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Clinical Micro 2 Spring 2023 > Exam 2 Antibiotic > Flashcards

Exam 2 Antibiotic Flashcards

1
Q

Define antimicrobial agent.

A

Chemical substance produced either by a microorganism or synthetically that can kill or suppress microorganisms.

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2
Q

Define bacteriostatic

A

Inhibits bacterial growth without killing.

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3
Q

What class of antibiotics inhibit DNA gyrase and topoisomerase

A

Quinolones; floaxin, ciprofloxacin, enoxacin

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4
Q

What antibiotic interacts with DNA causing loss of helical DNA structure?

A

Metronidazole

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5
Q

What antibiotic interacts with the RNA polymerase?

A

Rifampin

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6
Q
A
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7
Q

Define spectrum of activity in antibiotics.

A

It targets both gram negative and gram positive bacteria however it also targets normal flora.

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8
Q

Define MIC , minimum inhibitory concentration.

A

Maximum dilution of product that will inhibit growth of a test microorganism

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9
Q

MBC, minimal bactericidal concentration is defined as?

A

Greater than or equal to 99.9% reduction of visible colony forming units of a bacterial or fungal suspension suspension

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10
Q

Define breakpoint in ANTIMICROBIAL susceptibility test.

A

Concentration of antibiotic which defines in vitro whether a species or group of species is susceptible or resistant to an antibiotic/ANTIMICROBIAL.

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11
Q

What are the possible interpretation of antibiotic susceptibility testing and what do they mean?

A

S - Susceptible: A possible option for treatment for patient. Bacteria does not have any mechanism to overcome the antibiotic.
I - Intermediate: Bacteria is somewhat susceptible and may be an option for treatment if paired up with another kind of antibiotic.
R - Resistant: Bacteria is resistant to antibiotic and not a viable option for treatment

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12
Q

List different kinds of antibiotic classes that inhibit cell wall synthesis

A
  1. Beta lactams
  2. Fosfomycin
  3. Glycopeptides / lipoglycopeptides
  4. Monobactam
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13
Q

List different types of beta - lactams.

A
  1. Penicillins
  2. Cephalosporins
  3. Carbapenems
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14
Q

List different types of Glycopeptides / lipoglycopeptides

A
  1. Vancomycin
  2. Telco plan in
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15
Q

What is a type of monobactam?

A

Aztreonam

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16
Q

How does fosfomycin work against the bacteria cell wall?

A

It inhibits the enzyme at the first step of cell wall synthesis

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17
Q

What antibiotic targets the cell membrane?

A

Polymyxins

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18
Q

What antibiotics target folate synthesis?

A

Sulfonamides and trimethoprim

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19
Q

What antibiotic targets DNA gyrase?

A

Quinolones

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20
Q

What antibiotic targets RNA polymerase?

A

Rifampin

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21
Q

What antibiotics target the 50s subunit?

A
  1. Macrolides
  2. Clindamycin
  3. Linezolid
  4. Chloramphenicol
  5. Streptogramins
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22
Q

What antibiotic targets the 30S subunit?

A

Tetracyclines and aminoglycosides

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23
Q

List some criteria for an ideal antibiotic.

A
  • Non - toxic; limited side effects
    *Able to enter cell
    *Specific target
    *Sufficient concentration
    *Spectrum
  • Soluble in body fluids; remain active
  • Limited development of resistance
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24
Q

What determines the product produced from a beta lactam ring?

A

Depends on the addition to the beta lactam ring. The product can be penicillin, Cepheus, Carbapenems, or monobactam

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25
Q

Prefix ceph, or suffix cillin, penem denotes what?

A

A type of beta lactam

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26
Q

What structure is important in penicillin, cephalosporin, and Carbapenems?

A

The beta - lactam ring. It’s similar (enough) to Acyl-D-alanyl-D-alanine (important in cell wall synthesis) to be taken up by the bacteria.

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27
Q

Glycopeptides and lipoglycopeptides target what kind of bacteria?

A

Gram positive because they are so large so they cannot affect gram negative bacteria’s outer membrane

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28
Q

Glycopeptides / lipoglycopeptide interfere with cell wall synthesis how?

A

Forms a hydrogen bond to terminal D - alanyl - D - alanine moiety of NAM / NAG peptides preventing it from being incorporated into the cell wall by PBP.

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29
Q

What are examples of lipoglycopeptides?

A

Oritavancin, dalbavancin, and telavancin

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30
Q

Vancomycin inhibits cell wall synthesis by binding to…?

A

D - ala- D - ala terminal of the growing peptide during cell wall synthesis.

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31
Q

What antibiotic is used if the patient has a serious gram positive bacterial infection resistant to beta lactams (or allergic to beta lactam drugs)?

A

Vancomycin

32
Q

List situations vancomycin should not to be used in

A
  • Routine surgical prophylaxis
  • Empiric therapy (unless evidence of Gram
    -positive infection or prevalence of MRSA
    is high)
  • Treatment of a single positive blood
    culture
  • Continued use after susceptibility report
  • Eradication of MRSA colonization
33
Q

How do polymyxin interact with the bacteria’s cell membrane and what is a side effect?

A

Polymyxin antibiotics act as a detergent to the cell’s membrane shredding it. The down side is neurotoxicity and nephrotoxicity.

34
Q

How do lipopeptide antibiotics interact with a bacteria’s cell membrane?

A

Binds to and disrupts gram-positive cell membrane by inserting hydrophobic tail into membrane increasing permeability.

35
Q

What is colistin mainly used for? What is a side effect of taking colistin?

