Ch 4: Host Pathogen Relationships

Question 1

Pathology is the study of ____

Answer 1

Disease

Question 2

Etiology is the study of _____

Answer 2

Cause of disease

Question 3

What is Pathogenesis?

Answer 3

Disease process

Question 4

What is infection?

Answer 4

Colonization by microbe

Question 5

______ is the degree of pathogenicity

Answer 5

Virulence

Question 6

What is bacteremia?

Answer 6

Presence of bacteria in the blood

Question 7

______ is generalized inflammatory response to an infection

Answer 7

Sepsis

Question 8

Difference between infection vs disease?

Answer 8

Infection is invasion by parasitic microbes (can occur without causing disease)
Disease is changes in health, damage to host.

Question 9

Name the phases of disease

Answer 9

Incubation: time between introduction of organism to onset of symptoms
Illness: individual experiences signs and symptoms of disease
Convalescence: period of recuperation and recovery, infections diseases may still spread

Question 10

Who provided the first scientific definition of sepsis: “sepsis is a state caused by microbial invasion from a local infectious source into the bloodstream which leads to signs of systemic illness in remote organs”

Answer 10

Hugo Schottmuller

Question 11

ToF: Commensalism is when one benefits and the other neither benefits or is harmed

Answer 11

T

Question 12

ToF: Mutualism is when both organisms benefit

Answer 12

T

Question 13

What type of host pathogen relationship is when one organism benefits and the other is harmed?

Answer 13

Parasitism

Question 14

ToF: Opportunistic pathogens normally cause disease

Answer 14

F: Do not normally cause disease, but may under some circumstances (Normal flora in wrong environment, compromised immune system, disruption of homeostasis)

Question 15

Name four portals of entry of pathogenic microorganisms

Answer 15

Mucous membranes, skin, parenteral, placenta

Question 16

ToF: Mucous membranes of the respiratory tract are the easiest and most frequent portal of entry

Answer 16

T

Question 17

How is the mucous membranes of the respiratory tract a portal of entry for pathogens?

Answer 17

Microbes are inhaled into mouth or nose in droplets of moisture or dust particles

Question 18

How is mucous membranes of the GIT a portal of entry?

Answer 18

Microbes gain entrance through contaminated food and water or fingers and hands

Question 19

Most microbes that enter the GIT are destroyed by ____ and ______

Answer 19

Hydrochloric acid and enzymes of the stomach and small intestine

Question 20

Which diseases commonly enter through mucous membranes of the genitourinary tract?

Answer 20

Sexually transmitted diseases
Ex. Gonorreah, Syphilis, Chlamydiasis, HIV

Question 21

How do microbes enter through mucous membranes of the conjunctiva?

Answer 21

Mucous membranes that cover the eyeball and lines the eyelid

Question 22

ToF: Herpes ocularis commonly enters the body through mucous membranes of the conjunctiva

Answer 22

T

Question 23

Name two common diseases contracted via the skin?

Answer 23

Staphylococcus infections and Mycosis

Question 24

ToF: The skin is not an effective barrier for microorganisms to enter

Answer 24

F: When unbroken it is an effective barrier
Some microbes can gain entrance through openings in the skin (hair follicles and sweat glands)

Question 25

What is the parenteral portal of entry?

Answer 25

Microorganisms deposited into the tissues below the skin or mucous membranes through: punctures, injections, bites, scratches, surgery, etc.

Question 26

Name three common diseases contracted vis parenteral

Answer 26

Cytomegalovirus, Hepatitis, HIV

Question 27

What does LD50 mean?

Answer 27

Number of microbes in a dose that kills 50% of the organisms infected in a sample

Question 28

ToF: ID50 is the number of microbes in a dose that kill 50% of the organisms infected in a sample

Answer 28

F: ID50 is the number of microbes in a dose that causes disease in 50% of the organisms infected

Question 29

Name and describe the three steps of pathogens invading an organism

Answer 29

1. Adherence: pathogens have attachment structures (ex. Pili) 2. Invasion/Colonization: multiply (need food, water, space) and protect from host defenses (must compete with normal flora, immunity, etc.) 3. Cause damage: tissue destruction (ex. Toxic byproducts and degradation enzymes), production of toxins, escape of host defenses

Question 30

What is immunopathogenesis?

Answer 30

Excessive innate, immune and inflammatory responses triggered by the infection (superantigens; immune complexes precipitation)

Question 31

What is a virulence factor?

Answer 31

A pathogen-produced substance that promotes the establishment and maintenance of disease

Question 32

What are the types of virulence factors?

Answer 32

Adhesion factors, evading immune response, degradative enzymes, and toxins

Question 33

What are some adhesion factors?

