CP 1 - Intro to Antibacterial Agents

Question 1

Definition of antibiotics

Answer 1

chemical products of microbes that inhibits or kill organisms

Question 2

Definition of antimicobial agents

Answer 2

Include antibacterial, antifungal, antiviral eg antibiotics, synthetic compounds with similar effects, semi-synthetic (modified from antibiotics)

Question 3

Definition of bacteristatic

Answer 3

inhibition of bacterial growth eg protein synthesis inhibitors

Question 4

Definition of bactericidal

Answer 4

kill bacteria eg cell wall-active agents

Question 5

Definition of minimum inhibitory concentration - MIC?

Answer 5

minimum concentration of antibiotic at which visible growth is inhibited

Question 6

Definition of synergism

Answer 6

activity of 2 antimicrobials given together providing a greater outcome that the sum of the 2 separately

Question 7

Definition of antagonism

Answer 7

one agent diminishes the activity of another

Question 8

Definition of difference

Answer 8

activity unaffected by the addition of another agent

Question 9

one clinical example of synergism?

Answer 9

Beta-lactam & aminoglycoside combination therapy of streptococaal endocarditis

Question 10

what are the 5 antibiotic targets if it is aimed to inhibit critical process in bacterial cells

Answer 10

cell wall, protein synthesis, DNA synthesis, RNA synthesis, plasma membrane

Question 11

what compound is found in both gram -ve & +ve bacteria?

Answer 11

peptidoglycan - major compound of bacterial cell wall, polymer of N-acetyl muramic acid (NAM) & N-acetyl glucosamine (NAG)

Question 12

what are the 2 cell wall synthesis inhibitors?

Answer 12

Beta-lactams & glycopeptides

Question 13

what does all β-lactam antibiotics contain in their chemical structure?

Answer 13

β-lactam ring - structural analogue of D-alanyl-D-alanine (DADA) - competitive inhibitors

Question 14

what does β-lactam antibiotics interfere present in the bacteria?

Answer 14

Interfere with penicillin binding proteins (a transpeptidases involved in peptideoglycan cross-linking)

Question 15

what are the subclass within the β-lactam antibiotics ?

Answer 15

penicillins, cephalosporins, carbapenems, monobactams (Gram -ve only)

Question 16

how does glycopeptides work?

Answer 16

large molecules - bind directly to D-alanyl-D-alanine on NAm pentapeptides so inhibiting binding of transpeptidases and thus peptideoglycan cross-linking

Question 17

what are the target spectrum of glycopeptides?

Answer 17

only gram +ve - unable to penetrate gram -ve

Question 18

what are the 4 subclasses for protein synthesis inhibitor?

Answer 18

Aminoglycosides, Macrolides, Lincosamides, Streptograms (MLS), Tetracyclines, Oxazolidinones, others (Mupirocin, fusidic acid)

Question 19

Mechanism of action for aminoglycosides?

Answer 19

binds to 30s ribsomal subunit

Question 20

common example for aminoglycosides?

Answer 20

gentamicin

Question 21

common examples for MLS?

Answer 21

erythromycin, clindamycin (binds to 50s ribosomal subunit)

Question 22

common examples for tetracyclines?

Answer 22

doxytetracycline (binds to 30s ribosomal subunit & inhibit RNA translation)

Question 23

Common examples for oxazolidinones?

Answer 23

linezolid - binds to 50s ribosomal subunits & inhibits initiation of protein synthesis

Question 24

what are the 2 subclasses within DNA synthesis inhibitors?

Answer 24

Trimethoprim & suflonamides, Quinolones & fluoroquinolones

Question 25

MOA for trimethoprim & sulfonamides?

Answer 25

inhibit folate synthesis (folic acid is a purine synthesis precursor)

Question 26

what is the name of the drug which is combination of trimpethoprim & sulfonamides?

Answer 26

co-trimoxazole (trimethoprim-sulfamethoxazole)

Question 27

what are the common examples for quinolones & fluoroquinolones

Answer 27

inhibit one or more of 2 related enzyme involving DNA remodelling and replication

Question 28

common examples for quinolones & fluoroquinolones?

Answer 28

ciprofloxacin

Question 29

Common example for RNA synthesis inhibitors?

Answer 29

Rifampicin

Question 30

MOA of Rifampicin?

Answer 30

RNA polymerae inhibitors - prevents synthesis of mRNA

Question 31

what are the 2 agents for the plasmas membrane agents?

Answer 31

colistin - gram -ve, daptomycin - gram +ve, cyclic lipopeptides & destory cell membrane

Question 32

what are the common adverse effects for all drugs?

Answer 32

nausea, vomiting, headache, skin rashes, infusion reactions, allergic reactions, fungal infection - superficial and invasive candidiasis, C.diff infection

Question 33

what are the adverse effect for aminoglycosides?

Answer 33

reversible renal impariment on accumulation, irreversible ototoxicity (ear toxicity)

Question 34

adverse effect for B-lactams?

Answer 34

allergic reactions mainly

Question 35

adverse effect for linezolid

Answer 35

bone marrow depression

Question 36

what class of antibiotics can be used if patient allergic to B-lactams?

Answer 36

cephalosporins & carbapenems for non-severe pencillin allergic, aztreonam for severe allergic reactions (does not include a bicycles nucleus)

Question 37

common precipitating antibiotics for C.diff?

Answer 37

4Cs - co-amoxiclav (amoxicilin-clavulanate), cephalosporins, ciprofloxacin, clindamycin