last updated 15-07-2024

Infectious agents

Infectious agents

Infectious diseases are caused by microorganisms. These are classified into five main groups: bacteria, viruses, fungi, protozoa and helminths (worms). Each group requires its own specific drugs for treatment. These specific drugs should kill the microorganisms without being harmful to the host. This is called selective toxicity.

For more information on drugs in infectious diseases click here.


Most antibiotics will treat infectious diseases without regard to the organism.


Contamination with a microorganism alsways causes an infection.