your supervisor gives you two paper discs each impregnated w

your supervisor gives you two paper discs each impregnated with a different antibiotic-antibiotic A and antibiotic B. after performing the kirby bauer tests using E. coli, you measure a zone of inhibition of 26mm for antibiotic A and a zone of inhibition of 18mm for antibiotic B. Which antibiotic is more effective? give a detailed explanation.

Solution

If the bacterium is sensitive to the particular antibiotic, no growth will be observed. However, as the antibiotic diffuses further, its concentration is reduced. After a certain point, its concentration is so low that it can no longer inhibit the growth of the bacterium. Therefore, there is an area around the disks that will be clear against a dense growth (lawn) of the bacterium surrounding it, this zone of clearance is defined as the zone of inhibition.
The diameter of the zone of inhibition will determine the effectiveness of the antibiotic; the larger the diameter, the greater will be the sensitivity of the bacterium to the antibiotic.

A larger zone of inhibition 26mm around an antibiotic-containing A-containing disk indicates that the bacteria are more sensitive to the antibioticA than the antibiotic B as its zone of inhibition is 18mm.

So antibiotic A is more effective than antibiotic B