Midterm Flashcards

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1
Q

Some characteristics of Microbes include:

A

microscopic, phylogenetic diverse, metabolic diverse, can be beneficial, and can live in a symbiotic relationship with us

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2
Q

Microbiota means

A

collection of microbes colonizing our bodies without normally causing disease

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3
Q

Microbiome means

A

total number of microbial genomes in a defined environment

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4
Q

Resident Microbiota:

A

part of the normal microbiota throughout life; mostly commensal

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5
Q

Transient microbiota:

A

remain in/on the body for short period (in competition from other organisms, and is eliminated by the body’s defense cells)

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6
Q

Mutualism/Syntropy

A

all members benefit from the relationship

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7
Q

Commensalism

A

one member benefits, the other is unaffected

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8
Q

Amensalism

A

one member is harmed, the other is unaffected

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9
Q

Parasitism

A

one member benefits, the other is harmed

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10
Q

The two classes of microbes are:

A

1) Cellular microbes; 2) Acellular microbes

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11
Q

Characteristics of Acellular Microbes

A

Without a cell (Viruses, viroid, prions)
Require other organism to reproduce
Simple structures
Wide variety of shapes
Are ultramicroscopic

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12
Q

Characteristics of Cellular Microbes - Prokaryotes

A

Archaea and Bacteria
Common shapes (spheres, rods, spirillum, spirochete, vibrio)
Lack nucleus and membrane-bound organelles
<1.0 um in diameter

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13
Q

Key organelles of the Prokaryotic cell (7)

A
  1. Flagellum
  2. Ribosome
  3. Nucleoid
  4. Plasma membrane
  5. Cell wall
  6. Cytoplasm
  7. Glycocalyx
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14
Q

Characteristics of Cellular microbes - Eukaryotes

A

Algae, Protozoa, Fungi
Wide variety of morphology
5-100 um in diameter
Have a nucleus and internal membrane-bound organelles
Often multiple chromosomes

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15
Q

Key organelles of the Eukaryotic cell (13)

A
  1. Nucleolus
  2. Nuclear envelope with pores
  3. Ribosome
  4. Lysosome
  5. Mitochondrion
  6. Centriole
  7. Golgi
  8. Rough ER
  9. Smooth ER
  10. Cytoplasmic membrane
  11. Cytoskeleton
  12. Vesicles
  13. Cilium
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16
Q

Primary Pathogens …

A

cause a disease in healthy people; infection get worse by a weak or immature immune system

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17
Q

Opportunistic Pathogens …

A

only cause diseases when given opportunity

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18
Q

Obligate Pathogens …

A

require a host to fulfil their cycle

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19
Q

Facultative Pathogens …

A

host is only one of the niches they can exploit to reproduce

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20
Q

What are the two categories for the Host Range of pathogens?

A

Narrow (can only effect one); Broad (can infect many)

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21
Q

Pathogenicity:

A

pathogens potential to cause infection or disease

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22
Q

Virulence:

A

degree or severity of disease

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23
Q

Highly virulent pathogens…

A

always lead to a disease state

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24
Q

Pathogens with low virulence …

A

more likely to result in mild disease states

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25
Q

Continuum:

A

from avirulent to highly virulent

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26
Q

Fatality rates =

A

Number of deaths

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27
Q

The measures of Virulence are…

A

Medium Lethal Dose (LD50); Medium infectious dose (ID50)

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28
Q

LD50:

A

number of pathogens required to kill 50% of an experimental group of animals hosts

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29
Q

ID50:

A

number of pathogens needed to cause disease signs in 50% of an experimental group of hosts

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30
Q

Disease:

A

disruption of the normal structure or function of any body part, organ or system

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31
Q

Infectious disease:

A

disease caused by a pathogen that caused a disruption of the normal structure of function

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32
Q

Infection:

A

condition of a successful multiplication/colonization of a host by a microorganism

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33
Q

Sign:

A

something that can be observed by a person examining a patient

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34
Q

Symptom:

A

something that can be felt only by the patient

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35
Q

Syndrome:

