Pharmacology - Antibiotics Flashcards Preview

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Flashcards in Pharmacology - Antibiotics Deck (29)
1

Trimethoprim

Inhibits dihydrofolate reductase (prevents reduction of folic acid to tetrahydrofolate)

2

Sulfamethoxazole

Structural analog of para-aminobenoic acid (PABA). Competes with PABA to inhibit dihydrofolic acid synthesis, an intermediate step in formation of tetrahydrofolate.

3

Imipenem

Binds a PBP (penicillin binding protein) and inhibits final step of peptidoglycan synthesis in bacterial cell walls.

4

Cilastatin

Use in conjunction with imipenem - prevents renal metabolism of imipenem by competitively inhibiting dehydropeptidase in renal tubule brush border.

Remember: Imipenem is LASTING with CiLASTatin.

5

Bacitracin

Prevents mucopeptide transfer into growing cell wall, inhibiting cell wall synthesis.

6

Metronidazole

Binds DNA in susceptible cells, unraveling DNA's helical structure and breaking its strands.

7

Pyrimethamine

Acts the same way as trimethoprim and methotrexate; treats toxoplasmosis because it inhibits parasitic dihydrofolate reductase.

8

Penicillins and cephalosporins

Irreversibly bind penicillin binding proteins, AKA transpeptidases, which cross-link peptidoglycan in the bacterial cell wall.

NOTE: They do NOT bind to the cell wall glycoproteins! They bind to the transpeptidases!

9

Another word for penicillin binding proteins?

Transpeptidases!

10

What do transpeptidases do?

They cross-link peptidoglycan in the bacterial cell wall.

11

Vancomycin

Binds to terminal D-alanine residues of cell wall glycoproteins and prevents transpeptidases from forming cross-links.

Note: Vancomycin actually binds to the glycoproteins of the cell wall.

Side effects: Red man syndrome (histamine mediated), nephrotoxicity

12

Which binds to cell wall glycoproteins, vanc or penicillins?

Vancomycin

13

Fluoroquinolones

Interfere with DNA replication by binding to DNA gyrase

14

Beta lactamase

Degrades penicillin and cephalosporin.

15

Which antibiotics would require entry into the cell to function?

Tetracycline and macrolides for example - probably things that inhibit ribosomal assembly.

16

What are the commonly used drugs for invasive MRSA?

1. Vancomycin
2. Daptomycin
3. Linezolid

Remember: My Dapper Van is Lined with MRSA.

17

Daptomycin

Disrupts bacterial membrane through creation of transmembrane channels which cause leakage of intracellular ions, leading to depolarization of the cellular membrane and inhibition of DNA / RNA / protein synthesis.

Cannot permeate outer membrane of Gram Negative bacteria.

Is inactivated by pulmonary surfactant - do not use for pneumonieas.

Side effects: increased CPK and increased myopathy, especially in patients taking statins.

18

Linezolid

Inhibits bacterial protein synthesis by binding to the 50S subunit.

Basically like clinda.

Side effects: Thrombocytopenia, optic neuritis, high risk for serotonin syndrome.

19

Tetracyclines

Inhibit 30S subunit.

Bacteriostatic, bind to 30S and prevent attachment of amino-acyl tRNA; limited CNS penetration. Do not take with milk.

Remember: Buy AT 30, CCEL at 50.

20

Aminoglycosides

Bactericidal - inhibit formation of initiation complex and cause misreading of mRNA; also block translocation. Require O2 for uptake; therefore ineffective against anaerobes.

Mean GNATS caNNOT kill annaerobes.

Gentamicin
Neomycin
Amikacin
Tobramycin
Streptomycin

Nephrotoxic
Neuromuscular blockade
Ototoxic
Teratogenic

21

Macrolides

Azithromycin, clarithromycin, erythromycin. Inhibit protein synthesis by blocking translocation. bind to 23S rRNA of the 50S ribosomal subunit. bacteriostatic.

22

Chloramphenicol

Binds peptidyltransferase at 50S ribosomal subunit. bacteriostatic. Aplastic anemia and gray baby syndorme.

MOR: Plasmid-encoded acetyltransferase inactivates drug.

23

Clindamycin

Blocks peptide transfer at the 50s ribosomal subunit.

24

Carbapenems

Imipenem, meropenem, ertapenem, doripenem

beta lactam / broad spectrum / beta-lactamase resistant

25

Isoniazid

Decreased synthesis of mycolic acids. Need bacterial catalase peroxidase encoded by KatG to convert INH to active metabolite.

Think Wall of Ice + Acid

26

Rifamycin

Rifampin, rifabutin
Inhibits DNA dependent RNA polymerase.

27

Dapsone

PABA antagonist that acts to inhibit folic acid synthesis, behaves similarly to sulfonamides

28

Pyrazinamide

Thought to acidify intracellular environment by conversion to pyrazinoic acid, TB

29

Ethambutol

TB, decreases carbohydrate polymerization of mycobacterium cell wall by blocking arabinosyltransferase.