ch. 11 - interactions between microbes + humans Flashcards
1
Q
what are the differences between the bacteria that resides in our bodies and those that cause disease?
A
- they have functions
ex.) normal flora ( human microbiome)
2
Q
what is the human microbiome?
A
- the sum total of all microbes found on and in a normal human
- critically important to the health + functioning of its host organism
3
Q
what do our resident microbiota do to us?
A
- they colonize us for the long term + do not cause disease
4
Q
what does infection mean?
A
- microbes get past host defenses, enter tissues, + multiply
5
Q
what does disease mean?
A
- deviation from health
6
Q
what is an infectious disease?
A
- a pathogenic state caused directly by microorganisms or their products
7
Q
what are the types of symbiotic relationships that bacteria can live within their host through?
A
- mutualism
- commensalism
- parasitism
8
Q
what is mutualism?
A
- both host + microbe benefit
9
Q
what is commensalism?
A
- the microbe benefits + the host is unaffected
10
Q
what is parasitism?
A
- the microbe benefits + host is harmed
11
Q
what is microbial antagonism?
A
- normal biota are unlikely to be displaced by incoming microbes
- limited number of attachment sites
- chemical or physiological environment created by resident biota is hostile to other microbes
12
Q
where do babies get a microbiome?
A
- in utero
- birth
- breast milk
- caregivers
- environment
13
Q
what sites harbor known normal biota?
A
- skin + adjacent mucous membranes
- respiratory tract
- gastrointestinal tract
- outer opening of urethra, external genitalia, + vagina
- external ear canal and eye
14
Q
what is a pathogen?
A
- a microbe whose relationship w/ its host is parasitic + results in infection and disease
15
Q
what is an acute disease?
A
- quick but severe
- fade quickly
16
Q
what is a chronic disease?
A
- long-term, slower to develop
- doesn’t fade quickly
17
Q
what is an exogenous infection?
A
- occurs if a pathogen breaches the host’s external defense and enters sterile tissue
ex.) local and systemic diseases
18
Q
what is a local disease?
A
- a disease restricted to a single area
19
Q
what is a systemic disease?
A
- a disease that spreads to organs + systems
20
Q
what is an endogenous infection?
A
- occurs if normal microbiota enter sterile tissue
21
Q
what is an opportunistic infection?
A
- occurs when commensals take advantage of a change in the body’s environment that favors the microbe
22
Q
what is a primary infection?
A
- an infection that occurs in otherwise healthy bodies
23
Q
what is a secondary/opportunistic infection?
A
- an infection that occurs in a healthy body weakened by a primary infection
24
Q
what are the most common portals of entry?
A
- skin
- G.I.
- respiratory
- urogenital
25
what is virulence?
its ability to:
- establish itself in the host
- cause damage
*** higher the virulence, the less infectious dose
26
what is virulence factor?
any characteristic or structure of the microbe that contributes to its ability to establish itself in the host + cause damage
27
what is infectious dose (ID)?
- the minimum number of microbes necessary to cause an infection
- microorganisms w/ smaller infectious doses have greater virulence
ex.) ID for rickettsia is a single cell
ID for cholera is 1,000,000,000 cells
28
what are the stages of disease progression?
1) incubation period --> time between entry of microbe + symptom appearance
2) prodromal stage --> mild signs or symptoms
3) acute period (climax) --> signs + symptoms most intense
4) period of decline --> signs and symptoms subside
5) period of convalescence --> body systems return to normal
29
what are the steps involved for a microbe to cause disease?
1) finding a portal of entry
2) attaching firmly
3) surviving host defenses
4) causing damage (disease)
5) exiting host
30
how do pathogens get around host defenses?
- many pathogens have adhesins that allow them to adhere to specific tissues
- many pathogens use phagocytosis by body cells to enter cells or pass through defenses
- some pathogens have virulence factors --> enzymes can help pathogens resist body defenses
31
what does invasiveness mean?
- the ability of a pathogen to penetrate tissues + spread
32
what are other virulence factors?
- streptpkinase --> dissolves fibrin clots + allows dissemination of the bacteria
- leukocidins --> disintegrate neutrophils + macrophages (WBCs of the immune system)
- hemolysis --> dissolve RBCs
- biofilms --> immune cells cannot reach bacterial cells covered in biofilm
- toxic production
33
why do some bacteria secrete toxins?
