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Flashcards in Antibiotics Deck (86)
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1

Three desired properties of antibiotics

Broad Range (until + diagnosis)
Able to get to body tissues
Selectively Toxic

2

Give an three examples of a synergistic antibiotic interaction.

SxT will block sequential steps
Cell Wall/Membrane Inhibitors may allow drug entry
One drug may inhibit detox enzymes

3

Give three reasons for use of multiple antibiotic drugs

Systemic/multiple infections
Delaying resistance to long-term use
Synergisms

4

Three categories of patients that should be prescribed prophylactic antibiotics.

Known contact with a known agent
Before surgery with high likelihood of complications
Special Cases -- ex. predisposed to endocarditis, UTI, immunocompromised

5

How do new biofilm preventing coatings work?

Implanted devices are coated with a cationic detergent that interacts with the quaternary amine

Over the next several days, hydrolysis occurs and releases dead cells

6

What is fidaxomicin active against?

Inhibits RNA polymerase
G+

7

What is Bedaquiline active against?

c Subunit of ATP synthase rotor
Mycobacteria

8

Why is amoxicillin rarely prescribed alone?

Heightened resistance to the drug

9

Three primary types of cell wall inhibitors?

beta-lactams
Bacitracin
Glycopeptides (Vancomycin, Telavancin)

10

How do beta-lactams work?

Inhibit transpeptidation and activate autolysins in the cell wall

11

How do bacteria resist beta lactams?

beta-lactamases, lack of PBPs, autolysin mutations

12

What drugs are often given with beta lactams?

Beta lactamase inhibitors (Clavulinic acid, aulbactam, tazobactam)

13

Which penicilins are natural? Why use them?

Pen G, Pen V
Best vs. Gram + bacteria

14

Which penicillins are expanded spectrum? (i.e. also good against Gram -)

Ampicillin
Piperacillin
Mezlocillin

15

Which Penicillins are beta-lactamase resistant? (3)

Nafcillin
Oxacillin
Cloxacillin

16

Which penicillins are acid resistant?

Amoxycillin
Pen V
Oxacillin

17

Three most common penicillin +lactamase inhibitor combos

Augmentin = amoxicillin + Clavulanic acid
Ampicillin + Sulbactam
Zosyn/Tazomed = Piperacilin + Tazobactam

18

Which beta lactam structure provides some natural resistance to beta-lactamase?

Monobactams
(beta-lactam with one ring)

19

Three types of beta lactams?

Penicillins
Cephalosporins
Monobactams

20

Perks of 3rd and 4th generation cephalosporins?

Work on Gram +/-
Can Cross BBB

21

Examples of 3rd and 4th gen cephalosporins?

Ceftazidime, Cephotaxime, Caphtriaxone
Cefepime

22

Two downsides to monobactams

Effective vs G- only
Expensive

23

name a monobactam

Aztreonam

24

Pro and con of carbapenems?

Broad spectrum
Possibly toxic (leads to seizures)

25

Common problem with beta lactams?

Allergy (Pen>Ceph>Mono)

26

How does bacitracin work?

Blocks the de-phosphorylation of bactoprenol

27

When would you use bacitracin?

Topical
Almost only vs. G+

28

Side effects of bacitracin

Poor absorption
Renal Toxicity

29

Why is bacitracin so hard to absorb?

Its freakin huge

30

How do antibiotic glycopeptides (vancomycin, telavancin) work?

Bind to the end of amino acid side chain, blocking transglycosylation and transpeptidation.

31

What mutation provides bacteria resistance to anti-biotic glycopeptides?

Using Ala-Lactate rather than Ala-Ala

32

What bacterial subtype are Glycopeptides ineffective against?

G-

33

Why is oral vancomycin only effective in the GI tract?

Its fuckin huge. Its not getting through to the system.

34

What is cycloserine?

a D-ala analog that inhibits alanine racemase

35

Why should you exhibit caution with cycloserine?

Neurotoxic

36

What four types of drugs are used for Mycobacterium? (4)

Isoniazid/Ethionamine (INH)
Ethambutol (EMB)
Pyrazinamide (PZA)
RMP (Rifampicin)

37

How do isoniazid, ethionamines work?

Inhibit pyroxidine step in mycolic acid synthesis

38

How does ethambutol work?

Inhibition of arabinogalactan synthesis

39

How does pyrazinamide work?

