Exam 4 Flashcards
(425 cards)
1
Q
A single microbe causes
A
a particular disease
2
Q
Symbiosis
A
an association of two or more different species of organisms
- organisms living together
- at least one benefits from relationship
- other may be injured, relatively unaffected, may also benefit
3
Q
When microbe interacts with a larger organism:
- microbe =
- larger organism =
A
symbiont, host
4
Q
T / F: the term symbiosis is restricted to mutually beneficial relationships
A
F
5
Q
T / F: a disease can have multiple microbial causes
A
T
6
Q
Ectosymbiont
A
organism located on surface of another organism
7
Q
Example of ectosymbiosis
A
bacteria on skin
8
Q
Endosymbiont
A
organism located within another organism
9
Q
Endosymbiosis example
A
bacteria in gut
10
Q
Consortium
A
hosts that have more than one associated symbiont
11
Q
Types of microbial interactions (7)
A
mutualism, cooperation, commensalism, predation, parasitism, amensalism, competition
12
Q
Microbial interactions/relationships can be
A
intermittent, cyclic or permanent
13
Q
Mutualism
A
- reciprocal benefit to both partners
- relationship with some degree of obligation (typically cannot live separately)
- mutualist and host are codependent on each other
14
Q
An example of mutualism between organisms supports the idea of
A
coevolution
15
Q
Ruminants
A
animals (like cattle, sheep) that have a stomach with four compartments
16
Q
Rumen
A
upper part of the ruminant stomach
17
Q
Cooperation
A
relationship that benefits both organisms
- not an obligatory relationship (organisms could live independently)
18
Q
Cooperation typically involves
A
- syntrophic relationships
- linked carbon and nitrogen/sulfur cycles
19
Q
Commensalism
A
- similar to cooperation but it is unidirectional
- one organism benefits, other is not affected
- often syntrophic
- commensal can live separated from host
20
Q
Commensal lives off
A
metabolic byproducts of host
21
Q
An organism changing an environment, making it more suitable for another is an example of
A
commensalism
22
Q
Formation of multispecies biofilms is an example of
A
commensalism
23
Q
Predation
A
- one organism gains (predator) and the other is harmed (prey)
- predator usually kills prey
- predatory can attack from inside or outside
24
Q
Parasitism
A
- one organism gains (parasite) and the other is harmed (host)
- typically, host is not killed (until parasite can reproduce)
25
T / F: parasitism is between commensalism and predation
T
26
There is always some degree of ____ in a parasitic relationship
co-existence
27
Successful parasites have evolved to
co-exist in equilibrium with their hosts
28
Hallmark of parasitic relationship
- not beneficial for host
- host grows better without parasite
29
Ammensalism
association between two organisms where one organism is inhibited (harmed) and other is unaffected
30
Antibiosis
- specific type of ammensalism
- based on release of a specific compound
31
Example of ammensalism
antibiotic production by fungi and bacteria (antibiosis)
32
Competition
occurs when two organisms try to acquire or use the same resource
33
Two possible outcomes of competition
- one organism dominates
- two organisms share the resource
34
What organism learned how to use antibiotics before humans?
ants
35
Microbiome/microbiota
all of the microbes living in/on the human body
36
___ : ___ ratio of bacteria to human cells
1 : 1
37
___ : ____ ratio of nucleated cells
10 : 1
38
Metagenome
all the genes of the host and microbiota
39
Human microbiome (numerical value)
1,000,000+ genes
40
Human genome (numerical value)
23,000 genes
41
Superorganisms
- the gene-encoded metabolic processes of the host become integrated with those of the symbiont
- a blend of host and microbial traits where host and microbial cells co-metabolize various substrates, resulting in unique products
42
Microbiota varies depending on
- anatomical site
- age
- sex
- diet
43
Human microbiota begins at
birth
- unborn baby is sterile, inoculated during birthing process
44
What can disrupt the human microbiota?
antibiotic treatment, returns to "normal" after antibiotics are removed
45
Consortium
when microbiome becomes reasonably stable
46
Normal microbiota interaction with humans
mutualism
47
Normal microbiota often prevent
colonization by pathogens
48
Opportunistic pathogens
- under certain circumstances, the normal microbiota can become pathogenic
- compromised host
- debilitated host with lowered resistance to infection
49
T / F: microbiota can be considered part of the immune system
T
50
Pathogen
any disease-producing microorganism
51
Dysbiosis
a change in the microbiome, can result in health risks/illness
52
Pathogenicity
ability to produce pathological change or disease
53
In order to cause disease pathogens must
- get inside the host
- survive inside the host
54
Immunology
science concerned with immune responses
55
Immune system composition
composed of widely distributed molecules, cells, tissues, and organs
56
Immune system function
recognizes foreign substances (or microbes) and acts to neutralize or destroy them
57
Immunity
ability of host to resist a particular disease or infection
58
Innate immune system, specific or non specific?
non specific
59
Adaptive immune system, specific or non specific?
