Microbiology Flashcards
1
Q
What are the major differences between prokaryotes and eukaryotes?
A
Prokaryotes: \+no "true" nucleus (nucleoid) \+no paired chromosomes \+cell wall made of peptidoglycans \+divide by binary fission
Eukaryotes: \+possess a "true" nucleus and nucleolus \+nucleus surrounded by membrane \+contain organelles \+divide by mitosis
2
Q
What is the major difference between gram positive and gram negative bacteria?
A
Gram negative bacteria have a lipid bilayer outer membrane containing porin proteins.
3
Q
What are porins?
A
Proteins in outer membrane that regulate uptake of hydrophilic materials from the environment (sugars, amino acids, ions). Antibiotics often pass through porins to enter the cell.
ONLY IN GRAM-NEGATIVE BACTERIA
4
Q
What is a bacterial capsule?
A
+outermost structure of bacteria, tightly bound to cell wall
+usually polysaccharide
+functions: inhibits phagocytosis, promotes adherence, acts as a barrier to toxic compounds (e.g. antibiotics)
5
Q
What are flagella?
A
Proteins extending from cell surface of some bacteria; used for motility.
6
Q
What are fimbriae/pili?
A
Protein extending from cell surface of some bacteria; used as attachment structures to promote sexual conjugation and adhesion to human cells.
7
Q
What are sex pili?
A
Allow binding between bacteria; form a tube through which bacterial genes can be transferred.
8
Q
What codes for sex pili?
A
F plasmid
9
Q
What are the differences between fimbriae and pili?
A
Fimbriae: \+sticky projections \+adherence and attachment \+shorter than flagella \+hundreds per cell \+biofilm
Pili: \+hollow rod-like projections \+made of pilin protein \+longer than fimbriae, shorter than flagella \+typically 1-2 per cell \+sex pili mediate conjugation
10
Q
What are the functions of flagella?
A
+locomotion
+stimulation [of antibody formation]
+adhesion [to human cells]
11
Q
What are the structural differences between gram positive and gram negative bacteria?
A
Positive: \+thick (multi-layered) peptidoglycan layer \+many teichoic acids \+NO periplasmic space, porins, or outer membrane \+virtually no LPS content \+some have spores \+only produce EXOTOXINS \+sensitive to lysozyme
Negative: \+thin (single-layered peptidoglycan) \+NO teichoic acids \+possess periplasmic space, porins, and outer membrane \+high LPS content \+NO spores \+produce exotoxins AND endotoxins \+resistant to lysozyme
12
Q
What is the outer membrane in bacteria?
A
Only in gram negative bacteria LPS embedded in outer membrane Barrier to noxious environmental materials Sieve for small water-soluble molecules Adsorption site for bacteriophage Adsorption site for sexual pili Reservoir for proteases, enzymes, toxins
13
Q
What are the regions of LPS?
A
Lipid A - responsible for endotoxic activity of molecule
Core - contains unusual sugar (ketodeoxyoctonate)
O-antigen - specific polysaccharide; highly variable from one species and strain to another
14
Q
In terms of LPS, what happens when gram negative bacteria lyse?
A
- LPS binds LPS-binding protein
- Bound LPS attaches to macrophage
- Entire complex induces transcription of cytokines
- Cytokines induce coagulation, inflammation, and MAC lysis
15
Q
What is a major structural similarity between gram positive and gram negative bacteria?
A
Both can potentially have capsules.
16
Q
What kind of spore can ravage a hospital?
A
Clostridium
Obligate anaerobe
Super hard to get rid of
17
Q
What kind of bacteria have spores?
A
Only gram positive
18
Q
What do spores do for bacteria?
A
Protect from heat, radiation, and chemical/enzyme attacks
19
Q
Which pathogenic bacteria produce spores?
A
Bacillus
Clostridium
20
Q
What is the starter molecule for peptidoglycan synthesis?
A
NAG
21
Q
What is a colony forming unit?
A
Estimate of the number of living cells
22
Q
What is used to create divisions within bacteria?
A
Proteins
23
Q
What is an operon?
A
Two or more genes are controlled by ONE promoter –> polycistrionic mRNA
Only found in prokaryotes
24
Q
What are the terminal electron acceptors for bacterial anaerobic respiration?
A
Metals (nitrate, sulfate, etc)
25
Most human pathogens are ______ an/aerobes
Facultative anaerobes
26
Describe the components of an operon.
