Microbiology Flashcards
(116 cards)
1
Q
What percentage of the world’s deaths are caused by infections?
A
33%
2
Q
What are the two major emerging threats related to infection in high-income countries?
A
- Healthcare-associated infections
2. Antibiotic resistance
3
Q
List the four major types of micro-organisms which cause human infectious disease
A
- Viruses
- Bacteria
- Fungi
- Protists
4
Q
In 1876, who established that microbes can cause disease?
A
Robert Koch
5
Q
Koch’s postulates: #1
A specific ___________ is always associated with a given disease.
A
microorganism
6
Q
Koch’s postulates: #2
The microorganism can be __________ from the diseased animal and __________ in pure culture in the laboratory.
A
isolated, grown
7
Q
Koch’s postulates: #3
The cultured microbe will cause __________ when transferred to a healthy animal.
A
disease
8
Q
Koch’s postulates: #4
The _______ type of microorganism can be isolated from the newly _________ animal
A
same, infected
9
Q
Do prokaryotic cells have a nucleus?
A
No
10
Q
Do prokaryotic cells have internal membranes?
A
No
11
Q
How is prokaryotic DNA organised?
A
One circular chromosome in a nucleoid
12
Q
Which type of cells contain extensive and specialised organelles- prokaryotic or eukaryotic?
A
Eukaryotic
13
Q
How are bacteria named?
A
Genus, then species
14
Q
In the strain of E.coli known as “0157:H7,” what do the “O” and “H” refer to?
A
Different antigens
15
Q
Bacteria are most helpfully classified by shape and _________
A
staining
16
Q
The ability to take up stain is based on the __________ and accessibility of cell wall ____________________.
A
thickness, peptidoglycans
17
Q
List the four layers encapsulating gram negative prokaryotic cells (from outermost to innermost layer)
A
- Capsule
- Outer membrane
- Peptidoglycan layer
- Plasma membrane
18
Q
Which two layers make up the bacterial cell wall?
A
The outer membrane and the layer of peoptidoglycan
19
Q
Gram-positive bacteria have a uniformly dense cell wall consisting primarily of
A
peptidoglycan
20
Q
Which types of bacteria have a very this peptidoglycan layer and an outer membrane?
A
Gram negative bacteria
21
Q
An __________ is a toxic, heath stable lipopolysaccharide substance present in the outer membrane of gram negative bacteria that is released from the cell upon lysis.
A
Endotoxin
22
Q
What type of bacteria have lipopolysaccharide?
A
Gram negative bacteria
23
Q
Gram negative bacteria have what toxic substance in their outer membrane layer?
A
Lipopolysaccharide
24
Q
Peptidoglycans have 3-5 amino acid proteins, which is significant because it makes them resistant to
A
enzymatic destruction
25
What kind of enzymes assist with cross-linking of peptidoglycans?
Transpeptidase enzymes
26
Which class of antibiotic prevents the cross-linking of peptides by binding bacterial transpeptidases?
Beta lactam antiobiotics (penicillin,s cephalosporins, carbapenems)
27
Which class of antibiotic is only effective in gram positive bacteria?
Glycopeptides (e.g. Vancomycin)
28
Bacterial capsules are made up of
polysaccharides
29
What is the medical importance of the bacterial capsule?
It "hides" the immunogenic cell wall
30
Immunity requires antibodies to the _______
capsule
31
Which part of the bacteria confers virulence?
The capsule
32
Mobile genetic elements code for ________ and antibiotic resistent _______.
toxins, genes
33
These are DNA sequences that are able to move location in the genome
Transposons
34
Circular "extrachromosmal" DNA that replicates independently.
