Antibiotics

Question 1

What are the antibiotics?

Answer 1

They are chemical produced by a microorganism that kill or inhibit the growth of another microorganisms.

Question 2

What is the antimicrobial agent?

Answer 2

Chemical that killd or inhibits the growth of microorganisms.

Question 3

Source of antibiotics:

Answer 3

Chemical sources and naural sources (~80%).

Question 4

ABs from Chemical sources:

Answer 4

Sufonamides, quinolones, Trimethoprim, oxazolidinones.

Question 5

AbBs from natural source:

Answer 5

Penicillins, cephalosporins, carbapenems, Aminoglycosides, Tetracyclines, macrolides, Glycopeptides, chloramphenicol.

Question 6

Beta-lactams target:

Answer 6

PBPs in cell wall

Question 7

Mactolides target :

Answer 7

rRNA

Question 8

Aminoglycosides target:

Answer 8

Protein synthesis

Question 9

Rifamycins target

Answer 9

RNA polymerase

Question 10

Trimethroprim target:

Answer 10

Dihydrofolate reductase

Question 11

Fluoroquinolones target:

Answer 11

DNA gyrase, topoisomerase IV

Question 12

Glycopeptides target:

Answer 12

Cell wall peptidoglycan synthesis

Question 13

Total targets for antimicrobial activity:

Answer 13

10-15 targets

Question 14

Bacteria have approx …. essential genes:

Answer 14

200

Question 15

Antibiotics are classified several ways:

Answer 15

Mechanism of action, mode of action and spectrum of activity.

Question 16

Toxic metabolites for bacteria:

Answer 16

Metronidazole

Question 17

Drugs act on cell wall:

Answer 17

Penicillins, cephalosporins, carbapemems, glycopeptides.

Question 18

Drug acts on RNA polymerase :

Answer 18

Rifampin

Question 19

Drug acts on DNA Gyrase:

Answer 19

Fluroquinolones

Question 20

Drug acts on protein synthesis:

Answer 20

Nitrofurantoin

Question 21

Drugs act on 50s ribosome

Answer 21

Macrolides

Lincosamides

Question 22

Drugs act on 30s Ribosome

Answer 22

Aminoglycosides

Tetracyclines

Question 23

Drugs act on folic acid pathway:

Answer 23

TMP/SMX

Dapsone sulfoxone

Question 24

Drugs act on mycolic acid pathway

Answer 24

Isoniazide

Ethambutol

Question 25

Pencillin and cephalosporins Mode of action

Answer 25

They bind and block peptidase involved in cross-linking the glycan molecules

Question 26

Mode of action of vancomycin

Answer 26

Hinders peptidoglycan elongation

Question 27

Cycloserine mode of action

Answer 27

It inhibits the formation of the basic peptidoglycan subunits

Question 28

Structure of penicillin:

Answer 28

Thiazolidine ring Beta lactam ring Variable side chain (R group)

Question 29

Semisynthetic penicillin

Answer 29

Ampicillin and carbenicillin

Question 30

R group in penicillin:

Answer 30

It is responsible for the activity of the drug

Question 31

Penicillin enters to the cell through ..... and bind to ....

Answer 31

Porins, PBP

Question 32

After penicillin binding to PBP:

Answer 32

PBP can no longer synthesize protein essential to integrity of cell wall

Question 33

Drug has similar structure to penicillin but enhanced stability:

Answer 33

Cephalosporins

Question 34

Cephalosporins Gen that not given orally and easy to be resistence:

Answer 34

1st gen (cefalotin and cefalexin)

Question 35

Cephalosporins gen that more G-ves and more stable against beta-lactamases:

Answer 35

2nd gen (cefuroxime and ceftoxin)

Question 36

Cephalosporins gen that have broad spectrum against G-ves, useful in hospital-acquired infections and can penetrate CNS:

Answer 36

3rd gen( cefotaxime and ceftazidime)

Question 37

Cephalosporins gen that have extended spectrum against G+ves and can pemetrate G-ve outer membrane:

Answer 37

4th gen (cefepime and cefepirome)

Question 38

Anti- pseudomonal, less susceptible to development of resistance and are referred to as anti-MRSA cephalosporins.

Answer 38

5th gen (ceftaroline and ceftobiprole)

Question 39

E.g of Macrolides :

Answer 39

Erythromycin, clarithromycin, azithromycin

Question 40

Macrolides coverage:

Answer 40

GP except Enterococcus. GN: legionella, B. Pertussis Atypical : chlamydophila and mycoplasma

Question 41

Mechanism of action of macrolides :

Answer 41

They bind to 50s ribosomal subunit inhibiting protein synthesis

Question 42

Why clarithromycin and azithromycin used rarely?

Answer 42

Due to Gi upset

Question 43

E.g of lincosamides:

Answer 43

Clindamycin, chloramphenicol and linezolid

Question 44

Lincosamide has broad spectrum:

Answer 44

Chloramphenicol

Question 45

Clindamycin coverages:

Answer 45

GP except Enterococcus Most community-acquired MRSA Anaerobes

Question 46

Chloramphenicol coverages:

Answer 46

GP, GN and anaerobes (broad spectrum.

Question 47

Linezolid coverages:

Answer 47

GP including VRE + MRSA

Question 48

Mechanism of action of clindamycin:

Answer 48

It inhibits peptide bond formation at 50s ribososme

Question 49

Mechanism of action of chloramphenicol:

Answer 49

It inhibits peptidyl transferase action of tRNA at 50s ribosome

Question 50

Mechanism of action of linezolid:

Answer 50

It binds to 50s ribosome and prevents functional 70s initiation conplex

Question 51

E.g of Aminoglycosides:

Answer 51

Gentamicin, tobramycin, amikacin

Question 52

Aminoglycosides coverage

Answer 52

GN aerobic bacilli | Include pseudomonas

Question 53

Mechanism of action of aminoglycosides

Answer 53

They bind 30s subunits of ribosome inhibiting protein synthesis

Question 54

Contraindication of aminoglycosides:

Answer 54

Pre-existing hearing loss and renal dysfunction

Question 55

AE of aminoglycosides:

Answer 55

Nephrotoxicity (reversible) Ototoxicity (irreversible) Most is vestibular toxicity

Question 56

Aminoglycosides indications:

Answer 56

GP infection | Used with b-lactam or vancomycin in eterococcal infection

Question 57

Tetracyclines used in:

Answer 57

(Atypical bacteria) | GP, syphilis, Chlamydophila, Rickettsia, mycoplasma

Question 58

Mechanism of action if tetracyclines:

Answer 58

Binds 30s subunit of ribosome inhibiting protein synthesis

Question 59

E.g of topoisomerase inhibitors:

Answer 59

Flouroquinolones Rifampin Metronidazole

Question 60

What is the quinolones?

Answer 60

``` Nalidixic acid (comletely synthetic) A nitrogen atom within a heterocyclic structure ```

Question 61

Mechanism of action of Quinolones:

Answer 61

Inhibits DNA gyrase (unwinds supercoiled DNA helix prior to trsnscription + replication)

Question 62

Quinolones using

Answer 62

It active against most Gram- | And used in treatment of uncomplicated UTIs