Mechanisms of Pathogenesis Flashcards
Chapter 14 and Chapter 15 (172 cards)
1
Q
Define Pathology
A
scientific study of disease
2
Q
Define Etiology
A
Cause of a disease
3
Q
Define Pathogenesis
A
How a disease develops (structural/functional)
4
Q
Define Infection
A
Invasion/Colonization of the body by a pathogenic microbe
5
Q
Define Disease
A
Infection changes the normal status of health
6
Q
Define Host
A
Organism that harbors another organism
7
Q
Define Normal Flora
A
Permanent, (typically) nonpathogenic microbes
8
Q
What is resident flora?
A
Microbes that are always present on/in the human body
9
Q
What is transient flora?
A
Microbes that come and go
10
Q
Do babies in the womb encounter microbes?
A
No
11
Q
When do babies begin encountering microbes?
A
At birth
12
Q
What common microbes do babies encounter? (2)
A
- lactobacilli (mother’s vagina)
- feeding and breathing (URT and GIT)
13
Q
(T/F) There are more cells than bacteria in the body
A
False, bacteria > cells
14
Q
Define symbiosis
A
Association between 2+ species
15
Q
Example of Symbiosis
A
Host and Normal Flora
16
Q
Define Commensalism
A
One organisms benefits, other organism not affected
17
Q
Example of Commensalism
A
Staphylococcus epidermis (on our skin)
18
Q
Define Mutualism
A
Both organisms benefit
19
Q
Example of Mutualism
A
E. coli in the intestines (produce vitamins for the body)
20
Q
Define Antagonism
A
Competition between the microorganisms
21
Q
Define Competitive Exclusion
A
Normal Flora vs Pathogen over resources (food)
22
Q
Example of Antagonism
A
Bacteriocins in the large intestine (inhibit other bacteria)
23
Q
Define Parasitism
A
One organism benefits, other is harmed
24
Q
Example of Parasitism
A
Any successful pathogenic microorganism
25
Describe Probiotics
Live microbial cultures are applied/ingested to benefit the host
26
Define Opportunistic
Become pathogenic under certain circumstances
27
What are ways opportunistic pathogens are given opportunity? (3)
- normal flora disrupted/destroyed
- defense mechanisms compromised
- normal protective barriers disrupted
28
Examples of Opportunistic Pathogens (3)
- S. aureus (TSS)
- Pneumocystis jirovecii (pneumonia in AIDS patients)
- E. coli (UTI if moved to urethra)
29
Define Symptoms
Changes in body functions (pain and malaise)
30
Define Signs
VISIBLE changes (rash, fever, swelling)
31
Define Syndrome
Specific symptoms and signs associated with a disease
32
Define Infectious
Caused by bacteria, viruses, fungi, protozoa, and helminthes
33
Define Communicable Infectious Diseases
Contagious (directly or indirectly)
34
Define Non-Communicable Infectious Diseases
Caused by individual's normal flora, ingestion or preformed toxins, organisms in the environment (not contagious)
35
Define Non-Infectious
Caused by any other factor than infectious organisms
36
Define Incidence
Number of new cases contracted within a set population during a set time period
37
Define Prevalence
TOTAL number of people infected within a population at ANY time
38
Define Sporadic
Occurs occasionally in a population
39
Define Endemic
Disease that is always found in the region
40
Define Epidemic
Disease that many people acquire in a very SHORT period of time
41
Define Pandemic
An epidemic that is worldwide
42
Define Acute Disease
Symptoms develop rapidly, lasts a SHORT time
43
Define Chronic Disease
Symptoms develop slowly
44
Define Subacute Disease
Intermediate (between acute-chronic)
45
Define Latent Disease
Inactive until activation, then produces symptoms
46
Define Herd Immunity
Immunity in MOST of a population
47
(T/F) Pathogens can live without a host
False
48
Define Reservoir
Continual source of the disease causing organisms (living or inanimate objects)
49
Describe Human Reservoirs (3)
- transmit microorganisms directly/indirectly
- carries (asymptomatic people)
- convalescing patients (gradual recovery)
50
Describe Animal Reservoirs (3)
- wild and/or domestic
- zoonoses (primarily in animals, possible in humans)
- transmitted: bites, contaminated hides/feathers, food, insect vectors
51
What are examples of nonliving reservoirs of infection? (2)
- soil (fungal diseases)
- water (feces)
52
What are the modes of disease transmission (3)
- contact
- vehicle
- vector
53
Where do pathogens leave the host from?
