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Micro, Ass 3, Renee's Questions
Ass 3
111
Microbiology
Graduate
05/19/2011

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Cards

Term
1.     What is a broad spectrum antibiotic?
Definition
1.     one the is active against several types of microoorganisms
Term
2.     What is an antibiotic that is active against one or a very few types or microorganisms?
Definition
2.     Narrow spectrum
Term
3.     What type of antibiotic inhibits bacterial growth but does not kill?
Definition
3.     Bacteriostatic
Term
4.     When bacteriostatic drugs are withdrawn can bacteria continue to grow?
Definition
4.     yes
Term
5.     How do most bacteriostatic drugs inhibit growth?
Definition
5.     inhibit protein synthesis
Term
6.     What type of antibiotic kills bacteria?
Definition
6.     Bactericidal
Term
7.     Why are bactericidal drug actions inhibited by a –static drug?
Definition
7.     requires bacterial growth in order to impair
Term
8.     What are some advantages to –cidal drugs?
Definition
8.     Reduces the number of bugs, more rapid, irreversible damage to bugs
Term
9.     What is a disadvantages of –cidal drugs?
Definition
9.     cytotoxic storm
Term
10.  What do –static drugs prevent that give them an advantage?
Definition
10.  inhibition of bacterial toxins and inflammatory mediators
Term
11.  T/F Two static drugs can be used in combination to kill a pathogen.
Definition
11.  T – if mechanism is in different part or completely different pathways
Term
12.  T/F The same antibiotic may be cidal or static against different bacteria.
Definition
12.  T – Ex. Penicillin – cidal à pneumococci, static à enterococci
Term
13.  What is the lowest concentration of drug that inhibits the growth of the organism called?
Definition
13.  Minimal Inhibitory Concentration (MIC)
Term
14.  What are the 2 options for MIC testing?
Definition
14.  Turbidity and Viability
Term
15.  How is Turbidity used to determine the MIC?
Definition
15.  Determined by growing organism in tubes then adding various concentrations of drugs, lowest concentration tube where broth is clear.
Term
16.  How is Viability used to determine the MIC?
Definition
16.  Preinoculate blood agar plate then place antibiotic discs, allow to grow then determine zone of inhibition, diameter is compared to standards to determine sensitivity of the organism to that drug.
Term
17.  What is the Minimal Bactericidal Concentration (MBC)?
Definition
17.  Concentration of drug that actually kills the organism rather than the concentration that merely inhibits growth
Term
18.  How is the MBC determined?
Definition
18.  transfer clear broth tube to blood agar plate, MBC is the plate without growth
Term
19.  What type of drugs have an MBC equal or very similar to the MIC?
Definition
19.  Bacteriocidal
Term
20.  What is the relationship of MBC to MIC in Bacteriostatic drugs?
Definition
20.  The MBC is significantly higher than MIC
Term
21.  T/F MIC and MBC concentrations can be used to compare effectiveness of an antibiotic.
Definition
21.  F – Effectiveness is based on how much of the drug you can actually administer to the patient
Term
22.  What 5 differences can antibiotics target in bacterial cells?
Definition
22.  Cell wall synthesis, Cell membrane, DNA replication + Nucleotide Biosynthesis, Topoisomerases, Protein Synthesis
Term
23.  What type of antibiotics target the crosslinking in bacterial cell walls?
Definition
23.  Penicillin, Cephalosporins, Carbapenems, Monobactams
Term
24.  What do Peptide antibiotics target? what are 2 examples?
Definition
24.  Cell membrane; Polymyxins, Daptomycin
Term
25.  What drugs target DNA replication and Nucleotide Biosynthesis?
Definition
25.  Metronidazole, Sulfonamides, TMP-SMX
Term
26.  What do Quinolones target?
Definition
26.  Topoisomerase
Term
27.  What drug targets DNA-directed RNA polymerase?
Definition
27.  Rifampin
Term
28.  What causes an overgrowth of drug resistant strains of Clostridium difficile? What is this called?
Definition
28.  complication of antibiotics due to suppression of the normal flora of the bowel; Pseudomembranous Colitis
Term
29.  What are the normal cell wall hydrolyzing enzymes?
Definition
29.  autolysins
Term
30.  How do autolysins participate in killing the cell when peptidoglycan synthesis is inhibited?
Definition
30.  autolysins activity continues without a new unit to insert and cell will eventually lyse in hypotonic environment.
