Kirby-Bauer Disc Diffusion Assay

How effective is antibiotic A on Staphylococcus Aureus?

Kirby-Bauer Disc Diffusion Assay measures…

An organism’s response to anibiotics

What does Kirby-Bauer Disc Diffusion Assay determine about an antibiotic?

How effective it is to treat bacterial infections

Antibiotic LITERALLY means…

Without life

Antibiotic commonly means

Antibacterial

Bacteriocidal

Kills bacteria at once

Bacteriostatic

Prevents bacterial replication

Mode of Action

The action antibiotics take to act on the bacteria

What are the four inhibits of Mode of Action?

Peptidoglycan synthesis, lipopolysaccharide synthesis, DNA and RNA replication

One Mode of Action can prevent __________ synthesis

protein

One Mode of Action can _________ a bacteria’s ______ membrane.

damage; cell membrane

The four inhibiting factors and preventing translation is the work of what antibiotic type?

Bacteriostatic

Actively damaging the cell membrane is the work of what antibiotic type?

Bacteriocidal

What is the relationship between antibiotics and the immune system?

They work together. Antibiotics inhibit microbial replication, while the immune system destroys the microbes.

_______ slow or stop bacterial growth

Effective antibiotics

Some would argue that bacteriostatic drugs are better than bacteriocidal. What would likely be their reasoning?

They do not destroy normal flora externally or internally

Mueller-Hinton Agar

A rich, complex media ideal for organism growth

Why do we use Mueller-Hinton Agar in K-B assay?

If an antibiotic can slow or stop bacterial growth under ideal conditions, the organism growth will be controlled more effectively in the body with a functional immune system

Performing a lawn means…

To cover all surfaces of the agar with a bacterial strain

Zones of inhibition

Areas on the plate with no growth immediately around the antibiotic discs

Antibiotic A is considered a broad-spectrum antibiotic. What does broad-spectrum mean?

Works on a wide range of microbes