specific
60
Innate immune system: speed
- very fast response
- components always present
61
Innate immune system: specificity
- not very specific
- active against a wide variety of infectious agents
62
Innate immune system: memory
- no memory
- not enhanced upon repeated contact with pathogen
63
Adaptive immune system: speed
- response is slow
- components must be made
64
Adaptive immune system: specificity
- very specific
- active against a narrow range of infectious agents
65
Adaptive immune system: memory
- retains memory of invading pathogen
- response is enhanced upon repeated contact with pathogen
66
Innate immunity first line of defense
- barriers (skin, mucus membranes)
67
Innate immunity second line of defense
- antimicrobial peptides
- complement
- cytokines
- inflammation
- phagocytes
- NK cells
68
Adaptive immunity specific defense mechanisms (third line of defense)
- antibodies
- lymphocytes
- B cells
- T cells
69
Examples of excretions that keep microbes out
mucous, tears, wax, skin oils
70
T / F: skin is a highly effective barrier
T
71
T / F: innate and adaptive are completely separate systems
F
72
First and second line of defense are specific or non specific?
non specific
73
Skin
- strong mechanical barrier to microbial invasion
- inhospitable environment for most microbes
74
What characteristics of skin make it inhospitable for most microbes?
- dry, acidic environment
- dead, keratinized cells
- sloughing of surface cells
- toxic lipids, lysozyme
- normal microbiota
75
Common areas with mucous membranes/secretion
- mouth
- eyes
- ears
- nares (nose)
- respiratory tract
- gastrointestinal tract
- urogenital tract
- anus
76
Common antimicrobial substances in mucous
- lysozyme
- RNAse enzymes
- lactoferrin
77
Lysozyme
hydrolyzes bond connecting sugars in peptidoglycan
^ disintegrates cell wall
78
RNAse enzymes
degrade RNA (found in tears!)
79
Lactoferrin
sequesters iron
^ most bacterial pathogens need iron, lactoferrins "hide it," bacteria cannot get what they need
80
Two components of innate immune system
- chemical (humoral)
- cellular
81
Chemical (humoral) component of innate immune system
- antimicrobial peptides
- complement
- cytokines
82
Cellular component of innate immune system
- phagocytes
- natural killer cells
83
Antimicrobial peptides
small peptides ( ~ 12-50 amino acids) that have antimicrobial activity
84
Amphipathic
have hydrophobic and hydrophilic regions
85
Most antimicrobial activities function by
inserting into membrane
86
Antimicrobial peptides (AMPs) are abundant in
- external mucosa (eyes, genitourinary, skin, lung, trachea, mouth)
- immune cells (neutrophils)
- intestinal tract (duodenum)
87
The complement system
- heat sensitive component of serum (human blood)
- complement antibodies in the killing of bacteria
- complex system of > 30 serum proteins
88
Major activities of the complement system
- directly kill bacteria
- opsonizing bacteria
89
Membrane attack complex (MAC)
5 different complement proteins combine to form this
- C5b, C6, C7, C8 and C9
90
Opsonization
a process in which the surface of a microbe is coated with a substance called opsonin
91
What is special about opsonized microbes?
they are much more easily recognized and destroyed by phagocytic cells
92
Two types of opsonins
- complement protein C3b
- antibodies
93
Opsonization by antibodies or complement _____ affinity of phagocytes for microbe
increases
94
Opsonization by antibodies and complement further ____ binding and phagocytosis
increases
95
Cytokines
- soluble proteins or glycoproteins
- signaling molecules released by one cells population that act as intercellular mediators
96
Opsonized with antibodies degree of binding
+
97
Opsonized with complement C3b degree of binding
++
98
Opsonized with antibody and complement C3b
+++
99
One primary function of cytokines is to
induce inflammation
100
The inflammatory response
response of host tissues to damage or infection
101
The inflammatory response purpose
to recruit components of the immune system to the site of damage/infection
102
Cytokine signaling makes the tissue
- leaky to fluid (influx of plasma; containing antibodies, complement, etc.)
- sticky for leukocytes, leading to influx of neutrophils (pus)
103
Phagocytosis
process by which phagocytic cells recognize, ingest, and kill extracellular microbes
104
Two mechanisms for recognition of microbe by phagocyte
- opsonin-dependent recognition
- opsonin-independent recognition
105
Phagocytosis is greatly increased by
opsonization
106
Opsonin-independent mechanism is based on
detection of conserved microbial molecular structures that occur in patterns
107
Pathogen-associated molecular patterns (PAMPs)
- molecule/polymer found on surface of microbe but not host
- LPS of Gram (-) bacteria
- peptidoglycan / teichoic acids of Gram (+) bacteria
108
PAMPs are recognized by _______ on ____ cells
PRRs, phagocytic
109
One class of PRRs important in fighting infection are
toll-like receptors (TLRs)
110
TLRs
recognize and bind unique PAMPs of virus, bacteria, or fungi
111
Binding of TLRs and PAMPs
triggers a signal within the host cell which initiates the host response, resulting in phagocytosis
112
Once bound, microbes can be internalized into a
phaogsome
113
Phagosome fuses with a lysosome to become a
phagolysosome
114
Exocytosis
process used by neutrophils to expel microbial fragments after they have been digested
115
Phagolysosome fuses with ____, resulting in
cell membrane, extracellular release of microbial fragments
116
Macrophages and dendritic cells undergo process called
antigen presentation
117
Antigen presentation
links innate immunity with adaptive immunity
118
Cells of the immune system are collectively known as
leukocytes
119
Leukocytes
white blood cells
120
Phagocytic cells
- monocytes
- macrophages
- dendritic cells
- neutrophils
121
Natural killer cells (NK)
small population of lymphocytes
122
NK cells play an important role in
innate immunity
123
NK cells kill what type of cells?
