What factors affect the size of the inhibition zone?

What factors affect the size of the inhibition zone?

What factors affect the size of the inhibition zone?

The medium has an effect on the area’s size by influencing the organism’s growth rate, diffusion rate, and activity.

What factors other than the antimicrobial activity of the chemical affect the size of the zone of inhibition?

What factors affect the size of the inhibition zone produced by chemical? The agent’s diffusibility, the size of inoculum, type of medium and resistance mechanism are some of the factors that influence the size of the inhibition zone.

Does the Zone of Inhibition edge indicate?

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Question Answer
does the zone of inhibitions edge indicate the limit of antibacterial agent diffusion into the agar? No. Edge is not the unit of diffusion. diffusion occurs beyond edge, but concentration of Bactraicin is to dilute to be lethal -the edge represent MIC

What is the diameter of the zone of inhibition?

Measure from the centre of the antibiotic disk to the point on the circumference where there is a distinct edge. Divide this measurement by 2 for the area of inhibition. In this example, the radius of the zone is 16 mm.

What is the Zone of Inhibition quizlet?

Zone for inhibition. The area surrounding the disc that is free from bacterial growth. These are the two factors that determine the area of inhibition. 1) The antibiotic’s sensitivity to the organisms.

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What size zone of inhibition is required for an organism to be considered susceptible to bacitracin?


What is the bacitracin test used for?

The bacitracin susceptibility testing is used to identify Group A streptococci from other streptococci. Group A streptococci can be grown on blood agar and are sensitive to (killed off by) antibiotic bacitracin.

Which of the following could be a realistic representation of a zone of inhibition?

Which one of these could represent a real zone of inhibition? Both gram-positive bacteria and gram negative bacteria. To determine susceptibility and resistance, the size of the inhibition zone must be compared with the performance standards of that antimicrobial agent.

How do you perform a antibiotic susceptibility test?


  1. Select a pure culture plate of one of the organisms to be tested.
  2. Aseptically emulsify a colony from the plate in the sterile saline solution.
  3. Repeat until the turbidity of the saline solution visually match that of the standard turbidity.
  4. Take a sterile swab and dip it into the broth culture of organism.

What is the importance of susceptibility test?

Susceptibility testing is used to determine which antimicrobials will inhibit the growth of the bacteria or fungi causing a specific infection. This test can help healthcare professionals determine the most effective drugs to treat an individual’s infection.

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Why is an antibiotic susceptibility test performed?

An antibiotic sensitivity test (or susceptibility test) is performed to determine which antibiotic will be most effective against specific strains of bacteria or fungus that are infected.

What factors could affect a microorganism’s susceptibility to different antibiotics?

These factors include inoculum size and antibiotic concentrations, as well as the effect on serum and interactions with the host microbiota.

What is special about Mueller Hinton agar?

Mueller-Hinton has a few properties that make it excellent for antibiotic use. Starch has been shown to absorb bacteria toxins, which can interfere with antibiotics. It is also loose agar. This allows for better distribution of antibiotics than other plates.

How do you make a Mueller Hinton agar?

Preparation for Mueller-Hinton Aga

  1. Suspend 38 g of medium (or the components listed above) in 1 liter of purified water.
  2. Mix thoroughly.
  3. Heat with frequent agitation and boil for 1 minute to completely dissolve the components.
  4. Autoclave at 121degC for 15 minutes.
  5. Cool to 45degC.

What is the Colour of Mueller Hinton Agar?

Quality Control of MHA

Positive controls: Expected results
Escherichia coli ATCC(r) 25922 Good growth; pale straw coloured colonies
Pseudomonas aeruginosa ATCC(r) 27853 Good growth; straw coloured colonies
Staphylococcus aureus ATCC(r) 25923 Good growth; cream coloured colonies
Negative control:
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What pH is the Mueller Hinton agar?

7.3 +-