Microbiology Flashcards
(149 cards)
1
Q
How are infectious diseases influenced by genetic changes in mircroorganisms? (3)
A
Virulence, Host Range, Drug Resistance
2
Q
What are public health measures that have decreased infectious diseases? (3)
A
Clean Water, Clean Air, Vaccines
3
Q
What is an example of change in Host Range?
A
AIDs, SARS
4
Q
What are the 3 processes of the evolution of microorganisms?
A
- Development of increasing genome complexity
- Minor genetic changes resulting in changing pathogenicity, host range, drug resistance
- Natural selection
5
Q
What are some organisms that spontaneously lost their pathogenicity?
A
Syphilis, Scarlet Fever
6
Q
Cholera prevention is associated with what public health measure?
A
Clean Water
7
Q
What are some childhood diseases that are prevented from vaccines?
A
Smallpox, Polio, Diptheria, Measles, Mumps, Rubella
8
Q
What public health measure prevents respiratory infections like Tuberculosis?
A
Clean Air
9
Q
What well-known medical conditions have become recognized as infectious etiology?
A
Stomach ulcers- from H. pylori
Cervical cancer- Human papillomaviruses
10
Q
Why are these medical conditions important in understanding of microorganisms? Alzheimers, MS, Type 2 diabetes, Obesity. Heart attacks and stroke
A
Because they might be caused by infection
11
Q
Which one of the following infections has declined in severity because of improved hygeine?
A
cholera
12
Q
Development of a novel human infections can be caused by:
A
Changes in host range
13
Q
Drug resistant strains of mircoorganims can arise from?
A
Minor genetic changes such as point mutations
14
Q
What type of genetic material do bacteria have?
A
DNA with NO INTRONS
15
Q
What makes bacterias’ chromosomes different from eukaryotes?
A
Single, circular chromosome
16
Q
What is the nucleoid?
A
Non-membrane bound compartment of bacteria composed of the DNA that concentrates in one intracellular postion
17
Q
What makes bacterial ribosomes a good drug target?
A
They are 70S “Svedburg Units”, not 80S
18
Q
How do bacteria reproduce?
A
Binary Fission
19
Q
Four major common appearances of bacteria under light mircroscopy
A
Cocci(round), Bacilli (rods, vibrios-curved rods), Siprochetes (chains)
20
Q
Procedure for Gram Staining (5 steps)
A
- Fixation
- Stain (crystal violet)
- Iodine Treatment
- Decolorization with EtOH
- Counterstain with Safranin
21
Q
What is the basis for gram staining?
A
Cell walls between gram- and + significantly different, can narrow options FASTLY and CHEAPLY, seldom makes diagnosis
22
Q
Which gram stain has LPS?
A
Gram -
23
Q
What is different about Gram+ cell wall?
A
3X thicker layer of peptidoglycan, No exterior membrane
24
Q
What is different about Gram- cell wall?
A
Thinner layer of peptidoglycan, Exterior membrane
25
What other test is further for Gram- bacteria?
Acid Fast- do not stain gram+ but different from gram-
26
What 3 structural elements of bacteria have pathogenic significance?
LPS, Glycocalyx, Pilli/Fimbrae
27
What structural element found in gram- cell walls can cause septic shocK?
LPS
28
What structural element is a firm enclosure that resists phagocytosis and is a vaccine target?
Capsule
29
What are diverse mircobial communities that may host many organmisms and are more resistant than pure colonies?
Biofilms
30
What are slime layers?
Loose coating of polysaccharide the helps bacteria attach to host cells and form biofilms
31
What are slime layers and capsule made of?
Glycocalyx
32
What structural element is used for attachment and is often a virulence factor?
Pili/Fimbrae
33
What do flagella do?
rotate by a molecular motor to propel a bacteriium forward
34
Why are flagella a good immune target?
The polymers of flagellin aren't found in eukaryotes
35
What do about 50% of all antibiotics target?
70S bacterial ribosomes
36
3 drugs that target bacterial ribosomes
Aminoglycosides, Tetracyclines, Macrolides
37
How is spore formation triggered?
nutrient depletion
38
Why do we have to autoclave?