A

collection of signs and symptoms that signify a particular disease

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36
Q

Asymptomatic/Subclinical

A

infections lack symptoms but may still have signs of infection

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37
Q

Stages of Pathogenesis

A

Exposure, Adhesion, Damage or invading of host cells, infection, transmission

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38
Q

Invasion:

A

ability of pathogens to enter (invade) host cells

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39
Q

Invasiveness:

A

ability of a bacterial pathogen to rapidly spread through tissue

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40
Q

Koch’s postulates (1884):

A

systemic approach to confirm causative relationships between a disease and a pathogen

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41
Q

Molecular Koch’s postulates (1988)

A

inactivation of genetic factors results in diminishing virulence of the pathogen

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42
Q

Adapting Koch’s postulates (2016)

A

disease causation must take microbial interactions into account

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43
Q

Diseases can be classified in a number of ways (4)

A

Contraction of Disease
Pattern of infection and body spread
Longevity and severity of the developed disease
Outcome of the disease - mortality and morbidity

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44
Q

Communicable diseases:

A

infection spread between persons by direct or indirect mechanisms

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45
Q

Contagious diseases:

A

communicable diseases that is easily spread

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46
Q

Non-communicable diseases:

A

infection not spread between persons

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47
Q

Iatrogenic diseases;

A

infection contracted via a medical procedure

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48
Q

Nosocomial disease

A

infection acquired during a hospital stay

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49
Q

Zoonotic disease

A

infection is transmitted from animals to humans

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50
Q

Pattern of infection - Localized

A

infection confined to a body area

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51
Q

Pattern of infection - systemic

A

widespread infection in many body systems

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52
Q

Pattern of infection - Focal

A

infection site serves as source of the pathogen for a disease at another body site

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53
Q

Pattern of infection - mixed

A

multiple species contribute to infection

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54
Q

Pattern of infection: primary-secondary

A

Primary: infection in a previously healthy individual
Secondary: successive infection which can occur due to weakened immunity

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55
Q

Bacteremia

A

presence of bacteria in blood, usually transient, no replication

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56
Q

Septicemia

A

presence and replication of bacteria in blood

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57
Q

Viremia

A

presence of viruses in the blood

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58
Q

Toxemia

A

presence of toxins in the blood

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59
Q

Acute

A

pathological changes develop rapidly over hours or days

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60
Q

Chronic

A

pathological changes develop gradually over months or years and are slow to resolve

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61
Q

sub-acute

A

pathological changes take longer to develop than acute but arise more quickly than chronic

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62
Q

Latent

A

pathological changes appear a long time after infection, pathogen dormant

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63
Q

Morbidity

A

existence of a disease state and the rate of incidence of the disease

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64
Q

Mortality

A

measure of how many patients have died from a disease

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65
Q

5 stages of infection (in order)

A

Incubation Period
Prodromal Period
Illness
Decline
Convalescence

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66
Q

Viruses are

A

Obligate pathogens and can infect every organism

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67
Q

Narrow host range

A

most viruses infect only particular host’s cells

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68
Q

Broad host range

A

Generalists infect many kinds of cells or many different hosts

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69
Q

Non-enveloped viruses enclose by …

A

the capsid

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70
Q

enveloped viruses are wrapped in

A

hosts plasma membrane

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71
Q

Prokaryotic host infections via . . .

A

bacteriophages

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72
Q

Virulent phages trigger . . .

A

bacterial lysis (lytic cycle)

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73
Q

Temperate phages integrate into . . .

A

host genome

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74
Q

Life cycle of viruses (5 steps)

A

Attachment
Penetration
Uncoating
Replication
Assembly and release

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75
Q

Virion abundance in lytic life cycle (3 steps)

A

Inoculation
Eclipse
Burst

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76
Q

Burst size

A

number of virions

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77
Q

Viral titer

A

number of virions per volume

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78
Q

Latency

A

animal viruses remain dormant in host cells

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79
Q

Hantavirus pulmonary syndrome

A

rodent-borne disease infecting the lower respiratory system

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80
Q

Rapid mutation leads to antigenic drift … what is antigenic drift?