cells infected with pathogens
124
NK cells release
cytotoxic enzymes (granzymes)
125
NK cells play an important role in
innate immunity
126
Normal cells express a membrane protein called
class 1 major histocompatibility complex (MHC class 1)
127
Two ways NK cells recognize infected cells
1. NK cell encounters a host cell without MHC-1, releases granzymes and kills cells
2. ADCC (antibody-dependent cell-mediated cytotoxicity): antibodies bind to antigens on surface of infected host cells, NK cells bind to antibodies, kill infected cell
128
Antigens
substances that elicit an immune response
129
T / F: antigens cannot be large or complex molecules
F
130
Epitopes
antigenic determinant sites
131
Antibody affinity
strength with which antibody binds to its antigen at a given antigen-binding site
132
Antibody or immunoglobulin
large glycoprotein made by B lymphocytes
133
Where are antibodies found in the body?
found free in the body
134
Antibodies function
recognize and bind specific antigen
135
Immunoglobulin structure
4 polypeptide chains
- 2 heavy chains
- 2 identical light chains
- chains connected by disulfide binds
136
2 different regions in immunoglobulin chains
- constant regions
- variable regions
137
5 main modes of transmission
- airborne
- contact (direct or indirect)
- vehicle (food, water)
- vector borne (arthropod [insects], zoonotic [animal])
- vertical
138
Example of indirect contact transmission
needle/syringe, contaminated public surface
139
Dust particles are an important route of ______ transmission
airborne
140
Airborne transmission: pathogen suspended in air and travels less than or equal to ____
1 meter
141
Droplet nuclei
- usually propelled from respiratory tract of source organisms by sneezing, coughing, or vocalization
- can travel long distances
- smaller droplets can remain suspended
- small particles (1-4 micro m diameter)
142
COVID-19 is the ___ name
disease/syndrome
143
SARS-CoV-2 is the name of the ______
virus
144
SARS-CoV-2 genome is approximately _________ nt long
30,000
145
SARS-CoV-2 genome structure
- 4 structural genes it encodes
- 16 NSPs (non-structural proteins)
- 9 accessory factors
146
Influenza (the flu)
disease
147
Influenza is caused by
influenza virus
148
Influenza virus
- RNA virus; segmented genome
- 3 groups (A, B, C)
- family Orthomyxoviridae
149
Total genome size of influenza virus
12,000-15,000 nts
150
___ segments of RNA (-) in influenza virus
8
151
____ genes/proteins in influenza virus
11
152
Flu virus structure
- enveloped virus
- 2 viral proteins in the envelope (hemagglutinin [HA], neuraminidase [NA])
153
Influenza virus viral replication
- HA attaches to host sialic acid receptors
- receptor mediate endocytosis
- HA undergoes conformational change
- releases nucleocapsid into cytoplasm
- viral replication, transcription and assembly of new virions
- release by budding
- NA protein cleaves receptors, releasing new virions
- NA inhibitor, Tamiflu
154
Rarest flu type
C
155
____ different types of HA
16
156
____ different types of NA
9
157
Antigenic drift
accumulation of mutations in a strain within a geographic area
- nucleotide/amino acid changes
158
Antigenic shift
re-assortment of genomes (8 RNAs)
- two different strains of flu viruses infect the same cell and are incorporated into a single new capsid
159
Arboviruses
viruses transmitted by bloodsucking arthropods from one vertebrate host to another
160
An important feature of the influenza viruses is the
frequency with which changes in antigenicity occur
161
Arboviruses multiplication
multiply in tissues of vector without producing disease
162
T / F: arboviruses typically have vaccines
F
163
Contact transmission
coming together or touching of source/reservoir and host
164
Direct contact
physical interaction between source/reservoir and host
165
Indirect contact
involves an intermediate (usually inanimate)
166
AIDS is caused by
HIV
167
T / F: (technically) HIV does not kill
T
168
AIDS leads to
infection by opportunistic pathogens
169
HIV is a(n) RNA, protein or DNA virus?
