why is it important to know the category to which an infectious agent of a disease belongs?

The different groups of microorganisms have different biochemical pathways like cell wall synthesis, protein  syntheses  etc which are targeted to kill these infectious agents.  It is necessary to know the category to which an infectious agent of the disease belongs in order to identify proper targets and drugs for treatment of the diseases.   
If an infectious agent is assigned a group its pathogenicity can be understood and subsequent effective and preventive measures can be taken to prevent disease from spreading in the community