A

a population of viruses no longer recognized by host antibodies

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81
Q

Epidemiology examines what?

A

infectious diseases

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82
Q

Population-centered analyses focused on …

A

morbidity

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83
Q

total morbidity is

A

the number of diseased individuals

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84
Q

Incidence is

A

the number of new cases of a disease in that location over a specific time

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85
Q

Prevalence is

A

the total number of cases of a disease in a given location regardless of when the first case developed

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86
Q

Sporadic disease…

A

few cases within an area

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87
Q

endemic disease …

A

constant presence in a community

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88
Q

epidemic disease…

A

development of many cases in a community in a short time (outbreak)

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89
Q

pandemic disease …

A

worldwide spread of disease

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90
Q

Reproduction number (R0) defines…

A

contagiousness

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91
Q

when R0 <1, what happens?

A

disease will disappear

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92
Q

when R0 = 1, what happens?

A

endemic

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93
Q

when R0 > 1, what happens?

A

disease will spread

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94
Q

Spread can be modified by measures leading to the _______ __________ ________

A

Effective reproduction number (R)

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95
Q

5 Types of Pandemics discussed in class…

A

Black death
Smallpox
Spanish Flu
HIV/AIDS
COVID-19

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96
Q

Who is the father of Epidemiology?

A

John Snow (1813-1858)

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97
Q

Common source spread is a

A

single-source for all of the individuals infected

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98
Q

Incubation period is

A

time from exposure to the causative agent until the first symptoms develop characteristic for each disease agent

99
Q

Propagated Spread

A

direct or indirect person-to-person contact with the disease source

100
Q

3 types of agencies that track global diseases

A

Global Health Security Agenda (GHSA)
Health Canada
WHO

101
Q

Chain of Infection (6 links)

A

Pathogen
Reservoir
Portal of Exit
Mode of Transmission
Portal of Entry
Susceptible Host

102
Q

Three types of Reservoirs

A

Human Carriers
Animal Reservoirs
Environmental Reservoirs

103
Q

Passive Carriers

A

individuum is not infected; instead transfers pathogen mechanically to another host

104
Q

Active Carriers

A

individuum with or without signs or symptoms (asymptomatic or immune to the disease)

105
Q

Zoonoses

A

diseases that normally afflict animals or insects but can be transferred to humans

106
Q

Environment Reservoirs

A

presence of microorganisms in soil, water, air and food

107
Q

Three groups of Transmission

A

Contact transmission
Vehicle transmission
Vector transmission

108
Q

Direct contact transmission

A

person-to-person, involved body contact between hosts

109
Q

Vertical transmission

A

example, from mother to child during pregnancy and birth

110
Q

Horizontal transmission

A

kisses between hosts

111
Q

Droplet transmission

A

spread of pathogens in droplets of mucus by exhaling, coughing, and sneezing

112
Q

Indirect contact transmission

A

pathogens are spread from host to host by inanimate object called fomites

113
Q

Vehicle transmission of pathogens is through things such as…

A

water, food and air

114
Q

Waterborne transmission

A

spread of pathogens via water; important for many gastrointestinal diseases

115
Q

Airborne transmission

A

spread of pathogens via aerosols

116
Q

Foodborne transmission

A

spread of pathogens in and on foods

117
Q

Bodily fluid transmission

A

bodily fluids such as blood, urine and saliva can carry pathogens

118
Q

Vectors

A

living organisms that can transmit infectious diseases

119
Q

Mechanical vectors

A

an animal that carries a pathogen from one host to another without being infected itself

120
Q

Biological vectors

A

transmit pathogens and serve as host for some stage of the pathogen’s life cycle

121
Q

Disease vectors mainly belong to two classes of arthropods:

A

Arachnida and Insecta

122
Q

Prominent vector-borne diseases

A

Malaria, Dengue, Chagas disease, leishmaniasis and schistosomiasis

123
Q

Ways to break the chain of infection are

A

controlling or eliminating agent at the source of transmission; protect portals of entry; increase host’s defenses

