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Flashcards in Antibiotics Midterm Deck (42)
1

-illins

Related to PCN

2

-cyclins

Related to tetracyclins

3

-mycins

Related to macrolide antibiotics

4

What does Vancomycin target?

Peptidoglycan in cell walls, gram positive bacteria

5

What does Chloramphenicol target?

Ribosomal subunits

6

Bacteriostatic vs. Bactericidal

Bacterial growth vs. Bacterial death

7

MIC vs. MLD

Minimal inhibitory concentration vs minimal lethal dose. MIC is the lowest concentration needed to inhibit growth in 99% and MLD is minimal amount needed to kill 99.9%

8

Drugs that target essential metabolic pathways?

Sulfa/Trimethoprim
P-Aminosalicylic acid

9

Drugs that target nucleic acid synthesis

Rifampin and Rifabutin
Quinolones
Metronidazole (flagyl)

10

Drugs that disrupt bacterial membranes

Polymyxins/Colistin (Polymixin E)

11

Specific effect of sulfa drugs

These are broad spectrum antibiotics that inhibit folic acid biosynthesis from the start. Often used with trimethoprim which inhibits another step in the pathway by stopping the cell from using pools of materials it has already made. Both of these guys act as competitive inhibitors.

S + T = Bactrim

12

What other drug is Sulfa related to?

P-aminosalicylic acid - Effective against TB

13

Drugs that are bactericidal

Rifampin and Rifabutin
Quinolones
Metronizadole (Flagyl)
Polymixins

14

How do rifampin and rifabutin work?

narrow spectrum, gram + bacteria. Binds to beta subunit of RNA polymerase, inhibits transcriptional initiation

15

How do quinolones work?

inhibit DNA replication by inhibiting bacterial DNA gyrases and/or topoisomerase IV

16

How does flagyl work?

narrow spectrum, administered as a prodrug, disrupts DNA structure, inhibits DNA replication, causes breaks and mutations (enzymes to convert prodrug only in bacterial cells)

17

How do Polymixins work?

narrow spectrum, inserts hydrophobic tail into membrane, hydrophilic head group disrupts PE and LPS on membrane (host dos not have PE or LPS)

18

What drugs target the bacterial cell wall?

Vancomycin
PCN

19

How does Vanco work?

Prevents transglycosylation in the cell wall

20

How does PCN work?

Inhibits transpeptidation by mimicking the beta-lactam molecule to bind transpeptidases and carboxypeptidases.

All -cillins work in this way

21

What do we give -cillins to help the mfight bacteria resistances?

Clavulanic acid, which when given with the -cillin, fights the Beta-lactamase that inhibits the antibiotic.

Ex. Augmentin = Amoxicillin + clavulanic acid

22

What drugs target the cell membrane

Polymixins
Daptomycin

23

How do polymixins work?

Integrates a lipophilic tail in the outher membrane and destroys it. Effects Gram negative bacteria.

24

How does Daptomycin work?

Affects gram negative bacteria making it a good alternative to Vancomycin. Integrates lipophilic tail in membrane and destroys it. Calcium dependent though

25

What is the danger of targeting bacterial ribosomes?

Very similar to our mitochondrial ribosomes. Antibiotics can't cross this!

26

Antibiotics that inhibit the production of initiation complexes

Linezolid (member of oxazolidiones) - Inhibits the formation of 70s initiation complex by targeting the 50s subunit. Only works on gram positive bacteria.

27

Different effects for linezolid?

It is bacteriostatic against staph and enterococci but interacts more strongly with trep, killing it.

28

Antibiotics that inhibit peptide chain synthesis specifically by inhibiting recognition of protein synthesis structures?

Aminoglycosides
Streptinomycin
Tetracyclines

29

How do aminoglycosides work?

They target the proteins in the 30s subunit, are broad spectrum and are bactericidal.

Key antibiotic in this category is streptomycin.

30

What does streptomycin do?

1. Causes misreading/insertion in a chain
2. Causes structural protein failure in cell membrane
3. Cyclic polysomal blockade where 70s forms but falls apart

31

Problems with using aminoglycosides?

Toxicity, ineffective against most intracellular bacteria and can cause biofilm creation from catheters.

32

How does streptinomycin work?

Another type of antibiotic that inhibits protein synthesis, but it is an aminocyclitol antibiotic. It's bcteriostatic and causes unstable formation of 70s. Used to treat gonorrhea.

33

How do Tetracyclins work?

Broad spectrum antibiotic that treats chlamydia, mycoplasma, and rickettsia. Binds to 30s unit and inhibits binding of aa-tRNA to the activation site

34

Antibiotics that inhibit protein synthesis specifically by inhibiting peptidyl transfers

Cloramphenicol
Lincomycin and Clindamycin

35

How dos Chloramphenicol work?

Broad spectrum, bacteriostatic. Binds to 50s and alters tRNA structure to block peptidyl transfer

36

How do lincomycin and clindamycin work?

Narrow spectrum bacteriostatic, effective against gram positive. Same function as chloramphenicol

37

What antibiotics inhibit protein synthesis specifically by inhibiting translocation?

Macrolides
Ketolides
Streptogramins

38

How do macrolides work?

Medium spectrum, bacteriostatic that treats mycoplasma, chlamydia and gram +. We use these for patients allergic to PCN.

Targets 50s and stops transpeptidation

39

Examples of macrolides

Azithromycin, clarithromycin

40

How do Ketolides work?

Bind 50s unit and block exit of polypeptides. Ketolides differ from macrolides in that they bind two domains of 23s, whereas macrolides bind one domain.

41

What type of streptogramins do we have?

Streptogramins are the thid category of antibiotics that inhibit translocation. It comes in three types:
Dalfopristin
Quinupristin
and Synercid, whic his just D and Q together = bactericidal

42

Dalfopristin and Quinupristin

Binds to 50s and prevents elongation and facilitates binding of quinupristin to 50s, which causes premature release of peptide chains from the ribosome. Both of these are bacteriostatic alone