Mid Chemo

Question 1

Why do we combine antibiotics

Answer 1

1-broaden the effect and treat polymicrobial infections
2-prevent emergence of resistant organisms
3- synergistic effect

Question 2

What are the Results of antimicrobial combinations

Answer 2

1-Antibiotic synergism 1+1=3
2-Antibiotic antagonism1+1=0
3- antibiotic additive 1+1=2

Question 3

What substance is responsable for the injury to plasma membrane

Answer 3

Polymyxin B

Question 4

When is the best use fir antimicrobial cell wall inhibition?

Answer 4

When bacteria is young and actively growing (log phase)

Question 5

What are the affect sites of action in antimicrobial drugs

Answer 5

1-inhibit cell wall
2-inhibit protein synthesis
3-inhibit nucleic acid synthesis
4-injure plasma membrane
5- inhibit synthesis of metabolites

Question 6

Peptidoglycan percentages of cell wall in G+ve , mycobacterium and G-ve bacteria

Answer 6

G+=50%
G-= 10-20%
Mycobac=30%

Question 7

Peptidoglycan is composed of….

Answer 7

Sugar chain linked by short peptide chains containing(NAG)/(NAM)

Question 8

——— is connected by tetra peptide side chains

Answer 8

NAM

Question 9

____ have a beta lactam ring

Answer 9

Penicellin

Question 10

Ampicillin is active on?

Answer 10

G -ve but not p.aeruginosa

Question 11

Carbenicillin are active on?

Answer 11

P.aeruginosa

Question 12

Natural penicillin is only affictive on

Answer 12

G+ve

Question 13

What is the mechanism action of penicillin

Answer 13

It prevents peptidoglycan cross links in final stage of the pathway of cell wall forming (transpeptidase binding)

Question 14

How do we evade beta lactamase?

Answer 14

1 use non beta-lactam agent
2 use B-lactam+B-lactamase inhibitors(بلطجي)
3 steric inhibiton (large sidechains/cephalosporins)

Question 15

What is the penicillin binding protien

Answer 15

Transpeptidases

Question 16

What is the difference between old and new definitions of antibiotic?

Answer 16

The new produced wholly or partially by chemical synthesis

Question 17

What is super infection

And what is pre infiction

Answer 17

Overgrowth one type of microbes in response yo antibiotic(candida-yeast)
Pre=prophylaxis give drug before infection can occur

Question 18

What are the sources of antibiotecs

Answer 18

1-natural
2-synthesis
3-semis-synthesis

Question 19

What is the source of the following…
Penicillin
Cephalosporins
Chloramphenicol

Answer 19

Semi-synthesis = penicillin/cephalosporins

Synthetic=chloramphenicol

Question 20

What are the sources of antibiotics?(from microbes)

Answer 20

G+ve rods
Fungi
Actinomycetes

Question 21

Give examples for antibacterial
Broad spectrum
Narrow spectrum

Answer 21

Broad = tetra cyclines
Narrow = penicillin/isoniazid(myco)

Question 22

Bacteriostatic activity

Answer 22

The level that inhibits growth of an organism

Question 23

MIC?

Answer 23

Lowest concentration that inhibits growth of an organism

Question 24

MBC

Answer 24

Lowest concentration that kills 99.9% of bacteria

Question 25

Bacteriostatic MO?

Answer 25

``` Erythromycin Lincomycin Fusidic acid Tetracyclines Chloramphenicol Sulfanoamides ```

Question 26

Which bacteria has the highest amount of peptidoglycan in cell wall

Answer 26

G+ve 50%

Question 27

What is the main substance to attack of vancomycin?

Answer 27

D-alanine amino acid connection | D-alanyle-D-alanine

Question 28

The precursors in peptidoglycan are synthesized in———

Answer 28

Cytoplasm

Question 29

D-cycloserine affect on cellwall

Answer 29

Interferes with bacterial cell wall synthesis by competitively inhibiting L-alanine racemiase and D-alanine ligase

Question 30

How do precursors cross cell membrane?

Answer 30

By binding with lipid carrier molecules (bactoprenol)

Question 31

The work of Transglycolase Transpeptidase

Answer 31

=polymerize glycan chains | =Catalyses peptide cross linking

Question 32

Where does glycopeptide antibiotic works?

Answer 32

Only in G+ve bacteria

Question 33

What are transpeptidases

Answer 33

catalyze cross linking

Question 34

Why penicillin G can not be used orally

Answer 34

Because stomach acid will disrupt it

Question 35

Penicillinase resistant penicillin 3 examples

Answer 35

Methicillin (the first) Oxacillin Nafcillin

Question 36

Major clinical problem in many parts of the word…..

Answer 36

Staphylococci

Question 37

Staphylococcal resistance penicillins

Answer 37

Methicillin and the legendary cloxacillin

Question 38

Treat P.aeruginosa by

Answer 38

Jew flattener Cabencillin , ticarcillin Pipercillin , azlocillin

Question 39

Mycobacteria antibiotics

Answer 39

Ethambutol and isoniazid