Because spores survive high temperatures, dehydration, anti-septics, antibiotics
39
When do spores unpack into normal bacterial form?
When water and nutrients are plentiful again
40
Modified form of binary fission, 2 unequal copies, one daughter cell dies and other receives double cell wall and macromolecules that enable progeny to be thick and rugged
Spores
41
Significance of exponential growth to pathogenesis
low number of bacteria can produce very large numbers in very short time, generation time is limited by available nutrients
42
Describe bacterial growth in a test tube
Lag, Log, Stationary, Death
43
Why does bacterial growth help with diagnostic testing?
Short generation time
44
2 Benefits of Fermentation pathway
Don't have to completely break down glucose
| Different waste products--identification in lab testing
45
What are the usual waste products of Fermentation pathway
Organic acids and alcohols
46
What ability do Oxygen based ATP metabolism bacteria have to have?
An ability to detoxify reactive oxygen radicals
47
What are the waste products of Oxygen-ATP metabolism?
CO2, Water
48
Describe Quorum Sensing
Ability of some bacteria to sense their population density and alter their genetic expression accordingly
49
What is the process of bacteria altering their genetic expression to secrete virulence factors in high population density?
Quorum Sensing
50
What 3 things quorum sensing bacteria require?
Secreted Inducer
Receptor for Inducer
Transcription Activator that responds to levels of inducer
51
Why is quorum sensing beneficial to bacteria?
Conserve Energy, Coordinate their attack
52
3 common ways HAIs are transmitted
Direct Contact with individual
Indirect contact with equipment/inaminate objects
Respiratory transmission
53
Seven Strategies for Prevention of Transmission
Hand hygeine
Use of PPE
Isolation of infected individuals
Sterilization of patient care equipment
Clean environment
Room ventilation if expect respiratory infection
Proper disposal of sharps, infectious waste
54
What is the goal of Infection control?
To break the chain of infection
55
6 parts of the chain of infection
```
Infectious agent
Reservoir
Portal of exit from reservoir
Vehicle (means of transmission)
Portal of Entry
Susceptible Host
```
56
4 CDC Standard Precautions for exposure from blood or bodily fluids
Clean hands entering/leaving room
Cover mouth/nose with arm when coughing/sneezing
Gowns/gloves if soiling likely
mask/eye potection if body fluids likely
57
Airborne (respiratory) Precautions
N95 mask/gown, isolation room at negative pressure
58
Droplet precautions
mask and gown when entering the room
59
Contact precautions
gowns entering room, alcohol based products OK
60
Contact PLUS precautions
Room bleached, hand hygeine soap and water ONLY
61
Reverse (protective) Isolation
Used for immunocompromised patients
| People entering room wear surgical mask, gloves, gown
62
Sterilzation
Complete destruction of all forms of microbial life
63
Disinfection
Destruction of specific microorganims, does not kill spores
64
Antisepsis
Reduction of disease causing germs on body, surfaces
65
Examples of Critical devices
Enter the body
| Surgical equipment, implants, invasive devices
66
Semicritical items
contact mucous membranes and non intact skin
High level disinfectant
Respiratory therapy items, endoscopes, laryngoscope
67
Noncritical items
come in contact with intact skin, or non contact
| bedpans, BP cuffs, crutches, computers
68
6 techniques used for sterlization
Steam sterilization, Dry heat sterilization, Irradiation, Filtration, Gas, Plasma
69
Steam sterilization
autoclaving
70
Dry heat sterilzation
petroleum based liquids
71
Irradiation
damage to Nucleic acid, implants
72
Filtration
liquids that contain protein delicate compounds
73
Gas sterilization
sterilize surface of porous items
| **FLAMMABLE
74
Plasma sterilization
H2O2 to form free radicals, for resuable medical equipment
75
Bacterial genotypes (3) for identification
1. Biosynthetic genes
2. Catabolic genes
3. Drug resistance genes
76
Differences between eukaryotic and bacterial gene expression
Operators/Repressors, no enhancers, no RNA splicing, no post TRXN modification
77
RNA Polymerase
Binds to the promoter and intiates gene transcription, leads to production of mRNA
78
Promoter
Regulates when, where, and what level a gene is expressed
79
Describe Bacteria Genetic Material
Circular Chromosomal DNA
Plasmids that contain 2-3 genes
bacteriophages
80
What are bacteriophages?