RNA
170
Zika virus is special because
it is an Arbovirus and a vertical transfer disease
171
Contact with body fluids or contact with an open wound is an example of
direct contact
172
HIV life cycle
- virion has several viral protein spikes
- attachment to human cells is mediated by gp120 (attaches to CD4 receptor)
- enters cell by receptor mediated endocytosis
- carries reverse transcriptase into host cell
- also carries integrase and protease enzymes
- RNA genome is reverse transcribed into dsDNA, which integrates into human genome as provirus
- can remain latent (asymptomatic)
- can direct synthesis of viral RNA --> synthesis of new viral particles
173
Virion core consists of ___ viral proteins
4
174
4 viral proteins
P24, P17, P9, P7
175
4 viral proteins are generated from one precursor polyprotein called
Gag
176
Acute
- 2-8 weeks after infection
- acute retroviral syndrome
- infection is brought under control
- very non descript symptoms that go away quickly
177
Asymptomatic (latent) (HIV)
- may last from 6-10 months or years
- levels of detectable HIV in blood decease, although viral replication continues
- effects on immune functions may occur
178
Chronic symptomatic (HIV)
- can last months to years
- viral replication continues
- patient at risk of opportunistic pathogens and AIDS related cancers
179
3 proteins that must be found in HIV for viral genome to work
RT (reverse transcriptase), protease, integrase
180
Clinical definition of AIDS
HIV-infected individuals who have fewer than 200 CD4+ T cells/microliter of blood or a CD4+ cell percentage of lymphocytes of less than 14
181
Food/water transmission
transmission of pathogens in water and food (food poisoning)
182
T / F: food/water transmission may be the most common transmission type
T
183
Gastroenteritis (viral) is caused by what four major groups of viruses?
rotavirus, adenovirus, astrovirus and norovirus
184
Rotavirus, adenovirus and astrovirus deaths per year
~5-10 million deaths/year worldwide
185
Rotavirus, adenovirus and astrovirus transmission
viral diarrhea transmitted by fecal oral route
186
Norovirus cases per year
~23 million
187
Zoonotic diseases
human viral infection in animal reservoirs before transmission to and between animals
188
Zoonotic diseases genome type
RNA
189
T / F: many zoonotic diseases are on Select Agents list as potential bioweapons
T
190
Ebola hemorrhagic fever genome type
ssRNA (-)
191
What animal is a natural reservoir for ebola?
bats
192
T / F: there is a carrier state for ebola
F
193
Fab binds
antigen
194
T / F: Fab-antigen binding is highly specific
T
195
Fc mediates binding to
- cells of immune system
- complement system
196
Fc mediating binding of cells of immune system leads to
triggering of phagocytosis, opsonization
197
Fc mediating binding to complement system leads to
activation of complement
198
Primary antibody response is
slow
199
Concentration of antibody in serum is known as
antibody titer
200
Upon secondary exposure to same antigen, antibody production is
quicker
201
Secondary exposure characteristics
- shorter lag
- more rapid log phase
- longer persistence
- higher titer
- production of antibodies with a higher affinity for the antigen
202
Consequence of antibody-antigen binding
- opsonization
- agglutination
- complement
- neutralization
- precipitation
203
Major populations of lymphocytes include
T cells and B cells
204
B and T lymphocytes originate in _____ from ______
bone marrow, stem cells
205
Lymphocytes are only activated by
binding or recognition of specific antigen
206
Consequence of activation of lymphocytes is the production of
memory cells
207
B cells are mature in
bone marrow
208
B cells circulate in
blood
209
One of the primary roles of B cells is to
produce antibodies
210
T cells are mature in the
thymus
211
T cells can remain in the thymus, circulate in ______, or reside in _______
blood, lymphoid tissue
212
Activated T cells differentiate into
- T helper cells
- cytotoxic T lymphocytes (CTLs)
213
T helper cells (TH)
assist in antibody production
214
Cytotoxic T lymphocytes (CTLs)
ability to kill infected cells
215
TH cells help
B cells
216
CTLs are similar (in role) to
NK cells
217
T / F: of all the known bacterial species, very many are pathogenic to humans
F
218
Virulence factors are...
molecules produced by pathogens that contribute to the pathogenicity of the organism
219
Virulence factors are typically what type of molecules?
proteins
220
Common types of virulence factors
- toxins
- adhesions (pili/fimbriae)
- flagella
- immune evasion molecules
221
T / F: pathogenic bacteria can have one, few, or many virulence factors
T
222
Diphtheria is caused by what type of bacteria?
Gram (+), Corynebacterium diphtheriae
223
Some bacterial strains (of Corynebacterium diphtheriae) harbor
lysogenized bacteriophage
224
Bacteriophage genome contains
tox gene
225
Strains containing bacteriophage produce a(n) ______, that inhibits protein synthesis and is responsible for pathogenesis
exotoxin
226
Only virulence factor of C. diphtheriae
exotoxin
227
Diphtheriae toxin
AB toxin
228
AB toxin
- A and B protein held together by disulfide bond
- B portion binds to host cell receptors, triggers endocytosis
- A portion is released, enters and is active in cytoplasm of host cell, inhibits protein synthesis, kills cell
229
Diphtheria is a virus or a disease?
disease
230
Mycobacteria characteristics
- large group of bacteria
- normally found in soil, water, and house dust
- can cause a number of human infections that are difficult to treat
231
What is unusual about mycobacteria?
unusual cell wall
232
What is unusual about mycobacteria cell wall?