The same way it came in (portal of entry)
54
What is direct transmission?
person-to-person
55
What is congenital transmission?
mother to fetus/newborn
56
What is indirect transmission?
fomites (nonliving objects)
57
What is droplet transmission?
coughing, sneezing, talking
58
What is vehicle transmission?
Through a medium
59
How is water a vehicle of transmission?
fecal contamination
60
How is food a vehicle of transmission?
incompletely cooked food or improperly refrigerated foods; food poisoning
61
How is air a vehicle of transmission?
mucus droplets by droplet nuclei
62
What are the four vehicles of transmission?
- water
- food
- air
- body fluids and blood
63
What is vector transmission?
Through an arthropod (insect)
64
What are two examples of vector transmission?
- biological
- mechanical
65
What is an example of biochemical transmission?
- bitten by infected insect (lyme disease, malaria)
66
What is an example of mechanical transmission?
- transfer of microbe from feet or other body parts of insects to food/skin of person
- passive; no replication of microbe within vector (shigellosis, typhoid fever)
67
What are nosocomial infections?
Acquired in a hospital/medical facility
68
What are the three factors of nosocomial infections?
- microbe in hospital
- compromised patient
- chain of transmission
69
What are common bacterial nosocomial infections? (5)
- S. aureus (urinary and respiratory)
- Pseudomonas aeruginosa (burns & surgical wounds)
- E. coli (urinary tract, neonatal meningitis)
- Enterococcus (urinary tract & wound)
- Clostridium difficile (diarrhea)
70
What plasmids are antibiotic resistant?
R Plasmids
71
What causes endogenous infections?
Opportunistic microbes in an individual's normal flora
72
What causes exogenous infections?
Microbe that enter an individual through the environment
73
What increases an individual's risk to infection? (4)
- broken skin/mucous membranes
- surgery
- burns
- catheters
74
What suppresses an immune system? (4)
- drugs
- diabetes
- stress
- HIV
75
What are 4 ways a disease can be transmitted to a patient in a hospital?
- hospital staff
- other patients
- fomites
- ventilation system
76
How can we control the spread of nosocomial infections? (3)
- educate personnel
- practice good aseptic techniques
- monitor for drug resistance
77
What are emerging infectious diseases?
New or changing diseases
78
What causes emerging infectious diseases? (7)
- new strain (more virulent)
- overuse of antibiotics (resistance)
- global warming (increases survival rates of reservoirs/vectors)
- modern transportation
- natural transportation
- animal control measures
- failure to comply with public health measures
79
4 Contributing Factors to Emerging Infectious Diseases:
- genetic recombination
- evolution of new strains
- overuse of antibiotics
- changes in weather patterns
80
What is pathogenicity?
Ability of organism to cause disease
81
What is virulence?
Degree of pathogenicity
82
Steps for microbes to cause infection/disease are (4)
- ENTER organism
- ADHERE to tissues
- PENETRATE tissues
- DAMAGE cells
83
What are 3 portals of entry?
- mucous membranes
- skin
- parenteral route
84
What are examples of mucous membranes? (4)
- respiratory
- gastrointestinal
- genitourinary tract
- conjuncitva (eyes)
85
Describe skin
Largest organ & outermost protective layer
86
Examples of the parenteral route (4)
- bites
- punctures
- burns
- injections
87
How many microbes are needed to cause disease?
