Microbial Infectivity, Pathogenicity, and Virulence Flashcards
1
Q
Microbial entry can be used in two senses:
A
- Ingress of microorganisms into body cavities
- Penetration of microorganisms into deeper tissue after crossing the epithelial barrier
2
Q
It involves entry without crossing epithelial barriers.
A
Ingress of microorganisms into body cavities
3
Q
It involves microbes staying only on mucosal surfaces.
A
Ingress of microorganisms into body cavities
4
Q
It involves microbes passing through epithelia (single cell layers)
A
Penetration of microorganisms into deeper tissue after crossing the epithelial barrier.
5
Q
This is done with the help of insect bites, and cut surfaces.
A
Penetration of microorganisms into deeper tissue after crossing the epithelial barrier.
6
Q
The penetration of microorganisms into deeper tissue after crossing the epithelial barrier is done with the help of?
A
- insect bites
- cut surfaces
7
Q
Penetration of microorganisms into deeper tissue after
crossing the epithelial barrier is enabled by what?
A
receptors on the host cells
8
Q
It involved being enabled by receptors on the host cells.
A
Penetration of microorganisms into deeper tissue after
crossing the epithelial barrier
9
Q
What can burrow through the skin?
A
Parasites
10
Q
How do viruses bind to cell surfaces? by?
A
- attachment
- internalization
11
Q
Where do viruses bind into?
A
cell surfaces
12
Q
Damage from microbial infection is often the result of?
A
immune response
13
Q
Bacteria can also cause direct damage by producing what?
A
toxins
14
Q
Bacteria can also cause direct damage by producing toxins which cause:
A
- Helps bacteria to spread in tissues.
- Lysis of host cells
- Stops cell growth
- Exaggerate normal physiological conditions
15
Q
Bacterial toxin of Clostridium botulinum.
A
Botulinum toxin
16
Q
Bacterial toxin of Clostridium tetani
A
Tetanospasmin
17
Q
Bacterial toxin of Corynebacterium diphtheriae.
A
Diphtheria toxin
18
Q
Bacterial toxin of Escherichia coli
A
Heat-labile toxin
19
Q
Bacterial toxin of Vibrio cholerae
A
Cholera toxin
20
Q
Gene location of Clostridium botulinum
A
Bacteriophage
21
Q
Gene location of Clostridium tetani
A
Plasmid
22
Q
Gene location of Corynebacterium diphtheriae
A
Bacteriophage
23
Q
Gene location of Escherichia coli
A
Plasmid
24
Q
Gene location of Vibrio cholerae
A
Chromosome
25
Type of the toxin of Clostridium botulinum
Neurotoxin
26
Type of the toxin of Clostridium tetani
Neurotoxin
27
Type of the toxin of Corynebacterium diphtheriae
A-B ADP ribosylating
28
Type of the toxin of Escherichia coli
A-B ADP ribosylating
29
Type of the toxin of Vibrio cholerae
A-B ADP ribosylating
30
Anti-colonizing properties of the Host
- Sweep microbes away by liquid currents
- Kill microbes with host phagocytes
- Starve microbes for lack of needed nutrients
- Inhibit growth by secreting antimicrobial factors such as cationic peptides
31
What do bacteria do to overcome the host sweeping the microbes away by liquid currents.
Adhere to epithelial cells
32
What do bacteria do to overcome being killed with host phagocytes?
- Avoid being taken up
- Kill the phagocyte
33
What do bacteria do to overcome being starved of needed nutrients?
Derive needed nutrients from host cells
34
What do bacteria do to overcome having its growth inhibited by the host's antimicrobial factors? (i.e. cationic peptides)
Modify surface molecules (lipid A) to avoid cationic peptide binding
35
Example of bacteria overcoming being swept away by the host's liquid currents.
- Gonococci (they stick to the mucous membrane of the urethra)
36
What do gonococci do to avoid being swept away by the host's liquid currents?
Gonococci stick to the mucous membrane of urethra
37
Example of bacteria that avoid being killed by the host phagocytes by avoiding to be taken up.
Pneumococcus (It's surrounded by a slimy capsule that impairs uptake by neutrophils)
38
Example of bacteria that avoid being killed by the host phagocytes by killing it instead 🤪🔪
Certain streptococci (produce a toxin that punches holes in the neutrophil membrane).
39
What do pneumococci do to avoid being taken up by the host phagocytes?