- Gram (+) but does not stain Gram (+)
- outer membrane made of mycolic acids
233
Why do mycobacteria not stain Gram (+)?
do not retain the crystal violet stain because of mycolic lipid layer
234
"Outer membrane" made of mycolic acids (characteristics)
- protective waxy layer
- acts like outer membrane
- very hydrophobic
- resistant to penetration of some antibiotics
235
Staining process of mycobacteria (name and process)
- Ziehl-Neelson stain
- stain with carbol fuchsin
- heat over bunsen burner
- destain with HCl in isopropyl alcohol
- stain is removed from cells that are unprotected by a mycolic lipid bilayer
- cells are counter-stained with methylene blue
236
Tuberculosis transmission
- person to person spread of droplet nuclei in respiratory tract (cough)
- also transmitted from infected animals and their products
- reactivation of old, dormant infections
237
Does TB develop slowly or quickly?
slowly
238
Tuberculosis is caused by ______, and this was shown by ______
Mycobacterium tuberculosis (Mtb), Robert Koch
239
How many people worldwide have been infected with TB?
2 billion
240
Mtb virulence factors
- cell envelope composed of toxic components
- ability to survive phagocytosis
241
Toxic components of Mtb cell envelope and what they do
- mycolic acid, liparabinomannan, tregalose, dimycolate, phthiocerol dimycocerosate
- kill eukaryotic cells and protect Mtb from lysozyme and osmotic lysis
242
How Mtb is able to survive phagocytosis?
- kill macrophages
- resistant to oxidative killing
- inhibit diffusion of lysosomal enzymes
243
To prevent further spread of Mtb, what does the immune system do?
"walls off" the infection in hard nodules called Tubercle
244
Over time, tubercle can develop into
- caseous lesion
- Ghon's complex (calcified caseous lesion)
- tuberculous cavities
245
Tuberculous cavities
- tubercle liquefies
- forms air-filled cavity from which bacteria can spread
- spreading is called miliary tuberculosis
- also called reactivation tuberculosis because bacteria reactivated at initial infection site
246
Lyme disease and plague are examples of what type of disease?
arthropod-borne disease
247
T / F: arthropod-borne diseases are generally rare
T
248
Lyme disease is caused by
spirochete Borrelia burgdorferi
249
Three stages of lyme disease
initial, disseminated, late stage
250
Initial (localized) stage of lyme disease
- develops 1 week to 10 days after infection
- expanding, ring shaped, skin lesion
- flu like symptoms
- may go undiagnosed
251
Disseminated stage of lyme disease
- occurs weeks or months after infection
- neurological abnormalities
- heart inflammation
- arthritis
252
Late stage of lyme disease
- occurs years later
- demyelination of neurons
- behavioral changes
- symptoms resembling Alzheimer's disease and multiple sclerosis
253
Plague (black death, Bubonic plague) was caused by what type of bacteria?
Gram (-) bacteria Yersinia pestis
254
How many people did the plague kill?
75-200 million people (in Europe)
255
Plague transmission
- rodent to human, bite of infected flea
- direct contact with infected person, animal or product
- inhalation of contaminated airborne droplets
256
Yersinia pestis in the body
- multiply in blood and lymph
- survive and proliferate in phagocytic cells
257
Symptoms of plague
- subcutaneous hemorrhages
- fever
- buboes (enlarged lymph nodes)
258
If plague is acquired through ______, chances of death are extremely high
inhalation
259
Most critical virulence factor of Yersinia pestis
type III secretion system
260
Type III secretion system
- molecular syringe
- used to deliver yersinal proteins (YOPS) into host cells
- shuts down defence mechanisms
261
Clinical manifestations of Yersinia pestis
1. bubonic plague
2. pneumonic plague
262
Bubonic plague
- enlarged lymph nodes (buboes)
- 50-70% lethal of untreated
263
Pneumonic plague
- arises from primary exposure to infectious respiratory droplets of infected persons or cats
- 100% mortality if untreated
264
T / F: Y. pestis is a select agent
T
265
STDs worldwide cases per years
~300 million
266
T / F: STDs can be transmitted by nonsexual means
T
267
What is the most frequently reported sexually transmitted bacterial infection?
chlamydia
268
What type of bacteria is chlamydia?
Gram (-)
269
Chlamydial diseases in males
- asymptomatic
- urethral discharge, itching and inflammation of genital tract
270
Chlamydial diseases in females
- sometimes asymptomatic
- may cause pelvic inflammatory disorder
- if pregnant, can lead to miscarriage, stillbirth, and infant pneumonia
271
Venereal syphilis
- sexually transmitted
- infection results from intimate contact with an infected lesion of a sexual partner
272
Congenital syphilis
- acquired in utero
- passed from mother to baby
273
Syphilis is what a(n) _______ disease
ulcerative
274
____ stages of syphilis
3
275
Primary stage of syphilis
- appearance of chancre
- small, painless, reddened ulcer
- contains spirochetes
- highly infectious
- 33% of cases resolve at this stage
276
Secondary stage of syphilis
- bacteria spread throughout the body via lymph and blood
- appearance of skin rash
- rash is infectious
- loss of hair, malaise, fever
277
Second stage is followed by _____, which is
latent period, non-infectious
278
Tertiary stage of syphilis
- 40% of cases reach this stage
- formation of gummas (masses of dead, fibrous tissue in skin, bone and nervous systems)
- cognitive defects
- blindness
- madness
279
Antibiotic intervention is most effective
in early stages
280
Neisseria gonorrhoeae
causative agent of gonorrhea
281
Second most prevalent bacterial STI
gonorrhea
282
Neisseria gonorrhoeae can infect
the genitals, rectum, eyes and throat of men and women
283
Transmission of gonorrhea
sexual and/or vertical
284
Why is gonorrhea such a problem?
