What does the disk diffusion method measure?

• The pH level of the culture broth.

• The temperature of the agar medium.

• The zone of inhibition.

• The size of bacterial colonies.

Answer explanation

The disk diffusion method measures the zone of inhibition, which indicates the effectiveness of an antimicrobial agent against bacteria. A larger zone means greater effectiveness.

What does MIC stand for?

• Maximum Inhibitory Concentration

• Minimum Infective Concentration

• Minimum Inhibitory Concentration

• Maximum Infective Concentration

Answer explanation

MIC stands for Minimum Inhibitory Concentration, which is the lowest concentration of an antimicrobial that prevents visible growth of a microorganism. This is crucial in determining effective dosages for treatment.

Which of the following is used to determine the exact MIC value on an agar plate?

• Disk diffusion

• E-Test

• Broth dilution

• Automated systems

Answer explanation

The E-Test is a method that uses a strip with a gradient of antibiotic concentrations, allowing for the precise determination of the Minimum Inhibitory Concentration (MIC) on an agar plate, making it the correct choice.

What is the primary role of antibiotic susceptibility testing?

• To develop new antibiotics

• To determine bacterial sensitivity to antibiotics

• To measure antibiotic concentration in plasma

• To measure the body's immune response

Answer explanation

The primary role of antibiotic susceptibility testing is to determine bacterial sensitivity to antibiotics, helping clinicians choose the most effective treatment for infections.

Which organization provide breakpoints for interpreting AST results?

• WHO

• CLSI

• FDA

• EUCAST

Answer explanation

CLSI (Clinical and Laboratory Standards Institute) and EUCAST (European Committee on Antimicrobial Susceptibility Testing) provide breakpoints for interpreting antimicrobial susceptibility testing (AST) results, guiding clinical decisions.

What is the main advantage of automated systems like VITEK 2?

• Manual data recording

• High cost-effectiveness

• Reduced need for laboratory equipment

• Rapid and standardized results

Answer explanation

The main advantage of automated systems like VITEK 2 is their ability to provide rapid and standardized results, which enhances efficiency and accuracy in laboratory testing compared to manual methods.

Which medium is commonly used in the disk diffusion method?

• Blood agar

• MacConkey agar

• Mueller-Hinton agar

• Sabouraud agar

Answer explanation

Mueller-Hinton agar is the standard medium used in the disk diffusion method for antibiotic susceptibility testing, as it provides a consistent environment for bacterial growth and diffusion of antibiotics.

The disk diffusion method is also known as the __________ test.

Answer explanation

The disk diffusion method is commonly referred to as the Kirby-Bauer test, which is used to determine the susceptibility of bacteria to antibiotics by measuring the inhibition zones around antibiotic-impregnated disks.

The lowest antibiotic concentration that inhibits visible bacterial growth is called __________.

Answer explanation

The lowest antibiotic concentration that inhibits visible bacterial growth is known as the Minimum Inhibitory Concentration (MIC). This term is commonly abbreviated as MIC.

A __________ zone of inhibition in a disk diffusion test corresponds to increased bacterial resistance to the antibiotic.

Answer explanation

A smaller zone of inhibition indicates that the bacteria are less susceptible to the antibiotic, reflecting increased resistance. Therefore, a smaller zone corresponds to increased bacterial resistance.