They avoid being taken up using the slimy capsule surrounding them, impairing the uptake of neutrophils.
40
How to certain streptococci manages to kill the host phagocytes that initially aims to kill them instead?
They produce a toxin that punches holes in the neutrophil membrane.
41
Example of bacteria that overcome being starved for their needed nutrients.
Certain staphylococci (lyse red blood cells and use their nutrients hemoglobin as a source of iron)
42
Structural, Metabolic and other features of bacteria which promote disease development.
- Presence of capsule
- Intracellular replication
- Presence of high lipid content and mycolic acid in cell wall
- Exotoxin production
- Endotoxin production
- Tropism for specific tissue
- Localization and replication in sites with limited immunological responses
- Synergistic bacterial interaction
43
An example of bacteria with a bacterial characteristic of presence of capsule.
Bacillus anthracis
44
An example of bacteria with a bacterial characteristic of Intracellular replication
Brucella abortus
45
An example of bacteria with the presence of high lipid content and mycolic acid in cell wall.
Mycobacterium bovis
46
An example of bacteria with a bacterial characteristic of exotoxin production.
Clostridium tetani
47
An example of bacteria with a bacterial characteristic of endotoxin production.
Escherichia coli
48
An example of bacteria with a bacterial characteristic of Tropism for specific tissue.
Moraxella bovis
49
An example of bacteria with a bacterial characteristic of Localization and replication in sites with limited immunological responses.
Leptospira interrogans serovars
50
An example of bacteria with a bacterial characteristic of Synergistic bacterial interaction
- Fusobacterium necrophorum
- Arcanobacterium pyogenes
51
This bacterial characteristic can resist phagocytosis and multiply uninhibited in tissues.
Presence of capsule
52
This bacterial characteristic have the ability to survive within macrophages, making it an important virulence feature of brucellae.
Intracellular replication
53
This bacterial characteristic imparts resistance to environmental factors, detergents and disinfectants, and renders mycobacteria resistant to intracellular killing by macrophages.
Presence of high lipid content and mycolic acid in cell wall.
54
This bacterial characteristic involves the production of a potent neurotoxin, tetanospasmin that is responsible for the clinical signs of tetanus.
Exotoxin production
55
It acts as a pyrogen causing fever
Endotoxin
56
It causes intravascular coagulation and hypotensive shock.
Endotoxin
57
A bacterial characteristic with an endotoxin acting as a pyrogen causing fever as well as causing intravascular coagulation and hypotensive shock.
Endotoxin production
58
Bacterial characteristic that involves attachment to the conjunctiva of cattle leads to keratoconjunctivitis,
Tropism for specific tissue
59
Bacterial characteristic of spirochaetes localizing in the renal tubules and are shed in the urine of infected animals
Localization and replication in sites with limited immunological responses
60
An example of this is in ruminant foot lesions, Arcanobacterium pyogenes produces a growth factor for Fusobacterium necrophorum. And the production of Fusobacterium necrophorum facilitates survival of A. pyogenes at the site of infection.
Synergistic bacterial interaction
61
In ruminant fool lesions, _____ produces a growth factor for _____
- Arcanobacterium pyogenes
- Fusobacterium necrophorum
62
Leukotoxin production by ____ facilitates the survival of ____ at the site of infection.
- Fusobacterium necrophorum
- Arcanobactrium pyogenes
63
What does Fusobacterium necrophorum produces that facilitates the survival of Arcanobacterium pyogenes at the site of infection?
Leukotoxin
64
The number of microorganisms present in a patient must exceed a given ____ to cause disease.
threshold
65
The number of microorganisms present in a patient must exceed a given threshold to cause what?
disease
66
If the number of microorganisms is below that threshold, _____?
no signs and symptoms of disease will be apparent.
67
In some cases of microbial multiplication and clinical manifestations of disease, the numbers oscillate above and below the threshold, resulting in?
recurrent bouts of disease
68
The threshold of overt disease is not fixed by varies with?
with the physiological state of the host.
69
Variety of ways cell death comes in:
1. Direct action of cytolytic toxins
2. Activation of cell-killing white blood cells
3. Induction of programmed cell death
70
It is prominent in acute infections, however, some agents allow infected cells to survive to ensure their own survival.
Cell death
71
An example of bacteria that allow infected cells to survive to ensure their own survival.
Mycobacterium tuberculosis
72
It refers to immune mechanisms that are always present and available for action.