Term
31.  What type of enzyme is Penicillin Binding Proteins?
Definition
31.  transpeptidase
Term
32.  What does transpeptidase do?
Definition
32.  catalyzes the final crosslinking step in the synthesis of peptidoglycan
Term
33.  What does Penicillin do?
Definition
33.  Irreversibly binds at the active site of the transpeptidase enzyme that cross-links the peptidoglycan strands. inhibiting cross-linking
Term
34.  What are 3 ways resistance may develop?
Definition
34.  1. Production of penicillinases or β-lactamases; 2. Mutated PBP, so penicillin can’t bind 3. develop tolerance – inactivation of autolysin
Term
35.  What are β-lactam antibiotics structural analogs of?
Definition
35.  D-Ala-D-Ala end of peptidoglycan pentapeptide
Term
36.  What are 4 problems with Penicillin G?
Definition
36.  1. Hydrolysis by gastric acid; 2. Penicillinase sensitivity; 3. Allergic response; 4. Ineffective against gram neg. enterics
Term
37.  What is the breakdown product of penicillin that can be used to elicit different drug properties?
Definition
37.  6 aminopenicillanic acid (6-APA)
Term
38.  Which Penicillin has the highest activity against G+ cocci and bacilli?
Definition
38.  Narrow spectrum penicillins
Term
39.  What are examples of Narrow spectrum penicillins?
Definition
39.  G and V
Term
40.  What are Broader Spectrum Penicillins affective against?
Definition
40.  G+ and G- enteric bacilli
Term
41.  What are some examples of Broader Spectrum Penicillins?
Definition
41.  Ampicillin, Amoxicillin, Cyclacillin, Carbenicillin, Ticarcillin.
Term
42.  What drugs are considered the Antistaphylocococcal Penicillins? Examples?
Definition
42.  Narrow Spectrum/Penicillinase Resistant Drugs; Methacillin, Nafcillin, Oxacillin, closacillin, dicloxacillin
Term
43.  What drug has a similar structure and mechanism of action identical to penicillin?
Definition
43.  Cephalosporins
Term
44.  How do cephalosporins differ from penicillins?
Definition
44.  acid stability, penicillinase resistance, antigenically dissimilar
Term
45.  What is the progression of 1st to 4th generation cephalosporins?
Definition
45.  broadening in G- susceptibility; diminution of activity against G+; increased β-lactamase resistance; increased capability to enter CSF
