Question: What do you look for when you are trying to find out what is wrong with someone?

Hannah Tanner answered on 23 Jun 2014:

Because I work in a microbiology lab the things we are looking for are pathogens or the effects of pathogens. A pathogen is a virus, bacterium, fungus or parasite that can cause disease.

These are some of the main things we do in a diagnostic microbiology lab:

We can grow the pathogen from patient samples on agar plates – this works well for many bacteria and fungi. Once we have grown something we go on to do more tests to identify it and find out what antibiotics can kill it.

We can look for the DNA of the pathogen in patient samples – we often use this to look for viruses because virus are difficult and slow to grow.

We can look at patient samples down the microscope – we can use different dyes to show up different kinds of pathogens. We often use microscopy for looking for parasites in faeces or looking for fungus in skin, hair and nails.

Sometimes we use serology to look for antibodies or antigens in a patient’s blood. Antigens are bits of the pathogen that get into the blood. Antibodies are part of your bodies immune reaction to a pathogen. We can test for this to detect your bodies reaction to a pathogen or even to check someone has made antibodies to a vaccine.

Once we know what pathogens are in the patient’s samples we send a report to the doctors. Quite often, if we have found something unusual someone from the lab will speak to doctors on the phone to help explain about what we have found and how to treat it.