Number varies from person to person
88
What is ID50
Infectious dose for 50% of population, indication of virulence
89
What is LD50
Lethal dose of a toxin in 50% of population
90
Define Adhesins
Surface molecules on pathogen that bind to receptors on host cells/tissues
91
Where are adhesins found? (4)
- capsules
- fimbriae
- capsid
- virus envelope
92
What are biofilms?
Masses of microbes
93
Pathogen exits the GI tract by (2)
- diarrhea
- vomiting
94
Pathogen exits the Urogenital tract by (2)
- sexual contact
- urine
95
Pathogen exits blood by (2)
- insects
- needles
96
Pathogen exits the Respiratory tract by (3)
- coughing
- sneezing
- speaking
97
How do most bacteria cause disease?
Penetrating tissues
98
What are virulence factors?
Characteristic that help microbes cause infection/disease
99
Structural example of a virulence factor:
Pili (adhesion)
100
Physiological examples of a virulence factor (2):
- enzymes
- toxins
101
Describe adhesins
Proteins/glycoproteins that adhere to host
102
Describe Colonization of microbes
Microbe growth on epithelial cell surfaces (skin, mucous membranes)
103
Describe Invasiveness
Degree that microbe can invade and grow in host tissues
104
Describe Toxins
Poisonous substance to other organisms
105
What do capsules do
Resist Host Defenses
- phagocytosis
- complement
106
What are Streptococcus pyogenes cell wall made of?
Protein M
107
What are Mycobacteria cell wall made of?
Waxes (mycolic acid)
108
What are Neisseria gonorrheae cell wall made of?
Fimbriae (Opa proteins)
109
How do extracellular enzymes help microbes?
Breakdown and dissolve material found near cells
110
What does Hyaluronidase do?
Digests hyaluronic acid (bacterial cell membranes)
111
What does Coagulase do?
Increases clotting
112
What do IgA Proteases do?
Destroy antibodies
113
What does Streptokinase do?
Dissolves clots (digests fibrin)
114
What does Collagenase do?
Breaks down collagen
115
What do Hemolysins do?
Destroys RBCs
116
Alpha Hemolysis
Partially digests hemoglobin (green)
117
Beta Hemolysis
Completely digests hemoglobin (clear)
118
Gamma Hemolysis
No digestion
119
What do Leukocidins do?
Destroy neutrophils
120
(T/F) If phagocytosis occurs after entry, no damage occurs
True
121
What causes damage to the host cells (4)
- using host nutrients (siderophores)
- direct damage by injury (cell rupture)
- toxins
- causing hypersensitivity reactions
122
What uses a host cell's nutrients?
Siderophores
123
What are toxins?
Poisonous substances made by some microbes
124
What do toxins cause (5)
- fever
- cardiovascular disturbances
- neurological disturbances
- diarrhea
- shock
125
What is Toxemia?
Toxins in the blood
126
What is Intoxication?
Disease caused by ingestion of toxin
127
What are Exotoxins?
Produced INSIDE bacteria, released into SURROUNDING medium
128
What are Endotoxins?
Lipid A portion of LPS released from cell wall of GRAM NEGATIVE bacteria
129
Where are endotoxins located
Outer portion of the LPS (lipopolysaccharide) of gram - bacteria (Lipid A)
130
When are endotoxins released
When the gram - cell dies (cell wall breaks)
131
Symptoms of endotoxins (6):
- chills
- fever
- weakness
- aches
- shock
- death
132
Explain how Disseminated Intravascular Coagulation (DIC) occurs:
Endotoxins activate clotting cascade causing blockage of blood supply = tissue death
133
Outcomes possible because of endotoxins:
- fever/pyrogenic response
- septic shock
134
How do endotoxins cause pyrogenic/fever response? (5)
- Macrophage eats Gram - cell (phagocytosis)
- cell degrades = endotoxin released
- endotoxin stimulates macrophage to secrete IL-1
- IL-1 causes hypothalamus to produce prostaglandins
- PGs causes body temperature to rise
135
What does IL-1 stand for?