Plasmids
35
This type of independently replicating DNA can be passed down to progeny or transmitted between bacteria
Plasmids
36
Non-replicating, dormant form of bacteria that are resistant to drying, temperature, disinfection, and digestion.
spores
37
Bacillus spp and Clostridium spp are two examples of bacteria that can form ________
spores
38
Name four examples of bacteria virulence factors:
| 1. ___________ molecules
adhesion
39
Name four examples of bacteria virulence factors:
| 2. ___________ to degrade host proteins
Enzymes
40
Name four examples of bacteria virulence factors:
| 3. Degrade ___________ mediators
immune
41
Name four examples of bacteria virulence factors:
| 4. _________ host cells
Lyse
42
Gene regulation - bacterial growth. Describe what happens in the lag phase of bacterial growth
- no increase in cell numbers
- Adjustment to new environment
- Gene regulation
43
Gene regulation - bacterial growth. Describe what happens in the log or exponential phase of bacterial growth
- Cell doubling
- Slope of curve = growth rate of that organism in that environment
- This is where the person would have either a superficial infection, or bacteraemia
44
Gene regulation - bacterial growth. Describe what happens in the stationary phase of bacterial growth
- Nutrients become depleted
- Metabolites build up
- Divison stops
- Gene regulation
- ABSCESS
45
Gene regulation - bacterial growth. Describe what happens in the death phase of bacterial growth
- Exhaustion of resources
| - Toxicity of environment
46
Bacteria are most helpful classified by ________ and staining
shape
47
Shape of Streptococcus and Enterococcus bacteria?
Coccus/cocci = round
48
Shape of Enterobacter spp?
Bacillus/bacilli = rod-shaped; long
49
Shape of Vibrio cholera?
Vibrio = comma-shaped
50
Shape of Coccobacillus?
In between Coccus and Bacillus- oval
51
Shape of Campylobacter jejuni (spirilium)?
Rigid spiral
52
Shape of spirochete?
Coiled spirals
53
What are the three requirements for successful viral infection?
1. Enough virus
2. Cells accessible, susceptible, and permissive
3. Local antiviral defense absent or overcome
54
List the 5 types of viral transmission:
1. Horizontal (between members of the same species)
2. Iatrogenic (Due to activity of a health care worker)
3. Nosocomial (Infection occurs in hospital)
4. Vertical (Transfer of infection between parent and offspring)
5. Germ line (Agent transmitted as part of the genome - e.g. pro-viral DNA)
55
What is the most common route of entry for viral infections?
Respiratory tract
56
List the 5 methods of acquiring viral infections (body system "breach")
1. Respiratory tract
2. Alimentary tract (eating, drinking, etc)
3. Urogenital tract
4. Eye
5. Skin
57
Viral infections can be ________, __________ or _________.
acute, chronic, latent
58
This type of viral infection is characterised by a rapid onset of dz, a relatively brief period of symptoms, and resolution within days
acute
59
These types of viral infections are caused by pathogens with slow growth rates, promoting an infection that is persistent for long periods.
Chronic
60
This is an infection that is hidden, inactive, or dormant
Latent
61
Can latent infections be transmitted to another host, even without any visible signs of disease?
Yes
62
This is the capacity of a virus to cause disease in an infected host
Virulence
63
This is the amount of virus needed to kill 50% of infected animals
LD 50
64
How can virulence be quantified? (5)
1. LD 50
2. Mean time to death
3. Mean time to appearance of sx
4. Measurement of fever, weight loss
5. Measurement of pathological lesions
65
Viral genes affecting virulence fall into four classes:
| 1. Those that affect the abilty of the virus to ______
replicate
66
Viral genes affecting virulence fall into four classes:
| 2. Those that modify the ______ _________ mechanisms
host's defense
67
Viral genes affecting virulence fall into four classes:
| 3. Those that enable the virus to ______ in the host
spread
68
Viral genes affecting virulence fall into four classes:
| 4. Those which have intrinsic _______ _________ effects
cell killing
69
This describes that capability of a virus to infect a distinct group of cells in the host
Tropism
70
Tropism is determined by
the availability of virus receptors on the surface of a host cell.
71
A _________ host is a person who can become infected by an infectious agent.
susceptible
72
Name 5 risk factors that can accelerate risk of infection
1. Age (< 6 months old, and in the elderly)
2. Nutrition and sociocultural condition
3. Open wounds/invasive procedures
4. Suppressed immune system
5. Presence and/or number of infectious organisms
73
A ________ cell or host is one that allows a virus to circumvent its defenses and replicate.
permissive
74
What is the most common type of test used to detect levels of antibodies?
Enzyme-linked immunosorbent assay (ELISA)
75
ELISA assays are usually _________, using a reaction that converts the substrate into a coloured product which can be measured using a plate reader.
chromogenic
76
Which type of serologic testing enables you to run multiple tests for different viruses simultaneously?
