Exam 1 Flashcards
(123 cards)
1
Q
In 1918 the causative agent of influenza was wrongfully determined to be a bacterium isolated from the throat of patients – what is this an example of?
A
Normal flora
2
Q
The microbiome is the collection of all _____ in the human body
A
Microbial genomes
3
Q
The microorganisms living in (or colonizing) the human body
A
human microbiota
4
Q
What is the fine balance between flora and host with no disease known as
A
symbiosis
5
Q
When there is an imbalance between flora and host –> can cause disease
A
dysbiosis
6
Q
List seven ways the microbiome helps human health
A
- Protects against pathogens
- Synthesizes vitamins
- Develops the immune system
- Promotes intestinal angiogenesis
- Promotes fat storage
- Ferments dietary fiber, producing SCFA
- Modulate the central nervous system
7
Q
How does the microbiome stimulate the development of an active immune system?
A
Cross-reactive antibodies protect against related pathogens
8
Q
How does the microbiome protect against colonization by pathogens
A
Competes for nutrients and produces anti-microbial compounds
9
Q
What is the current view on the sterility of the womb?
A
The placenta and fetus are sterile, first exposure to bacteria comes from vagina or through c-section
10
Q
At what age is full colonization thought to be achieved?
A
2-3 years old
11
Q
Potentially pathogenic bacteria colonization is more likely for which type of birth
A
Caesarean
12
Q
Should cerebral spinal fluid contain bacteria?
A
No – the central nervous system should not
13
Q
What does the bacterial population on skin mainly consist of?
A
Mainly Gram +, some Gram - that can be transient/permanent, and bacteriophages that may contribute to homeostasis
14
Q
Are the eyes and ears sterile?
A
The eyes have bacteria and the outer ear has bacteria, but the inner ear is sterile
15
Q
List two bacteria that often colonize the upper respiratory tract
A
Staphylococcus aureus and Streptococcus pneumoniae
16
Q
Is there normal flora in lungs?
A
Yes
17
Q
Out of the digestive system, which organ has the least amount of bacteria?
A
The stomach because it is a highly acidic environment
18
Q
Why did researchers initially believe bacteria outnumber human cells by ten-fold
A
Because they were sampling from the colon (which has a very large number of bacteria)
19
Q
Which parts of the urinary tract are sterile?
A
The urethra and bladder are colonized, the ureters and kidney are sterile
20
Q
Which parts of the reproductive tract are sterile?
A
The vagina and penis are colonized, the uterus and ovaries/testes are sterile
21
Q
List four sterile sites in the body
A
- CSF
- Blood
- Tissues/organs
- Bone marrow
22
Q
The presence of normal flora that can be transient or permanent, often providing some benefit to the host, and doesn’t disrupt normal body functions
A
colonization
23
Q
Causing damage to the host due to microbial factors or due to host immune response, can be due to opportunistic or strict pathogens
A
infection
24
Q
TB, gonorrhea, and the plague are all caused by what type of pathogens
A
strict pathogens
25
List Koch's postulates
1. Pathogen is present in every case of disease and not in healthy patients
2. Can be isolated and grown in pure culture
3. Causes the same disease when healthy host is inoculated
4. The same pathogen must be isolated from the diseased host
26
The skin and mucosal surfaces are what type of natural barrier
Physical
27
Flushing/sloughing is what type of natural barrier
Mechanical
28
Acids, enzymes, and bile are what type of natural barrier
Chemical
29
The normal flora are what type of natural barrier
microbiological
30
What is the difference between stratified epithelia and simple epithelia
Stratified is directly exposed to the environment and is not easily penetrated, simple is a single layer that must allow for absorption in internal areas and is more vulnerable to penetration
31
How must bacteria enter the host?
Through injury or between cells
32
A protein in the epidermis that is resistant to enzymatic digestion by most microbes
Keratin
33
what cleaves NAM-NAG in peptidoglycan at mucosal surfaces
lysozyme
34
The bile salts in the small intestine do what to help the gastrointestinal tract
They disrupt bacterial membranes and DNA
35
What type of bacteria have teichoic acids linked to peptidoglycan that can be antigenic
Gram positive
36
List the four functions of innate immune cells (neutrophils, dendritic cells, macrophages)
1. Phagocytosis
2. Present antigens
3. Secrete immune molecule signals
4. Initiate the adaptive immune response
37
What cells are abundant in the blood, are very short-lived, move into tissue in response to infection, and are the primary component of pus (they explode)
neutrophils
38
What cells are phagocytic, are few in number (with a slightly longer life), and have a precursor that circulates in the blood and differentiates after migrating into tissue
macrophages
39
What is the key player at the center of the innate and adaptive immune response
dendritic cells
40
What is the cause of erythema (redness), edema (swelling), heat, & pain in an infection
cytokines
41
What does the production of pro-inflammatory and chemotactic cytokines result in?