Activated by mycobac enzyme, inhibits trans-translation

40

Concerns with using INH?

Also blocks your own Vitamin B6 synthesis

41

Two primary kinds of cell membrane disruptors?

Polymyxins (Colistin)
Daptomycins (Cubicin)

42

How do polymyxins work?

Dissolve phosphatidylethanolamine (a specialized PL in G- membranes)

43

When would you use Polymyxins?

As a last resort for resistant bugs
Topically

44

How does daptomycin work?

Dissolves in the membrane and disrupts potential

45

When would you use daptomycins?

G+ Cocci (MRSA)

46

How would you give daptomycins?

IV probably with beta-lactams

47

Two examples of anti-metabolites?

Sulfonamides (Sulfone) and Trimethoprim

48

How do anti-metabolites work?

They inhibit individual steps in the pyramidine synthesis pathway

49

How might bacteria become resistant to antimetabolites?

Overproduction of PABA

50

Four common nucleic acid inhibitors?

Fluoroquinolones (Ciprofloxacin, moxifloxacin)
Fidaxomycin (Dificid)
Rifamycin (Rifampin, Rifabutin, Rifaximin)
Metronidazole

51

How how fluoroquinolones work?

Inhibition of DNA gyrase

52

Important side effects of fluoroquinolones?

Associated with prolonged QT interval

53

How does fidaxomycin (Dificid) work?

Targets the switch region of RNAP
Prevents interaction of RNAP with DNA

54

When would you use fidaxomycin?

Its an alternative to vancomycin commonly used in cases of vancomycin resistance.

55

How does rifamycin (rifampin, rifabutin, rifaximin) work?

Blocks RNA polymerase elongation subunit

56

When would you use rifamycin?

With Isoniazid to delay mycob. resistance
Meningitis
Poxviruses

57

Significant side effect of rifamycin?

Can make you sweat and turns urine orange

58

How does metronidazole work?

Reduced complex with ferredoxin interacts with DNA and breaks DNA strands (Free Radical)

59

Two targets metronidazole tends to be used against?

Protazoa
Anerobic Bacteria

60

List five common protein synthesis inhibitors.

Aminoglycosides
Tetracycline
Chloramphenicol
Macrolides
Lincosamides

61

How do aminoglycosides work?

Bind to 30S Ribosome, block initiation by preventing attachment of tRNA(methinonine)

62

Examples of aminoglycosides?

Streptomycin, Neomycin, Gentamycin, Tobramysin, amikacin

63

What would you use aminoglycosides for?

G- enterics
Synergy with cephalosporin/penicillin

64

How does tettacycline work?

Inhibits binding of aa-tRNA to the A-site of 30S ribosome

65

Examples of tetracyclines?

Doxycycline, tigecycline

66

How do bacteria become resistant to tetracycline?

Efflux Pumps

67

What do you use tetracyclines for?

Rickettsia, Chlamydia, Mycoplasmas

68

Side effects of tetracyclines?

Toxicity, Dissiness, Tinnitus, Fluorescent teeth

69

Who should you never give tetracycline to?

Pregnant people

70

How does chloramphenicol work?

Inhibits peptidyl transferase rxn

71

Why is chloramphenicol use no longer recommended?

Resistance and Toxicity

72

Examples of macrolides?

Erythromycin, Clarithromycin, Azithromycin

73

How do macrolides work?

Bind to rRNA and inhibit translocation (50s)

74

How might bacteria resist macrolides?

Methylation of rRNA

75

When would you use macrolides?

G+ and some G-

76

Side effects of macrolides?

Assoc. with prolonged QT
Increased risk of CV death

77

Example of a lincosamide?

Clindamycin

78

How do lincosamides work?

bind to rRNA and inhibit tanslocation (50S)

79

When would you use lincosamides?

Anerobes, Anti-Malarial

80

Problems with lincosamides?

Can't get to CNS
One use can cause major disruption of native flora
Long term use allows C diff colonization

81

When would you use nitrofurantoin?

UTI

82

When would you use Streptogramins?

VRE and VRSA

83

What do Mupirosins do? When would you use them?

Inhibit ile-tRNA synthase
G+

84

When would you use Oxazolidinones?

Treat VRE and MRSA

85

What do methenamines do? What do you treat with them?

Releases formaldehyde in acidified urine
UTI

86

What two drugs are used to wake up persister cells?

C10
BF8