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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
Q

_______ is a cyclic analog of alanine

A

Cycloserine

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26
Q

Also crosses blood brain barrier and is an NMDA receptor agonist (with uses and side effects)

A

Cycloserine

27
Q

Inhibits Mycobacteria by affecting synthesis of mycolic acid (abundant wax in the cell wall)

A

Isoniazid and Ethionamide

28
Q

Inhibits Mycobacteria by affecting attachment of mycolic acid in the cell wall

A

ethambutol

29
Q

Binds 23S rRNA and prevents formation of 70s initiation complex.

A

Oxazolidinones (linezolid)

30
Q

Bind 16s rna of 30s subunit and prevent the binding of the A site

A

tetracyclines

31
Q

Bind to 30S subunit and distort A site, causing translation misreading, which inhibits protein synthesis.

A

Aminoglycosides

streptomyosin, gentamycin, tobramycin

32
Q

Bind to 50S subunit and inhibit PA peptidyltransferase activity.

A

Chloramphenicol

Lincosamides

33
Q

amino acid on the tRNA at the A site attacts the bond between tRNA amino acid at the P site

A

peptidyltransferase

reaction

34
Q
  • Bind 23S rRNA in the 50S subunit and block the translocation reaction aa#2
  • also prevent formation of the 50S PA subunit
A

Macrolides

erythromycin, azithromycin, clarithromycin

35
Q
  1. Disruption of bacterial cell wall
  2. Inhibition of
    protein synthesis
  3. Inhibition of nucleic acid synthesis
  4. Antimetabolites
A

Basic Mechanisms of Antibiotic action

36
Q

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.

A

Quinolones

ciprofloxacin and other -floxacins

37
Q

Inhibit the enzymes that untangle nucleic acids during DNA replication and RNA transcription

A

Quinolones

38
Q

Bind to bacterial RNA polymerase and prevent the initiation of transcription

A

Rifampin & Rifabutin

39
Q
  • a prodrug with no inherent antimicrobial activity

* produces DNA-damaging radicals under anaerobic conditions via enzymes functioning in anaerobes and microaerophiles

A

Metronidazole

40
Q

Stops the precursors to folic acid

A

antimetabolites

Sulfonamides, trimethoprim, dapsone, and p-aminosalicylic acid

41
Q

Big problem for clinical treatment of infections.

_______ can often be transmitted to other bacteria

A

Resistance (drug resistance)

42
Q

What four ways to bacteria resist antibiotics?

A
  1. impermeable membrane
  2. Target modification
  3. Antibiotic modification
  4. efflux pump
43
Q

the bacterial cell membrane develops an impermeable barrier which blocks antibiotics

A

impermeable barrier

44
Q

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

A

target mdoification

45
Q

the cell produces substances (enzyme) that degrades and inactivates the antibiotic before it can harm the bacteria.

A

antibiotic modification

46
Q

the anitbiotic is actively pumped out of the bacteria for that it cannot harm the bacteria

A

efflux pump

47
Q
  • contains a plasmidborne

- hydrolysis of b-lactam ring by b-lactamase

A

penicillins, cephalosporins

48
Q
  • does not contains a plasmidborne

- change in penicillin-binding protein

A

methicillin

49
Q
  • contains a plasmidborne

- efflux pump pushes drug out of cell

A

tetracylcines

50
Q
  • does not contains a plasmidborne

- mutations in 23S rRNA

A

oxazolidinones

51
Q
  • does not contains a plasmidborne

- mutations in genes encoding DNA gyrase and topoisomerase IV

A

quinolones

52
Q
  • contains a plasmidborne

- change in binding site in the peptidoglycan target (D-alanine – D-alanine changed to D-alanine – D-lactate)

A

vancomycin

53
Q
  • New mutations of bacterial genes that
    encode the targets of antibiotics
  • Pre-existing resistance genes that are
    transmitted from one bacterium to another
A

the origin and transmission of drug resistance

54
Q

some can promote their own

transfer by conjugation

55
Q

drug resistance genes are carried on ______

56
Q
  • can package non-phage DNA

= transfer by transduction

A

Transducing bacteriophage

57
Q
  • mutations

- transfer by transformation

A

Bacterial chromosomal genes

58
Q

hop into other genetic elements

A

transposons

59
Q
  • segments of DNA containing
    complete sets of genes
  • found on plasmids, transposons, and bacterial chromosomes
60
Q

development and spread of drug-resistant pathogens caused by antibiotic treatment, which destroys drug-sensitive strains

A

superinfection

61
Q

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

A

superinfection

62
Q

Clostridium difficile (spore-forming agent of pseudomembranous colitis)

MDR (multi-drug-resistant) gram-negative rods

MRSA (methicillin-resistant Staphylococcus aureus) Candida or other fungi

A

Common organisms in Superinfections

63
Q 
• 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
A

Pr eventing emergence of drug resistance

Microbiology (46 decks)

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