Operon = encodes multiple genes, but controlled by one promoter
Operator = segment of DNA that is located adjacent to a promoter and usually binds a repressor protein
Promoter = RNA pol binds here to translate the operon
27
How do bacteria become resistant to antibiotics?
Through genetic mutation
28
Why are mutations easy to see in bacteria?
Bacterial genome is haploid, therefor unable to mask mutations
29
What structural component of bacteria is the functional equivalent of most of the organelles in a eukaryotic cell?
The cell membrane
30
How do you clinically differentiate and ID bacteria?
1. Morphology and gram stain
2. Growth condition/abilities
3. ID products of metabolism
4. Simple chemical or enzymatic tests
5. Molecular techniques (RFLP, sequencing, etc)
31
What is ribotyping and what are the pros/cons of using it?
Form of sequencing bacteria. Genes that code for ribosomal RNA are cut and separated by electrophoresis. The resulting fingerprint is visualized with fluorescent probes.
Pros:
rapid
reproducible
works for a wide range of bacterial specieis
Cons:
expensive
32
How do you clinically differentiate between strains of bacteria?
Molecular techniques are powerful, but they cannot differentiate between strains. Must use basic chemical/enzymatic tests to ID strains.
33
How is transcription controlled in an operon?
Transcription initiation controlled by the -35 and -10 box, found in the promoter region (RNA pol binding site)
34
Which mechanisms produce genetic change in bacteria?
1. Rapid mutation rate, rapid generation time
| 2. DNA acquisition from environment or other bacteria/organisms
35
What is a silent mutation?
Base substitution in DNA that has no effect on the polypeptide produced. Can still have significant effect on gene expression due to changing mRNA stability.
36
What is the main difference between transposons and insertion sequences?
Transposons can pick up and carry other genes with them (e.g. antibiotic resistance). Insertion sequences cannot.
37
What is pathogenicity?
Ability of an organism to gain entry into a host's tissues and bring about an anatomic or physiological change
38
What is virulence?
Degree of pathogenicity of a parasite
39
What are three virulence factors?
1. Structural (cell wall, capsule, pili)
2. Biochemical (exotoxins, enzymes)
3. Genetic (plasmids, phages)
40
What is bacterial competence?
Ability of bacterium to take up naked DNA from the environment
41
What are two examples of adherence factors?
Adhesins (surface projections) and biofilms (aggregate of microorganisms in which cells adhere to each other and resist clearance)
42
How does Neisseria gonorrhea protect against antibodies?
By producing anti-IgA proteases
43
Which cells are the number one responders to infection?
Neutrophils
44
What are the five main mechanisms of exotoxins?
1. Inhibit [protein synthesis]
2. Hyperactivate [cellular proteins]
3. Form [pores in cellular membranes]
4. Interfere [with nerve transmission]
5. Activate [T-cells nonspecifically]
45
What are bactericidal antibiotics?
Antibiotics that target the cell wall, causing lysis.
46
What are examples of bactericidal drugs?
Beta lactams
Vancomycin
Daptomycin (cell membrane only)
47
What are bacteriostatic antibiotics?
Inhibit bacterial growth and/or replication.
48
What are the classes of bacteriostatic antibiotics?
Abx that inhibit RNA synthesis
Abx that block protein synthesis
Abx that target DNA or DNA synthesis
Antimetabolite abx
49
Antibiotic that inhibits RNA synthesis
Rifamycin
50
Abx that block protein synthesis
Aminoglycosides
Macrolides
Tetracyclines
51
Abx that target DNA/DNA synthesis
Quinolones
| Metronidazole
52
Antimetabolite abx
Trimethoprim-sulfamethoxazole
53
What are the gram positive and negative Beta Lactams?
Penicillins
Cephalosporins
Carbapenems
Monobactams
54
What are the gram positive cocci Beta Lactams?
Vancomycin
| Daptomycin
55
What are the TB drugs?
Isoniazid
Ethambutol
Pyrazinamide
56
What are the classes of penicillins?
Natural penicillins
Anti-staphylococcal penicillins
Aminopenicillins
Extended spectrum penicillins
57
What are the natural penicillins?
V and G
58
What are the anti-staphylococcal penicillins?
Nafcillin
Oxacillin
Dicloxacillin
59
What are the aminopenicillins?
Ampicillin
| Amoxicillin
60
What are the extended spectrum penicillins?
Piperacillin
Ticarcillin
Carbenicillin
61
What are the Beta Lactamase inhibitors?