Interleukin 1 (Endogenous pyrogen)
136
What else could the macrophage secrete during endotoxic shock? (2)
- Tumor Necrosis Factor (TNS)
- Cachetin
137
What causes the release of Mediators?
Tumor Necrosis Factor & IL-1
138
What do Mediators cause? (3)
- increased permeability of capillaries (loss of fluids)
- rapid decrease in B.P.
- Impaired blood flow to kidneys
139
What does Endotoxic Septic Shock cause? (8)
- chills
- fever
- vomiting
- diarrhea
- rapid decrease in blood pressure
- convulsions
- shock
- death
140
Which bacteria are major producers of Endotoxic Septic Shock? (6)
- P. aeruginosa
- E. coli
- Klebsiella
- Proteus
- Enterobacteria
- Salmonella typhi
141
What are Exotoxins?
Proteins/Enzymes produced by Gram + bacteria (& some Gram -) that destroy/inhibit parts/functions of cells
142
How can we destroy Exotoxins?
Heat or chemicals
143
Where are Endotoxin genes carried in? (2)
- plasmids
- bacteriophages
144
What are antitoxins?
Things the body produces that gives immunity against exotoxins
145
What are toxoids used for? (2)
- vaccines
- stimulate antitoxins
146
How are Exotoxins named?
According to the cell they attack or the disease they are associated with
147
What pathogen secretes Diphtheria Toxin?
Corynebacterium diptheriae
148
What do Diphtheria toxins do?
Inhibits protein synthesis (A-B toxin)
149
What pathogen secretes Erythrogenic Toxin?
Streptococcus pyogenes
150
What do Erythrogenic Toxins do?
Damages blood capillaries under the skin
151
What pathogen secretes Botulinum Toxin?
Clostridium botulinum
152
What do Botulinum Toxins do?
- prevents nerve impulses
- inhibits release of acetylcholine
- flaccid paralysis
153
Describe Clostridium botulinum (4)
- gram +
- spore forming
- anaerobic rod
- found in soil, canned foods, water, intestinal tracts of animals
154
How long does it take for symptoms of Clostridium botulism to appear?
12-46 hours
155
What are the symptoms of Clostridium botulism? (5)
- poor vision
- difficulty swallowing
- weakness
- faulty speech
- death
156
How would you treat a patient with the Adult Form of Botulism?
Trivalent antitoxin to A,B, & E
157
How can we prevent Infant Botulism?
Do not give infants honey
158
What do Tetanus Toxins do?
Inhibit nerve cell impulses form muscle relaxation
159
What pathogen secretes Tetanus Toxins?
Clostridium tetani
160
What do Vibrio Entertoxins (Cholera Toxin) do?
Release large amounts of fluid & electrolytes ("rice water stools")
161
What do Staphylococcal Enterotoxins do?
(Superantigen) Affects intestinal tract in releasing fluid & electrolytes
162
What do Staphylococcal TSS Toxin do?
(Superantigen) Toxic Shock Syndrome Toxin
163
What gram bacteria do endotoxins occur in?
Gram -
164
What are exotoxins made of?
Protein
165
What are endotoxins made of?
Lipid
166
What gram bacteria do exotoxins occur in?
Gram + and Gram -
167
Which toxins can be made into toxoids?
Exotoxins
168
Which toxin is found in LPS of gram - cells?
Endotoxins
169
Can Endotoxins be destroyed by heat?
No
170
Can endotoxins be made into toxoids?
No
171
How are viruses able to avoid host defenses? (2)
- grow inside cells where the immune system cannot reach
- they attack immune cells (HIV)
172
What are the Cytopathic Effects (CPE) of viruses?
- kills cell
- inhibits protein, DNA, RNA synthesis
- toxic to cells
- syncytia formation
- antigenic changes cause destruction by immune system
- chromosomal damage can activate oncogenes
