Question

LT Normal , 1 No Spac. Heading 1 Heading 2 Subtitle Paragraph Styles What is the difference between broad-spectrum, narrow-spectrum, and selectively-toxic drugs? What is the mode of action of: beta-lactams (penicillin), polymyxins, chloroquines, quinolones, aminoglycosides, tetracyclines, sulfonamides (sulfa drugs), synthetic azoles What mechanisms of resistance do bacteria actually gain from resistance genes? (hint: there are What is a superinfection? What is the difference between a Kirby-Bauer susceptibility test, E-test diffusion test and tube dilution test? What do they have in common?

Answer 1

1. Broad spectrum drug like broad spectrum antibiotic is the one which can act on wide range of disease causing organisms. Example is penicillin.

Narrow spectrun drug is the one which can act only one few specific disease causing organisms.

Selective toxicity of a drug targets sites that are unique to micro organism or that are essential for the survival of the organism.than to the host.

2. Mode of action of penicillin-- Penicillin kills bacteria by inhibiting trans peptidase essential in the fial step of cell wall synthesis.

Polymixins damage the outer and inner membranes of gram negative bacteria and kill them

Chloroquine ---it prevents the formation of hemozoin from heam which is formed from heamoglobin digestion in RBCs. Free Heam will kill the parasite by destroying their membranes.

Quinolones--prevent bacterial DNA from unwinding and duplicating.

Aminoglycosides bind to the 30S sub unit of the ribosomes. This will lead to misreading of the genetic code.

Tetracyclins---These prevent translation by preventing tRNA binding to the 30S unit of ribosomes.

Sulfonamides--Preventing the folic acid synthesis.

Synthetic azoles---Inhibits the synthesis of ergosteros which is a main fungal sterol.