- Vasodilation of blood vessels and migration of leukocytes into tissue
42
What type of cytokines are IL-1, IL-6, IFNGamma, and TNF
pyrogens (fever-causing)
43
What affects the hypothalamus, elevates body temperature, and stimulates killing by leukocytes
pyrogen cytokines
44
Where is complement produced?
The liver
45
Where is complement produced?
The liver
46
What three functions does the complement cascade carry out
1. enhanced phagocytosis (opsonization)
2. chemoattraction (recruits phagocytes to site of infection)
3. destroys pathogenic bacteria (cytolysis)
47
What does C3a do?
increase permeability of blood vessels
48
What does C3B do?
enhances phagocytosis by macrophages
49
What does C5a do?
inflammation & chemoattractant for phagocytes
50
What does C5b do?
Initiates membrane attack complex
51
What type of bacteria are more protected against the MAC and why
G + because of the thick peptidoglycan layer
52
Which complement pathways are innate and which are adaptive
Alternative and MBL = innate, classical pathway = adaptive
53
What sticks to peptidoglycan, teichoic acid, LPS, etc. on the surface of microbes
C3b
54
Mannose binding lectin binds to receptors on bacteria but not in humans why?
Human cells covered by sugars such as sialic acid
55
IFNGamma triggers differentiation into what type of helper cell
Th1
56
IL-4 and IL-13 trigger differentiation into what type of helper cell
Th2
57
What type of helper cells target intracellular infections
Th1
58
What are the most potent antigens that stimulate both humoral and cell-mediated immunity
proteins
59
What antigens stimulate only humoral immunity
Carbohydrates/sugars
60
What are weak antigens of the adaptive immune response
Lipids and nucleic acids
61
CD4 T cells bind to what type of MHC
MHCII
62
What type of helper T cell stimulates the cellular immune response (phagocytes and CTLs)
Th1
63
What type of helper T cell stimulates the humoral response (B cells)
Th2
64
BCRs can recognize what types of antigens
Proteins, polysaccharides, and lipopolysaccharides
65
What type of MHC receptors do B cells have
MHC-II
66
Are memory cells produced in cases of T cell independent (TI) antigens
NO
67
What is the difference between TI-1 and TI-2 antigens
TI-1 = LPS, recognized by TLR or BCR
TI-2 = bacterial capsular polysaccharide, repetitive structure cross-links BCR
68
Children under 5 cannot mount an effective response to what type of antigens
TI-2 antigens
69
What antibody is located in the membrane of B cells, is the first Ab synthesized in an infection, is a pentamer, agglutinates bacteria, and activated the classical complement cascade
IgM
70
What antibody is the main one in human serum, makes up 80% of the Ab pool, is able to cross the placenta, and opsonized pathogens/activates the classical complement cascade
IgG
71
What is the antibody most prominent in mucosal tissues, is produced in its secretory form through oral vaccination, prevents attachment, is transferred to newborns through breast milk, and is the key Ab to protect against enteropathogens
IgA
72
What antibody makes up a small percentage of the pool, is responsible for allergic reactions, binds to Fc receptors on mast cells/basophils to cause histamine production, and is important in controlling parasitic infections
IgE
73
What antibody is found in trace amount in blood serum, is a monomer, is found in the B cell membrane (serving as antigen-binding receptor), and cannot cross the placenta
IgD
74
Where do all complement cascade pathways converge
Production of C3 convertase
75
What type of vaccine has live pathogen that is not virulent due to being grown at a different temperature, mutated, genetically modified, passaged in a laboratory, etc.
Live attenuated
76
A killed whole pathogen (bacteria cells) makes up what kind of vaccine?
Inactivated vaccine
77
List pros and cons of inactivated vaccines
- safe and easy to produce
- inactivation needs to be confirmed, immunity not as long-lasting, leads to Th2 response, does not elicit IgA response, requires larger doses/booster shots
78
What function to adjuvants have and what type of vaccines require them
trap and slow release of antigen, inactivated vaccines
79
Polysaccharide-capsule vaccines, conjugate vaccines, and recombinant protein vaccines are what type of vaccines
Subunit vaccines
80
List the pros and cons of subunit vaccines
Pros - safe
cons - may lack PAMP (innate --> adaptive ppor), may only result in humoral response
81
How do vaccines with capsular polysaccharide become effective in children under 2
conjugate vaccines
82
What is the main antibody generated by a conjugate vaccine
IgG
83
What type of vaccine is made up of inactivated bacterial exotoxin
Toxoids
84
What types of antibodies do oral and systemic vaccination produce
- oral = secretory IgA
- systemic = IgG/IgM depending on antigen
85
Beta-lactam drugs, vancomycin, and bacitracin all target what
Peptidoglycan synthesis
86
Polymyxin B targets what
membrane integrity
87
Sulfamethoxazole/trimethoprim (SXT) target what
folic acid synthesis
88
tetracyclines, aminoglycoside, and macrolides/lincosamides target what
protein synthesis
89
fluoroquinolones and metronidazole target what
bacterial DNA
90
What are the four main considerations when choosing an antibacterial agent
1. Susceptibility of pathogen
2. Site of infection
3. Patient factors
4. Safety
91
What are the five main mechanisms of antibacterial agents?
