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Microbiology > Principle 4- Part B > Flashcards

Principle 4- Part B Flashcards

1
Q

_______ can impact pathogen by targeting some
function necessary for its reproduction or
survival

A

antimicrobial agents

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2
Q

When antimicrobial agents are targeted function is very specific to pathogen ______ _____ _____ occurs

A

high therapeutic index

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3
Q

the following antimicrobial agents, b-lactams, Glycopeptides, and Polypeptides, are involved in disruption of the ____ ____ ____.

A

bacterial cell wall

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4
Q 
– peptidoglycan repeat unit forms in
cytoplasm
     • involves use of uridine
     diphosphate (UDP) as a 
     carrier
– repeat unit then transported across
membrane by bactoprenol (“lipid”) 
– repeat unit attached to growing
peptidoglycan chain 
– cross-links formed by transpeptidation
A

Steps of peptidogylcan synthesis.

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5
Q

________ creates crosslinks in peptidoglycan

A

Transpeptidation

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6
Q

_________ is the exchange of one peptide bond for another

A

Transpeptidation

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7
Q

_______ antibiotics inhibit transpeptidation

A

b-lactam

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8
Q

_______ is a ring structure that is similar to the D-ala —– D-Ala bond

A

b-lactam

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9
Q

high activity against most gram positive bacteria. low against gram negative; destoryed by acid and penicillinase.

A

Penicillin G

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10
Q

More acid resistant than penicillin G

A

Penicillin V

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11
Q

Active against gram + and gram - bacteria; acid stable

A

ampicillin

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12
Q

Penicillinase-resistant, bet less active than penicillin G; acid-labile

A

Methicillin

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13
Q

Two newer classes of b-lactam antibiotics

A

Carbapenems and monobactams

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14
Q

Not antibiotics, but help b-lactam antibiotics by preventing their degradation by b-lactamases

A

b-lactamase inhibitors

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15
Q

________ are enzymes produced by some bacteria that are resistant to b-lactam antibiotics

A

b-lactamases

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16
Q

clavulanic acid, sulbactam, and tazobactam

A

Examples of b-lactamase inhibitors:

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17
Q

________ binds terminal D-Ala-D-Ala and sterically inhibits addition of peptidoglycan subunits to the cell wall.

A

Vancomycin

stops production

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18
Q

_______ binding to existing peptidoglycan chains inhibits the transpeptidation reaction that crosslinks the chains

A

Vancomycin

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19
Q

________ has been important for treatment of
antibiotic resistant staphylococcal and
enterococcal infections

A

vancomycin

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20
Q

Vancomycin and teichoplanin are _______.

A

glycopeptides

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21
Q

______ prevent recycling of lipid carrier.

A

bacitracins

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22
Q

______ Binds phospholipids and disrupts outer and inner membranes of gram negative bacteria (topical because of more general mode of action = toxic)

A

polymixins

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23
Q

bacitracins and polymixins are exampls of ________.