- no vaccine
- resistant to many, many antibiotics
285
Why is gonorrhea so resistant?
- extremely competent, highly efficient transformation system
- type IV pili
- retractable pili
- bind extracellular DNA
- bring it into the cell
286
Pili has an even higher affinity for DNA if it contains
DNA uptake sequence
287
Gastroenteritis
inflammation of stomach and intestinal lining
288
Food poisoning
food is source of pathogen
289
Food-borne infection
pathogen must colonize host
290
Food intoxication
ingesting a toxin made my bacteria
291
Botulism
caused by Clostridium botulinum
292
Clostridium botulinum
- obligate anaerobe
- endospore-forming
- Gram (+) rod
293
Botulinum toxin
- neurotoxin that binds to synapses of motor neurons
- prevents signal being transmitted across synapse
- causes flaccid paralysis (cannot contract muscles)
294
T / F: botulinum toxin is the most powerful toxin known to humans
T
295
Most common form of botulism
infant botulism
296
Anthrax is what type of disease?
zoonotic
297
T / F: anthrax is not a select agent
F
298
What determines anthrax disease manifestation?
portal of entry
299
3 forms of anthrax
- cutaneous
- inhalation
- gastrointestinal
300
Cutaneous anthrax
- infection through cut or abrasion of skin
- clinical manifestations ( 1-15 day incubation, skin papule that ulcerates, headache, fever, nausea)
- treatable with antibiotics
301
Inhalation/pulmonary anthrax
- inhalation of endospores
- resembles influenza
- if bacteria reach the bloodstream, usually fatal
- even with antimicrobial therapy (75% fatality)
302
Gastrointestinal anthrax
- ingestion of endospores
- very uncommon
303
Cryptococcosis
systemic fungal disease causes by a yeast Cryptococcus neoformans
304
Cryptococcosis characteristics
- acquired by inhalation of dried pigeon droppings
- mild disease
- pneumonia-like disease
- serious disease including meningitis in immunocompromised patients (AIDS)
305
Prevalence of Hepatitis B
2 billion people
306
Prevalence of malaria
- 200-300 million people annually
- 500,000-1 million deaths
307
Hep C prevalance
180 million people
308
Dengue prevalance
50-100 million people
309
Tuberculosis prevalance
2 billion people chronically infected
310
Malaria is a(n) _____ borne disease
arthropod
311
Malaria is endemic in ____ countries
106
312
Malaria is caused by
species of parasitic protozoan called Plasmodium
313
5 plasmodium species that commonly cause human infection
- P. falciparum
- P. vivax
- P. malariae
- P. ovale
- P. knowlesi
314
What is the most dangerous species of plasmodium?
P. falciparum
315
What is the most common species of plasmodium?
P. falciparum
316
Malaria involves ___ reproductive stages
3
317
Malaria has ______ and ______ stages
haploid, diploid
318
Plasmodium life cycle: Part 1
- in liver
- mosquito takes a blood meal and injects infective form of plasmodium known as sporozoites
- haploid sporozoites migrate to the liver and enter hepatic cells
- undergo asexual reproduction to form a schizont
- schizont ruptures and releases merozoites into bloodstream (haploid)
319
Only diploid section occurs
within the mosquito
320
Part 2 of plasmodium life cycle
- erythrocyte replication cycle
- merozoite enters red blood cell
- forms a ring structure called the trophozoite
- the trophozoites matures into a schizont which produces more merozoites
- erythrocyte lyses, releasing merozoites into blood stream
321
Part 3 of plasmodium life cycle
- some trophozoites mature into a gametocytes
- gametocytes differentiate into male (microgametocytes) and female (macrogametocytes) forms
- gametocytes are ingested by mosquito when it takes a blood meal from an infected person
322
Mosquito stage of plasmodium life cycle
- in the mosquito gut the microgametocyte (male) and macrogametocyte (female) fuse to form diploid zygote called ookinete (diploid)
- ookinete migrates through the gut wall and forms the oocyst
- oocyst undergoes meiosis to form haploid sporozoites
- oocyst ruptures and sporozoites migrate to the mosquito salivary glands
323
_________ can result from erythrocyte lysis
anemia
324
T / F: diploid stage of plasmodium life cycle is large
F
325
Why are periodic attacks of chills, fever and sweating experienced with malaria?
due to the synchronized lysis of erythrocytes and release of merozoites
326
Chloroquine
interferes with replication of plasmodium in erythrocytes
327
Why would a malaria vaccine be challenging to develop?
