Epidemiology of infectious disease - infectious disease mechanisms Flashcards
1
Q
microorganisms present on the surface of and within the human body
A
flora/microflora
2
Q
flora that typically have no adverse effect
A
commensalism
3
Q
flora that may offer benefit to the host
A
mutualism
4
Q
flora compete with ____ for resources and can inhibit their growth
A
disease-producing microorgansims
5
Q
microorganisms which cause disease
A
pathogens
- direct destruction of host cell
- interfere with host cell metabolism
- exposure of host cell to toxins
6
Q
protein + infection = ?
A
prion
7
Q
why are prions not true “microorganisms”
A
no DNA or RNA
mutated protein particles
8
Q
creutzfeldt-jakob disease, kuru, bovine spongiform encephalopathy
A
prion
9
Q
how can prions be damage
A
accumulate in nerve cell axons
slowly progressive noninflammatory neuronal degeneration
10
Q
virus DNA or RNA core surrounded by ?
A
protein coat
+/- lipoprotein envelope
11
Q
entire virus particle is ?
A
virion
12
Q
protein coat of the virus is ?
A
capsid
13
Q
how are viruses obligate intracellular pathogens
A
- bind to receptors on host cell
- enter the host cell
- convert cell metabolism to produce viral nucleic acids and proteins
- cell eventually loses normal function and often undergoes lysis
14
Q
some viruses undergo ____ following initial infection
A
a period of latency
15
Q
unicellular microorganisms that can be either aerobic or anaerobic
A
bacteria
16
Q
describe the characteristics of a bacteria
A
- surrounded by rigid cell wall
- peptidoglycan
- +/- protective outer capsule - no organized nucleus, mitochondria, or ER
- single chromosomes or plasmids
- can be mobile - flagella
- can have pili for:
- mobility
- adherence
- genetic exchange
17
Q
bacteria can be categorized by: (3)
A
- shape
- grouping
- straining
18
Q
shapes of bacteria (3)
A
- cocci
- bacilli
- spirochete/spirilla
19
Q
grouping of bacteria (3)
A
- diplo - sphere
- strepto - chains
- staphylo - clusters
20
Q
staining of bacteria (3)
A
- gram positive (G+)
- gram negative (G-)
- acid-fast
21
Q
bacteria can produce 2 things:
A
- endotoxins/exotoxins
- endospores
22
Q
common resident microbes on skin and mucous membranes
A
fungi
23
Q
two types of fungal infections
A
- mycoses
- mycotic
24
Q
fungal infections can be: (3)
A
- opportunistic pathogens
- limited to surface areas of the body - superficial mycoses
- invade deep tissues - systemic mycoses
25
unicellular fungi is __ and multicellular fungi is ____
yeast
mold
26
fungi that reproduce by budding, form structures known as pseudohyphae
yeast
27
fungi that reproduce by forming branching tubules known as hyphae
can form highly resistant spores
mold
28
describe charcteristics of protozoa
unicellular, complex organisms
nucleus and organelles
motile via cilia, flagella, ameboid motion
spend part of their lifecycle outside humans
29
protozoa are transmitted via: (3)
1. host-to-host contact
2. contaminated water or food
3. arthropod vectors
can form cysts to aid help transmission
30
wormlike parasites that transmit through ingestion of fertilized eggs or penetration of infectious larval stages through skin
wormlike parasites
31
nematodes (roundworms), cestodes (tapesworms), trematodes (flukes)
wormlike parasites
32
describe ectoparasites
infect external body surfaces
causes damage or inflammation due to bite or burrowing
33
how do ectoparasites spread
contact with mature (arthropod) or immature (eggs, larvae) forms
34
mites, chiggers, lice, fleas
ectoparasites
35
what are rickettsiae
G- bacteria, obligate intracellular pathogens
infect but does not create disease in arthropod vectors
target endothelial vascular cells
36
describe mycoplasmas
capable of independent replication
dont produce cell wall
<1/3 the size of bacteria - DNA 1/2 size of normal bacteria chromosome
37
describe chlamydiae
obligate intracellular pathogens
transmitted directly between susceptible hosts
reproduce through binary fission
38
"holding tank" for infection
reservoir
39
____: opportunistic infection
endogenous
40
____: external environment
exogenerous
41
source of infection
- infected person, animal, arthropod
- contaminated air, water, soil, food
- treating carrier or sanitizing environment source can reduce spread of infection
