Exam 1 Flashcards
1
Q
What organism caused the plague?
A
Yersinia pestis (gram negative rod)
2
Q
Who is Leeuwenhoek?
A
Created the first microscope. Discovered “animalcules” or organisms.
3
Q
Who is Jenner?
A
Used the first vaccine and began process to lead to the eradication of smallpox
4
Q
Who is Pasteur?
A
Disproved the theory of spontaneous generation (organisms generated from rotting organic material). Created pasteurization
5
Q
Who is Semmelweis?
A
Hungarian physician. Discovered that washing hands was crucial in preventing child bed fever and post op infections by studying midwives and doctors activities Before deliveries
6
Q
Who is Lister?
A
First to use “antisepsis” to control surgical infections
7
Q
Who is Lina Hesse?
A
First to use Agar (gelatin) to solidify growth material for bacteria
8
Q
When was the golden age of microbiology?
A
1880-1900. First pathogens identified
9
Q
Who discovered penicillin?
A
Flemming. Discovered a certain mold inhibiting the growth of other bacteria. This was penicillin.
10
Q
What is Koch’s Postulates?
A
Establishes an organism is the cause of a disease.
11
Q
What are the requirements for Koch’s postulates?
A
- The same organism must be found in all cases of a given disease
- Organism must be isolated and grown in pure culture (agar/broth)
- Organism from pure culture must reproduce the disease when inoculated into a healthy animal.
- Organism must then again be isolated from sick animal
12
Q
Describe cocci bacteria
A
Round bacteria
Streptococci (strep= chain, cocci= round)
Staphylococci (staphylo= grapes, clusters)
13
Q
Describe Bacilli organisms
A
Rod shaped.
Coccibacilli = very short rods
Vibrio = curved rods
Spirochaetes= spiral rods such as Lyme diseased
14
Q
What are actinomycetes?
A
Filaments with branching
15
Q
Examples of appendages in a cell
A
Flagella
Fimbriae
Pili
16
Q
What is contained in cytoplasm?
A
Chromosomes, plasmids, ribosomes, inclusions
17
Q
Describe flagella
A
Long, slender, whip like structures that promote bacteria movement. Can only be seen using special stains
Monotrichous - single flagella
Peritrichous - tufts or multiple flagelli
18
Q
Describe Fimbrae
A
Appendage of a cell. Finger like and made of proteins. Enable bacteria to attach to substances
19
Q
Describe pili
A
Appendage of cell. Act as a channel to transfer dna between cells
20
Q
What is the capsule
A
Material secreted by bacteria that covers the exterior of the cell, often made of polysaccharide (sugar). More prominent in some cells than others
21
Q
Describe cell wall
A
A strong layer made of peptidoglycan (proteins and sugar) that maintains shape and integrity of the cell. Principal target for antibiotic action and stains using gram stain in some organisms
22
Q
Describe the peptidoglycan layer
A
Cross links horizontally and vertically. Made of polymerized NAG and NAM (sugars). Very strong lattice that protects the cell from environment
23
Q
Describe gram positive organisms
A
Thick peptidoglycan layer and no outer membrane. Are stained by crystal violet
24
Q
Describe gram negative organisms
A
Has an outer membrane and a thin peptidoglycan layer. Is not stained by crystal violet after alcohol/acetone is used to remove dye
25
Describe the gram stain
Crystal violet is used to dye all bacteria dark purple
Iodine acts as a mordant and fixes the crystal violet to the bacteria
Alcohol/acetone washes out the stain from gram NEGATIVE organisms
Safranin (newer step) acts as a counter stain. stains gram negative bacteria pink
26
What is the purpose of acid fast staining?
Some bacteria can not be stained by the gram stain due to lipids in the cell walls making the bacteria waxy (ex, tuberculosis). Can be stained using powerful and toxic red acid fast stain
27
Describe the process of acid fast staining
- staining with strong red stain
- washing out stain with mixture of acid and alcohol
- counter staining blue or green
Acid fast organisms are sometimes referred to as AFB (active fast bacilli)
28
What does a lipid bilayer in the cell wall do
Contains proteins that act as channels to control entry of substances in and out of the cell
29
In gram negative bacteria what does the cell membrane contain?
