Question

How zone size may be affected? Diffusion rate of antibiotic Growth rate of microbe Тешp and pH

Answer 1

Diffusion rate of antibiotic : if the diffusion rate of antibiotic is more powerful then the zone around the antibiotic more clear so clear zone size will be increased and if the diffusion rate of antibiotic is less then there will be no clear zone around the antibiotic disk .

Growth rate of microbe : after using the antibiotic disc on culture plate and still the rate of growth of microbes are increasing on culture plate then the zone around the antibiotic will decreased or there will not be formed any zone around the antibiotic . In the other hand if the rate of growth of microbes become less after using the proper antibiotic ,then there will be formed large size of clear zone around the antibiotic .

Temperature & pH : maintaining of pH level of the medium is very essential for zone size because in different pH level the zone size around the antibiotic will be different for different antibiotic like increase the pH level the zone size will be decrease in penicillin drug and conversely zone size will be increase in macrolide drug .

Temoarature should be kept within 35-37°c during incubation because at low temparation growth of microbes is low thus the zone size automatically will be grater than normal result . So temparature is very essential factor which effect on the zone size