Not essential viruses that infect bacteria
contain small number of genes
can encode virulence factors*
81
Operon
Cluster of genes whose expression is controlled by one promoter
82
Ways that transcription is regulated in bacteria
By metabolic products or defiencies directly
83
Two types of transcriptional regulation
Positive or Negative Regulation
84
Inducible/Positive Expression
When lactose is present the genes to metabolize lactose are induced by lactose
85
Repression/Negative Regulation
if trp is present, trp repressor binds to trp operator so that trp trxn is repressed
86
Ames Test
Tests possible mutagens to see if things are carcinogenic
| Quick and Cheap, 85% accurate
87
3 mechanisms for Gene Exchange
Transformation, Conjugation, Transduction
88
How was gene exchange in bacteria discovered?
In a classical experiment using mice and viral and nonviral bacteria
89
Transformation
Cell lysis, neighboring bacteria picks up DNA fragments and incorporates through recombination
90
When is transformation used in medicine?
Hep B vaccine, insulin production, virus vectors in gene therapy
91
Conjugation
transfer of F-factor plasmid via a sex pillus. Plasmos can seperate from chromosome and be incorporated into some host genes.
92
Transducion
Virus mediated transmission of DNA between bacteria
93
Generalized Transduction
Phage lyses bacteria and releases all its DNA
94
Specialized Transduction
Phage inserts itself into chromosome and acquires regional DNA from bacteria
95
Transposons
Can insert themselves and relocate into different sites, pick up different bits of DNA as they move around, move drug resistance genes around together?
96
How can drug resistance come about so quickly?
Through a combo of gene exchange mechanisms plus point mutations in the host bacteria, a very drug resistant strain of bacteria like MRSA can come about.
97
Mutualism
Symbiosis, Organism 1 benefits, Organism 2 benefits
98
Commenalism
organism 1 benefits, organism 2 neither benefits not is harmed
99
Parasitism
organism 1 benefits, organism 2 is HARMED
100
Name 3 cases where commensalism can cause disease?
1. Injury or poor hygeine carries bacteria somewhere is doesn't belong
2. Immunosuppresion
3. Commensal in mother infects neonate during birth
101
Normal Flora
Commensal and beneficial to healthy individuals from colonization resistance
Some gut bacteria are beneficial
102
Colonization resistance
A form of symbiosis that even commensals participate in. Prevents pathogen from successfully colonizing the body. Function of innate immunity.
103
S. epidermis, C. albicans, S. aureus
Commensals found on skin
104
Streptococci, Staphylococci, Neissera
Commensals found in nose and throat
105
S. mutans
Commensal found in mouth, will cause cavities and endocarditis with poor dental hygeine
106
Strep, lactobacilli, yeasts
Commensals in the small intestine
107
baceteriods, eubacterium, coliform, clostridium
Commensals in the large intestine
108
pH maitenance in the Vagina
lactobacilli maintains low pH in Vagina, Candida overgrowth follows rising pH
109
group B strep
Commensal in vagina that can cause sepsis and meningitis in newborns if vaginal delivery without antibiotics
110
Asymptomatic infections
host defenses clear pathogen before any symptoms of disease are noted
111
communicable
Infection passed from host to host
112
Noncommunicable infection
comes from the environment, not a previous host (Think botulism)
113
latent infection
disease subsides but microorganisms remain in the body and can restart disease later
114
chronic carrier state
host survives disease but continues to shed the pathogen indefinitely (TB)
115
epidemic
much more frequent infection than usual
116
pandemic
worldwide distribution of infection
117
Obligate intracellular parasites
all viruses, few bacteria.
| Must enter the host cells to reproduce
118
Facultative intracellular parasites
Can reproduce outside host cells when they need to (ie bacteria)
119
Opportunistic pathogens
very unlikely to cause disease in a healthy person, will take advantage of a host that is injured or immunosuppresed
120
Commensals
usually non-pathogens with some opportunistic pathogens
121
Virulence
A numerical measure of pathogenicity
122
ID50
50% infectious dose- Lower value corresponds to fewer infecting organisms are needed for successful colonization of host
123
LD50
50% Lethal dose- lower value corresponds to fewer infecting organisms are needed to kill the host
124
Virulence factors
Gene products expressed by pathogens that directly contribute to the disease process. Can be drug targets.