An endotoxin (LPS)
30
Describe Ribosomes
Made of RNA and protein, sure if protein production and a good target for antibiotics as cells can not survive without ribosomes
31
Describe bacterial chromosomes
A single long circular molecular of DNA that is not separated from cytoplasm
32
True or false bacteria are Prokaryotic?
True. Bacteria have no nucleus there for they are Prokaryotic
33
Describe plasmids
Small circular pieces of DNA that can be transferred between bacteria. May contain the genes for antibiotic resistance and producing different variants
34
What are inclusions?
Granules in the cytoplasm. May act as storage of various substances. Toxins molecules for storage and metabolism
35
Describe endospores
Dormant and very resilient. Develop in cytoplasm and send signals to create spores if it is sensed the environment is tough. Only formed by certain genera of bacteria. Germinate new cell when environment is favourable again
Ex. Cdiff cells
36
What are domains
How bacteria are organized. Lacking nuclei (prokaryotes) or not (eukaryotes)
37
What is the kingdom classification for Prokaryotic organisms
Monera
38
What are used in naming bacteria
Genus and species are used whenever we call a bacterium by its name
Ex. Staphylococcus (genus) aureus (species)
39
What classification is used
| Most frequently in clinical practise
Family, genus, species
| Ex. Escherichia (genus) Coli (species), a member of the Enterobacteriaceae family
40
What is Aerobic?
An organism that grows in air. Obligate aerobic if must have oxygen
Capnophilic if CO2 is needed
41
What is facultative anaerobe?
Grows in air, and can grow without oxygen
42
What is anaerobe?
Grows without oxygen. Most species find oxygen toxic as a result of struggling to deal with wastes product produced in oxygenated environments
43
What is microaerophilic?
Grows in low concentration of oxygen but not in its absence or in air. A specialized lab condition
44
requirements for bacterial growth?
- carbon source
- nitrogen source
- essential nutrients (vitamins)
- correct temp
- right atmosphere
- inorganic ions, iron
- Ph
- water
45
Describe carbon sources
Simple carbohydrates such as sugars and proteins. Some organisms are able to fix or steal CO2 from the air
46
Describe nitrogen sources
Proteins, peptides and amino acids, DNA, nitrates, ammonium salts
Some organisms can fix or steal nitrogen right from the air
47
Describe fastidious bacteria
Require more complex organic molecules such as blood and vitamins go grow.
48
True or false human pathogens are usually mesophiles
True. They require a temperature of 20-40° to grow. Other bacteria can grow below 15° and above 45°
49
What does oxygen act as in AEROBIC organisms
Acts as a final electron accepter
50
True or false: ANAEROBIC organisms can detoxify o2
False. Anaerobic organisms lack the means to detoxify O2
51
What is iron required for
Iron is required for enzyme action (cofactor). Bacteria produces sidedophores which bind to iron and make it possible to import it
52
What pH do bacteria prefer
They prefer a neutral pH. Bacteria tends to die in acidic (<6) solutions which is why things can be preserved in vinegars etc
53
Why do bacteria need to be in water
Bacteria require soluble nutrients for diffusion into the cell. So it thrives in water
54
How does bacteria multiply?
Bacteria multiply through BINARY FISSION. A single cell separates to form two new cells and so on. Multiply rapidly
55
What can limit the growth of bacteria?
Availability of nutrients, temperature (too hot or too cold) and the ability to remove toxic products as they can accumulate and damage the cells
56
What is generation time?
The time required to divide, most organisms it is measured in minutes
57
Why does honey preserve well?
Sugar content. Lots of sugar makes it very difficult for bacteria to grow
58
What are the phases of growth of microbial populations?
1. Lag phase
2. Log phase
3. Stationary phase
4. Death phase
59
Describe the lag phase
First phase. Bacteria first introduced and beginning to adapt to environment. Active synthesis of enzymes and other constituents
60
Describe the log phase
Second phase. Bacteria begins rapidly growing, antibiotics most active during this phase
61
Describe the stationary phase
Third phase. Reproduction rate equals death rate, nutrients begin to deplete and toxic materials begin to accumulate
62
Describe the death phase
Death rate exceeds reproduction rate. Final phase.
63
Describe active transport
Enzymes move substrate into the cell, requiring energy.