Clavulanic acid
Sulbactam
Tazobactam
62
What is the mechanism of action for anti-staphylococcal penicillins?
Have large R side groups which make them resistant to Staphylococcal beta-lactamases
63
Mechanism of action for aminopenicillins
Addition of an amino group to the R side chain --> penetration through PORINS of SOME gram negatives (especially enteric rods)
64
Aminopenicillins are particularly useful for _____.
Enteric rods
65
Mechanism of action for extended spectrum penicillins
Better able to penetrate GRAM NEGATIVE PORINS than aminopenicillins
66
Mechanism of action for Beta Lactamase inhibitors
Bind beta-lactamases and act as a sponge to take up all the beta-lactamases and protect beta-lactam ring of antibiotic from being degraded
67
What are natural penicillins active against?
Most streptococcal species (not S. pneumoniae)
Most gram positive anaerobes
Treponema pallidum (spirochete)
68
Natural penicillins are ineffective against _____.
Aerobic and anaerobic gram negative rods
69
What is the function of transpeptidases?
Catalyze the cross-linking of peptidoglycan residues in the bacterial cell wall
70
What is the mechanism of action for Beta Lactam abx?
Bind transpeptidases and block this reaction, resulting in weak cell walls and bacterial lysis if bacteria are actively growing
71
Aerobic gram-positive bacteria
Staph
Strep
Enterococci
Listeria
72
Which antibiotic first became resistant to penicillin and how did it do so?
Staph aureus
Made Beta-Lactamase: enzyme that breaks beta-lactam ring, inactivating the antibiotic
73
Which bacteria causes syphilis?
Treponema pallidum
74
Beta-lactam ring is the important structural component of which antibiotic?
Penicillin
75
Which bacteria are mostly resistant to penicillin?
```
Staph aureus (always)
Strep pneumo (most of the time)
```
76
What would you use to treat MRSA?
Vancomycin
CANNOT use anti-staphylococcal penicillins
77
What would you use to treat MSSA?
Nafcillin
CAN use anti-staphylococcal penicillins
78
What would you use to treat MSSE?
Nafcillin
CAN use anti-staphylococcal penicillins
79
Methicillin resistance is due to _______.
Altered PBP
80
```
Catalase positive
Coagulase positive
Gram positive
Cocci
Clusters
```
Staph aureus
81
```
Catalase positive
Coagulase negative
Gram positive
Cocci
Clusters
Novobiocin sensitive
```
Staph epidermidis
82
```
Catalase positive
Coagulase negative
Gram positive
Cocci
Clusters
Novobiocin resistant
```
Staph saprophyticus
83
Catalase negative
Gram positive
Cocci
Chains
Strep
84
Gram positive
Lancet shaped diplococci
Alpha hemolytic
Optochin sensitive
Strep pneumo
85
Gram positive
Cocci
Alpha hemolytic
Optochin resistant
Strep viridans
86
```
Gram positive
Cocci
Beta hemolytic
Positive cAMP test
Bacitracin resistant
```
Strep agalactiae
87
Gram positive
Cocci
Non-hemolytic
Strep bovis
88
Gram positive rods
Terminal spores
Positive for lecithinase alpha toxin
Clostridium perfringens
89
```
Gram positive
Non-spore forming
Bacilli
Actin rockets
Tumbling motility
```
Listeria monocytogenes
90
```
Gram positive
Branching
Bacilli
Obligate aerobe
Partially acid fast
```
Nocardia asteroides
91
Gram positive
Bacilli
Spore forming
Anaerobic
C. Diff
92
Gram positive
Cocci
Grows in 6.5%
Hydrolyzes esculin
Enterococcus faecelis
93
Spectrum of activity for aminopenicillins
Same as natural penicillins, with the addition of some strains:
E. coli
Shigella
Salmonella Enterica
Borrelia burgdorferi
94
Extended spectrum penicillins treat....
Same as natural penicillins, with the addition of:
Some strains of pseudomonas aeruginiosa
95
Five types of exotoxins
1. Inhibiting protein synthesis
2. Hperactivation of cellular proteins
3. Form pores in cellular membranes
4. Interfere with nerve transmission
5. Non-specific activation of T cells
96
Corynebacterium diphtheriae toxin
Inhibits protein synthesis
| Acts at elongation factor-2
97
S. dysenteriae toxin
Shiga toxin
Inhibits protein synthesis
Damage intestinal epithelium and glomerular endothelial cells
Leads to kidney failure
98
V. cholerae toxin
Hyperactivation of cellular proteins
99
Staph aures toxin
Creates pores causing hemolysis and tissue damage via LOSS OF IONS
Indirect cell lysis
100
C. perfringens toxin
Membrane-disrupting toxins with phospholipase C activity
Targets cholesterol
Direct cell lysis
101
Clostridium tetani toxin
Interferes with nerve transmission
102
What part of LPS is a toxin?
