If you go to a hospital and have diagnostic tests done, the sample is inoculated in a gel with agar and peptones.

Most people know agar for its use in food, but it has much more of a role in our daily lives than we think. For example, a long list of infectious diseases can be quickly diagnosed thanks to agar and peptones.  

But let’s take it one step at a time. When you develop symptoms of a respiratory, digestive or urinary system disease, you visit a medical center. There, a sample will be taken and inoculated in a suitable medium to check if the microorganisms that cause this disease are present in your sample. This medium is solid or liquid agar enriched with peptones and different substances (hydrates, sugar). This provides an optimum medium for the bacteria to grow, and thus, to quickly diagnose whether the symptoms displayed are related to the presence of a certain bacteria in your body. In addition, different antibiotics can be tested in the culture media to find out which one affects the bacteria the most, so as to choose the most effective treatment.