Question

2) List the major targets of an antimicrobial drug What do all of these ta common? all of these targets have in 3) Why is the Kirby-Bauer test standardized? 4) What is the advantage of the broth dilution tests for antibiotic sensitivity over Kirby Bauer? 5) In general, why are Gram negative bacteria resistant to some of the antibiotics that Gram positive bacteria are sensitive to? 6) Fill in the following chart. ANTIBIOTIC CELLULAR TARGET AMPICILLIN CHLORAMPHENICOL ERYTHROMYCIN GENTAMICIN PENICILLIN STREPTOMYCIN TETRACYCLIN VANCOMYCIN | - 124-

Answer 1

2).

Antimicrobial agents are drugs commonly used to treat microbial infections. The common targets of agents is to kill or inhibit the growth of microorganism.

the major targets of antimicrobial drugs in microorganism are

• cell wall synthesis
• DNA gyrase in bacteria
• metabolic enzymes
• DNA directed RNA polymerase
• protein synthesis

3).

Kirby bauer test is used to check the susceptibility of antibiotic towards microorganism.It is also known as disc diffusion test. It is also used to determine whether the organism is resistant or susceptible to a particular antibiotic. This is used select the specific antibiotic for infection.

4).

agar broth dilution method help to determine the lowest concentration of antimicrobial agent which inhibit the microorganism.

In Kirby bauer test is to know whether the antibiotic is sensitive or resistant to microorganism.

5).

gram negative bacteria are more resistant to antibiotic due to its impermeable cell wall. The gram positive bacteria have peptidoglycan layer easily absorb antibiotic and it is easily destroyed.

6).

ANTIBIOTIC	CELLULAR TARGETS
Ampicillin	inactivating penicillin binding proteins (PBP) in the bacterial cell wall.
Chloramphenicol	inhibit protein synthesis
Erythromycin	inhibit bacterial protein synthesis by binding to 50 S subunit of ribosome.
Gentamicin	it bind to 30 S subunit of ribosome to inhibit bacterial protein synthesis.
Penicillin	inhibit peptidoglycan production in gram positive bacteria
Streptomycin	inhibit protein synthesis by binding to 30 S ribosome
Tetracyclin	inhibit protein biosynthesis
Vancomycin	inhibit cell wall biosynthesis