Lipid A: endotoxin that stimulates an inflammatory response
103
Digestive enzymes secreted by bacteria
```
Hyaluronidase
Collagenase
Lecithinase
Fibrinolysin
Streptolysin O
```
104
Common illnesses from Listeria monocytogenes
Food poisoning
Neonatal sepsis
Meningitis
105
Common diseases from Clostridium perfringens
```
Food poisoning
Necrotizing enteritis
Cellulitis
GAS GANGRENE
Septicemeia
```
106
Actinomyces diseases
Abscesses above diaphragm
| Infections after dental work
107
Proprionibacterium illnesses
Acne
108
How is diphtheriae transmitted?
Respiratory droplets; person to person
109
Where is Listeria monocytogenes found?
Intestinal tract of many animals
110
Where is Actinomyces found?
Endogenous oral flora
111
Calling card of diphthereiae
Bullneck
| Myocarditis
112
Sulfur granules
Actinomyces
113
First generation cephalosporins
Cefazolin
| Cephalexin
114
Second generation cephalosporins
Cefuroxime
115
Third generation cephalosporins
Ceftriaxone
116
Fourth generation cephalosporin
Cefepime
117
Extended spectrum penicillins good for...
Pseudomonas
| Better able to penetrate gram negative porins than aminopenicillins
118
Beta-lactamse inhibitors are combined with...
Aminopenicillins
| ESPs
119
Most potent, broad spectrum drugs available
ESP + Beta-Lactamase inhibitor
| Carbapenems
120
Penicillin toxicities
Type I hypersensitivity: rash, anaphylaxis
| Type II hypersensitivity: hemolytic anemia
121
First gen cephalo's used for
GAS
Viridans
S. pneumo
122
Treat pseudomonas with
ESP + BLI
Fourth generation cephalosporin (cefepime)
Carbapenems
123
Hail Mary drug
Imipenem
124
Use Vanco for...
MRSA
S. pneumo
Enterococci
125
Vancomycin mechanism
Cell wall inhibitor
| binds to D-Ala-D-Ala building block of peptigoglycan
126
Patient with history of penicillin allergy should not be given....
Cephalosporins
127
Carbapenem toxicity
Seizures in patients with CNS disease or renal insufficiency
| N/V/D
128
Aminoglycosides
Streptomycin
Gentamicin
Amikacin
129
Aminoglycosides toxicity
Nephrotoxicity
| Ototoxicity
130
Macrolides
Erythromycin
Clarithromycin
Azithromycin
131
Ketolides
Telithromycin
132
Toxicities of Macrolides and Ketolides
N/V/D
Inhibition of cytochrome p-450
Visual disturbances
133
DNA gyrase inhibitors
Quinolones
134
RNA polymerase inhibitors
Rifamycins
135
Anti-folate drugs
TMP/SMX
136
Treat CA-MRSA with
TMP/SMX
137
TMP/SMX toxicities
Rash
| GI
138
Treat C. diff with
Metronidazole
139
TB drugs block_____
Mycoic acid synthesis
140
Treat TB with
Isoniazid + Rifapentine
141
Antibiotics that target protein synthesis
```
Aminoglycosides
Macrolides
Clindamycin
Tetracyclines
Streptogramins
```
142
Antimetabolites
TMP/SMX
| Metronidazole
143
T/F
Ceftaroline is active against MRSA
True
144
Active against pseudomonas
Cefepime
ESPs
Carbapenems
Aztreonam
145
Useful in empiric treatment of CA-pneumonia
Levofloxacin
146
Drug of choice for Legionella, Mycoplasma, and Chlamydia
Macrolides
147
Used for anerobic infections; many strains of CA MRSA are susceptible
Clindamycin
148
Drug of choice for Neisseria gonorrhoeae
Ceftriaxone
149
Used for MRSA, strep pneumo, and serious C. diff
Vancomycin
150
Commonly used for UTIs, bacterial diarrhea
Cipro
151
Used to treat less serious C. diff
Metronidazole
