bacterial Endocarditis
An example of a Subacute Disease
a disease that appears a long time after the infection due to the inactivity of the Pathogen
give an example (provided in the notes) of a Latent Disease
a disease transmitted from an infected host directly or indirectly to another
Influenza, Tuberculosis, and Herpes Infection
Give 3 examples (provided in the notes) of Communicable diseases
Communicable disease that is easily spread
Measles and Chickenpox
Give 2 examples of Contagious diseases
a disease NOT spread from host to host; it originates from outside of the host, or from an Opportunistic Pathogen within the host
Tetanus, Botulism, Acne, and Tooth Decay
Give 4 examples (provided in the notes) of Noncommunicable diseases
an infection confined to a small area of the body
an infection that serves as a source of infection for other areas of the body
initial infection within the host
an infection that follows the Primary infection, and may be caused by an Opportunistic Pathogen
infections acquired while in a health care facility
Exogenous, Endogenous, and Iatrogenic
What are the 3 types of nosocomial infections?
type of nosocomial infection where the pathogen is acquired from the health care environment
type of nosocomial infection where the pathogen arises from Normal Microbiota due to factors within the health care setting (such as exposure to Chemotherapy)
type of nosocomial infection that results from modern medical procedures (use of Catheters, Invasive Diagnostic procedures, and Surgery)
What is the most effective way to reduce Nosocomial infections?
Staphylococcus, Streptococcus, and Hantaviruses
What 3 pathogens are transmitted through Airborne Transmission by being carried on dust particles?
Measles and Mycobacterium tuberculosis
What 2 pathogens are transmitted through Airborne Transmission in dried airborne droplets?
type of vehicle transmission where the pathogen is spread via contaminated water
What type of vehicle transmission is important in the spread of Gastrointestinal Diseases such as Giardiases, Cholera, and Amebic Dysentery?
______-_____ Infection is a major source of disease in the world
type of vehicle transmission that involves the spread of pathogens in or on poorly-processed, poorly-cooked, or poorly-refrigerated foods
spread of pathogens by vectors (animals, especially Arthropods, that transmit diseases from host to host)
vectors that serve as a host for multiplication of the pathogen as well as transmitting it
Mosquitoes, Ticks, Mites, Lice, Fleas, Blood-sucking flies, and Blood-sucking Bugs are all examples of what kind of vectors?
vectors that transmit pathogens passively by carrying them on their body parts
Houseflies and Cockroaches (which can contaminate water, food, and skin with Salmonella and Shigella) are both examples of what kind of vector?
How Infectious diseases are classified
By the body systems they affect, the taxonomic groups of the causative agent, their longevity and severity, and how they are spread to their host