Concentration inside the cell is higher than the outside (working against gradient)
By pumping from the INSIDE out organisms can become resistant to antibiotics
64
Describe group translocation
Enzymes modify a substance as it enters the cell.
Diffusion of the altered substrate is reduced
Energy is required
65
Describe facilitated diffusion
Enzymes aid diffusion but no energy is required (passive transport)
Molecules must bind to specialized membrane proteins in order to be shuttled in
No modification of substrate
Concentration inside does not exceed exterior concentration
66
Describe listeria monocytogenes
AEROBIC gram POSITIVE rod
Preferred pH 4.6-9.2
Grows best in refrigerator temperature
67
Describe anabolism
Building organic molecules using smaller molecules and energy
68
Describe Catabolism
Breakdown of chemical nutrients with release of energy
69
What is ATP
Adenosine triphosphate. How cells store energy
70
How do cells get energy?
- nutrients
- sunlight in some specialized species
- using oxygen and other substances to accept electrons
71
What is glycolysis
Catabolism
Glucose is broken down to pyruvic acid
Series of steps from 6 carbon molecule to TWO 3 carbon molecules
Products can enter respiration or fermentation
72
Describe aerobic respiration
Krebs cycle
Pyruvate degraded to CO2 and H2O
Only in AEROBIC organisms
Results in more energy production
73
Describe electron transport chain (Aerobic)
Electrons pass along the electron transport chain to terminal electron acceptor (O-)
A lot of energy is generated by ATP synthesis as protons flow down the proton gradient
74
Describe fermentation
Anaerobic process. Electrons are transferred to form other organic compounds (ex.ethanol) instead of oxygen.
Different bacteria produce different products (ex.cheese, wine, beer)
Only two ATP produced from one glucose
75
What are facultative anaerobes
Use respiration in air and can switch to fermentation I’d there is no oxygen
76
Describe lipid catabolism process
Lipase: breakdown lipids -> glycerol -> glycolysis
| Fatty acids are oxidized
77
Describe protein catabolism
Proteases digest protein
Protein -> amino acids -> protein synthesis or further breakdown
Once it becomes a carbohydrate it is fed into the Krebs cycle
78
Describe sanitizing
Removing of debris. Rendering safe to handle. Happens before disinfection.
79
Describe disinfection.
Reduction in number of microbes present
80
Describe sterilization
Elimination of all forms of life except prions
81
How do disinfectants reduce number of organisms
By the microbial death rate. Constant for combo of circumstances (bug,agent,temperature)
At low levels of disinfection some bacteria may be inhibited rather than killed
82
What is the mechanism of action of disinfectants
Proteins denaturation or by membrane damage
83
Describe denaturation of proteins
Results in loss of secondary and tertiary structure with consequent loss of function.
One way step can not go back after this has happened
84
Describe some disinfectant methods
- using chemicals (antiseptics, bactericide, bacteriostatic agent)
- pasteurization (using moderate heat)
- preservation (drying, osmotic methods, reduces numbers and prevents Re growth)
85
What factors are important in chemical disinfectant activity
Concentration of chemical
Time of exposure to disinfectant
Number and type of microbes present
Nature of material to be disinfected
86
What is the mode of action of chemical disinfectants
Disruption of cell membranes
| Denaturation of proteins
87
What will low level disinfectants do
```
Kill vegetative (actively growing) Bacteria, enveloped viruses and some fungi
Often used for environmental and non critical equipment cleaning
```
88
What will intermediate disinfectants do
Kill all bacterial pathogens(except spores), most fungi, most viruses
89
What do phenol based disinfectants do?
Disrupt cell membranes and precipitate proteins
90
What do alcohol disinfectants do
Denature proteins
70% alcohol is more effective than 100%
Requires adequate time for activity however
91
What are the 2 types of oxidizing disinfectants
Halogens (bleach, iodine, chlorine)
| Hydrogen peroxide
92
Describe halogens
Iodine, bleach, chlorine, fluorine
Used in water supplies or for handling blood spills
Inactivated by organic materials, activity drops after opening
Corrosive
Risk of chlorine gas if acidified
93
Describe hydrogen peroxides
Intermediate to high level disinfection. Some used as chemical sterilants
Active in presence of organic materials
Detergent properties which improves cleaning ability
Widely available in wipes etc
94
What is peracetic acid
Hydrogen peroxide combined with acetic acid
Powerful highly reactive disinfectants
Not affected by protein or enzymes
95
What is performic acid
H2o2 (hydrogen peroxide) combined with formic acid
Powerful highly reactive disinfectant
Not affected by protein or enzymes
96
What are high level disinfectants
Substances able to kill spores, tubercle bacilli and viruses given enough time
Ex. Ortho-phthalaldehyde
With sufficient time of exposure and concentration these agents become chemical sterilants
97
What is UV disinfectant used for
Water, waste water, air and surface disinfection
98
Describe antiseptics
Disinfectants that are safe for use on skin, take time to work
Resistance can develop to these if too much use
(Ex. Alcohols triclosan (used for hand washing))
99
What are transient flora?