1. Inhibit cell wall synthesis
2. Inhibit protein synthesis
3. Affect nucleic acid synthesis
4. Disrupt cell membrane function/structure
5. Interfere with normal metabolic pathways
92
Which type of bacteria have interbridges made up of amino acids between NAM-NAG strands
G +
93
Penicillins, cephalosporins and cephamycins, carbapenems, and monobactams are what type of antimicrobial agent
beta lactams
94
What is the mode of action of beta lactams
Transpeptidase irreversibly binds to beta lactam instead of D-ala-D-ala (competitive inhibition)
95
what is transpeptidation
crosslinking of NAM-NAG strands
96
Natural penicillins are only effective against what type of bacteria
gram +
97
what is the difference between narrow spectrum and broad spectrum semisynthetic penicillins
narrow -- only G+, more resistant to penicillinases
broad -- also effective against G-
98
what is the benefit of cephalosporins and cephamycins
have two R groups that allow for more molecular modifications
99
what is the advantage of 3rd, 4th, and 5th generation cephalosporins and cephamycins
they can target both G- and G+, can cross the blood-brain barrier, and are more resistant to beta-lactamases
100
list benefits and downsides of carbapenems (meropenem included)
- protection against beta lactamases
- gram negative resistance common in nosocomial infections
101
Monobactams have what structure and are only active against what type of bacteria
Single beta lactam ring and only effective against G-
102
What is the glycopeptide (vancomycin and teichoplanin) mechanism of action and downside
Binds D-Ala-D-Ala and inhibits enzyme binding, not effective against G-
103
What is the polypeptide (bacitracin) mechanism of action
inhibits dephosphorylation/recycling of bactoprenol, which stops addition of NAM-NAG units
104
What type of bacteria are resistant to bacitracin and how is this usually delivered
G -, topically but can sterilize GI tract before surgery
105
What do anti-mycobacterials target
mycolic acid synthesis, arabinogalactan synthesis, and D-Ala-D-Ala synthesis
106
What type of antimicrobials disrupt cellular membranes
lipopolypeptides and polypeptides
107
How do polymyxin B and E function
Bind to LPS, alter membrane permeability, used topically/can cause kidney toxicity
108
Macrolides and lincosamides bind to which ribosome subunit
50S
109
Aminoglycosides and tetracyclines bind to which ribosome subunit
30S
110
How do macrolides and lincosamides function
bind to exit tunnel of polypeptide chain, preventing protein elongation
111
Macrolides are typically not useful for what type of bacteria
G -
112
Clindamycin works for what and does not work for what
G - anaerobes
does not work for G - aerobes and enerococci
113
How do aminoglycosides function
Binds to 16S RNA which causes misreading or premature release of ribosome
114
Aminoglycosides are most effective against what
- Aerobic G -
(streptococci and enterococci are resistant --> can't cross peptidoglycan)
115
What is a good way to make aminoglycosides functional for G + bacteria as well
Couple with beta lactam or glycopeptide to interfere with peptidoglycan synthesis
116
How do tetracyclines function
Block binding to tRNA to ribosome to inhibit protein synthesis
117
How do tetracyclines enter and what are some tips to make more effective
enter via porins or active transport, good for intracellular bacteria, orally well absorbed, calcium/milk decreases absorption, avoid sun exposure, can cross the placenta (no to pregnant women and children under 7)
118
What do quinolones, metronidazole, and refampin target
nucleic acid synthesis
119
How do quinolones function
bind to bacterial type II topoisomerase (higher affinity for bacterial than human)
120
What are some advantages or quinolones
broad spectrum, well absorbed and distributed, and relatively nontoxic
121
How does metronidazole function
reduced in anaerobic environment, damages DNA/proteins/membranes
122
Synthetic sulfonamides, dapsone, and trimethoprim function how
inhibiting folic acid --> precursor to purines and pyrimidines
123
List some benefits of sulfonamides and trimethoprim
- broad spectrum
- good for tissue distribution
- UTIs/sinus infections/middle ear infection
- can cross blood-brain barrier
