bacterial pathogenesis

Question 1

define parasitic organism

Answer 1

organism that harms or lives at the expensive of another organism

Question 2

define normal microbiota

Answer 2

organisms that colonize the body without normally causing disease

Question 3

define infection

Answer 3

when a parasitic organism is growing and multiplying within or on a host, the host is said to have an infection

Question 4

define infectious disease

Answer 4

infection of a host by a microbe that results in some damage to the host and/or alteration of normal function of the host

Question 5

define nosocomial infection

Answer 5

an infection that develops within a hospital/other type of clinical care facility

Question 6

define pathogen

Answer 6

a microbe that’s able to cause disease

Question 7

define pathogenicity

Answer 7

the ability of a pathogen to cause disease

Question 8

define opportunistic pathogen

Answer 8

an organism that’s part of the normal microbiota that becomes pathogenic under certain situations (ie immune system becomes compromised by disease, old age, use of antibiotics)

Question 9

define virulence

Answer 9

refers to the degree/intensity of pathogenicity

Question 10

what three factors is virulence determined by

Answer 10

invasiveness, infectivity, pathogenic potential

Question 11

define invasiveness

Answer 11

the ability to spread to adjacent or other tissues

Question 12

define infectivity

Answer 12

the ability of an organism to establish a focal point of infection

Question 13

define pathogenic potential

Answer 13

the degree of damage the microbe can cause to the host

Question 14

define toxigenicity

Answer 14

the ability of the microbe to produce toxins

Question 15

how can the virulence of a microbe be measured experimentally

Answer 15

by determining the infectious dose or lethal dose of a pathogen, which is the dose required to infect or kill 50% of the hosts in a given time period

Question 16

list 5 portals of entry

Answer 16

skin, respiratory tract, gastrointestinal tract, urogenital system, direct entry (injection sites, bites, burns, wounds, surgical processes)

Question 17

describe how pathogens can enter via the skin

Answer 17

ducts of sweat glands, mammary glands, hair follicles, conjunctiva (membrane of eyes/eyelids) via contaminated fingers/flies/towels

Question 18

describe how pathogens can enter via the respiratory tract

Answer 18

inhalation of air containing pathogens

Question 19

describe how pathogens can enter via the gastrointestinal tract

Answer 19

food, water, contaminated fingers

Question 20

describe how pathogens can enter via the urogenital system

Answer 20

during sexual intercourse, some can travel from the skin to the urethra and vagina

Question 21

how do pathogens exit the body

Answer 21

usually via urine, feces, saliva, tears, etc

Question 22

list the 3 possible outcomes of a pathogen gaining entry to the body

Answer 22

1. may pass through as a harmless transient
2. could colonize and become part of normal microbiota
3. could colonize and cause disease

Question 23

list 4 things that determine whether or not a microbe will cause disease to a host

Answer 23

number of organisms the host is exposed to, virulence (invasiveness, infectivity, pathogenicity), host’s immune status at the time of infection, whether or not the desired portal of entry was used

Question 24

list 7 things a successful pathogen must be able to do

Answer 24

maintain a reservoir
be transmitted to the host
adhere/colonize/invade the host
evade host defense mechanisms
multiply and grow in the host
have the ability to damage the host
leave the house + enter the reservoir of another host

Question 25

what is a reservoir

Answer 25

a site in which the organism can persist and maintain its ability to infect prior to entering another host

Question 26

what can a reservoir be (3 examples)

Answer 26

a human (with active infection or a carrier), an animal, a nonliving reservoir (ie soil, water, food)

Question 27

list 2 modes of transmission

Answer 27

direct or indirect

Question 28

what is horizontal contact

Answer 28

direct contact, ie kissing, sexual contact, or shaking hands

Question 29

what is vertical contact

Answer 29

transmission from mother to baby

Question 30

at what distance can airborne droplets infect someone

Answer 30

less than 1 meter

Question 31

what is a vector

Answer 31

a living organism that can transmit disease to humans

Question 32

what are two types of vectors

Answer 32

mechanical and biological

Question 33

describe a mechanical vector

Answer 33

transmits the pathogen to its host passively on their feet and body parts

Question 34

describe a biological vector

Answer 34

transmits pathogen actively. The pathogen completes part of its life cycle in the vector before it can be transmitted

Question 35

describe indirect modes of transmission

Answer 35

transmission via an inanimate object called a vehicle

Question 36

list some vehicles of pathogens

Answer 36

doorknobs, drinking glasses, utensils, dirty towels

Question 37

what is a formite

Answer 37

an inanimate vehicle

Question 38

describe how pathogens adhere to a host

Answer 38

pathogen attached to host tissues at the portal of entry via factors on bacterial called adhesins

Question 39

what are adhesins

Answer 39

factors on bacteria that allow them to attach themselves to host tissues

Question 40

what are adhesins made of

Answer 40

glycoprotein or lipoprotein

Question 41

where on bacteria are adhesins found

Answer 41

capsule, fimbriae, flagellum

Question 42

define colonization of the bacteria in the host

Answer 42

occurs after they adhere. Colonization refers to the establishment of a site of microbial reproduction

Question 43

T or F: colonization always causes damage

Answer 43

false; some bacteria can be non invasive

Question 44

describe how streptococci are invasive

Answer 44

they produce hyaluronidase (spreading factor). it degrades hyaluronic acid that glues epithelial cells together

Question 45

what does staphylokinase do

Answer 45

dissolves blood clots

Question 46

list how pathogens can evade host defenses

Answer 46

production of a biofilm or capsule, or specialized surface proteins that help them evade phagocytosis. Produce toxins that destroy phagocytes, some kill macrophages after being engulfed, some prevent the fusion of a phagosome with the lysosome, some gram neg can lengthen the O side chain of the LPS, some use host-derived actin tails to propel themselves from one host to another

Question 47

list 3 ways in which the pathogen can damage the host

Answer 47

using the host's nutrients, causing direct damage in the area of invasion, by producing toxins

Question 48

list the 2 types of toxins that pathogens can produce

Answer 48

exotoxin and endotoxin

Question 49

what is an exotoxin

Answer 49

a protein produced by a bacterium

Question 50

what type(s) of bacteria produce exotoxins

Answer 50

both gram pos and gram neg

Question 51

T or F: exotoxins are soluble in body fluids

Answer 51

true

Question 52

are exotoxins potent

Answer 52

yes

Question 53

are exotoxins stable in heat

Answer 53

no; destroyed by 60-80 C

Question 54

T or F: the body can generate antibodies against exotoxins

Answer 54

true

Question 55

describe how vaccines are made using exotoxins

Answer 55

exotoxins are inactivated via heat or chemicals (now called a toxoid). Toxoid gets injected, body makes antibodies against it, and now the person is immune

Question 56

bacterial source of endotoxins?

Answer 56

gram neg only

Question 57

what is the endotoxin made of

Answer 57

the lipid A portion of the LPS in gram neg bacteria

Question 58

T or F: endotoxins are protein in nature

Answer 58

false; are lipid in nature

Question 59

are endotoxins heat stable

Answer 59

yes; up to 250 C

Question 60

describe the potency of endotoxins

Answer 60

lower potency: only toxic at high doses bc they're relatively weak

Question 61

define immunogenic

Answer 61

host recognizes the thing as foreign

Question 62

is an endotoxin weakly or strongly immunogenic

Answer 62

weakly

Question 63

symptoms of exotoxinxs

Answer 63

effect is variable depending on the exotoxin

Question 64

symptoms of endotoxins

Answer 64

fever, chills, weakness, shock, death

Question 65

T or F: the portal of exit is often identical to the portal of entry

Answer 65

true