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0. Foundations of Medicine > Antimicrobial Chemotherapy 1 > Flashcards

Antimicrobial Chemotherapy 1 Flashcards

1
Q

<p>What are antibiotics only active against?</p>

A

<p>Bacteria</p>

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2
Q

<p>What are bactericidal?</p>

A

<p>Antimicrobial that kills bacteria (penicillins)</p>

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3
Q

<p>What does sensitive mean?</p>

A

<p>An organism is sensitive if it is inhibited or killed by the antimicrobial available at the site of infection</p>

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4
Q

<p>What is minimal bactericidal concentration (MBC)?</p>

A

<p>Minimum concentration of antimicrobial needed to kill a given organism</p>

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5
Q

<p>What is bacteriostatic?</p>

A

<p>Antimicrobial that inhibits the growth of bacteria</p>

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6
Q

<p>What does resistant mean?</p>

A

<p>Organism is resistant if it is not killed or inhibited by the antimicrobial available at the site of infection</p>

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7
Q

<p>What is minimal inhibitory concentration (MIC)?</p>

A

<p>Minimum concentration of antimicrobial needed to inhibit the growth of a given organism</p>

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8
Q

<p>What are the routes of antimicrobial administration?</p>

A

<p>Topical (applied to a surface such as the skin)</p>

<p>Systematic (taken internally, such as orally or parentally)</p>

<p>Parenteral (administered intravenously or intramuscularly)</p>

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9
Q

<p>What is parenteral administeration?</p>

A

<p>Administered intravenously or intramuscularly</p>

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10
Q

<p>What can antibiotics do to bacteria?</p>

A

<p>Kill or inhibit it</p>

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11
Q

<p>What are the 3 areas of bacterial metabolic activity that antibiotics can act on?</p>

A

<p>Inhibition of cell wall synthesis</p>

<p>Inhibition of nucleic acid synthesis</p>

<p>Inhibition of protein synthesis</p>

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12
Q

<p>Why are humans not harmed by antibiotics that inhibit cell wall synthesis?</p>

A

<p>Human cells do not have cell walls</p>

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13
Q

<p>What bacteria inhibit cell wall synthesis?</p>

A

<p>B-lactams:</p>

<p>Penicillins<br></br>Cephalosporins</p>

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14
Q

<p>How do B-lactams stop cell wall synthesis?</p>

A

<p>Disrupting peptidoglycans synthesis by inhibiting enzymes (penillin-binding proteins, PBPs) responsible for cross linking the chains</p>

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15
Q

<p>What proteins do B-lactams target?</p>

A

<p>Penicillin binding proteins (PBPs)</p>

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16
Q

<p>What do glycopeptides act on?</p>

A

<p>Gram positive bacteria, they are unable to penetrate the wall of gram negative</p>

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17
Q

<p>What are examples of glycopeptides?</p>

A

<p>Vancomycin</p>

<p>Teicoplanin</p>

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18
Q

<p>How are glycopeptides given and why?</p>

A

<p>Paternally because they are not absorbed from the GI tract</p>

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19
Q

<p>How do glycopeptides work?</p>

A

<p>Inhibit cell wall synthesis at a stage earlier than B-lactams, inhibiting the seemble of a peptidoglycan precurser</p>

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20
Q

<p>What do glycopeptides inhibit?</p>

A

<p>Peptidoglycan precurser</p>

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21
Q

<p>What allows selective action on bacteria protein synthesis?</p>

A

<p>Differences between bacterial and mammalian ribosomes</p>

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22
Q

<p>What are different classes of drugs used to inhibit protein synthesis?</p>

A

<p>Aminoglycans</p>

<p>Macrolides</p>

<p>Tetraclyclines</p>

<p>Oxazolidinones</p>

<p>Cyclic lippeptide</p>

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23
Q

<p>What do aminoglycans act on?</p>

A

<p>Gram negative bacteria</p>

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24
Q

<p>How do aminoglycans work?</p>

A

<p>Insert a different amino acid into the protein</p>

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25
Q

<p>What do macrolides act on?</p>

A

<p>Gram positive bacteria</p>

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26
Q

<p>What are macrolides an alternative to?</p>

A

<p>Penicillins for people who are allergic</p>

27
Q

<p>How do tetracyclines work?</p>

A

<p>Masks the codon on mRNA so the tRNA cannot bind</p>

28
Q

<p>What is an example of a oxazolidinone?</p>

A

<p>Linezolid</p>

29
Q

<p>How do oxazolidinones work?</p>

A

<p>Prevents the starting codon on the mRNA to be recognised by tRNA</p>

30
Q

<p>What is an example of cyclic lippeptide and what does it work against?</p>

A

<p>Daptomycin which works against gram positive bacteria, MRSA in particular</p>

31
Q

<p>How does cyclic lippeptide work?</p>

A

<p>Creates pores on the cell membrane causing leakage of ions and change of membrane potential, change prevents protein, DNA and RNA synthesis</p>