124
Q

Physical methods of Control - heat (examples)

A

boiling, dry-heat oven, incineration, autoclave, pasteurization

125
Q

Physical methods of control - cold (examples)

A

Refrigeration, freezing

126
Q

Physical methods of control - pressure (examples)

A

High-pressure processing, hyperbaric oxygen therapy

127
Q

Physical methods of control - desiccation (examples)

A

Simple desiccation, reduce water activity, lyophilization

128
Q

Physical methods of control - Radiation (exmaples)

A

ionizing radiation, nonionizing radiation

129
Q

Physical methods of control - Sonication (example)

A

sonication

130
Q

Physical methods of control - filtration (examples)

A

HEPA filtration, membrane filtration

131
Q

High-level germicides . . .

A

kill vegetative cells, fungi, viruses and endospores, and can lead to sterilization

132
Q

intermediate-level germicides . . .

A

cannot kill all viruses and are less effective against endospores

133
Q

Low-level germicides . . .

A

kill vegetative cells and some enveloped viruses, but are ineffective against endospores

134
Q

methods leading to microbial death (ends with what suffix)

A

-cide or -cidal

135
Q

Methods leading to microbial growth inhibition (ends with what suffix)

A

-stat or -static

136
Q

Degree of control is described by a

A

death curve

137
Q

In-use test determines the . . .

A

effectiveness of a chemical disinfectant for a microbe

138
Q

Disk-diffusion methods tests …

A

the effectiveness of a chemical disinfectant against a particular microbe

139
Q

The white (or clear) area surrounding the microbial disk is called

A

the zone of inhibition

140
Q

BSL-I has what severity

A

little to no pathogenic potential

141
Q

BSL-II has what severity

A

greater pathogenic potential but vaccines and treatments are readily available

142
Q

BSL-III has what severity

A

serious or lethal human disease for which vaccines and treatments may be available

143
Q

BSL-IV has what severity

A

extremely dangerous pathogens for which no treatments or vaccines are available

144
Q

Bacteria reproduce fast and efficient asexually; three main methods of this are?

A

Binary fission
Snapping division
Budding

145
Q

Generation time means

A

doubling time

146
Q

Gram-positive cell wall has _________ layers of peptidoglycan

A

multiple

147
Q

What two acids are covalently linked to peptidoglycan

A

Teichoic and lipoteichoic acids

148
Q

Gram-positive cell wall has an outer membrane.
True or False?

A

False, it often has a protein layer called the Surface (S)-layer and glycosyl-chains

149
Q

Surface (S)-layer is

A

a self-assembly of identical subunits into crystalline lattices with distinguished by their symmetry

150
Q

Gram-negative cell wall is made up of a

A

thinner layer of peptidoglycan with a bilayer membrane (containing lipopolysaccharides)

151
Q

Murein lipoproteins stabilize __________ ________ and _____ it to the peptidoglycan

A

outer membrane; anchor

152
Q

Lipopolysaccharide has three core parts, these are?

A

Lipid A, Core, O-antigen

153
Q

LPS is known as an

A

endotoxin

154
Q

Toxin

A

substances that contribute to pathogenicity

155
Q

Exotoxin

A

are secreted out of the cell during cell life

156
Q

Endotoxin

A

are released upon cell lysis

157
Q

A-active subunits cause

A

changes in host/toxic

158
Q

B-binding binds to

A

host cell receptors and delivers A subunits to the host range

159
Q

Sporulation

A

asymmetric cell division; engulfment by the mother cell, synthesis and formation of cortex and coat, maturation and lysis of mother cell

160
Q

Glycocalyx is comprised of

A

capsule and slime layer

161
Q

Capsule is

A

well-defined firmly cell-bound polysaccharide layer

162
Q

Slime layer is

A

loosely associated with cell

163
Q

The function of glycocalyx is

A

protection against immune system (anti-phagocytotic factors)

