Question

3. Which of these antibiotics would be classified as narrow-spectrum antibiotics? grampos sneg) 4. Which of these antibiotics would be classified as broad-spectrum antibiotics? lics? (will kill both 5a. Ampicillin is a form of penicillin. If the zone of inhibition for a susceptible strain of E. coli is mm, and for a strain of S. aureus is 29 mm, which one is inhibited by the lower concentration or ampicillin? 5b. Would you need a higher dose of ampicillin to cure an infection caused by E. coli or by S. aureus on. Assume you are testing a new strain of S. aureus for resistance to ampicillin and gentamicin. For this strain, both antibiotics give a zone of inhibition of 18 mm. To which antibiotic(s) is this strain resistant? To which is it susceptible? 6b. Why would the same zone of inhibition not give the same answer for both antibiotics? 7. Why do hospital laboratory workers perform antimicrobial susceptibility tests? 8. Gram-negative bacteria may be resistant to certain antibiotics to which gram-positive bacteria are susceptible. Describe how structural differences between these two bacterial types could account for this difference in susceptibility.

Answer 1

Hello,

3.Narrow range antibiotics work against selected microorganisms only.Here,Amoxicillin,Penicillin,Streptomycin and Vancomycin are narrow spectrum antibiotics as they can work on only one microorganism or none in some case.

4.Broad spectrum antibiotics can work against large number of microorganisms.Here,Ampicillin,Chloramphenicol,Erythromycin,Gentamycin,Rifampin,Tetracyclin are broad spectrum antibiotics as they are effectively working against more than one microorganism.

5a.Since large zone size is observed against S.aureus this means S.aureus will be inhibited at even low concentration of ampicillin.

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