antibiotics and resistance tables

Question 1

Trimethoprim resistance

Answer 1

Plasmid-coded, trimethoprim-resistant dihydrofolate reductase.

Question 2

Penicillins resistance

Answer 2

Hydrolysis of ß-lactam ring by ß-lactamase enzyme; decreased Cephalosporins permeability of bacteria to the antibiotic; altered penicillin binding proteins.

Question 3

Methicillin resistance

Answer 3

Altered penicillin binding proteins (not in ß-lactamase). (a ß-lactamase-resistant penicillin).

Question 4

Aminoglycosides resistance

Answer 4

Enzymatic modification of drug by plasmid-coded enzyme; decreased permeability of bacteria to the antibiotic; mutation alters site to which antibiotic normally binds (e.g. S12 ribosomal protein for streptomycin).

Question 5

Tetracyclines resistance

Answer 5

Interference with transport of drug into cell.

Question 6

Chloramphenicol resistance

Answer 6

Detoxification of drug by acetylation of hydroxyl.

Question 7

Erythromycin resistance

Answer 7

Enzymatic methylation of 23S ribosomal RNA.

Question 8

Ciprofloxacin & Rifampin resistance

Answer 8

Altered target enzymes (gyrase, RNAP)

Question 9

Vancomycin resistance

Answer 9

Alteration of cell wall precursor target.

Question 10

Antimetabolites (sulfonamides, trimethoprim)

Answer 10

Inhibit synthesis of dihydrofolate, ultimately nucleic acid synthesis.

Question 11

Antimetabolite flucytosine

Answer 11

inhibits thmidylate synthetase and ultimately DNA synthesis

Question 12

Isoniazid

Answer 12

Inhibits synthesis of mycolic acid (specific for Mycobacteria)

Question 13

b-Lactams, penicillins, cephalosporins

Answer 13

Interfere with cell wall biosynthesis. Inhibition of transpeptidation weakens cell wall. Autolytic enzymes of bacteria then promote lysis.

Question 14

Cycloserine, bacitracin, glycopeptides, vancomycin, teichoplanin, caspofungin

Answer 14

Interfere with cell wall biosynthesis.

Question 15

Polymyxins, polyenes, nystatin, amphotericin B, daptomycin

Answer 15

Disrupt membrane integrity.

Question 16

Aminoglycosides (streptomycin)

Answer 16

Inhibit protein synthesis by binding to a specific protein of 30S ribosomal subunit.

Question 17

Aminoglycosides (gentamicin, kanamycin, neomycin, amikacin, tobramycin)

Answer 17

Bind to 30S ribosomal subunit at multiple sites. Inhibit protein synthesis.

Question 18

Tetracyclines

Answer 18

Block protein synthesis by inhibiting binding of amino-acyl t-RNA to 30S subunit.

Question 19

Erythromycin, azithromycin, clindamycin, chloramphenicol

Answer 19

Bind to 50S ribosomal subunit. Inhibit protein synthesis at chain elongation step.

Question 20

Oxazolidinones (linezolid)

Answer 20

Bind rRNA on both ribosomal subunits (new)

Question 21

Streptogramins (dalfopristin, quinupristin)

Answer 21

Bind to 50S ribosomal subunit (new)

Question 22

Mupirocin

Answer 22

Binds isoleucyl tRNA synthetase, preventing charging of Ile-tRNA and thus affecting protein synthesis.

Question 23

Fluoroquinolones (ciprofloxacin)

Answer 23

Inhibit bacterial DNA gyrase.

Question 24

Nitroimidazoles

Answer 24

Fragment DNA

Question 25

Rifampin

Answer 25

Binds to bacterial RNA polymerase and blocks transcription.

Question 26

Azoles (fluconazole, ketoconazole)

Answer 26

Inhibit ergosterol synthesis.

Question 27

Ethambutol

Answer 27

Unknown, anti-TB

Question 28

Pyrazinamide

Answer 28

Unknown, anti-TB