32
Q

<p>How can antibiotics inhibit DNA synthesis?</p>

A

<p>Directly</p>

<p>Indirectly (acting on precursors for DNA synthesis)</p>

33
Q

<p>What are some inhibitors of nucleic acid synthesis?</p>

A

<p>Co-trimoazole</p>

<p>Flouroquinolones</p>

34
Q

<p>What is co-trimoazole a combination of?</p>

A

<p>Trimethoprim and sulphamethoxazole</p>

35
Q

<p>What does co-trimoxazole inhibit?</p>

A

<p>Steps in purine synthesis (2 of the 4 bases)</p>

36
Q

<p>What is co-trimoxazole commonly used to treat?</p>

A

<p>Urinary tract infections</p>

<p>Chest infections</p>

37
Q

<p>How does flouroquinolones work?</p>

A

<p>Inhibit DNA synthesis directly by preventing the wrapping of DNA</p>

38
Q

<p>Who can flouroquinolone not be used in and why?</p>

A

<p>Children as it interferes with cartilage growth</p>

39
Q

<p>What areflouroquinolones effective against?</p>

A

<p>Gram negative bacteria</p>

40
Q

<p>How are flouroquinolones administered?</p>

A

<p>Orally</p>

<p>Parenterally</p>

41
Q

<p>How can antibiotic sensitivity of an organism be measured?</p>

A

<p>In the lab</p>

42
Q

<p>Why would we want to measure antibiotic sensitivity of an organism?</p>

A

<p>Predict if an infection will respond to treatment with that antibiotic</p>

43
Q

<p>How is resistance acquired by bacteria?</p>

A

<p>Genetically</p>

44
Q

<p>What are the 2 types of resistance?</p>

A

<p>Inherent resistance</p>

<p>Acquired resistance</p>

45
Q

<p>What is inherent resistant?</p>

A

<p>All strains of a given species are naturally resistant to antibiotics</p>

46
Q

<p>What is an example of inherent resistance?</p>

A

<p>Streptococci always resistant to aminoglycans</p>

<p>Gram negative always resistant to vancomycin</p>

47
Q

<p>What is acquired resistance?</p>

A

<p>May be present in some strains but not others</p>

48
Q

<p>What are the 2 ways that acquired resistance can be obtained?</p>

A

<p>Spontaneous mutation (change in structure or function which no longer allows the antibiotic to act)</p>

<p>Spread of resistance (genes that code for resistance can spreads from organism to organism or from species to species, being carried on plasmids or transposons)</p>

49
Q

<p>What is resistance spread using?</p>

A

<p>Plasmids or transposons</p>

50
Q

<p>What are plasmids?</p>

A

<p>Extra chromosomal packages of DNA</p>

51
Q

<p>What are transporons?</p>

A

<p>Packets of DNA which insert themselves into the chromosome</p>

52
Q

<p>What causes selective pressure and encourages new resistant organisms to outgrow sensitive strains?</p>

A

<p>Widespread use of antibiotics</p>

53
Q

<p>What are some current issues in antibiotic resistance?</p>

A

<p>B-lactamase production</p>

<p>Extended spectrum B-lactamases (ESBLs)</p>

<p>Carbapenemase producing enterobacteriaceae (CPE) or carbapenum resistance enterobacteriaciae (CRE)</p>

<p>Alterations of penicillin binding protein (PBP) target site</p>

<p>Glycopeptide resistance</p>

54
Q

<p>What is B-lactamase?</p>

A

<p>An enzyme that cleave the B-lactam ring of the antibiotic thus render it inactive</p>

55
Q

<p>What produces B-lactamases?</p>

A

<p>Most hospital stains of staphyloccocuc</p>

<p>Common in gram negative bacteria</p>

56
Q

<p>What produces extended spectrum B-lactamases (ESBLs)?</p>

A

<p>Some gram negative bacteria</p>

57
Q

<p>What are carbapenemase producing enterobacteriaceae (CPE) and carbapenum resistant enterobacteriaiae (CRE)?</p>

A

<p>Extremely resistant gram negative organisms to the carbapenems</p>

58
Q

<p>What is alteration of penicillin binding protein (PBP) active site?</p>

A

<p>Develop resistance by changing the structure of their PBP (enzymes involved in peptidoglycan synthesis)</p>

59
Q

<p>What alters their penicillin binding proteins?</p>

A

<p>Staph.Aureus known as methicillin resistant Staph.Aureus or MRSA</p>

60
Q

<p>What can glycopeptides usually be relied on to treat?</p>

A

<p>Gram positive bacteria</p>

61
Q

<p>What is an example of glycopeptide resistance?</p>

A

<p>Some enterococci is vancomycin resistant</p>

62
Q

<p>What are the 2 ways to combat B-lactamases?</p>

A

<p>Introduce a second component to the antibiotic (B-lactamase inhibitor) protecting the antibiotic from enzyme degradation</p>

<p>Modify the antibiotic side chain producing new antibiotic resistant to the actions of B-lactamase</p>

63
Q

<p>What is an example of an antibiotic using a B-lactamase inhibitor?</p>

A

<p>Amoxicillin plus the inhibitor clavulanic acid</p>

64
Q

<p>What is an example of an antibiotic with a modified side chain to be resistant to the actions of B-lactamase?</p>

A

<p>Flucloxacillin</p>

0. Foundations of Medicine (167 decks)

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