Term
46.  What oral cephalosporin is affective against Gram + cocci (staph & strep)?
Definition
46.  Cephalexin (Keflex)
Term
47.  What has rendered many 2nd and 3rd generation cephalosporins inaffective?
Definition
47.  Extended Spectrum β-Lactamases
Term
48.  What type of antibiotic crosses the blood brain barrier and is effective against Enteric G- bacteria?
Definition
48.  3rd Generation – Ceftriaxone
Term
49.  What antibiotic is effective against E. Coli?
Definition
49.  4th Generation – Cefepime
Term
50.  What in Carbapenems allows movement through the outer membrane of G- bacteria?
Definition
50.  small hydroxyethyl side chain
Term
51.  What is the structure of the Carbapenems?
Definition
51.  β-lactam ring attached to five-membered cyclic ring with carbon
Term
52.  What are Carbapenems highly resistant to?
Definition
52.  β-lactamases
Term
53.  What are 3 examples of Carbapenemases?
Definition
53.  KPC, OXA, Metallo-β-lactamases
Term
54.  How do the carbapenems create Resistance?
Definition
54.  altered porin channes decreasing permeability
Term
55.  What type of antibiotic can be used in penicillin allergic patients?
Definition
55.  Monobactams
Term
56.  What is the drug of choice for MRSA?
Definition
56.  Vancomycin
Term
57.  What was the first strain to show resistance to Vancomycin?
Definition
57.  Enterococcus faecalis
Term
58.  What is Vancomycin restricted to?
Definition
58.  Gram + organisms
Term
59.  What kind of antibiotic is Streptomycin and what kind of action does it have?
Definition
59.  aminoglycoside antibiotic, Bactericidal
Term
60.  What is an Aminoglycosides?
Definition
60.  aminosugars linked by a glycosidic bond to an aminocyclitol
Term
61.  What kind of damage can Amionoglycosides cause to the human body?
Definition
61.  Kidney and/or 8th cranial nerve damage
Term
62.  How do Aminoglycosides produce a –cidal mechanism?
Definition
62.  1. few streptomycin molecules enter the cell through imperfections in the growing membrane; 2. Binds to 30S ribosomal protein, distorts and causes misreading; 3. Misreading causes “bad” proteins to be made, more membrane leakiness, more streptomycin enters;
Term
63.  How does Daptomycin (peptide antibiotic) target bacteria?
Definition
63.  Cell membrane
Term
64.  How does it irreversibly bind to the bacterial cell membrane?
Definition
64.  calcium-dependent membrane insertion of molecule
Term
65.  What is the mechanism of action of Daptomycin?
Definition
65.  Irreversibly binds to bacterial cell membrane, rapidly depolarizes the cell membrane, Efflux of K+, Cell death by multiple failures in biosystems.
Term
66.  What is Daptomycin active against?
Definition
66.  G+ infections; MRSA, VRE, S. pyogenes
Term
67.  T/F Resistance to Daptomycin is rare.
Definition
67.  T
Term
68.  In the Lungs, what does Daptomycin bind avidly with making it ineffective against pneumonia?
Definition
68.  Pulmonary Surfactant
Term
69.  What is an example of an antibiotic that has Nucleotide Biosynthesis activity?
Definition
69.  Sulfonamide
Term
70.  What is the mechanism of action of sulfonamide?
Definition
70.  Blocks dihydropteroate synthetase;
Term
71.  At what point in the synthesis of folic acid synthesis does trimethoprim inhibit?
Definition
71.  dihydrofolate reductase; DHF –Xà THF
Term
72.  How can bacteria become resistant to Trimethoprim?
Definition
72.  mutations in DHFR
Term
73.  How does resistance develop to Sulfonamides?
Definition
73.  slowly and stepwise
Term
74.  What does the mixture of Trimethoprim-Sulfamethoxazole have activity against?
Definition
74.  broad spectrum activity against aerobic bacteria and pheumocystis
Term
75.  What is a way that bacteria can thymidine to get around the inhibition of folic acid?
Definition
75.  from DNA released from dead cells in the pus of a cyst or abscess
Term
76.  What Bacterial enzymes are a target for quinolones?
Definition
76.  DNA gyrase, Topoisomerase IV
Term
77.  What Quinolone is most active against Gram – aerobic bacteria?
Definition
77.  Ciprofloxacin
Term
78.  What spectrum or bacteria are Quinolones active against?
Definition
78.  G- aerobic, G- enteric rods or cocci, G+ and anaerobic
Term
79.  How can drugs be used to attenuate protein synthesis in Bacteria while not affecting us?
Definition
79.  Bacteria have 70S R with 30S and 50S subunits, while we have 80S R with 40S and 60 S subunits
Term
80.  What drugs are active against 30S?
Definition
80.  Aminoglycosides, Tetracyclins
Term
81.  What does Neosporin contain?
Definition
81.  Polymyxin B Sulfate (Gram – rods, alters cell membranes), Bacitracin Zinc (Gram+), Neomycin Sulfate (broad spectrum)