164
Q

4 types of anthrax

A

Cutaneous
Inhalation
Gastrointestinal
Injection

165
Q

Plasma membrane disruption

A

toxins form pores in host cell membranes that cause cell leakage

166
Q

Cytoskeleton alterations

A

toxins modulate hosts actin polymerization and thereby cell shape

167
Q

Protein synthesis disruption

A

Toxins prevent eukaryotic protein biosynthesis

168
Q

Cell cycle disruption

A

toxins stop or stimulate host cell division

169
Q

Signal transduction disruption

A

toxins subvert second messenger pathways

170
Q

cell-cell adhesion disruption

A

toxins cleave proteins that bind host cells together

171
Q

Vesicle trafficking

A

toxins modulate vesicle traffic and fusion inside host cells

172
Q

Exocytosis

A

toxins paralyze movement of cytoplasmic vesicles

173
Q

Superantigens

A

stimulates excessive activation of immune system cells

174
Q

Virulence factors (definition)

A

factors which cause a severe disease state in a susceptible host

175
Q

Types of virulence factors

A

Toxins, degradative enzymes, and invasins

176
Q

Bacterial invasion has two types, these are

A

zipper and trigger

177
Q

Zipper bacterial invasion is defined as

A

surface proteins bind host receptors that signal phagocytic uptake

178
Q

Trigger bacterial invasion is defined as

A

injection of bacterial effectors to induce pinocytosis

179
Q

Injectosome

A

needle for injections of cytotoxins (termed effector proteins)

180
Q

Filamentous adhesins are

A

appendages extending from bacterial surfaces presenting an adhesion at its distal end

181
Q

examples of filamentous adhesins include:

A

fimbriae, pili, flagella

182
Q

Pattern of movement in flagella results from

A

alternating swimming and tumbling - biased random walk

183
Q

Actin-based motility inside host cells spread through

A

cytoplasm, cellular exit and enter neighboring cells

184
Q

Niche factors are

A

factors of a pathogen can be a colonization factor of commensal

185
Q

Niche factors include:

A

adhesion factors
antiphagocytic factors

186
Q

Three main forces have been found to shape genome evolution:

A

gene gain; gene loss; gene change

187
Q

Prokaryotic pathogens reproduce . . .

A

asexually

188
Q

Mechanisms of Horizontal gene transfer are

A

Transformation, Transduction, Conjugation

189
Q

Transformation is:

A

uptake, uptake, integration and functional expression of naked fragments of extracellular DNA

190
Q

Transduction is:

A

bacteriophages transfer bacterial DNA from a previously infected donor cell to the recipient cell

191
Q

Pseudolysogeny:

A

Phage genome fails to replicate (as in lytic production) or become established as a prophage

192
Q

Phage assembly is perfect.
True or false?

A

False; phage assembly is not perfect.

193
Q

Lysogenic conversion means

A

process with mutually benefit for phage and host

194
Q

Conjugation:

A

direct DNA transfer between donor and recipient cell

195
Q

Once a new piece of DNA has entered a cell, what happens to it?

A
  1. New DNA capable of autonomous replication (plasmid)
  2. New DNA not capable of own replication
    Then recombination
196
Q

Recombination is when

A

two DNA molecule exchange portions by breaking and reforming their sugar phosphate backbones

197
Q

Homologous recombination

A

two recombining molecules have long stretches of sequence homology

198
Q

Site Specific recombination

A

short sequence motives recognized by a site-specific recombinases

199
Q

Bacterial genomes comprise of:

A

stable regions: core genome
variable regions: flexible gene pool

200
Q

Pathogens and commensals share habitats with:

A

bacteriophages, amoeba, insects, annelids, fungi, plants and mammals

201
Q

When diagnosing a patient; what are important things to gather?

A

medical history, family and social history, physical examination and the signs and symptoms

202
Q

What should be labelled on a sample collection?

A

patient name, medical record number, patient location, collection date and time, specimen type/source, test required, name of ordering physician

203
Q

identification of microbes often starts with …

A

isolation or visualization

204
Q

What is a limitation of identification by colony morphology?