42
acquired from a healthcare setting, especially a hospital
nosocomial infections
- must not show signs of infection at time of visit to facility
- generally - up to 2 days post-admit, within 3 days after discharge
- ICU patients at higher risk
43
acquired outside a hospital or healthcare facility setting
community-acquired infections
43
acquired outside a hospital or healthcare facility setting
community-acquired infections
43
acquired outside a hospital or healthcare facility setting
community-acquired infections
44
infections that are commonly or primarily spread by sexual activity
sexually transmitted infections
45
decreased baseline immune system
immunocompromised hosts
46
characteristics of immunocompromised hosts
due to disease, meds, malnutrition
increased susceptibility to infections
increased severity and duration of infections
increased rates of opportunistic infections
47
means by which the pathogen leaves the reservoir, often via secretions, blood, placental transfer
portal of exit
48
physical contact with the infection reservoir
direct contact
49
respiratory particles pass through air from reservoir to host
droplet transmission
50
spread of droplet transmission within ___ of infected reservoir
3 ft
51
smaller respiratory particles; remains in air longer
airborne transmission
52
spread via agent that carries the pathogen and takes it to the host
vector transmission
53
required for life cycle of pathogen for vector transmission
biological vector
54
not essential to life cycle of pathogen for vector transmission
mechanical vector
55
access point for the microorganism to infect the host
portal of entry
56
disruption of skin or mucous membranes via injury, medical procedure, surface lesion from disease, direct inoculation
penetration
57
exposure of pathogen to intact skin or mucous membrane ex. STI
direct contact
58
spread of pathogen from mother to fetus via placenta or during birth
vertical transmission
59
entry of pathogens through upper or lower rsp tract
inhalation
60
entry of pathogens through oral cavity and GI tract
ingestions
61
pathogens must be able to survive ___ and ___ during ingestions
acidic gastric environment
peristalsis of GI tract
62
reduced gastric acid = ?
increased susceptibility to ingested infections
63
spread of pathogens through ___ is also a form of ingestion
breast milk
64
infections beginning at portal of entry and progressively invade local tissues
local spread
65
infections may enter the body at one site and ___ to one or more sites elsewhere in the body
disseminate
66
infections that disseminate are commonly ___
circulatory/hematologic
67
things that increase likelihood of contracting infection or having worse disease course or outcomes
risk factors
68
7 risk factors of hosts
1. immunosuppressive meds
2. immunocompromised status due to disease
3. impaired inflammatory response
4. poor nutrition
5. very young/elderly
6. severe stress
7. coinfection or superinfection
69
deviation from and/or interruption of normal structure and/or function of 1+ cells, tissues, organs, or organ systems
disease
70
occurs when pathogen enters a host and multiples inside of it
infection
71
ability of organism to cause disease
pathogenicity
72
likelihood of causing severe disease
potency of organsim
virulence
73
likelihood of infecting a host after an exposure
infectivity
74
likelihood of producing harmful toxins
toxigenicity
75
likelihood of producing adaptive immune response
immunogenicity
76
likelihood of binding with immune system receptors
antigenicity
77
likelihood of altering antigens
antigenic variability
78
natural mutation over time of viral antigens
antigenic drift
79
2+ viruses combining to create a new set of antigens
antigenic shift
80
collective terms for ways microorganisms avoid destruction by the host
pathogenic defense mechanisms
81
presence of 2+ pathogens simultaneously
coinfection
82
secondary (new) infection arising when a primary (initial) infection is already present superinfection
superinfection
83
multiplication of pathogenic organisms in the host
compete with normal flora for nutrients and space
colonization
84
minimum number of microbes necessary to establish infection
can be very low or very high
infectious dose
85
how do pathogens avoid detection (4)