- not to hurt us but to kill other bacteria that are trying to take over its resources
34
what are the two types of toxins that bacteria can secrete?
- exotoxins
- endotoxins
35
what are exotoxins?
- proteins that are secreted
ex.)
- neurotoxins act on the nervous system
- enterotoxins act on the GI tract
36
what are endotoxins?
- they are released upon disintegration of gram-negative bacteria
- may cause blood coagulation + endotoxic shock
37
what are antitoxins?
- produced by the host body
- neutralize toxins
38
characteristics on exotoxins? (toxicity, heat denaturation at 60 degrees celsius, manner of release)
- toxicity: toxic in minute amounts
- heat denaturation at 60 degrees celsius: unstable
- manner of release: secreted from live cell
39
characteristics on endotoxins? (toxicity, heat denaturation at 60 degrees celsius, manner of release)
- toxicity: toxic in high doses
- heat denaturation at 60 degrees celsius: stable
- manner of release: released by cell via shedding or during lysis
40
what is a sign?
objective evidence of disease as noted by an observer
ex.)
- elevated temperature (fever)
- edema (accumulation of fluid in afflicted tissue
- granulomas + abscesses (walled-off collections of inflammatory cells and microbes in the tissues
- lymphadenitis (swollen lymph nodes)
41
what is a symptom?
subjective evidence of disease as sensed by the patient
ex.) pain, soreness, fatigue
42
what is a syndrome?
a disease identified by a certain complex of signs + symptoms
43
what are major portals of exit of infectious diseases?
- coughing, sneezing
- insect bite
- skin cells + open lesions
- urine
- removal of blood
- feces
44
what is a reservoir?
- primary habitat where a pathogen originates/lives
ex.) human or animal carrier, soil, water, + plants
45
what is a transmitter?
individual or object from which an infection is acquired (how it spreads)
- syphilis: reservoir + transmitter are the same
- hepatitis A: reservoir is a human, transmitter is food
46
what are vectors (transmitters)?
- biological --> purposeful spread
ex.) tick, mosquitoes, fleas
- accidental (mechanical) --> objects spread
ex.) pencil, doorknob
larger animals can also spread infections:
mammals: rabies
birds: psittacosis
lizards: salmonellosis
47
what is a carrier (transmitter)?
- transmits
- doesn't get sick
48
what is zoonosis?
- an animals disease can now replicate in humans
- human does not contribute to the natural persistence of the microbe
- spread is promoted by close associations between humans + animals
49
what does communicable mean (infectious)?
- easily spreadable from individual to another
- also means infectious
50
what does contagious mean?
- a disease that is highly communicable, especially through direct contact
ex.) influenza, measles --> highly contagious
hansen's disease (leprosy) --> weakly communicable
51
what does noncommunicable mean?
- an infectious disease that does not arise through transmission of the infectious agent from host to host
52
what does nosocomial infection mean?
- infections acquired during a hospital stay
- 2-4 million cases a year, 90,000 deaths
53
what are health care-associated infections (HAIs)?
- occur as result of receiving treatment for another condition
ex.) pneumonia, surgical site infection, G.I. illness, UTIs, bloodstream infections
54
what is epidemiology?
- study of frequency + distribution of disease and other health-care related factors in defined populations
many disciplines: anatomy, microbiology, psychology, etc.
all forms of disease: heart disease, cancerm mental illness, drug addiction
55
what is prevalence?
- total number of existing cases in a given population
total number of cases in population divided by total number of persons in population x 100 = %
56
what is incidence?
- the number of new cases over a certain time period
- number of new cases in a designated time period divided by total number of susceptible persons (usually reported per 100,000 persons)
57
what is mortality rate?
- rate of death
- measures the total number of deaths in a population due to a certain disease
58
what does morbidity mean?
the amount of disease
59
what is an endemic disease?
- a disease that is always present in certain areas (expected)
60
what is an epidemic?
- a high amount of disease that is unexpected
61
what is an outbreak?
-a high amount of disease that is unexpected but is contained
ex.) hospitals, schools, churches
62
what is a pandemic?
- a high amount of disease that is unexpected but is across continents