125
Siderophores
A molecule that binds and transports Iron in mircroorganisms
126
Name the 5 major activities of Virulence Factors
1. Adhesion
2. Survive in extreme environments
3. Immune evasion
4. Takeover host cell
5. Poison the host
127
Give an example of adhesion
Pili, slime layer, adhesins sticking to host surfaces. Creation of biofilm
128
An example of survival in extreme environments
pH tolerance, siderophores, resistance to drying or detergents
129
An example of immune evasion
Capsules resist phagocytosis, IgA proteases, inductions of macrophage apoptosis, "serum resistance" factors escaping complement
130
An example of host cell takeover
Actin polymerization pathways, endosome escape routes
131
An example of poisoning the host cell
Tissue degrading enzyme secretions, endotoxins and exotoxins
132
What are endotoxins?
naturally occuring, exposure causes overactivation of immune system
133
Gram negative endotoxin, Gram positive endotoxin
negative- LPS, LOS
| positive- teichoic acids
134
What are exotoxins?
Among the most toxic substances known, secreted by bacteria
exposure induces neutralizing antibodies
you can raise vaccines of inactivated toxoid form of exotoxin
135
Koch's Postualte- what is it?
Proof of Causality of infectious agent- THE GOLD STANDARD
136
Structural appearances and features of Gram negative Cocci
(neisseria) diplococci- not quite spherical, grows on chocolate agar, LOS endotoxin in membrane, IgA protesase
137
Structural appearances and features of Staphylococci
Coagulate plasma (causes abscess), grows in clumps, catalase positive
138
Structural appearances and features of Streptococci
grows in chains (divide and stay attached), use serotypes to identify strains, catalase negative, cell wall include pili
139
Name the 3 important Staphylococci
S. aureus, S. epidermis, S. saprophyticus
140
Gram positive, staphylococci, coagulase positive, causes abscesses, R- nose and skin, T- direct, fomites
S. aureus
141
Gram positive, staphylococci, catalase positive, coagulase negative, non-hemolytic, novobiocin sensitive, R- skin, mucous membranes T- infected piercings
S. epidermis
142
Gram positive, staphylococci, catalase positive, coagulase negative, non-hemolytic, novobiocin resistant, R- women reproductive tract, T- UTIs "honeymoon cystitis"
S. saprophyticus
143
Gram positive, streptococci, catalase negative, alpha hemolytic, optochin sensitive, R=T- throat, when fluid clearnace from lungs is altered
S. pneumoniae
144
Gram positive, streptococci, catalase negative, alpha hemolytic, optochin resistant, has tissue degrading enzymes, R and T- mouth (can lead to decalcification, plaque, endocarditis
Veridans Streptococci- s. veridans, s. sanguis
145
Gram positive, betahemolytic, bacitracin sensitive, reacts to group A antiserum, has pili, numerous toxins, R and T- pharynx and skin, sore throats
Group A strep- s. pyogenes
146
Gram positive, streptococci, beta hemolytic, resistant to bacitracin, CAMP test positive, Capsule, R+T- genital tract, transmits meningitis to neonate
Group B strep- S. agalctiae
147
Gram positive, streptococci, gamma hemolytic, bile resistant, anaerobic, R+T- normal flora of colon, causes abscesses, UTIs
Group D- Enterococcus fecalis
148
Gram negative, grows on chocolate agar, ferments maltose, multiple serotypes, capsule, R+T- 5% of all people in respiratory tract, transmitted by droplets
N. meningitides (meningitis)
149
Gram negative, grows on chocolate agar, does not ferment maltose, NO capsule--pili to allow attachment, R+T- sexual and/or neonatal transmission. Chronic infection may be asymptomatic
N. gonorrhoeae (gonorhea)