1. intracellular pathogens
2. capsules
3. mimicry of host
4. antigenic variation
86
how do pathogens interfere with host immune processes (4)
1. production of membrane-damaging toxins to destroy leukocytes
2. interference with complement activation
3. production of proteases to destroy immune molecules
4. inhibition of host immune response
87
production of __ to destroy other host tissues
toxins
88
production of ___ to promote pathogen spread and survival
enzymes
89
enzymes that forms fibrin clot to surround and protect microbe
coagulase
90
enzyme that breaks down CT
hylauronidase
91
enzyme that breaks down clots that limit spread of pathogen
fibrinase
92
enzyme that neutralizes bactericidal effects of H2O2, allowing survival after phagocytosis
catalase
93
stages of infection
1. incubation - pathogen replicate without visible s/s
2. prodrome - initial appearance of symptoms
3. acute - max impact of infectious process
4. declining - gradually improving s/s
5. convalescence - containment and elimination of pathogen, repair of damage, resolution of symptoms
6. resolution - total elimination of pathogen without residual s/s
94
what is subclinical infection
no clinically apparent s/s
95
what is insidious infection
lengthy prodromal phase
96
what is fulminant infection
abrupt onset of acute phase
little or no prodrome
97
inflammatory response resulting in significant amounts of pus formation
suppurative inflammation
98
dead leukocytes (especially neutrophils), dead cells, fluid
pus
99
what bacteria that cause pus formtion
purulent, suppurative, pyogenic
100
common manifestations of suppurative inflammation
- pustule - superficial collection of pus within or just below epidermis
- abscess - collection of pus in an enclosed tissue space
101
nodular inflammatory lesions that encase substances that are not easily destroyed by usual inflammatory and immune responses
granulomatous inflammation
102
two things that can cause granulomatous inflammation
foreign bodies - splinters, sutures, silica, asbestos
pathogens - mycobacterium tuberculosis, syphilis, deep fungal infections
103
multinucleated, coalesced macrophages that surround large particles that cannot be readily phagocytized
giant cells
104
surrounds and contains offending agent and macrophages processing it
epithelioid cells
105
___ eventually surrounds and encapsulates the area of inflammation
fibrous tissue
106
damage to host cells in the absence of adequate host inflammatory response, associated usually with viruses
cytopathic-cytoproliferative reaction
107
how do cytopathic-cytoproliferative reactions cause damage
- cause cells to fuse
- cause cells to become discohesive
- cause cells to proliferate and form morphologic lesions
- some viruses replicate within cells and make viral inclusion bodies
108
intranuclear inclusion with halo
CMV
109
eosinophilic cytoplasmic inclusions
rabies
110
ground-glass cytoplasm in hepatocytes
hep B
111
death of tissue
necrosis
112
how does necrosis occur
enzymatic degradation, inadequate blood supply, trauma, toxins
113
extensive necrosis
gangrene
114
necrosis that can happen without infection
aspectic necrosis
115
phagocytes unable to remove dead tissue adequately often has to be ___
debrided - surgically removed
116
5 types of tissue necrosis
1. coagulate - proteins from dead cells denatured and form a firm gel-like substance
- maintains tissue rchitecture
- mainly hypoxic environments
2. liquefactive - dead cells are liquefied (pus)
- seen with bacterial and fungal infections, brain infarcts
3. caseous - white, friable necrotic tissue
- "cheesy" seen with mycobacteria, fungi, foreign bodies
4. fat - lipases destroy fatty tissues
- may see calcium deposits
5. fibrinoid - damage to vascular structures by immune processes
- immune complexes deposited in vessel walls
117
- ongoing insult to body or dysregulation of the immune response
- simultaneous destruction and dealing of tissue from the inflammatory process
chronic inflammation/scarring
118
describe fibrous scarring
- large amounts of tissue destruction or damage in tissues unable to regenerate, primarily with collagen
- loss of function of cells
- damage to cells = increased risk of DNA damage and cell mutation = increased risk for tumors/cancers