A

polypeptides

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24
Q

Second line treatment for Mycobacterium tuberculosis

A

Cycloserine

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25
_______ is a cyclic analog of alanine
Cycloserine
26
Also crosses blood brain barrier and is an NMDA receptor agonist (with uses and side effects)
Cycloserine
27
Inhibits Mycobacteria by affecting synthesis of mycolic acid (abundant wax in the cell wall)
Isoniazid and Ethionamide
28
Inhibits Mycobacteria by affecting attachment of mycolic acid in the cell wall
ethambutol
29
Binds 23S rRNA and prevents formation of 70s initiation complex.
Oxazolidinones (linezolid)
30
Bind 16s rna of 30s subunit and prevent the binding of the A site
tetracyclines
31
Bind to 30S subunit and distort A site, causing translation misreading, which inhibits protein synthesis.
Aminoglycosides | streptomyosin, gentamycin, tobramycin
32
Bind to 50S subunit and inhibit PA peptidyltransferase activity.
Chloramphenicol | Lincosamides
33
amino acid on the tRNA at the A site attacts the bond between tRNA amino acid at the P site
peptidyltransferase | reaction
34
* Bind 23S rRNA in the 50S subunit and block the translocation reaction aa#2 * also prevent formation of the 50S PA subunit
Macrolides | erythromycin, azithromycin, clarithromycin
35
1. Disruption of bacterial cell wall 2. Inhibition of protein synthesis 3. Inhibition of nucleic acid synthesis 4. Antimetabolites
Basic Mechanisms of Antibiotic action
36
Interfere with type II topoisomerases (DNA gyrase or topoisomerase IV) and stabilize DNA double strand breaks. This is important in the Inhibition of nucleic acid synthesis.
Quinolones | ciprofloxacin and other -floxacins
37
Inhibit the enzymes that untangle nucleic acids during DNA replication and RNA transcription
Quinolones
38
Bind to bacterial RNA polymerase and prevent the initiation of transcription
Rifampin & Rifabutin
39
* a prodrug with no inherent antimicrobial activity | * produces DNA-damaging radicals under anaerobic conditions via enzymes functioning in anaerobes and microaerophiles
Metronidazole
40
Stops the precursors to folic acid
antimetabolites Sulfonamides, trimethoprim, dapsone, and p-aminosalicylic acid
41
Big problem for clinical treatment of infections. | _______ can often be transmitted to other bacteria
Resistance (drug resistance)
42
What four ways to bacteria resist antibiotics?
1. impermeable membrane 2. Target modification 3. Antibiotic modification 4. efflux pump
43
the bacterial cell membrane develops an impermeable barrier which blocks antibiotics
impermeable barrier
44
modification of components of the bacteria which are targeted by the antibiotic, meaning the antibiotic can no longer bind properly to its target in order to destroy the bacteria
target mdoification
45
the cell produces substances (enzyme) that degrades and inactivates the antibiotic before it can harm the bacteria.
antibiotic modification
46
the anitbiotic is actively pumped out of the bacteria for that it cannot harm the bacteria
efflux pump
47
- contains a plasmidborne | - hydrolysis of b-lactam ring by b-lactamase
penicillins, cephalosporins
48
- does not contains a plasmidborne | - change in penicillin-binding protein
methicillin
49
- contains a plasmidborne | - efflux pump pushes drug out of cell
tetracylcines
50
- does not contains a plasmidborne | - mutations in 23S rRNA
oxazolidinones
51
- does not contains a plasmidborne | - mutations in genes encoding DNA gyrase and topoisomerase IV
quinolones
52
- contains a plasmidborne | - change in binding site in the peptidoglycan target (D-alanine – D-alanine changed to D-alanine – D-lactate)
vancomycin
53
- New mutations of bacterial genes that encode the targets of antibiotics - Pre-existing resistance genes that are transmitted from one bacterium to another
the origin and transmission of drug resistance
54
some can promote their own | transfer by conjugation
plasmids
55
drug resistance genes are carried on ______
Plasmids
56
- can package non-phage DNA | = transfer by transduction
Transducing bacteriophage
57
- mutations | - transfer by transformation
Bacterial chromosomal genes
58
hop into other genetic elements
transposons
59
- segments of DNA containing complete sets of genes - found on plasmids, transposons, and bacterial chromosomes
integrons
60
development and spread of drug-resistant pathogens caused by antibiotic treatment, which destroys drug-sensitive strains
superinfection
61
Killing of normal flora removes the inhibitory effect of the normal flora (which produce antibacterial substances & compete for essential nutrients). This allows for uninhibited growth of potentially pathogenic bacteria & fungi
superinfection
62
Clostridium difficile (spore-forming agent of pseudomembranous colitis) MDR (multi-drug-resistant) gram-negative rods MRSA (methicillin-resistant Staphylococcus aureus) Candida or other fungi
Common organisms in Superinfections
63
``` • give drug in high concentrations • give two or more drugs at same time • use drugs only when necessary • possible future solutions - continued development of new drug - use of bacteriophages to treat bacterial disease ```
Pr eventing emergence of drug resistance

Microbiology (46 decks)

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