Answer 33

Pili: short, rigid and numerous Adhesions: molecules that bind to specific receptors on tissues

Question 34

A _______ prevents phagocytosis by macrophages or neutrophils by not being ‘seen’ by these cells

Answer 34

Capsule

Question 35

__________is when antigenic similarity occurs between molecules found on some disease-causing microorganisms and specific previously healthy body cells/tissues

Answer 35

Antigenic mimicry

Question 36

What is antigenic shift?

Answer 36

Genetic alteration occurring in an infectious agent that causes change in antigen protein. This stimulates the production of antibodies by the host immune systems

Question 37

ToF: Antigenic shift had been studied in influenza type A viruses

Answer 37

T: they experience this change once every 10 years

Question 38

Describe how the inhibition of phagolysosome fusion that allows pathogens to avoid immune response

Answer 38

Bacteria is enclosed in phagosome and lysosome needs to fuse to destroy it. They stop this fusion and bacteria stays alive in the phagosome

Question 39

______ attack certain types of white blood cells, preventing phagocytosis. They release and rupture lysosomes

Answer 39

Leukocidins

Question 40

What do hemolysins do?

Answer 40

Cause the lysis of red blood cells. Ex. Streptococci

Question 41

What do coagulase do?

Answer 41

cause blood to coagulate, blood clots protect bacteria from phagocytosis from white blood cells Ex. Staphylococci (causes boils and abscesses)

Question 42

ToF: Kinases dissolve blood clots

Answer 42

T

Question 43

ToF: Kinases do not help the spread of bacteria (bacteremia)

Answer 43

F

Question 44

What is the mechanism of Hyaluronidase?

Answer 44

Breaks down hyaluronic acid (found in connective tissues) and is a spreading factor. It also allows bacteria to use hyaluronan as a carbon source

Question 45

Which of the following is produced by Streptococci, Staphylococci and Clostridium? A) Kinases B) Collagenase C) Hemolysis D) Hyaluronidase

Answer 45

D) Hyaluronidase

Question 46

ToF: Collagenase breaks down collagen

Answer 46

T

Question 47

ToF: Colstridium perfringens uses kinases to spread through muscle tissue

Answer 47

F: uses collagenase to spread through muscle tissue

Question 48

What is a necrotizing factor?

Answer 48

Causes death (necrosis) to tissue cells Caused by Streptococcus class A (flesh eating bacteria)

Question 49

What are toxins?

Answer 49

Poisonous substances produces by microorganisms (can be exotoxins or endotoxins)

Question 50

What is it called when toxins are in the bloodstream?

Answer 50

Toxemia

Question 51

ToF: Exotoxins are released intracellular

Answer 51

F: released extracellularly

Question 52

How do Leukotoxins function?

Answer 52

Invoke a very strong immune response, affect T cells which release a lot of cytokines that cause severe symptoms

Question 53

How do cytotoxins damage tissues?

Answer 53

Disrupt host plasma membrane by targeting protein channels and phospholipid disruption

Question 54

What pathogen is responsible for causing symptoms of botulism, prevention transmission of signal from nerve cell to muscle cell?

Answer 54

Clostridium botulinum

Question 55

What pathogen is responsible for the symptoms of tetanus?

Answer 55

Clostridium tetani

Question 56

ToF: Clostridium botulinum and Clostridium tetani are examples of neurotoxins

Answer 56

T

Question 57

ToF: Endotoxins are present in Gram positive bacteria

Answer 57

F: Gram negative bacteria

Question 58

ToF: Endotoxins are part of the outer portion of the cell wall

Answer 58

T: the lipid A portion of

Question 59

ToF: Endotoxins are not very stable and can be destroyed easily

Answer 59

F: they are very stable and cannot be destroyed easily

Question 60

Macrophages release _____ when they attack some gram negative cells. This binds to many tissues of host and may cause to blood capillaries and the blood brain barrier.

Answer 60

Tumor necrosis factor (TNF)

Question 61

What is the main symptom of endotoxins?

Answer 61

Pyrogenic response: Macrophages ingests gram negative bacteria Release interleukin-1 in bloodstream IL-1 travels to hypothalamus and produces prostaglandins and it reset the body’s thermostat

Question 62

Name factors effecting susceptibility to resistance of host

Answer 62

Age, stress, diet, pre-existing disease, gender, behaviour, weather and the first line of defense

Question 63

What type of toxin causes leukopenia followed by leukocytosis, activation of complement, thrombocytopenia, disseminated intravascular clotting, loss of eater and decrease in blood pressure, and eventually death?

Answer 63

Endotoxin