- eukaryotic cells
- vaccine would have to work against all stages of the plasmodium life cycle
328
RTS vaccine is based upon
recombinant protein
329
Fungal infections are known as
mycoses
330
Superficial mycoses
- outermost layers of skin and hair
331
Cutaneous mycoses
- extend deeper into epidermis
- invasive hair and nail diseases
- different diseases distinguished according to causative agent and area of body affected
332
Subcutaneous mycoses
- involve dermis, subcutaneous tissue and fascia
- caused by saprophytic inhabitants of soil
- introduced in soil-contaminated puncture wounds
- develops slowly over a period of years
- nodules form and ulcerate
- organisms spread along lymphatic channels, producing more nodules
333
Most common fungal disease type
cutaneous
334
Cutaneous mycoses are transmitted by
direct contact
335
Why is it difficult to treat fungal infections?
fungi are eukaryotes
336
Azoles (role and examples)
- inhibit the synthesis of ergosterol (the main fungal sterol - equivalent of cholesterol in humans)
- Fluconazole, Clotrimazole
337
Polyenes (role and examples)
- bind/interact with ergosterol in fungal membrane, alters membrane fluidity
- Amphotericin B, Nystatin
338
Echinocandins
inhibit cell wall synthesis (beta-glucans)
339
What could/would cause an increase in fungal infections?
climate change
340
Excystation is essentially the same as
germination
341
Excystation leads to formation of
metacyst
342
Toxoplasmosis
- fecal-oral transmission from infected animals
- ingestion of undercooked meat, congenital transfer, blood transfusion, or tissue transplant
343
Toxoplasma gondii is a
protist
344
Malaria diagnosis
demonstration of parasites within Wright or Giemsa-stained red blood cells and serological tests
345
Amebiasis is caused by
protozoan Entamoeba histolytica
346
Amebic dysentery (amebiasis) infection
ingestion of mature cysts from fecally contaminated water, foods or plants
347
In the lower intestine, the ingested mature cyst undergoes ________
excystation
348
The metacyst rapidly divides to produce
8 trophozoites
349
Trophozoites move to the ______ where they can _______ and _______
large intestine, live asymptomatically, invade intestinal epithelium
350
Trophozoites release a toxin that destroys ____, causing _____
epithelial cells, diarrhea
351
T / F: trophozoites may spread to additional sites in the body and cause secondary infection
T
352
Amebiasis diagnosis
observation of trophozoites in fresh, warm stools or cysts in ordinary stools, and serological tests
353
Toxoplasma gondii reservoir(s)
wild rodents, birds, small mammals, cats (kittens)
354
In toxoplasmosis, _____ are shed in animal feces
oocysts
355
In toxoplasmosis, when oocysts are ingested, they transform into _____
tachyzoites
356
T / F: tachyzoites cannot cross placenta and infect fetus
F
357
Toxoplasmosis diagnosis
serological tests
358
Toxoplasmosis clinical manifestations
- usually asymptomatic or mild symptoms
- encephalitis can be fatal in immunocompromised hosts
359
Antimicrobial chemotherapy
compounds that destroy pathogenic microbes or inhibit their growth within host
360
Most chemotherapeutic agents are
antibiotics
361
Antibiotics
microbial products or their derivatives that kill susceptible microbes or inhibit their growth
362
Who developed the concept of selective toxicity?
Paul Ehrlich
363
Prontosil red
dye with antibacterial properties only in vivo
364
T / F: prontosil red has effects in vitro
F
365
Ernest Duchesne observed that
certain molds kill bacteria
366
Who made the connection between Penicillium and the chemical penicillin?
Alexander Fleming
367
One of the products of prontosil red once broken down
sulfanilamide
368
Selman Waksman did what?
- isolated Streptomycin from Streptomyces bacteria
- discovered the antibiotic
369
Prodrug
drug is only active once metabolically processed and product of this is active in the body
370
Selective toxicity
ability of drug to kill or inhibit pathogen while not damaging host (or doing very little damage)
371
Therapeutic dose
drug level in the body required for clinical treatment
372
Toxic dose
drug level at which drug becomes too toxic for patient (produces side effects)
373
Therapeutic index
ratio of toxic dose to therapeutic dose
374
Side effects
undesirable effects of drugs on host cells
375
Narrow-spectrum drugs
attack only a few different pathogens
376
Broad spectrum drugs
attack many different pathogens
377
Bacteriocidal drug
kills microbes
378
Bacteriostatic drug
inhibits growth of microbes
379
Three ways to clinically determine the level of antimicrobial activity
1. dilution susceptibility tests
2. disk diffusion tests
3. the E-test (MIC and diffusion)
380
Minimal inhibitory concentration (MIC)
lowest concentration of drug that completely inhibits growth of pathogen
381
Disk diffusion tests
- agar plate is inoculated with bacteria being tested for
- antibiotic treated disks are placed on agar
- drug diffuses into agar, establishing concentration gradient
- zones of clearing can be observed
- larger zone of clearing = drug is efficient against bacteria
382
Kirby-Bauer method
- standardized method for disk diffusion test
- sensitivity/resistance determined from tables relating diameter of zone of clearing to efficacy
383
The E-test
- combination of disk diffusion method and MIC
- uses strip containing a gradient of an antibiotic
- intersection of elliptical zone of inhibition with strip indicates MIC
384
When would it not be helpful to prescribe a bacteriostatic drug?