Term
82.  What is the Mechanism of Tetracycline?
Definition
82.  Inhibition of protein synthesis by binding 30S ribosome, block acceptor site, inhibiting aminoacyl-tRNA binding.
Term
83.  What is Tetracyclin active against?
Definition
83.  gram + and gram -
Term
84.  Why should Tetracyclin be avoided during the latter half of pregnancy and in children under 8 years?
Definition
84.  can cause permanent discoloration of the teeth and enamel
Term
85.  What is a side effect of Chloramphenicol?
Definition
85.  penetrates human mitochondreia and inhibits mitochondrial protein synthesis, causing bone marrow depression
Term
86.  What is a type of Macrolide Antibiotic?
Definition
86.  Erythromycin
Term
87.  How do Macrolides terminate the peptide linking?
Definition
87.  binds reversibly at 2 sites on the 50S ribosome causing dissociation of the tRNA
Term
88.  Which drug is one of the least toxic drugs?
Definition
88.  Erythromycin
Term
89.  What drug was the first ketolide antibiotic and is active against most respiratory tract pathogens?
Definition
89.  Telithromycin
Term
90.  What is a serious side effect of clindamycin?
Definition
90.  pseudomembranous colitis
Term
91.  What antibiotic is active against Vancomycin-resistant enterococci and MRSA?
Definition
91.  Quinupristin/Dalfopristin (Synercid)
Term
92.  What are 5 ways to reduce antimicrobial resistance to antibiotics?
Definition
92.  1. Rapid diagnosis to reduce inappropriate use
Term
93.  What is Innate resistance?
Definition
93.  a trait of bacterial species that was present before the introduction of antimicrobial agents
Term
94.  What is Acquired (Emergent) resistance?
Definition
94.  antimicrobial agent USE-DRIVEN selection and accumulation of resistant bacterial strains
Term
95.  What are 2 origins of acquired resistance?
Definition
95.  New Single Mutation, Acquisition of DNA from other bacteria (Horizontal Gene Transfer)
Term
96.  T/F Once resistant strains of bacteria are present in a population, exposure to antimicrobial drugs favors their survival.
Definition
96.  T
Term
97.  What are the 5 principles of Antimicrobial Resistance?
Definition
97.  1. Resistance is likely to emerge
Term
98.  Can integrons contain simultaneous resistance to several classes of antibiotics?
Definition
98.  Yes
Term
99.  T/F the use of one antibiotic can activate the expression of a whole gene cassette.
Definition
99.  T
Term
100.       How does antibiotic selective pressure create resistance?
Definition
100.        Cells that have an integron for resistance of a particular antibiotic will survive. Removal of that antibiotic can cause the integron to be lost because its not necessary.
Term
101.       What is an example of an enzyme used by bacteria for drug inactivation?
Definition
101.        β-lactamases
Term
102.       How do altered porins in G- bacteria create resistance?
Definition
102.        decreased access to target
Term
103.       How do altered PBP’s create resistance?
Definition
103.        Penicillin cannot bind to the cell’s altered PBP’s allowing cross-linking to occur.
Term
104.       What other proteins can be involved in bacterial resistance to drugs?
Definition
104.        Outer membrane Proteins (OMP); Porins; PBP
Term
105.       T/F Virtually all G- express a gene for a β-lactamase.
Definition
105.        T – occurs at least in low levels in the periplasmic space
Term
106.       What is the mechanism that bacteria use for tetracycline resistance?
Definition
106.        altered Efflux pumps, protection of ribosomal target sites
Term
107.       T/F Penicillin resistance due to β-lactamase production occurs in S. pneumonia
Definition
107.        F
Term
108.       What do β-lactamases target?
Definition
108.        penicillins and cephalosporins
Term
109.       What will bind to β-lactamases to inhibit them?
Definition
109.        Clauvanic Acid and Sulbactam
Term
110.       What are persisters? What protects them?
Definition
110.        small number of dormant survivor bacterial without antibioticresistance mechanism; Biofilms
Term
111.       T/F You intend on being attacked by an Octopus after Assessment 3.
Definition
111.        T – Great I’ll help you defend it
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