Here are some other terms you might use, depending on the specific area of expertise:

* Bacteriologist: Specializes in bacteria.

* Virologist: Specializes in viruses.

* Mycologist: Specializes in fungi.

* Parasitologist: Specializes in parasites.

* Epidemiologist: Studies the distribution and causes of diseases in populations.

* Infectious disease specialist: A medical doctor who specializes in treating infectious diseases.

The best term to use depends on the specific context. For example, if you are talking about someone who studies the spread of bacteria in hospitals, you might call them a medical microbiologist or a hospital epidemiologist.