if the patient has a weakened immune system
385
4 different targets of antimicrobial drugs
1. cell wall synthesis
2. protein synthesis
3. nucleic acid synthesis
4. metabolic antagonists (folic acid biosynthesis)
386
Penicillin mode of action (inhibition target)
- blocks the enzyme that catalyzes transpeptidation (formation of cross-links in peptidoglycan)
- inhibits cell wall formation
- leads to lysis of cell
387
T / F: penicillin only acts on growing bacteria
T
388
Most crucial feature of penicillin molecule is the
beta lactam ring
389
Penicillin's are often called
beta lactam antibiotics
390
Basic structure of penicillin
6-aminopenicillanic acid
391
Cephalosporins are structurally and funcitonally similar to
penicillin's
392
T / F: cephalosporins are not considered beta lactam antibiotics
F
393
No zone of inhibition in a disk diffusion indicates that the bacteria is _____ to the drug
resistant
394
A large zone of inhibition in a disk diffusion indicates that the bacteria is ____ to the drug
sensitive to
395
T / F: E-test is more quantitative than disk diffusion
T
396
In protein inhibition, many antibiotics bind specifically to the _____, or they
bacterial ribosome, inhibit a step in protein synthesis
397
Steps in protein synthesis that antibiotics might inhibit
- aminoacyl-tRNA binding
- peptide bond formation
- mRNA reading
- translocation
398
Tetracyclines are bacteriostatic or bacteriocidal?
bacteriostatic
399
Tetracyclines combine with _______, inhibiting
30S ribosomal subunit, binding of aminoacyl-tRNA molecules to the A site of the ribosome
400
Two main mechanisms of nucleic acid synthesis inhibition
- block DNA replication
- block transcription
401
Blocking of DNA replication
- inhibition of DNA polymerase
- inhibition of DNA helicase
402
Blocking of transcription
- inhibition of RNA polymerase
403
T / F: drugs that inhibit nucleic acid synthesis are highly selectively toxic
F
404
Quinolones act by inhibiting what?
bacterial DNA gyrase and topoisomerase II
405
Are quinolones:
- broad or narrow spectrum?
- bacteriostatic or bacteriocidal?
broad, bacteriocidal
406
Metabolic antagonists
molecules that are structurally similar to naturally occurring metabolic intermediates
407
How do metabolic antagonists work?
block functioning of metabolic pathways by competitively inhibiting the use of metabolites by key enzymes
408
Folic acid biosynthesis inhibitors are useful because
- bacteria must synthesize their own folic acid
- humans need to take up folic acid in their diet
- humans do not have the mechanisms bacteria have for synthesizing folic acid, so folic acid biosynthesis inhibitors don't effect human cells at all, but kill bacteria efficiently
409
Virus-specific enzymes and life cycle processes
- reverse transcriptase
- protease
- helicase
410
Tamiflu is a ________ inhibitor
neuraminidase
411
Anti-HIV drugs
- reverse-transcriptase inhibitors
- protease inhibitors
- fusion inhibitors
412
Reverse transcriptase inhibitors
- nucleotide/nucleoside analogs
- non-nucleoside RT inhibitors
413
Protease inhibitors (HIV)
mimic peptide bond that is normally attacked by the protease
414
Fusion inhibitors (HIV)
prevent HIV entry into cells
415
Why are antifungal and antiprotozoal drugs less available and less effective?
because it is difficult to target the cells causing the disease/infection without targeting human cells
416
Antifungal and antiprotozoal drugs often have _____ therapeutic index and are _____
low, toxic
417
Some antibiotics that inhibit ________ synthesis are used against protozoa
bacterial protein
418
Vaccine
preparation of microbial antigens used to induce protective immunity
419
Immunization
- result obtained when vaccine stimulates immunity
- body produces antibodies and activated T cells to protect host from future infection
420
Adjuvant
- substance mixed with antigens in vaccines to enhance the rate and degree of immunization
- can be any nontoxic material that prolongs antigen interaction with immune cells and stimulates the immune response to the antigen
421
A vaccine may consist of
- killed cells
- living, weakened (attenuated) microbes
- inactivated toxins (protein produced and secreted by microbe)
- purified microbial material or antigen
- mRNA
422
If a microbe is attenuated, it is
live but avirulent
423
If a microbe is inactivated it is
killed
424
Possible problems from whole cell vaccines
- immunosuppressed at risk of getting disease
- attenuated strains may revert to being virulent
- multiple boosters may be required
425
Typical forms of subunit vaccines include
- capsular polysaccharides
- surface antigens
- inactivated exotoxins (toxoids)