A

For multi - drug resistant GNR and its side effect is significant renal toxicity

36
Q

Daptomycin is effective against what kind of gram positive bacteria?

A

Cocci especially resistant strains such as MRSA, and VRE, vancomycin resistant entercoccus sp.

37
Q

Daptomycin is not effective in treating respiratory infection, why?

A

The lung surfactants bind to the drug inactivating it.

38
Q

List classes of antibiotics that inhibit protein synthesis

A
  • Aminoglycosides
  • Macrolide-lincosamide-
    streptogramin (MLS)
  • Ketolides
  • Oxazolidinones
  • Chloramphenicol
  • Tetracyclines
  • Glycylglycines
39
Q

What are examples of macrolides antibiotic?

A

Erythromycin, azithromycin, and clarithromycin

40
Q

When are macrolide antibiotics bacteriocidal? They’re usually bacteriostatic.

A

If infective dose of bacteria is low and drug concentration is high

41
Q

What does the MLS antibiotic classes target to inhibit protein synthesis?

A

23S and 50S ribosomal RNA subunits. Inhibiting the subunits disrupts the translocation that happens to grow peptide chains

42
Q

Aminoglycosides activity of spectrum is?

A

Broad spectrum however cannot be taken up by anaerobic bacteria intracellularly. Antibiotic inhibits protein synthesis through inhibition of 30S ribosome subunit.

43
Q

What is a side effect of aminoglycosides?

A

Nephrotoxicity, auditory, and vestibular toxicity

44
Q

Lincosamide target what part of the bacteria to inhibit protein synthesis?

A

50S ribosomal unit to prevent elongation of the polypetide.

45
Q

What is a risk associated with lincosamide?

A

Increased risk of C. diff infection

46
Q

What is the spectrum of activity for lincosamides?

A

Gram positive and some anaerobic gram negative bacterias.

47
Q

What is an example of lincosamide?

A

Clindamycin

48
Q

Streptogramin examples are?

A

Quinupristin and dalfopristin

49
Q

Dalfopristin inhibits protein synthesis…?

A

By changing the confirmation of the 50S ribosomal subunit blocking protein synthesis and bacterial growth.

50
Q

A good antibiotic to pair quinupristin with?

A

Dalfopristin

51
Q

Examples of oxazolidinones are?

A

Linezolid and tedizloid

52
Q

What do oxazolidnones target to prevent protein synthesis?

A

Binds to 23S ribosomal RNA of the 50S subunit preventing formation of the functional 70S initiation complex. This prevents bacterial translation and replication.

53
Q

What kind of bacteria are oxazolidnones effective against?

A

Gram positive and mycobacteria

54
Q

Chloramphenicol prevent protein synthesis by…?

A

Targeting the 50S subunit inhibiting transpeptidation.

55
Q

Chloramphenicol is effective against

A

Gram negative and gram positive bacteria

56
Q

What is a side effect of chloramphenicol antibiotics?

A

Can cause aplastic anemia

57
Q

Tetracycline / Doxycycline inhibits protein synthesis how?

A

Binds to 30S subunit so incoming tRNAs with amino acids cannot bind to ribosome.

58
Q

Tetracycline / Doxycycline side effects are?

A

Cutaneous phototoxcity - photoallergic immune reaction and toxicity in the upper GI

59
Q

Glycylglycines inhibit protein synthesis by…?

A

REVERSIBLY binding to 30S ribosomal subunit

60
Q

True or false, glycylglycines are effected by the same resistance mechanisms as tetracycline.

A

False

61
Q

Glycylglycines have what kind of side effects

A

GI side effects

62
Q

What are the three antibiotics that inhibit DNA & RNA synthesis?

A

Fluoroquinolones, metronidazole, and rifampin

63
Q

Fluoroquinolones target and bind to what in the bacteria?

A

DNA gyrase and topoisomerase

64
Q

What is a side effect of fluoroquinolones?

A

Affects tendons causing tendonitis and rupture

65
Q

Metronidazole targets…?

A

The helical structure of DNA and disrupts it.

66
Q

What is require to activate metronidazole?

A

A reduced environment (anaerobic)

67
Q

What does rifampin target in the bacteria?

A

Binds to RNA polymerase

68
Q

What is the downside of rifampin?

A

Bacteria can develop spontaneous mutations (insensitive RNAP) and is sometimes used with other drugs.

69
Q

Sulfonamides works by?

A

Disrupting the bacterial folic acid pathway by inhibiting dihydropteroate synthase (different than trimethoprim).

70
Q

What kind of bacteria does sulfonamide are vulnerable to?

A

Gram positive and negative except P. aeruginosa

71
Q

Trimethoprim kill bacteria by targeting …?

A

Dihydrofolate reductase of the folic acid pathway. (Sulfonamides target dihydropteroate synthase).

72
Q

Sulfonamide side effects are

A

vomiting, nausea, and hypersensitivity reactions. They are antagonist to warfarin, phenytoin, and oral hypoglycemic agents.

73
Q

Nitrofurantoin kill bacteria how?

A

Flavoproteins (nitroreductases) reduce the nitrogen group that turns into reactive intermediates that damages ribosomes and other macromolecules such as DNA, RNA, and proteins.

74
Q

Nitrofurantoin are good against what kind of bacteria?

A

Gram positive and gram negative except P. aeruginosa. Its used to treat uncomplicated UTIs

75
Q

How does lipoglycopeptides work?

A
  1. Allows cell wall binding that inhibits cell synthesis.
  2. Increases permeability and polarize cell membrane potential

Clinical Micro 2 Spring 2023 (17 decks)

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