A

Morphology is media-dependent

205
Q

Complex media supports …

A

growth of most aerobic and facultative aerobic organisms

206
Q

Enriched media contains …

A

specific growth factors enhancing the growth of certain bacteria

207
Q

Selective media allows …

A

some organisms to grow while inhibiting others

208
Q

Differential media allows . . .

A

for identification of organism based on their growth and appearance on the media

209
Q

Samples from sterile body sites should be done (grown) on. . .

A

complex media or enriched media

210
Q

Samples of collection site with normal microbiota should be grown on …

A

selective media

211
Q

Most pathogenic microbes can be detected in vitro in an overnight culture under aerobic conditions. What are some exceptions . . .

A

anaerobic bacteria
slow-growing bacteria
fastidious bacteria
obligate intracellular bacteria

212
Q

Acidic dyes stain …

A

alkaline structures

213
Q

Basic dyes stain …

A

acidic structures

214
Q

Simple stains are composed of

A

single basic dye

215
Q

Differential stains are used to

A

distinguish between different cells, chemicals or structures

216
Q

Special stains are used to

A

identify specific microbial structures

217
Q

Neisseria meningitides characteristic

A

Diplococcus, gram-negative

218
Q

Streptococcus pneumonia characteristcs

A

diplococcus, gram-positive

219
Q

Haemophilus influenza characteristics

A

rod, gram-negative

220
Q

Escherichia coli characteristics

A

rod, gram-negative

221
Q

Chocolate agar

A

extreme nutrient-rich media with lysed blood cells

222
Q

Blood agar

A

rich medium

223
Q

Hektoen agar

A

selective/differential media to recover gram-negative all-rounders

224
Q

Analytical profile index (API) is

A

biochemical panel for identification of clinical relevant bacteria

225
Q

API is interpreted as a …

A

dichotomous key

226
Q

Most widely used molecular method in the clinical laboratory:

A

Nucleic acid Amplification tests (NAAT) (like PCR)

227
Q

Goal of PCR

A

produce copies of a particular DNA fragment for sequencing and visualization of mutagenesis

228
Q

Key ingredients of PCR

A

DNA polymerase, primers, nucleotides, buffer and template

229
Q

PCR have three cycles (steps), these are:

A

Denaturation, Annealing, Extension

230
Q

When direct detection of a pathogen is not possible, what may help with diagnosis of acute infections?

A

Detection of specific antibodies or microbial antigens

231
Q

Immunological tests are …

A

culture-independent

232
Q

Agglutination:

A

process that occurs if an antigen is mixed with its corresponding antibody present in body fluids

233
Q

Direct agglutination:

A

antibodies react with antigens on cells or acellular particle such as viruses and form agglutinates

234
Q

Indirect agglutination:

A

antibodies or antigens are bound to latex beads forming larger agglutinates in presence of respective antigen or antibody

235
Q

Hemagglutination assay:

A

patient’s serum can be directly used to detect a specific pathogen

236
Q

Enzyme-linked immunosorbent assays (ELISAs) use . . .

A

antibodies to detect the presence of antigens or vice versa

237
Q

Direct ELISA:

A

antigens are immobilized in the well of a microtiter plate

238
Q

Indirect ELISA:

A

quantifies antigen-specific antibody rather than antigen

239
Q

Point-of-Care devices

A

obtain diagnostic results in a short time

240
Q

Characteristics of POC devices

A

Speed, portability, convenience

241
Q

Examples of POC devices

A

pregnancy, blood sugar, cholesterol, drugs, infectious diseases

242
Q

Good POC have what two attributes

A

High sensitivity, high specificity

243
Q

5 methods of laboratory diagnosis (for identification of microbes);

A

Conventional techniques;
Biochemical methods based on semiautomatic and automatic systems;
Molecular-biological techniques;
Immunological techniques;
Mass spectrometry (MS)-based semiautomatic methods.

244
Q

Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry:

A

generate organism specific mass spectral fingerprints; allows species identification; can be done in less than an hour