Automation and Random Access Analyser
77
Which testing method is the best of non-cultivable viruses?
Viral nucleic acid detection testing (PCR)
78
What is the most common type of viral nucleic acid detection test?
PCR
79
What type of serologic test for viral infections can also quantify viral load?
PCR
80
Explain concepts of viral prevention
1. PPE: Gloves, masks
| 2. Vaccines, chemoprophylaxis, immunoprophylaxis
81
Which four common viruses are there currently no vaccines for?
1. HIV
2. HCV
3. CMV
4. EBV
82
HAART drugs are used to treat
HIV
83
Lamivudine is used to treat
HBV
84
Ribavarin and PEG intereron are used to treat
HCV
85
Tamiflu is used to treat
Influenza
86
Acyclovir is used to treat
HSV
87
Ganciclovir is used to treat
CMV
88
What are the 5 main methods used to diagnose infectious disease?
1. Microscopy
2. Bacterial culture
3. Tissue culture
4. Serology
5. Molecular techniques (PCR)
89
What type of laboratory test is more sensitive for detecting very small numbers of bacteria- microscopy or culture?
Culture
90
What is the main strength of bacterial culture?
| It's good for bacteria you can _________ and ________.
stain, grow
91
What type of lab test is best for antiobiotic susceptibility testing?
Bacterial culture
92
Bacterial culture provides provisional identification of bacteria based on the bacteria's ___________.
metabolism
93
What is the time frame to achieve results in a bacterial culture?
24 hours for provisional identification,
| 48 hours to get definitive information
94
What are the limitations of bacterial culture?
1. Slow (definitive results take 48 hours)
2. Labour intensive
3. Some microorganisms are "unculturable," such as syphilis
95
How is HIV mainly diagnosed?
Serology
96
This lab test can show the response of the immune system to pathogens
serology
97
Which type of lab testing is helpful in the detection of antibodies in viral infections?
Serology
98
In serology testing, how can you distinguish between acute and chronic infections? (hint: Antibodies)
The presence of different isotypes IgM vs IgG can distinuish between acute and chronic infection
99
Which two types of bacteria don't stain well and are also difficult to culture? What is a better test to diagnose infections with these microorganisms?
Chlamydia and mycoplasm infections
| Serology
100
What is the main limitation with serology testing, in terms of looking for antibodies?
Antibodies can take weeks to develop
101
This lab technique that takes a specific sequence of DNA and amplifies it to be used for further testing. It amplifies dsDNA molecules (fragments) with the same size and sequence by enzymatic method and cycling condition.
PCR
102
Four steps of PCR:
| 1. _______________ by heat
Denaturation
103
Four steps of PCR:
| 2. Annealing ________ to target sequence
primer
104
Four steps of PCR:
| 3. ___________ TAQ DNA polymerase synthesizes in the 5' to 3' direction
Extension
105
Four steps of PCR:
| 4. The first PCR cycle ends with _____ new DNA strands that are identical to original target
two
106
Which type of laboratory testing in helpful in determining the causative agent in viral encephalitis?
PCR
107
PCR testing has a good ___________ predictive value- a high probability that people with a negative test truly DON'T have the disease.
negative
108
Which lab technique is used to monitor viral load? (e.g. HIV or HCV)
PCR
109
Main limitation of PCR:
| Can only be used to identify the presence or absence of a _________ pathogen or gene.
known
110
This type of culture may consist of a single cell, a population of cells, or a whole or part of an organ
Tissue culture
111
What type of culture is helpful in studying
1. the cytopathic effects on cells
2. expression of viral proteins detected at the cell surface
Tissue culture
112
What laboratory technique is used to differentiate bacteria by the chemical and physical properties of the cell walls?
Gram staining
113
Safranin or fuchsine is the counterstain that shows up as pink or red in what type of bacteria?
Gram negative bacteria
114
Name some examples of gram positive bacteria
1. Staphylococcus
2. Streptococcus
3. Enterococcus
4. Listeria
5. Lactobacillus
115
Name some examples of gram negative bacteria
1. E.coli
2. Pseudomonas
3. Chlamydia
4. Yersinia pestis
116
Acid-fast stains such as Ziehl-Neelsen, or fluorescent stains such as auramine are used to identify what type of bacteria?
Mycobacteria