Organisms that are acquired on hands during routine work, can include resistant organisms, easily transmitted
Carriage (carrying flora) can be eliminated by hand washing
100
Describe the methods of sterilization
- heat (dry or moist)
- gas and liquid (good for things that can’t handle heat)
- irridiation
- filitration (doesn’t eliminate viruses, used as disinfectant in pharmacies)
101
Describe autoclaving
Form of sterilization using moist heat at increased pressure for a defined time
Used on surgical instruments
Should be checked often
102
Describe gas sterilization.
Requires an aeration step after sterilization.
| Icludes ethylene oxide, formaldehyde gas, hydrogen per oxide vapour
103
Describe radiation sterilization
Used in industry for plastic objects, fluid, (not use much in hospitals)
Uses microwave or gamma radiation.
104
Describe prions
Caused by transmissible misfiled proteins
No nucleic acid and found in neurological tissue
Agents are RESISTANT to disinfection or sterilization with radiation or gas
Fabrics must be incinerated and materials that just be kept have to be sterilized in alkaline conditions and autoclaved
105
What are the different relationships between hosts and microbes
Commensal
Normal flora (micro biome)
Opportunist
106
Describe commensal relationship
Microbe received benefit but no harm to host
107
Describe opportunist relationship
Microbe received benefit, and is able to cause disease if host defenses are weakened
108
Define pathogenicity
The ability of an organism to cause disease
109
Define virulence
The extent to which an organism can cause severe disease
110
What forms of transmission of infection is there
Micro biome, people, animals, environment, vectors and fomites
111
Defines vector
A small organism (insect or tick) that transmits and infectious agent
112
Define fomites
An inanimate object that transmits infection when contaminated
Ex. Door knob
Very common
113
What are exotoxins
Toxins excreted from the bacterial cell
May disrupt cells or interfere with their function
Ex. Tetanus
114
What are virulence factors
Properties that enable organism to infect
May enable organism to invade hosts Defenses via a slime layer
May improve access to bodies nutrients via colonization factors (fimbrae)
115
What substances help organisms invade
- hemolysins: cause lysis of red blood cells and damage body cells
- leukocidins: kill white blood cells
- hyaluronaise: break down connective tissues
- collagenease: break down collagen
116
Examples of bacterial toxins ?
- enterotoxins (gut)
- neurotoxins
- protein synthesis inhibitors (kill or damage organs, diphtheria)
- superantigens
117
Describe super antigens
Toxins that bind to macrophages and short circuit the mechanism that stimulates the immune system causing a dramatic response and damage to the body
Ex toxic shock syndrome
118
Describe endotoxin
Substance found in the outer membrane of gram NEGATIVE organisms (not an exotoxin)
Causes fever, BP drop leading to poor organ perfusion
Acts by binding macrophages and causing release of active substances (cytokines)
119
How does DNA transfer between organisms?
Conjugation
Transformation
Transduction
120
Describe conjugation
Transfer of genetic material (nucleic acid) by direct contact if cells especially important in gram NEGATIVEs
Mediated by pili
Allows transfer of plasmids
121
Describe transformation
Free extra cellular DNA can be taken up by some bacteria and incorporated to the bacterial genome
(Pick up DNA floating around and transform )
(Strep and pneumonia good at this)
122
Describe transduction
Genetic material is transferred via a bacterial virus (bacteriophage) infection of the bacteria 2 things happen:
Phage takes over bacteria and rapidly destroys it (lytic infection)
Phage incorporates with bacteria and gives it new properties (transduction)
Bacteriophages can treat infections in some cases