Innate immunity
73
2 Types of Microbial Immunity
1. Innate Immunity
2. Adaptive Immunity
74
They are usually classified as humoral or cellular.
Adaptive immune responses
75
Adaptive immune responses are usually classified as?
- humoral
- cellular
76
It leads to production of circulating antibodies such as Immunoglobulins (IgA, IgG, IgM) and Complement System (serum proteins)
Humoral immunity
77
Circulating antibodies examples of Humoral immunity
- Immunoglobulins (IgA, IgG, IgM)
- Complement System (serum proteins)
78
Examples of Immunoglobulin
- IgG
- IgM
- IgA
79
Examples of Complement system as circulating antibody
serum proteins
80
It causes production of immune system cells that destroy infected cells.
Cellular immunity
81
It is associated with chronic inflammation.
Cellular Immunity
82
Such responses can cause damage to the host cell.
- Innate Immunity
- Adaptive Immunity
83
The balance between positive factors that promote health, and negative factors that predispose to disease can determine the what?
the health and welfare status of animal populations
84
Stages of Infectious Disease
1. Encounter
2. Colonization
3. Spread / Penetration
4. Damage
5. Resolution
85
2 types of encounter of infectious disease
1. Endogenous
2. Exogenous
86
Major routes of transmission of Infectious Disease
- Direct contact
- Inhalation/ Droplet infection
- Ingestion/ fecal-oral route
- Inoculation/ trauma
- Transplacental
87
Conditions for infectious disease colonization
- Temperature and pH
- Inactivation of IgA (IgA protease)
- Production of adhesins, mucolytic enzymes.
88
Types of spreading of infectious disease
1. Direct extension
2. Destroying cells
3. Self-propulsion
89
Direct extension of infectious disease spread can be found where?
- Along tissue planes
- Veins
- Lymphatic vessels
90
Mechanisms of damage of Infectious Disease
- Bulk effect
- Toxin mediated
- Altered function of host systems
- Host response to infection
91
Resolution of Infectious Disease
- Host response
- Treatment
92
What should a cell wall contain to impart resistance to environmental factors, detergents and disinfectants, rendering mycobacteria resistant to intracellular killing by macrophages?
Mycolic acid
93
Attachment to the conjunctiva of cattle leads to what?
Keratoconjunctivitis
94
The ability of a microbe to damage a host.
Pathogenicity
95
This is caused by a pathogen or organism known as "virulence"
Degree of pathogenicity/ Damage
96
Pathogen or organism that causes damage / degree of pathogenicity
Virulence
97
These are traits that confer pathogenicity.
Virulence Factors
98
Virulence factors include:
- Adhesins
- Toxins
- Capsules
99
In bacteria, they are only expressed when they are required.
Genes
100
It allows the bacteria to attach to the host cell membrane, resisting flushing action of body fluids.
Adhesins
101
2 General Types of Toxins
1. Exotoxins
2. Endotoxins
102
These are proteins produced inside pathogenic bacteria, most commonly gram-positive bacteria, as part of their growth and metabolism.
Exotoxins
103
These are secreted or released into the surrounding medium following lysis.
Exotoxins
104
These are lipid portions of lipopolysaccharides (LPSs) that are part of the outer membrane of the cell wall of gram-negative bacteria.
Endotoxins
105
They are liberated when the bacteria die and the cell wall breaks apart.
Endotoxins
106
Where do microbes stay after their ingress straight into the body cavities?
mucosal surfaces
107
They may be classified as exotoxin and endotoxin
Toxins
108
Bacterial source of exotoxin
Mostly from gram-positive bacteria
109
Bacterial source of Endotoxin
Gram-negative bacteria
110
Its relation to microorganism is that it's a metabolic product of growing cell.
Exotoxin
111
The toxin is present in LPS in outer membrane of cell wall and released with destruction of cell or during cell division.
Endotoxin
112
Its chemistry include proteins, that are usually with two parts (A-B)
Exotoxin
113
Chemistry of Endotoxin?
Lipid portion (lipid A) of LPS of outer membrane
114
It is specific for a particular cell structure or function in the host.
Exotoxin
115
It is has a general effect on body, such as fever, weaknesses, aches, and shock; They all produce the same effects.
