Antimicrobial Agents

Question 1

Antimicrobial drugs
Used in

Gram +ive sporing Rod Bacillus

Yersinia(Gram -ive straight Rods)

Neisseria gonorrhoeae (Gram -ive Cocci)

Vibrio Cholera (Enteric Curved Rods bacteria)

Borrelia burgdorferi (spiral -ive bacteria)

Chlamydia trachomatis

Rickettsia species

Answer 1

Tetracyclines

Question 2

Antibiotic is used in :

Streptococcus pyogens(Gram +ive Cocci)

Neisseria gonorrhoea (Gram -ive Cocci)

Campylobacter (Enteric Curved Rods Bacteria)

Bordetella pertussis (Respiratory. Straight Rods)

Answer 2

Erythromycin

Answer 3

Doxycycline

Answer 4

Fluroquniolones

Question 5

BALM TOP QuaNtity
Is a deviation refers to

Answer 5

Chemical Structure of Antibiotics

Betalactams , Aminoglycosides , Lincosamides , Macrolides , Tetracyclines ,Oxazolidinones , Phenicols , Quinolones , Nitroimidazole , Glycopeptides etc..

Question 6

Define broad spectrum antibiotics

With Ex

Answer 6

antibiotics have activity against both gram positive and gram negative bacteria.

F.ex : tetracycline and chloramphenicol.

Question 7

Define Extended spectrum antibiotics

Answer 7

antibiotics which have had chemical modifications which increase their gram negative coverage

Question 8

β-lactam group of Antibiotics effective agains ……

Answer 8

both Gram Positive and Gram Negative bacteria

Question 9

Mode of action of β-lactam

Answer 9

inhibit Transpeptidases

Question 10

Second Generation of Cephalosporins is Cefuroxime
✔️or✖️

Answer 10

✔️

Question 11

What is Extented spectrum betalactamases (ESBLs)

Answer 11

Enzyme destroy Beta lactam ring of Cephalosporins .

Question 12

treatment of staphylococcal infections.
List its mechanism

Answer 12

Fucidic acid

inhibits protein synthesis by forming a stable
complex with elongation factor EF-G, and the ribosome

Question 13

causes toxicity to bone marrow. So use is
restricted.

Answer 13

Phenicols (Inhibitor of protein synthesis)

Question 14

are used to treat ESBL (Extented spectrum betalactamases)

Answer 14

Carbapenems

Question 15

used in patients with severe allergic reactions to Beta Lactams..

Due to high molecular weight, only effective against G+ve bacteria

Answer 15

Vancomycin

Question 16

Mixture of polypeptides From Bacillus subtilis

Treat Serious nephrotoxicity in topical use

Answer 16

Bacitracin

Question 17

What are the antibiotics that interfere with DNA synthesis of bacteria

And how can they interfere

Answer 17

Nitroimidazole
Quinolones

inhibiting bacterial DNA replication
by inhibits DNA gyrase ( Topoisomerase II) activity.

Question 18

Not prescribed for pregnant women

Answer 18

Quinolones(inhibit nucleic acid synthesis)

Question 19

Cross resistance
VS
Antimicrobial resistance
VS
Multiple resistance

Answer 19

Cross resistance , a single mechanism confers resistance to multiple antimicrobial with closely
related antimicrobial agents

Antimicrobial resistance, is the ability of microorganism to survive and reproduce in the presence of antimicrobial does that were previously thought effective against them

Multiple resistance, multiple mechanisms are involved to multiple antimicrobial agents is seen with unrelated antimicrobial agents.

Question 20

Antibiotics binds with 30 S ribosome

Answer 20

Tetracycline
Amino-glycosides (ex. Gentamycin)
Macrolides (ex. Erythromycin)

Question 21

Antibiotics binds with 50 S ribosome

Answer 21

Phenicols (ex.Chloromophenicol)
Lincosamides (ex. Clindamycin)

Question 22

Antibiotics inhibits the conversion of folic acid into purine and pyrimidines

Give Ex.

Answer 22

Antibiotics interfere with Metabolism ;

Sulfonamides
Trimethoprim

Question 23

Effective against both Gram Positive and Gram Negative bacteria

Answer 23

Beta lactam

Sulfonamides

Trimethoprim

Question 24

Mechanism of action of Vancomycin

Answer 24

prevents \
-elongation
-cross-linking of peptidoglycan chain

Question 25

Antipseudomonal agent for betalctams and aminoglycoside resistant
Gram negative bacteria

Answer 25

Polimyxin (causes destruction of cytoplasmic membrane)

Question 26

Innate Resistance develops due to overuse and misuse of antimicrobial agents
✔️or✖️

Answer 26

✖️

Question 27

Bacteria isolated from clinical specimen are subjected to

Answer 27

Antimicrobial Susceptibility testing

Question 28

Give Ex of Innate Resistance

Answer 28

Intrinsic Resistance of Gram-negative bacteria to Vancomycin

Question 29

There is two types of Acquired Resistance

Answer 29

Mutational and Transferable drug resistance

Question 30

Define Acquired resistance

Answer 30

Conversion of a drug susceptible bacteria into drug resistant bacteria
by bacterial gene transfer mechanisms

Question 31

List the mechanisms of acquired resistance. With Ex

Answer 31

Conversion of active drug into inactive drug derivative
Ex. Inactivation of betalactam antibiotics by Betalactamase Production

Change in shape of target sites
Ex. Alteration of Pencillin binding proteins (PBPs)

Question 32

Explain Disc Diffusion method of Antimicrobial Susceptibility testing

Answer 32

1- bacterium is inoculated on the solid medium

2- antibiotic discs are applied.

3- antibiotic in the discs diffuses through the solid medium

Question 33

How can I know from Disc Diffusion method
if bacteria is resistant

Answer 33

If there is no zone inhibition seen around the antibiotic disc.

Question 34

List the mechanism of Broth Dilution method for Antimicrobial Susceptibility testing

Answer 34

antimicrobial agent is prepared in Nutrient broth

Each tube is inoculated with a fixed amount of suspension of the test organism.

Question 35

1- Minimum inhibitory concentration (MIC)-

VS

2- minimum bactericidal concentration (MBC)

Answer 35

1- Lowest Conc of drug at there is no visible growth

2- obtained by culturing
from each tube (showing no growth) onto a nutrient agar plate