Microbiology

Question 1

There are four major sites in the bacterial cell that are sufficiently different from the human cell that they serve as the basis for the action
of clinically effective drugs

Answer 1

cell wall, ribosomes, nucleic acids, and cell membrane

Question 2

Selective toxicity

Answer 2

selective inhibition of the growth of the microorganisms without damage to the host.

Question 3

Broad-spectrum antibiotics

Answer 3

are active against several types of microorganisms.

Question 4

Narrow-spectrum antibiotics

Answer 4

are active against one or very few types.

Question 5

Bactericidal drugs

Answer 5

kill bacteria, whereas bacteriostatic drugs inhibit the growth of the bacteria but do not kill.

Question 6

Penicillins and cephalosporins

Answer 6

act by inhibiting transpeptidases, the enzymes that catalyze the final cross-linking step in the synthesis of peptidoglycan.

Question 7

Exposure of the bacterial cell to lysozyme,

Answer 7

is present in human tears, results in degradation of the peptidoglycan and osmotic rupture similar to that caused by penicillin.

Question 8

They are also bactericidal and acts on Gram positive bacteria.

Answer 8

Glycopeptides: Vancomycin, Bacitracin & Cycloserine

Question 9

act at the level of the 30S ribosomal subunit.

Answer 9

Aminoglycosides & tetracyclines

Question 10

act at the level of the 50S ribosomal subunit.

Answer 10

chloramphenicol, erythromycins, and clindamycin

Question 11

Inhibition of mRNA Synthesis

Answer 11

Rifampin

Question 12

Inhibition of Precursor Synthesis :

Answer 12

Sulfonamides& Trimethoprim;

Question 13

Inhibition of DNA Synthesis

Answer 13

Fluoroquinolones

Question 14

Antifungal drugs

Answer 14

These drugs have selective toxicity because fungal cell membranes contain ergosterol, whereas human cell membranes have cholesterol.

Question 15

Bacteria, do not have sterols in their membranes and therefore are resistant to these drugs.with the exception of

Answer 15

Mycoplasma

Question 16

Polymyxins

Answer 16

It is active against gram-negative rods, especially P. aeruginosa

Question 17

Daptomycin

Answer 17

It is active against gram-positive cocci. such as S. aureus

Question 18

Amphotericin B

Answer 18

disrupts fungal cell membranes by binding at the site of ergosterol in the membrane).

Question 19

Isoniazid

Answer 19

inhibits the synthesis of mycolic acid; a long chain fatty acid found in the cell wall of mycobacteri

Question 20

Isoniazid

Answer 20

tuberculosis and other mycobacterial diseases.

Question 21

Metronidazole

Answer 21

effective against anaerobic bacteria and certain protozoa because it acts as an electron sink, taking away the electrons that the organisms need to survive. It also forms toxic intermediates that damage DNA.