Endotoxin
116
Its heat stability is unstable and can usually be destroyed at 60-80 degrees Celsius (except staphylococcal enterotoxin)
Exotoxin
117
It is stable with heat and can withstand autoclaving (121 degrees Celsius for 1 hour)
Endotoxin
118
Its toxicity is high
Exotoxin
119
Its toxicity is low
Endotoxin
120
It is not fever-producing
Exotoxin
121
It is fever-producing.
Endotoxin
122
It can be converted to toxoids to immunize against toxin ; neutralized by antitoxin.
Exotoxin
123
It is not easily neutralized by antitoxin; therefore, effective toxoids cannot be made to immunize against toxin.
Endotoxin
124
Its lethal dose is small
Exotoxin
125
Its lethal dose is considerably large
Endotoxin
126
Its representative diseases are
- Gas gangrene
- Tetanus
- Botulism
- Diphtheria
- Scarlet Fever
Exotoxin
127
Its representative diseases are:
- Typhoid fever
- Urinary tract infections
- Meningococcal meningitis
Endotoxin
128
It ingests a gram-negative bacterium.
Macrophage
129
The bacterium is degraded in a what, releasing endotoxins that induce macrophage to produce cytokines IL-1 and TNF-α
Vacuole
130
The cytokines are released into the bloodstream by the macrophages, through which they travel to?
the hypothalamus of the brain
131
The cytokines induce the hypothalamus to produce ____, which reset the body's thermostat to a higher temperature, producing fever.
prostaglandins
132
What happens when the cytokines induce the hypothalamus to produce prostaglandins?
Reset the body's "thermostat" to a higher temperature, producing fever
133
What does the capsule interfere with to inhibit phagocytic engulfment? (to bind to complement and antibodies)
Opsonization
134
It is found on the capsule to bind to IgG to act as "immune disguise" to inhibit phagocytic engulfment.
Protein A
135
To inhibit phagocytic engulfment, Protein A found on the capsule binds to IgG antibody to act as?
"immune disguise"
136
Genes involved in disease often appear as?
groups
137
The term for when genes involved in disease appear as groups.
Pathogenicity Islands
138
It can be a source of genes encoding virulence.
Bacteriophages
139
The ____ are chromosomal and can also be in plasmids
Pathogenicity islands
140
They can integrate genes into microbial chromosomes.
Bacteriophages
141
Importance of Studying Virulence Factors
- The use of genomic techniques has led to the identification of new virulence factors.
- Understanding pathogenesis
- Prevalence in clinical bacterial isolates
- Knowledge about virulence factors may serve as targets for new therapies.
142
Identification of _____ is necessary for diagnosis of infectious diseases.
Etiological agent
143
Accuracy and validity of a laboratory examination is highly dependent on:
- Specimen selection
- Specimen collection
- Specimen transport
- Submission of samples
144
Samples should be taken from a patient before what?
antimicrobial therapy
145
It should be avoided or minimized.
Contamination
146
It may be required in the laboratory diagnosis of bacterial infection.
Transport media
147
Examples of Transport media.
- Amie's transport media
- Stuart's transport media
148
_____ of samples may be required in laboratory diagnosis of bacterial infection.
Refrigeration
149
In laboratory diagnosis of bacterial infection, samples should be:
1. in leak-proof containers
2. labelled properly
3. transported with secondary/ tertiary packaging
150
It contains charcoal that prolongs the viability of microorganisms.
Amie's transport media for swabs.
151
Laboratory Diagnosis being done for bacterial infection:
1. Examination of stained smears
2. Cultural and biochemical characteristics
3. Biochemical techniques
4. Serology
5. Next generation sequencing (NGS)
6. MALDI-TOF
152
It is done using blood agar and MacConkey agar plates (24-48 incubation at 37 deg Celsius)
Routine isolation
153
Examples of Biochemical techniques
- Catalase
- Oxidase test
154
It is based on nucleic acid detection.
Molecular techniques
155
It is the collection of two serum samples, 2 weeks apart.
Serology
156
The four-fold rise in _____ demonstrates recent infection in Serology.
Antibody titer
157
It can sequence the DNA of bacteria (millions of DNA simultaneously)
Next generation sequencing (NGS)
158
What does MALDI-TOF stands for?
Maltrix-Assisted Laser Desorption/Ionization Time-of-Flight
159
It is a technique that uses a laser to measure the mass of molecules in a sample
Mass Spectrometry
160
It can identify bacterial isolates using their mass.
Mass Spectrometry
